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Journal articles on the topic 'Seedling stage'
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1
Lorca, E. Agostina, Ana E. Ferreras, and Guillermo Funes. "Seed size and seedling ontogenetic stage as modulators of damage tolerance after simulated herbivory in a woody exotic species." Australian Journal of Botany 67, no. 2 (2019): 159. http://dx.doi.org/10.1071/bt18093.
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Herbivory is one of the most important threats that plants face during early stages of development. Previous studies have indicated that seed size and seedling ontogeny strongly influence the response to herbivory at the seedling stage. However, little is known about their interactive effect. We simulated herbivory on seedlings of the exotic Gleditsia triacanthos L. and evaluated the combined effects of seed size and ontogenetic stage at which herbivory occurred on tolerance to herbivory. A greenhouse experiment was performed, with three non-overlapping levels of seed size. Seedlings from each seed size were clipped at two ontogenetic stages (two and five leaves). After three weeks, seedling survival, height, leaf number and dry biomass were measured. Damaged seedlings were not able to reach the size of the undamaged ones. Seedlings from small seeds showed the lowest values in most of the growth variables. Seedlings cut at two-leaf stage showed a higher compensation capacity than those cut at five-leaf stage. Seedlings from large seeds cut at ontogenetic stage I showed the highest compensation capacity in most of the variables. Partly compensating herbivory at this stage may be an advantage for the expansion of this exotic species to new areas.
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Pannwitt, Heike, Paula R. Westerman, Friederike De Mol, and Bärbel Gerowitt. "Demographic Processes Allow Echinochloa crus-galli to Compensate Seed Losses by Seed Predation." Agronomy 11, no. 3 (March 17, 2021): 565. http://dx.doi.org/10.3390/agronomy11030565.
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The effect of weed management that targets the seed stage on subsequent life stages is largely unknown. Post-dispersal seed predation reduces the number of seeds from the soil surface before the seeds contribute to the seedbank. Density-dependent processes can mitigate the effect of seed predation in subsequent life stages. In this study, we tested if (i) targeting the seed stage affects the subsequent seedling stage; (ii) if density-dependent mortality in subsequent life stages partly compensates seedling abundance; and (iii) if the magnitude of final seed production depends on seed predation. We fully parameterized a model for the summer-annual weed Echinochloa crus-galli (L.) P. Beauv. Field data from three maize fields in north-eastern Germany were obtained, in the presence or absence of seed predation and different population levels of the weed species. Seeds of E. crus-galli were applied in autumn and the number of seedlings, adult plants, and seed production per m2 was determined the following season. Seed predation reduced the number of seedlings. Density-dependent mortality during the seedling stage increased fecundity with decreasing seedling density, and, thus, compensated for lower numbers of seedlings. The final level of seed production per m2 did not depend on seed predation and initial population densities, but differed among fields. We conclude, solely targeting the seed stage can scarcely limit the population growth of E. crus-galli.
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Cong Dien, Doan, and Takeo Yamakawa. "Phenotypic Variation and Selection for Cold-Tolerant Rice (Oryza sativa L.) at Germination and Seedling Stages." Agriculture 9, no. 8 (July 25, 2019): 162. http://dx.doi.org/10.3390/agriculture9080162.
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Owing to its origin in tropical and subtropical areas, rice is susceptible to cold stress. Low temperatures at the germination and seedling stages can result in seed loss, a delayed transplanting period, and lower final yield. In this study, 181 rice varieties from around the world were investigated for cold tolerance at the germination and seedling stages. At the germination stage, the responses of different rice varieties were examined based on the germination index, coleoptile length, and radicle length at low (13 °C) and control temperatures (25 °C). Significant variations in the germination index, coleoptile length, and radicle length were observed among varieties. Low temperature significantly decreased germination ability, and coleoptile and radicle growth in the studied varieties. At the seedling stage, cold tolerance of the rice varieties was evaluated based on the leaf color score under natural low temperature. Similar to the germination stage, at the seedling stage, significant variation in root and shoot growth was observed in the response of rice varieties to low temperature conditions. Based on the results from both the germination and seedling stages, two varieties (Hei-Chiao-Chui-Li-Hsiang and Ta-Mao-Tao) were selected as the best cold-tolerant varieties. Our results also indicate the benefits of warming treatments to protect rice seedlings from low temperature conditions.
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Huang, Zhenying, and Yitzchak Gutterman. "Seedling desiccation tolerance of Leymus racemosus (Poaceae) (wild rye), a perennial sand-dune grass inhabiting the Junggar Basin of Xinjiang, China." Seed Science Research 14, no. 2 (May 2004): 233–39. http://dx.doi.org/10.1079/ssr2004172.
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Leymus Racemosus, The Mammoth Wild Rye, Is A Rhizomatous Perennial Grass, Mainly Distributed In The Moving Or Semi-Stabilized Sand Dunes In Deserts Of The Junggar Basin In Xinjiang, China. The Revival Ability Of The Young Seedling After Periods Of Desiccation Can Be Influenced By Several Factors: (1) The Stage Of Seedling Development – The Later The Stage At Dehydration, The Longer The Root Length And The Lower Is The Percentage Of Seedlings That Survive; (2) The Length Of The Period Of Desiccation – The Longer The Period That The Seedlings Are Under Desiccation, The Lower Is The Percentage Of Seedlings That Survive; (3) Endosperm Size – The Smaller The Proportion Of Endosperm That Remains In The Caryopses, The Lower Is The Percentage Of Seedlings That Revive, Determined By (A) The Stage Of Seedling Development, And (B) The Proportion Of The Endosperm That Is Removed By Cutting; And (4) Caryopsis Size – The Larger The Polymorphic Caryopses, The Higher Is The Percentage Of Young Seedlings That Revive From Periods Of Desiccation. The Physiological And Ecological Implications Of L. Racemosus Seedling Desiccation Tolerance Are That Under Extreme Desert And Unpredictable Environmental Conditions, The Chances Of Seedling Establishment Are Increased.
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Durr, C., and J. Boiffin. "Sugarbeet seedling growth from germination to first leaf stage." Journal of Agricultural Science 124, no. 3 (June 1995): 427–35. http://dx.doi.org/10.1017/s002185960007338x.
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SUMMARYThe growth of sugarbeet (Beta vulgaris L.) seedlings was investigated under laboratory conditions in 1990 and 1991. Three phases were identified during heterotrophic growth in the dark, based on the changes in dry weight, carbon and nitrogen contents. The perispermic reserves were first transferred to the young seedling. All the components of the seedling (cotyledons, hypocotyl, radicle) began to elongate and their dry weights increased. The seedling separated from the seed at the end of this first period, 4 days after imbibition had started at 20 °C. During the second period, there was a major redistribution of material between organs, mainly from cotyledons to the hypocotyl. The different organs elongated rapidly. From the start of the third period, 6 days after sowing at 20 °C, the organs began to lose weight and gradually ceased to elongate. The dry weights of the whole seedlings and of each organ were proportional to the initial seed weights. The elongations and changes in dry weights obtained at different temperatures coincided when time was expressed as thermal time using a base temperature of 3·5 °C. The growth of the seedling after illumination depended on the heterotrophic growth duration. If emergence occurred after 100 °Cd, the relative growth rate of the seedling decreased. In field conditions, plant variability at the end of sugarbeet establishment is due not only to variations in seed weights but also to environmental conditions that control emergence delay.
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Ratnayake, Sunil, and David R. Shaw. "Effects of Harvest-Aid Herbicides on Sicklepod (Cassia obtusifolia) Seed Yield and Quality." Weed Technology 6, no. 4 (December 1992): 985–89. http://dx.doi.org/10.1017/s0890037x00036587.
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Experiments were conducted in 1989 and 1990 to study the effects of 220 g ai ha-1AC 263,222, 840 g ai ha-1glufosinate, 560 g ai ha-1glyphosate, and 840 g ai ha-1paraquat on sicklepod seed production and quality when applied at R5, R6, R7, and R8 growth stages of sicklepod. No seed were produced on plants treated at R5 with paraquat and glufosinate; glyphosate was the least effective herbicide at this growth stage. Although sicklepod seed germinated after AC 263,222 application at R5, no seedling emergence occurred. Normal seedlings, seedling emergence, and seedling radicle length were reduced by all herbicides applied to parent plants at R5, R6, and R7 growth stages. AC 263,222 applied at R7 reduced normal seedlings and seedling emergence more than any other herbicide. No effects were observed on any of the variables investigated when herbicides were applied at R8.
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Putnik-Delic, Marina. "Resistance of some wheat genotypes to Puccinia triticina." Zbornik Matice srpske za prirodne nauke, no. 115 (2008): 51–57. http://dx.doi.org/10.2298/zmspn0815051p.
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Thirty-four wheat genotypes were tested for resistance characteristics to Puccinia triticina at different growth stages. At seedling stage in a greenhouse, latency period, infection frequency and reaction type were determined. In the field, time of spike appearance, and infection intensity were followed. Weak (r = 0.322) to strong (r = 0.660) correlation was found between resistance characteristics at seedling stage (LPxIFxRT, in the greenhouse) and in adult plants (infection intensity and AUDPC, in the field). The values of AUDPC (area under the disease progress curve) were also strongly related to resistance characteristics of seedlings (r = 0.598). As pseudoresistant in the field (especially equal to adult plant resistance) according to other stresses reactions were considered genotypes which were the most sensitive at seedling stage (20?C) and at adult stage they did not express maximal infection intensity, particullar Evropa 90 and Suvaca. Adult plant resistance as the sum of specific and pseudoresistance was observed on genotypes Tiha, Zlatka and Eva.
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Cheng, C., L. M. Pei, T. T. Yin, and K. W. Zhang. "Seed treatment with glycine betaine enhances tolerance of cotton to chilling stress." Journal of Agricultural Science 156, no. 3 (April 2018): 323–32. http://dx.doi.org/10.1017/s0021859618000278.
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AbstractChilling injury is an important natural stress that can threaten cotton production, especially at the sowing and seedling stages in early spring. It is therefore important for cotton production to improve chilling tolerance at these stages. The current work examines the potential for glycine betaine (GB) treatment of seeds to increase the chilling tolerance of cotton at the seedling stage. Germination under cold stress was increased significantly by GB treatment. Under low temperature, the leaves of seedlings from treated seeds exhibited a higher net photosynthetic rate (PN), higher antioxidant enzyme activity including superoxide dismutase, ascorbate peroxidase and catalase, lower hydrogen peroxide (H2O2) content and less damage to the cell membrane. Enzyme activity was correlated negatively with H2O2 content and degree of damage to the cell membrane but correlated positively with GB content. The experimental results suggested that although GB was only used to treat cotton seed, the beneficial effect caused by the preliminary treatment of GB could play a significant role during germination that persisted to at least the four-leaf seedling stage. Therefore, it is crucial that this method is employed in agricultural production to improve chilling resistance in the seedling stage by soaking the seeds in GB.
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Bryant, Tim B., Seth J. Dorman, Dominic D. Reisig, DeShae Dillard, Roger Schürch, and Sally V. Taylor. "Reevaluating the Economic Injury Level for Brown Stink Bug (Hemiptera: Pentatomidae) at Various Growth Stages of Maize." Journal of Economic Entomology 113, no. 5 (August 25, 2020): 2250–58. http://dx.doi.org/10.1093/jee/toaa173.
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Abstract Economic yield loss and reduction in grain quality from brown stink bug, Euschistus servus (Say), feeding injury in early and late stages of maize, Zea mays (Poales: Poaceae, Linnaeus), development was assessed in Virginia and North Carolina in 2018 and 2019. Varying levels of stink bug infestations were introduced to seedling maize (V2—early stage), and a range of late-stages of maize, including 1) the last stage of vegetative development (V12/V14), 2) prior to tasseling, 3) at tasseling (VT), and 4) across all tested late growth stages. Euschistus servus infestation levels included 33, 67, and 100% of maize seedlings, and 25, 50, 100, and 200% of plants during later stages. Infestations were maintained on seedling maize for 7 d, and 8 or 16 d in reproductive stages. Infestation level in seedling maize had an impact on grain yield. Infestation level and growth stage both had an impact on grain yield in reproductive maize. The percentage of discolored kernels was also affected by infestation level, but not growth stage. Regression analysis between grain yield and infestation level indicated that the average economic injury level is 7% in seedling maize (7 bugs/100 plants) and 12% (12 bugs/100 plants) from the last vegetative stages (V12/V14) through pollination (VT). The economic injury level in the late vegetative stages is only applicable when infestations are present for an extended period of time (16 d), emphasizing the need for continued scouting of maize throughout the season to make informed management decisions.
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Bisognin, Dilson Antônio, Luis Velasquez, and Irvin Widders. "Cucumber seedling dependence on cotyledonary leaves for early growth." Pesquisa Agropecuária Brasileira 40, no. 6 (June 2005): 531–39. http://dx.doi.org/10.1590/s0100-204x2005000600002.
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The objective of this work was to evaluate the dependence of cucumber (Cucumis sativus L.) seedlings on cotyledonary leaves for early growth and establishment. Sets of two uniform emerging seedlings were used to quantify the initial growth and dry matter accumulation, as well as the intensity and stage of cotyledon damage in seedling establishment and to determine cotyledon protein, amino acid and carbohydrate contributions to the growing seedling. Cucumber seedling establishment was found to be highly dependent on cotyledonary leaves. Root system establishment was highly dependent on the health of the aerial part. One cotyledon was enough to maintain aerial growth of seedlings after unfolding the first true leaf. Cucumber seedlings depended on both cotyledons to keep root system growth at least until leaf area was equivalent to cotyledon area. Covering one or both cotyledons of seedlings with one unfolded leaf increased carbohydrate content of uncovered cotyledon and leaves compared with control seedlings. Cucumber seedlings are highly dependent on cotyledonary leaves and aerial parts are less dependent than root system. Cotyledon damage at early stages of plant establishment would adversely impact crop yield by reducing plant density, an important yield component, or slowing down seedling growth and establishment.
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Edelman, Nichole F., and Michelle L. Jones. "Evaluating Ethylene Sensitivity within the Family Solanaceae at Different Developmental Stages." HortScience 49, no. 5 (May 2014): 628–36. http://dx.doi.org/10.21273/hortsci.49.5.628.
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The family Solanaceae, which includes both important crop and ornamental species, is generally considered to have high sensitivity to ethylene. Our objectives were to evaluate ethylene sensitivity between accessions with the family Solanaceae and to determine whether similar sensitivity was observed in seedlings and mature plants. For the seedling evaluations, seeds were germinated and grown in the dark on filter paper saturated with 0 or 100 μM 1-aminocyclopropane-1-carboxylic acid (ACC; the immediate precursor to ethylene). The relative hypocotyl length at 100 μM ACC was compared with untreated control (0 μM) seedlings. Mature plants were treated with 0 or 10 μL·L−1 ethylene in the dark for 24 hours. Ethylene responses including flower abscission, flower senescence, and epinasty were observed and quantified. Seedlings and mature plants were classified as having no response, low, medium, or high ethylene sensitivity based on the severity of the ethylene responses observed. Sensitivity differences were observed among seedling, juvenile, and mature plants, and a range of ethylene responses and symptom severity was observed between accessions within a species. The majority of the accessions were classified as medium or high ethylene sensitivity at both the seedling and mature plant stages. Solanum melongena ‘Black Beauty’ (eggplant) had a low response to ethylene at the seedling stage and a high response at the mature plant stage, whereas Petunia ×hybrida ‘Daddy Orchid’ had a high response at the seedling stage and a low response at the mature plant stage. Peppers (Capsicum annum), tomatoes (Solanum lycopersicum), and tomatillos (Physalis ixocarpa) exhibited both floral and vegetative symptoms of ethylene damage, whereas calibrachoas (Calibrachoa ×hybrida), eggplants, nicotianas, and petunias exhibited only floral symptoms. The most common floral response to ethylene treatment was flower abscission, which was observed in almost all of the Solanum, Capsicum, and Nicotiana accessions. We consistently observed ethylene-induced epinasty in the genus Capsicum and in all of the Solanum except eggplant. Our results indicated that developmental stage influenced ethylene sensitivity, and there was not a consistent correlation between seedling and mature plant responses within the Solanaceae accessions that we evaluated.
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Diniz, Fábio Oliveira, Múcio Silva Reis, Eduardo Fontes Araújo, Luiz Antônio dos Santos Dias, Tuneo Sediyama, and Camilla Atsumi Zanuncio Sediyama-Bhering. "Incidence of pathogens and field emergence of soybean seeds subjected to harvest delay." Journal of Seed Science 35, no. 4 (2013): 478–84. http://dx.doi.org/10.1590/s2317-15372013000400009.
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This study aimed at evaluating seed health quality, as well as seedling emergence in the field, of eight soybean cultivars (UFV-16, Splendor, Vencedora, Confiança, UFV-18, UFV-TN 105, Garantia, and Celeste) subjected to different harvest periods. To this, seeds were harvested at the growth stages R8, R8+15 days, and R8+30 days, and then submitted to health test and to the test of seedling emergence in field. Results showed that although seeds harvested at 15 and 30 days after the stage R8 had shown a significant increase of fungi infection, especially by Fusarium spp., Phomopsis spp., and Epicoccum spp., the percent seedling emergence in the field was reduced only to seeds harvested 30 days after the reproductive stage R8. Cultivars have shown differentiated behavior between each other in relation to the percent incidence rate of fungi and seedling emergence in the field; and the seeds least infected by fungi were those allowing the highest percent emergence of seedlings in the field.
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Yao, Linling, Jialin Huang, and Shibao Zhang. "An Improved Protocol for Asymbiotic Seed Germination and Seedling Development of Paphiopedilum tigrinum." Horticulturae 7, no. 9 (September 9, 2021): 298. http://dx.doi.org/10.3390/horticulturae7090298.
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Paphiopedilum tigrinum is an endangered orchid with high ornamental value. However, seed germination and seedling regeneration in P. tigrinum is very difficult in vitro. Little is known about why P. tigrinum seedlings are difficult to propagate or how to improve the seed germination and seedling rates of this species. In this study, we investigated the developmental process of P. tigrinum from asymbiotic seed germination to seedling rooting by comparing it with P. appletoniantum, a much easier species for germination and seedling formation. We found that asymbiotic seed germination in P. tigrinum is limited by severe browning of the protocorm at the seed germination stage, and protocorm rooting at the differentiation stage was also proved to be difficult. The optimal medium for seed germination of P. tigrinum was a modified Harvais (mHa) medium supplemented with 0.5 mg·L−1 kinetin (Kin), 0.1 g·L−1 activated charcoal (AC) and 100 mL·L−1 coconut water (CW). At the protocorm differentiation stage, seedlings with 1–2 leaves were obtained on a 1/4 MS medium supplemented with 1.0 mg·L−1 6-benzylaminopurin (BA), 0.3 g·L−1 AC and 50–100 mL·L−1 CW after culturing for 120 day. At the seedling subculture stage, a 1/2 MS medium supplemented with 0.5–1.5 g·L−1 AC and 100 mL·L−1 CW was better for leaf and root growth of P. tigrinum. At the rooting stage, a 1/2 MS medium supplemented with 1.0 g·L−1 AC, 0.5 g·L−1 dolomite flour, 15 g·L−1 potato homogenate and 30 g·L−1 banana homogenate was most suitable for the growth and rooting of seedlings. This study has established an effective protocol for seed germination and seedling regeneration of P. tigrinum.
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Khalid S. Alshallash, Khalid S. Alshallash. "Biological Control of the Weedy Plant (Rumex crispus) at the Seedling Growth Stage by the Green Dock Beetle (Gastrophysa viridula)." journal of King Abdulaziz University - Meteorology, Environment and Arid Land Agriculture Sciences 28, no. 1 (February 14, 2019): 21–31. http://dx.doi.org/10.4197/met.28-1.3.
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In four glasshouse experiments, the effectiveness of the adult green dock beetle Gastrophysa viridula (Coleoptera: Chrysomelidae), at the effective number of applied individuals, for use as a biological control agent of curled dock, Rumex crispus (Polygonaceae) were studied. The feeding of the beetle was investigated at four different numbers of beetle (0, 1, 2, 3) and at four seedling growth stages of the plant, defined by the average of leaf area per plant (1-1.22 , 2-4.45, 3-11.56, and 4-71.52 cm2/plant). Grazing by one, two or three dock beetles did not result in a significant reduction in dock dry weight or shoot numbers at the youngest growth stage. However, both at later seedling growth stages were significantly affected (P ? 0.0001), at any beetles number. The increase of beetle numbers caused nonsignificant increased effect, in some trials, confirming the impact of a single beetle. Three months after beetle grazing, dock seedlings of first, second and third growth stages were not able to regrow, however, some plants at the 4th growth stage, re-emerged. This suggested that the highest effect of beetle's feeding occurs on the early seedling stages. Statistical analysis showed a positive correlation (0.77) between dry weight and shoot number at all the four seedling growth stages, thus confirming the impact of the beetle on both the dry weight and shoot numbers. Combining beetle grazing with other control methods at older dock seedling stages could, therefore, provide better suppression
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Harrison, Susan, and Marina LaForgia. "Seedling traits predict drought-induced mortality linked to diversity loss." Proceedings of the National Academy of Sciences 116, no. 12 (March 4, 2019): 5576–81. http://dx.doi.org/10.1073/pnas.1818543116.
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Trait-based approaches are increasingly used to predict ecological consequences of climate change, yet seldom have solid links been established between plant traits and observed climate-driven community changes. Most analyses have focused on aboveground adult plant traits, but in warming and drying climates, root traits may be critical, and seedlings may be the vulnerable stage. Relationships of seedling and root traits to more commonly measured traits and ecological outcomes are poorly known. In an annual grassland where winter drought-induced seedling mortality is driving a long-term decline in native diversity, using a field experiment during the exceptionally dry winter of 2017–2018, we found that seedling mortality was higher and growth of seedlings and adults were lower in unwatered than watered sites. Mortality of unwatered seedlings was higher in species with shorter seedling roots, and also in species with the correlated traits of small seeds, high seedling specific leaf area (SLA), and tall seedlings. Adult traits varied along an axis from short-stature, high SLA and foliar N, and early flowering to the opposite values, and were only weakly correlated with seedling traits and seedling mortality. No evidence was found for adaptive plasticity, such as longer roots or lower SLA in unwatered plants. Among these species, constitutive variation in seedling root length explained most of the variation in survival of a highly vulnerable life stage under winter drought. Selective loss of species with high adult SLA, observed in this community and others under drought stress, may be the byproduct of other correlated traits.
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Guimarães, Gabriel Castanheira, Sttela Dellyzette Veiga Franco da Rosa, Luis Filipe Serafim Coelho, Adriano Delly Veiga, and Aline da Consolação Sampaio Clemente. "Minimum period to assess the potential of germination of coffee seeds." Journal of Seed Science 35, no. 3 (2013): 347–52. http://dx.doi.org/10.1590/s2317-15372013000300011.
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In recent research, early stages of coffee seedling development were identified, after radicle protrusion, in which all the essential parts of the seedling can be assessed to demonstrate the potential of seed germination to generate normal plants. Thus, the objective of this research was to develop studies to reduce the time on the germination test. Ten seed lots of coffee were assessed through the germination test, every two days, from the tenth day of sowing, according to the morphological criteria of the seedlings. The data were compared to the standard germination test and analyzed by means of regression analysis and segmented nonlinear regression and planteau response model. It was concluded that the assessment of coffee seedlings at 16 days, in stage S1, provides the similar result of the pattern germination test, allowing a significant reduction of time in order to demonstrate the germination of the seed lots; the seedling assessment coffee in stage S2 does not have reduction of the time for assessing the coffee germination, in relation to the pattern.
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Buntin, G. David. "Simulated Insect Defoliation of Seedlings and Productivity of Winter Small-Grain Crops." Journal of Entomological Science 29, no. 4 (October 1, 1994): 534–42. http://dx.doi.org/10.18474/0749-8004-29.4.534.
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Insects, such as grasshoppers, Spodoptera spp. armyworms and flea beetles, occasionally defoliate seedlings of autumn-planted small grain crops. Seedlings of wheat, Triticum aestivum L., barley, Hordeum vulgare L., oats, Avena sativa L., rye, Secale cereale L., and triticale, X Triticosecale Wittmack, were mechanically clipped at the soil surface to simulate insect leaf injury for various periods after planting up to the 1-, 2-, and 4-leaf stages. Defoliation up to the 4-leaf stage (i.e., ≥ 30 days after planting) delayed spike emergence of all crops by several days. Seedling defoliation generally had little adverse effect on grain yield and test weight of rye in any year and reduced yield of triticale in one of three years. Furthermore, plants of both species defoliated in the 2- and 4-leaf stages were less severely damaged by cold temperatures and yielded as much or more than nondefoliated plants when late freezes occurred. Seedling defoliation up to the 4-leaf stage also had little negative effect on grain yield and test weight of wheat. Grain yield of barley and oats declined with increasing length of defoliation period in two of three seasons with most of the reduction occurring when defoliation exceeded 20 days. Results imply that seedling defoliation up to the 4-leaf stage has little effect on grain yield and test weight of winter wheat, rye, and triticale. Defoliation only adversely affected yield of barley and oats when it occurred beyond the 2-leaf stage. As long as plant stand is not reduced, economic thresholds for seedling pests of winter small-grain crops that do not allow for the loss of most leaf tissue for several weeks after planting probably are too conservative.
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Sane, Noor Us, Dhiman Bhusan, Papon Kumar Deb Nath, Yoshiyuki Murata, and Md Anamul Hoque. "Improving salinity tolerance in transplanted aman rice (Oryza sativa L.) by exogenous application of proline." Journal of the Bangladesh Agricultural University 17, no. 2 (June 28, 2019): 194–99. http://dx.doi.org/10.3329/jbau.v17i2.41943.
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Salinity is the major factor reducing crop yield in coastal areas of Bangladesh. Proline (Pro) application with suitable crop varieties having higher yield potential could contribute to the improvement of crop production in saline areas. The main objective of this study was to investigate the mitigation of adverse effects of salinity in aman rice by exogenously applied Pro. The experiment was carried out at the farmer’s field of Batiaghata, Khulna. Characteristically, the soil was silty clay loam having pH 6.7, EC 4.6 dS m–1, CEC 23 meq/100 g soil, organic matter 0.71%. Rice (Oryza sativa L.) variety BR23 was used as plant material. The experiment was laid out in a randomized complete block design with three replications. There were different treatment combinations namely control (no Pro), 25 mM Pro at seedling stage, 25 mM Pro at vegetative stage, 25 mM Pro at seedling and vegetative stages, 50 mM Pro at seedling stage, 50 mM Pro at vegetative stage, 50 mM Pro at seedling and vegetative stages, 100 mM Pro at seedling stage, 100 mM Pro at vegetative stages, and 100 mM Pro at seedling and vegetative stages. Recommended doses of N, P, K, S and Zn fertilizers were applied to the all experimental plots. Thirty-day-old seedlings were transplanted in the experimental plots. Proline solutions were sprayed over plant leaves with the help of sprayer as per treatments. Salinity caused significant reductions in growth and yield of BR23 by decreasing plant height, number of effective tillers, panicle length, filled grains panicle-1 and 1000-grain weight. On the other hand, exogenous application of Pro showed a significant increase in growth and yield of BR23 under saline conditions. Results also revealed that growth and yield of rice did not increase proportionally with the increasing doses of Pro. Proline application resulted in significant increases in K+/Na+ and nutrient uptake by rice under salinity. The present study suggests that exogenous application of Pro confers tolerance to salinity in aman rice by increasing K+/Na+ ratio and nutrient uptake.
J. Bangladesh Agril. Univ. 17(2): 194–199, June 2019
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Oh, Wook, Erik S. Runkle, and Ryan M. Warner. "Timing and Duration of Supplemental Lighting during the Seedling Stage Influence Quality and Flowering in Petunia and Pansy." HortScience 45, no. 9 (September 2010): 1332–37. http://dx.doi.org/10.21273/hortsci.45.9.1332.
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Increasing the photosynthetic daily light integral (DLI) during the seedling stage promotes seedling growth and flowering in many bedding plants. Our objective was to determine the impact of increased DLI for different periods during the seedling stage on young plant quality and subsequent growth and development. Seeds of petunia (Petunia ×hybrida Vilm.-Andr. ‘Madness Red’) and pansy (Viola ×wittrockiana Gams. ‘Delta Premium Yellow’) were sown into 288-cell plug trays and placed under a 16-h photoperiod provided by sunlight plus 90 μmol·m−2·s−1 [supplemental lighting (SL)] or 3 μmol·m−2·s−1 [photoperiodic lighting (PL)] from high-pressure sodium lamps when the ambient greenhouse photosynthetic photon flux was less than 400 μmol·m−2·s−1 from 0600 to 2200 hr. Plants were grown at 20 °C under PL or SL for the entire seedling stage or were exposed to SL for one-third or two-thirds of the seedling stage. Seedlings were then transplanted into 10-cm pots and grown until flowering with SL at 20 °C. Shoot dry mass of transplants increased linearly with increasing DLI provided to seedlings in petunia (y = −4.75 + 1.86x, R2 = 0.76) and pansy (y = −3.94 + 3.47x, R2 = 0.78) in which y = dry mass (g) and x = DLI (mol·m−2·d−1). SL during the last two-thirds or the entire plug stage increased shoot dry mass and the number of leaves in both species compared with SL during the earlier stage or PL. SL during the last two-thirds or the entire plug stage accelerated flowering, but plants had a lower shoot dry mass and flower bud number at first flowering compared with that in SL during the first third or two-thirds or that in PL. Therefore, SL generally had greater effects on transplant quality and subsequent flowering when provided later in the plug stage than if provided earlier in production.
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Grarper, David F., and Will Healy. "Modification of Petunia seedling Carbohydrate Partitioning by Irradiance." HortScience 25, no. 9 (September 1990): 1073d—1073. http://dx.doi.org/10.21273/hortsci.25.9.1073d.
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Petunia × hybrida Villm. `Red Flash' plants were irradiated for either 10 or 20 mol day1 photosynthetic photon flux (PPF) in growth chambers using one of the following treatments: 175 μmol m-2 s-1 for 16 h, 350 μmol m-2 s-1 for 8 or 16 h or 350 μmol m-2 s-1 for 8 h plus 8 h incandescent day extension (5 μmol m-2 s-1 PPF). These four treatments were designed to examine the effects of increased peak and total daily integrated PPF as well as increased photosynthetic (Pn) period and photoperiod resulting from supplemental irradiance treatment of seedlings. Previous seedling petunia research indicated a greater response to supplemental lighting during expansion of the second true leaf. Therefore, seedlings were sampled for analysis at the two leaf stage and also later at the four leaf stage to examine effects at a later stage of growth.Increasing total integrated PPF increased total carbohydrate production, seedling dry weight, rate of seedling growth, and acid invertase activity once the seedlings reached the two leaf stage. Increasing total PPF resulted in greater partitioning into ethanol soluble sugars rather than starch at the two leaf stage. Increasing the photoperiod only, with an incandescent day extension treatment, reduced total carbohydrate production at the two leaf stage.Maximal oxygen evolution was observed when seedlings received 350 μmolm-2s-1 for 8 h when expressed on a leaf area or dry weight basis. The use of an 8 h day extension treatment to extend the photoperiod from 8 to 16 h resulted in the lowest rates of oxygen evolution on a leaf area basis.
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Jin, Songheng, Brett Moule, Dapao Yu, and G. Geoff Wang. "Fire Survival of Longleaf Pine (Pinus palustris) Grass Stage Seedlings: The Role of Seedling Size, Root Collar Position, and Resprouting." Forests 10, no. 12 (November 25, 2019): 1070. http://dx.doi.org/10.3390/f10121070.
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Longleaf pine (Pinus palustris Mill.) forest is a well-known fire-dependent ecosystem. The historical dominance of longleaf pine in the southeast United States has been attributed to its adaptation known as the grass stage, which allows longleaf pine seedlings to survive under a frequent surface fire regime. However, factors affecting post-fire survival of grass stage seedlings are not well understood. In this study, we measured live and dead longleaf pine grass stage seedlings to quantify the role of seedling size, root collar position, and sprouting in seedling survival following a wildfire in the sandhills of South Carolina. We found that fire resulted in almost 50% mortality for longleaf pine grass stage seedlings. Fire survival rate increased with seedling size, but a size threshold for fire tolerance was not supported. Fire survival depended on the position of root collar relative to the mineral soil. Seedlings with protected root collars (i.e., buried in or at the level of mineral soil) experienced <21%, while seedlings with exposed root collars (i.e., elevated above mineral soil) suffered >90% post-fire mortality. Ability to resprout contributed to 45.6% of the total fire survival, with the small seedlings (root collar diameter (RCD) < 7.6 mm) almost exclusively depending on resprouting. Our findings had significant implications for fire management in longleaf pine ecosystems, and the current frequency of prescribed fire in sandhills might need to be lengthened to facilitate longleaf pine natural regeneration.
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Cunha, Fábio Sanchez da, Antonio Elton da Silva Costa, Alexandre Sandri Capucho, Rita de Cássia Souza Dias, and Francine Hiromi Ishikawa. "Identification of sources of resistance to damping-off (Rhizoctonia solani) in two phenological phases of watermelon." APRIL 2019 13, (04) 2019 (April 20, 2019): 628–34. http://dx.doi.org/10.21475/ajcs.19.13.04.p1675.
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Sources of resistance to damping-off caused by Rhizoctonia solani were researched in watermelon accessions, in which thirty accessions were inoculated in two phenological phases (at seeding and seedling stages). The completely randomized design with five replications per accession was used in both phenological stages. The inoculation in seeding stage was carried out at the time of sowing, while for seedling the inoculation was done 15 days after sowing. In both stages the evaluation occurred 15 days after inoculation using a rating scale. At seeding stage, six accessions were moderately resistant to CMM-2967 of R. solani. However, no accession resistant to CMM-1053 and CMM-1052 isolates was recognized. Three accessions were resistant to CMM-1053 at the seedling stage. Posteriorly, inoculation was carried out using only accessions classified as resistant in the previous evaluations using both phenological stages. For CMM-1053, factorial scheme of 2x4 were used (two stages and four accessions). For assessments against isolate CMM-2967 a factorial scheme of 2x12 (two stages and 12 accessions) was used. We confirmed the results of first two experiments for both isolates. At seeding stage, all accessions were classified as susceptible to CMM-1053. However, at the seedling stage, only Crimson Swett was susceptible. For the CMM-2967, inoculated at the seeding stage, the accessions were classified into two groups (resistant and susceptible) (Scott-Knott at 5%). At seedling stage there was no statistical difference among eleven accessions and they were all classified as resistant. Due to difficulty of finding sources of resistance to damping off, the method of inoculation at seedling stage showed more efficient for this pathosystem and could facilitate the work of breeders and plant pathologists.
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Jones, Elizabeth R., Lisa M. Curran, Debra D. Wright, and Andrew L. Mack. "Differential effects of mammalian seed predators on the regeneration of five Papua New Guinean tree species and implications for sapling recruitment." Journal of Tropical Ecology 24, no. 3 (May 2008): 259–67. http://dx.doi.org/10.1017/s026646740800494x.
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Abstract:Although herbivores may account for a significant source of seed and seedling mortality in many tropical tree species, plant species differ in their response to seed damage. Here we investigate the relative effects of seed predation on the regeneration of five tree species in a mid-elevation Papua New Guinean rain forest. Exclosure treatments and shade-house experiments were monitored from November 2004 to March 2006 to assess the differential effects of seed predation on seed viability and seedling growth. Results indicate that although seed predators attack all five focal species, they influence the seedling populations in two, Cerbera floribunda and Microcos grandiflora, and minimally affect the seedling populations of Terminalia impediens, Pandanus penicillus and Endiandra latifolia in the years measured. Predation and germination frequencies were compared to the abundance of focal species at several life stage classes to explore potential correlations between species-specific seed mortality patterns and life stage distributions. We found that the species-specific influence of mammalian seed predators correlated with abundance distributions in three life stages. Species with high survivorship after seed predator attacks displayed a significant decrease in abundance from the seedling-to-sapling transition, while those species with high seed mortality demonstrated relatively even distributions of seedlings, saplings and adults (> 10 cm dbh). These contrasting patterns suggest that differential seed predation effects on regeneration may play a key role in the recruitment of individuals to the sapling stage.
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Rosales-Robles, Enrique, James M. Chandler, Scott A. Senseman, and Eric P. Prostko. "Influence of Growth Stage and Herbicide Rate on Postemergence Johnsongrass (Sorghum halepense) Control." Weed Technology 13, no. 3 (September 1999): 525–29. http://dx.doi.org/10.1017/s0890037x00046145.
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Studies were conducted to observe the effect of full and reduced rates of postemergence (POST) herbicides on seedling and rhizome johnsongrass (Sorghum halepense) at different growth stages. Herbicides and labeled rates included primisulfuron at 40 g/ha, nicosulfuron at 35 g/ha, fluazifop-P at 210 g/ha, and clethodim at 140 g/ha. Contour graphs to predict johnsongrass control at different growth stages and herbicide rates were developed. Excellent seedling and rhizome johnsongrass control was obtained with reduced rates of herbicides applied at the three- to five-leaf stages. Primisulfuron at 20 g/ha resulted in 90% or greater control of seedling johnsongrass in the three- to four-leaf stage. Rhizome johnsongrass at this growth stage required 30 g/ha of primisulfuron for the same level of control. Nicosulfuron at 17.5 and 26.3 g/ha provided 90% or greater control up to the four-leaf stage of seedling and rhizome johnsongrass, respectively. Fluazifop-P and clethodim were more effective than primisulfuron and nicosulfuron. Fluazifop-P at 105 g/ha resulted in 90% or greater control of seedling and rhizome johnsongrass up to the seven- and five-leaf stages, respectively. Clethodim at 35 g/ha controlled seedling johnsongrass at least 90% up to the eight-leaf stage. Clethodim at 70 g/ha provided 90% or greater control of rhizome johnsongrass if applied at the three- to four-leaf stages.
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Zhang, Yiting, Hao Dong, Shiwei Song, Wei Su, and Houcheng Liu. "Morphological and Physiological Responses of Cucumber Seedlings to Supplemental LED Light under Extremely Low Irradiance." Agronomy 10, no. 11 (November 2, 2020): 1698. http://dx.doi.org/10.3390/agronomy10111698.
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In order to inhibit spindling growth and improve quality of cucumber seedlings under low irradiance, effects of supplemental light-emitting diodes (LED) light (SL) on morphological and physiological characteristics of cucumber seedlings at different growth stages under extremely low irradiance (ELI) were investigated. Supplementary monochromatic, dichromatic and trichromatic LED light on cucumber seedlings were conducted in experiment one, and supplements of combination ratios and intensity of blue and red LED light (RB) were conducted in experiment two. The morphological and physiological parameters of cucumber seedlings were promoted effectively by supplemental monochromatic red light or dichromatic containing red light (RB and RG) under ELI as early as one-leaf seedling stage, as demonstrated by suppressed length of hypocotyl and first internode, increased stem diameter and biomass, higher net photosynthetic rate (Pn) and soluble sugar content. Monochromatic or additional green light was not beneficial to cucumber seedlings under the ELI. The length of shoot and hypocotyl decreased, while stem diameter and leaf area increased as early as one-leaf seedling stage by RB SL. Root activities, root–shoot ratio, activities of catalase (CAT) and peroxidase (POD), as well as palisade–spongy ratio in the leaf of cucumber seedlings were promoted effectively by increasing blue light proportion (1R1B/1R2B). Increasing light intensity (50/75) enhanced soluble sugar accumulation in leaves. There were synergistic effects of RB ratio and light intensity on increasing stem diameter, leaf area, seedling index and decreasing hypocotyl cell area of the vertical section. In conclusion, 1R2B-75 may be the optimal SL to inhibit spindling growth of cucumber seedlings under ELI condition.
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Safitri, Heni, Bambang Sapta Purwoko, Iswari Saraswati Dewi, and Sintho Wahyuning Ardie. "SALINITY TOLERANCE OF SEVERAL RICE GENOTYPES AT SEEDLING STAGE." Indonesian Journal of Agricultural Science 18, no. 2 (January 30, 2018): 63. http://dx.doi.org/10.21082/ijas.v18n2.2017.p63-68.
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<p class="abstrakinggris">Salinity is one of the most serious problems in rice cultivation. Salinity drastically reduced plant growth and yield, especially at seedling stage. Several rice genotypes have been produced, but their tolerance to salinity has not yet been evaluated. The study aimed to evaluate salinity tolerance of rice genotypes at seedling stage. The glasshouse experiment was conducted at Cimanggu Experimental Station, Bogor, from April to May 2013. Thirteen rice genotypes and two check varieties, namely Pokkali (salt tolerant) and IR29 (salt sensitive) were tested at seedling stage. The experiment was arranged in a randomized complete block design with three replications and two factors, namely the levels of NaCl (0 and 120 mM) and 13 genotypes of rice. Rice seedlings were grown in the nutrient culture (hydroponic) supplemented with NaCl at different levels. The growth and salinity injury levels of the genotypes were recorded periodically. The results showed that salinity level of 120 mM NaCl reduced seedling growth of all rice genotypes, but the tolerant ones were survived after 14 days or until the sensitive check variety died. Based on the visual injury symptoms on the leaves, five genotypes, i.e. Dendang, Inpara 5, Inpari 29, IR77674-3B-8-2-2-14-4-AJY2, and IR81493-BBB-6-B- 2-1-2 were tolerant to 120 mM salinity level, while Inpara 4 was comparable to salt sensitive IR29. Hence, Inpara 4 could be used as a salinity sensitive genotype for future research of testing tolerant variety. Further evaluation is needed to confirm their salinity tolerance under field conditions. </p>
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Azad, Md Salim, and Md Mehedi Hasan Sumon. "Species Specific Responses to Age on Nodule Formation, Seedling Growth, and Biomass Production of Acacia auriculiformis at Nursery Stage." Journal of Botany 2016 (August 16, 2016): 1–8. http://dx.doi.org/10.1155/2016/6960783.
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Nodulation responses of leguminous trees are very important for intercropping to reduce reliance on artificial nitrogen input through nitrogen fixation in agroforestry system. This study was carried out to evaluate the status of nodulation (i.e., the number of nodules and their shape and size) in root and biomass production of plant growth parameters (i.e., number of leaves, shoot height, root biomass, and shoot biomass) of A. auriculiformis seedlings. The assessment was conducted 60 days after seed germination. The study revealed significant differences in nodule number per seedling, leaf number per seedling, shoot height, and biomass accumulation (both green and oven dry weight) with seedling age (p<0.05). The study also revealed significant correlation among the variables of nodulation responses and biomass production. The results obtained using principal component analysis (PCA) justified correlation matrix of nodulation responses and biomass production of this species. The PCA showed that root biomass per seedling, leaf number per seedling, nodule number per seedling, shoot height, age of seedling, and shoot biomass per seedling were clustered with PC1 (with an eigenvalue of 5.59) and root shoot ratios were clustered with PC2 (with an eigenvalue of 1.82). Our study justified that shoot height may be an important determinant of nodule formation of A. auriculiformis.
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Ramsay, Carol A., and Garrell E. Long. "SURVIVAL OF LARCH CASEBEARERS, COLEOPHORA LARICELLA (HUBNER), ON FOLIAGE OF EIGHT SEEDLING CONIFERS." Canadian Entomologist 120, no. 11 (November 1988): 993–96. http://dx.doi.org/10.4039/ent120993-11.
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AbstractA no-choice feeding study was used to evaluate larch casebearer development and survival on eight species of conifer seedlings and two foliar stages of larch from molting to the fourth-instar larvae through adult eclosion. Percentage survival through adult eclosion varied on foliage of western larch (spring—flush stage, 44%; fall—bud set stage, 23%), Douglas-fir (40%), grand fir (26%), Englemann spruce (26%), western white pine (10%), and lodgepole pine (6%). No survival occurred on ponderosa pine or western hemlock. The rate of development differed among conifer seedling species, and between foliar stages of larch.
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Harbaugh, Brent K. "095 ROSETTING OF LISIANTHUS INFLUENCED BY CULTIVAR, SEEDLING AGE, PHOTOPERIOD, AND TEMPERATURE." HortScience 29, no. 5 (May 1994): 441f—441. http://dx.doi.org/10.21273/hortsci.29.5.441f.
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Rosetting response was determined for four lisianthus [Eustoma grandiflorum (Raf.) Shinn.] cultivars exposed to photoperiod and temperature treatments during stage 1(14 to 43 days after sowing) and stage 2 (43 to 79 days after sowing) seedling development. Stage 1 seedlings were exposed to short days (12 h photoperiod) or long days (18 h photoperiod) in combination with high (26C) or low temperatures (12C). After stage 1 treatments, stage 2 seedlings were divided and exposed to the same treatment combinations resulting in 16 treatments. Seedlings were then grown at 22C for 120 days to determine rosetting response. Cultivars responded differently to temperature and photoperiod. Short day-high temperature exposure during either stage 1 or stage 2 resulted in the greatest number of rosetted plants (50 to 100%) for `Yodel White', `HeidiPink', and `BlueLisa'. `GCREC-Blue' did not rosette with short day-high temperature. Low temperature during stage 1 did not prevent rosetting when stage 2 seedlings were subsequently exposed to high temperature, but low temperature during stage 2 decreased rosetting of seedlings exposed to high temperature in stage 1. Less rosetting occurred with long day-high temperature than with short day-low temperature, especially for `Blue Lisa'.
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Maiti, R., P. Vidyasagar, and P. Banerjee. "Characterization of salinity tolerance in rice ( Oryza sativa L.) genotypes at the germination and seedling stages." Acta Agronomica Hungarica 56, no. 2 (June 1, 2008): 139–47. http://dx.doi.org/10.1556/aagr.56.2008.2.3.
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The present work was conducted to study the genotypic variability of rice genotypes at the germination and seedling stages at different levels of salinity (0 M, 0.15 M, 0.2 M and 0.25 M NaCl). The results showed that increasing salinity decreased germination and seedling growth. Significant genotypic variability exists in the germination and seedling stages in response to different NaCl concentrations. Most of the genotypes showed more than 90% germination in the control, indicating good seed vigour. Two genotypes, VBR 638 (93%) and VBR 644 (84%), were selected as being tolerant to salinity at 0.2 M NaCl at the germination stage. Therefore, these could be used as source materials for genetic improvement for salinity tolerance at the germination stage. A considerable amount of genotypic variability was also found under control and saline conditions at the seedling stage with respect to the variables shoot height, root length, shoot and root dry weight. The high heritability observed for these variables offers good scope for genetic improvement for salinity tolerance both at the germination and seedling stages. The genotypes VBR 616, VBR 628, VBR 645, VBR 640, VBR 611, VBR 620, VBR 612, VBR 618, VBR 644, VBR 629, VBR 625 and VBR 630 were selected as being tolerant to salinity at the seedling stage.
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Pramuk, Lee Ann, and Erik S. Runkle. "Photosynthetic Daily Light Integral During the Seedling Stage Influences Subsequent Growth and Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola." HortScience 40, no. 4 (July 2005): 1099C—1099. http://dx.doi.org/10.21273/hortsci.40.4.1099c.
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The photosynthetic daily light integral (DLI) dramatically increases during the spring, but effects of DLI on seedling growth and development have not been characterized for many species. We quantified the effects of DLI on growth and development of Celosia, Impatiens, Salvia, Tagetes, and Viola during the seedling stage and determined whether there were any residual effects of DLI on subsequent growth and development after transplant. Seedlings were grown in growth chambers for 18–26 days at 21 °C with a DLI ranging from 4.1–14.2 mol·mol·m-2·d-1. Average seedling shoot dry weight per internode (a measure of quality) increased linearly 64%, 47%, 64%, and 68% within this DLI range in Celosia, Impatiens, Tagetes, and Viola, respectively. Seedlings were then transplanted to 10-cm containers and grown in a common environment (average daily temperature of 22 °C and DLI of 8.5 mol·m-2·d-1) to determine subsequent effects on plant growth and development. Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola occurred 10, 12, 11, 4, and 12 days earlier, respectively, when seedlings were previously grown under the highest DLI compared with the lowest. Except for Viola, earlier flowering corresponded with the development of fewer nodes below the first flower. Flower bud number and plant shoot dry weight at first flowering decreased as the seedling DLI increased in all species except for flower number of Tagetes. Therefore, seedlings grown under a greater DLI flowered earlier, but plant quality at first flowering was generally reduced compared with that of seedlings grown under a lower DLI.
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FISCH, Simey Thury Vieira, Isolde Dorothea Kossmann FERRAZ, and William Antonio RODRIGUES. "DISTINGUISHING Campa guianensis Aubl. FROM Campa procera D.C. (MELIACEAE) BY MORPHOLOGY OF YOUNG SEEDLINGS." Acta Amazonica 25, no. 3-4 (1995): 193–200. http://dx.doi.org/10.1590/1809-43921995253200.
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Seedling morphology was studied in Campa guianensisAubl. and Carapa proceraD. C. from germination to 90 days age. In both species germination is hypogeal and cryptocotylar. Both have rare albino seedlings. Though both species have compound leaves when adult, C, proceraputs out an average total of six simple leaves at germination, while leaves of C. guianensisare compound at all stages. This is the best diagnostic character for separation of the two species at the young seedling stage. Not diagnostic, but none the less useful, is the fact, that polyembryonic seeds are often found in C. procera,but not observed in C guianensis.
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Petrovic, Gordana, Dusica Jovicic, Zorica Nikolic, Gordana Tamindzic, Maja Ignjatov, Dragana Milosevic, and Branko Milosevic. "Comparative study of drought and salt stress effects on germination and seedling growth of pea." Genetika 48, no. 1 (2016): 373–81. http://dx.doi.org/10.2298/gensr1601373p.
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Seed germination is first critical and the most sensitive stage in the life cycle of plants compromise the seedlings establishment. Salt and drought tolerance testing in initial stages of plant development is of vital importance, because the seed with more rapid germination under salt or water deficit conditions may be expected to achieve a rapid seedling establishment, resulting in higher yields. The aim of this study was to determine whether the pea seed germination and seedling growth were inhibited by the salt toxicity and osmotic effect during the seedling development, and also identification of the sensitive seedling growth parameters in response to those stresses. Based on the obtained results, pea has been presented to be more tolerant to salt than water stress during germination and early embryo growth. Investigated cultivars showed greater susceptibility to both abiotic stresses when it comes growth parameters compared to seed germination.
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Song, Libing, Jiming Jin, and Jianqiang He. "Effects of Severe Water Stress on Maize Growth Processes in the Field." Sustainability 11, no. 18 (September 17, 2019): 5086. http://dx.doi.org/10.3390/su11185086.
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In this study, we investigated the effects of water stress on the growth and yield of summer maize (Zea mays L.) over four phenological stages: Seedling, jointing, heading, and grain-filling. Water stress treatments were applied during each of these four stages in a water-controlled field in the Guanzhong Plain, China between 2013 and 2016. We found that severe water stress during the seedling stage had a greater effect on the growth and development of maize than stress applied during the other three stages. Water stress led to lower leaf area index (LAI) and biomass owing to reduced intercepted photosynthetically active radiation (IPAR) and radiation-use efficiency (RUE). These effects extended to the reproductive stage and eventually reduced the unit kernel weight and yield. In addition, the chlorophyll content in the leaf remained lower, even though irrigation was applied partially or fully after the seedling stage. Severe and prolonged water stress in maize plants during the seedling stage may damage the structure of the photosynthetic membrane, resulting in lower chlorophyll content, and therefore RUE, than those in the plants that did not experience water stress at the seedling stage. Maize plants with such damage did not show a meaningful recovery even when irrigation levels during the rest of the growth period were the same as those applied to the plants not subjected to water stress. The results of our field experiments suggest that an unrecoverable yield loss could occur if summer maize were exposed to severe and extended water stress events during the seedling stage.
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Pramuk, Lee Ann, and Erik S. Runkle. "Photosynthetic Daily Light Integral During the Seedling Stage Influences Subsequent Growth and Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola." HortScience 40, no. 5 (August 2005): 1336–39. http://dx.doi.org/10.21273/hortsci.40.5.1336.
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The photosynthetic daily light integral (DLI) dramatically increases during the spring when the majority of bedding plants are commercially produced. However, the effects of DLI on seedling growth and development have not been well characterized for most bedding plant species. Our objectives were to quantify the effects of DLI on growth and development of Celosia, Impatiens, Salvia, Tagetes, and Viola during the seedling stage and determine whether there were any residual effects of DLI on subsequent growth and development after transplant. Seedlings were grown in growth chambers for 18 to 26 days at 21 °C with a DLI ranging from 4.1 to 14.2 mol·m–2·d–1. Average seedling shoot dry weight per internode (a measure of quality) increased linearly 64%, 47%, 64%, and 68% within this DLI range in Celosia, Impatiens, Tagetes, and Viola, respectively. Seedlings were then transplanted to 10-cm containers and grown in a common environment (average daily temperature of 22 °C and DLI of 8.5 mol·m–2·d–1) to determine subsequent effects on plant growth and development. Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola occurred 10, 12, 11, 4, and 12 days earlier, respectively, when seedlings were previously grown under the highest DLI compared with the lowest. Except for Viola, earlier flowering corresponded with the development of fewer nodes below the first flower. Flower bud number and plant shoot dry weight at first flowering (plant quality parameters) decreased as the seedling DLI increased in all species except for flower number of Tagetes. Therefore, seedlings grown under a greater DLI flowered earlier, but plant quality at first flowering was generally reduced compared with that of seedlings grown under a lower DLI.
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Rajametov, Sherzod Nigmatullaevich, Eun Young Yang, Myeong Cheol Cho, Soo Young Chae, and Hyo Bong Jeong. "Screening of pepper (Capsicum l.) seedlings tolerance to low temperature." Agrarian Scientific Journal, no. 11 (November 23, 2020): 78–82. http://dx.doi.org/10.28983/asj.y2020i11pp78-82.
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This study was conducted on screening for 21 pepper genotypes tolerant to low temperature and their duration for survival in 3-4 (38 days after sowing), and 4-6 (47 days after sowing) true leaf seedling growth stages (LS). It was detected that response of seedlings on low temperature were different and ranged among the genotypes depends on growth stages. Seedlings in early 3-4 LS growth stage were more susceptible than 4-6 LS seedlings, where the first symptoms of leaf cold damages (LCD) were revealed within 7 days after transplanting (DAT) and 12 DAT in pepper seedlings, respectively. There were identified that the susceptible genotypes in 3-4 LS can be tolerant in 4-6 LS, or show opposite pattern, where tolerant one in next the growth stage, plant becomes susceptible. Low temperature negative impact on chlorophyll content (CHL) in leaves, however depends on seedling growth stage and genotype might be ranged. The lowest content of CHL were observed in early growth 3-4 LS seedlings than 4-6 LS. And, it was revealed that cold susceptible pepper genotypes in which CHL reduced significantly during cold treatment, showed good ability to recovery of CHL after treatment of seedlings in NT condition, whereas cold tolerant genotypes with high CHL content during low treatment, can reduce significantly of CHL after transfer of seedlings to NT condition for recovery. According to screening were selected relatively cold tolerant pepper genotypes LT8 and LT9 in early 3-4 LS, and LT8, LT13, LT18, LT20 and LT21 in 4-6 LS, where LCD were below 45 and 10%, respectively.
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Rosenani, A. B., R. Rovica, P. M. Cheah, and C. T. Lim. "Growth Performance and Nutrient Uptake of Oil Palm Seedling in Prenursery Stage as Influenced by Oil Palm Waste Compost in Growing Media." International Journal of Agronomy 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/6930735.
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The use of composted oil palm wastes in the oil palm nursery as an organic component of growing medium for oil palm seedlings seems promising in sustainable oil palm seedling production. This study was conducted to investigate the effects of six oil palm waste compost rates (0, 20, 40, 60, 80, and 100%) on the growth performance of oil palm seedling and nutrient uptake in the prenursery stage (0–3 months). The addition of oil palm compost reduced the soil bulk density (1.32 to 0.53 g cm−3) and increased soil pH (4.7 to 5.1) of growth media. Oil palm waste compost treatment produced positive growth performance up to 70%. A regression analysis indicated in 72% of compost and topsoil mixture as a polybag growth medium was optimum in producing best growth performance of oil palm seedling in the prenursery stage. Foliar analysis implied highest nutrients uptake (N, P, K, Mg, Ca, Fe, Zn, and Cu) for seedlings grown in 60 to 100% compost media.
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Pivatto, María Sosa, Guillermo Funes, Ana E. Ferreras, and Diego E. Gurvich. "Seed mass, germination and seedling traits for some central Argentinian cacti." Seed Science Research 24, no. 1 (February 17, 2014): 71–77. http://dx.doi.org/10.1017/s0960258513000366.
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AbstractSeed size is one of the most important traits in the regenerative phase of a plant's life cycle; however, for cactus species the relationship of seed size and germination characteristics and seedling traits is still unclear. We studied the relationship between seed mass and germination and seedling characteristics in 17 cactus species from central Argentina, belonging to different genera and life forms. We measured seed mass, total seed germination, light requirements for germination and mean time to germination for these 17 cacti species; in addition, we recorded seedling size and shape in 15 species. To test light requirements we performed germination experiments under laboratory conditions at 25/15°C (day/night temperatures) and under light or dark conditions. We also calculated seedling volume by measuring seedling height and width. A shape index was obtained by dividing height by width (a value of 1 indicates ‘globose’ seedlings, whereas, as this value increases, seedlings become ‘columnar’). We found no significant relationship between seed mass and any of the germination characteristics considered. However, species with heavier seeds produced bigger seedlings, which were more cylindrical. Adult growth was not totally determined by seedling ‘growth form’, because some species that had globose seedlings were columnar at the adult stage.
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Zhang, Jianhua, and M. A. Maun. "Effects of partial removal of seed reserves on some aspects of seedling ecology of seven dune species." Canadian Journal of Botany 69, no. 7 (July 1, 1991): 1457–62. http://dx.doi.org/10.1139/b91-188.
Full textAbstract:
Greenhouse studies were conducted to determine the effects of partial removal of endosperm or cotyledons from seeds of seven dune species on seed germination, seedling emergence, seedling size, and dry matter allocation. Different proportions (0, 30, and 60%) were surgically removed from seeds of Agropyron psammophilum, Calamovilfa longifolia, Elymus canadensis, Leymus arenarius, Panicum virgatum, Lupinus perennis, and Strophostyles helvola. Partial removal of seed reserves caused a significant reduction in seedling variables 1 or 2 weeks after planting in sand. For example, seedling height, leaf area, dry weight of leaves, stem, and roots were significantly lower than control. The data suggest that the principal determinant of seedling size at an early stage was the amount of energy reserves in the endosperm or cotyledons of seeds. In addition to reduction in food reserves, partial removal of seed reserves caused some physiological damage to seedlings. In grass species, seedlings from surgically treated seeds devoted more dry matter to the roots and less to the leaves and stem than control seedlings. In dicot species, however, plants from treated seeds devoted more dry matter to the leaves and less to the roots. Key words: seed injury, seed germination, seedling size, energy allocation, dune plants.
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Sharma, Shipra, Sandeep Arora, and Pushpa Lohani. "Effect of Drought on Antioxidant System at Seedling and Vegetative Stage of Eleusine coracana." International Journal of Applied Sciences and Biotechnology 3, no. 4 (December 30, 2015): 642–50. http://dx.doi.org/10.3126/ijasbt.v3i4.13685.
Full textAbstract:
Adverse environmental factors like drought stress result in increased levels of ROS that adversely affect the growth and productivity of plants. The alleviation of oxidative damage and increased resistance to environmental stresses is correlated with an efficient antioxidant system. Antioxidant non enzymatic system as well as enzymatic system neutralize the effects of these reactive oxygen species and help plants to survive in stress conditions. The study was carried out with the aim to understand the effect of drought on antioxidant system in seedling and vegetative stages of drought tolerant as well as sensitive genotypes of Eleusine coracana. Drought was imposed by withholding water for 8 days at seedling and vegetative stages of drought tolerant ie PRM-6107 and sensitive ie PES-400 genotypes of E. coracana. Different enzyme assays and biochemical analysis were performed in leaf samples by following the standard protocols. With the induction of drought, an increment in the level of ascorbate, flavonoid, phenol and proline was recorded in PRM-6107 whereas no significant increase was observed in PES-400. The level of these antioxidants was more in seedling stage than at vegetative stage. Similarly the level of antioxidant enzymes like ascorbate peroxidase, catalase, guaicol peroxidase, superoxide dismutase and glutathione reductase was high in tolerant genotype as compared to sensitive genotype under unstressed condition. Under stress condition, the level of catalase, ascorbate peroxidase and guaicol peroxidase increased at seedling stage while the levels of glutathione reductase and superoxide dismutase increased significantly at vegetative stage of both the genotypes. These results show that PRM-6107 is drought tolerant because the level of antioxidants as well as antioxidative enzymes is high in this genotype in seedling and vegetative stages. Also, the elevated levels of antioxidants and antioxidative enzymes at seedling stage show that plant start combating drought more strongly at seedling stage than at vegetative stage. Int J Appl Sci Biotechnol, Vol 3(4): 642-650
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James,, R. A., J. A. Kirkegaard, and R. Munns. "Contribution of Rhizoctonia to reduced seedling growth of direct-drilled wheat: studies with intact cores." Australian Journal of Agricultural Research 48, no. 8 (1997): 1231. http://dx.doi.org/10.1071/a97029.
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Wheat seedlings were grown in intact cores of soil removed from 2 field experiments in southern New South Wales where the soil-borne pathogen Rhizoctonia solani had been implicated as a cause of slower seedling growth in direct-drilled soil compared with cultivated soil. Experiments were conducted with intact cores in controlled environments using fumigation to assess the role of Rhizoctonia in the growth responses. Seedling growth was lower in direct-drilled cores than cultivated cores from both sites at a very early stage. The growth reductions were completely removed by fumigation, confirming previous reports that biological factors rather than physical factors were responsible for reduced growth. In cores from the Galong site, Rhizoctonia symptoms were severe at the 5-leaf stage (8 on a scale of 0-10) and the reduction in leaf growth at earlier stages coincided with the appearance of Rhizoctonia symptoms on the roots. Seedling growth was not reduced until the severity was >5. This corresponded with a root-cutting experiment where shoot growth was unaffected until 3 of the 5 seminal roots of healthy seedlings were removed. Pre-sowing soil disturbance to a depth of 5 cm in unfumigated soil increased shoot growth from 47 to 84% of the fumigated controls with no further improvement when the depth of disturbance was increased to 10 cm, suggesting the pathogens responsible were confined to the 0-5 cm layer and were not completely eliminated by disturbance. Pre-sowing disturbance had no effect on shoot growth in fumigated soil. In cores from the Harden site, Rhizoctonia symptoms were moderate at the 5-leaf stage; however, reductions in leaf and root growth at earlier stages occurred 7 days before any symptoms of Rhizoctonia or other pathogens were visible on the roots. The results suggest that other inhibitory organisms are present at the Harden site and cause significant reductions in seedling growth in the absence of visible disease symptoms. Pythium spp. pathogenic to wheat are known to be present at the site but their role has not been confirmed. Further studies are required to identify the inhibitory organisms and to determine the mechanisms by which they reduce early seedling growth.
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Finneseth, C. L. H., Desmond R. Layne, and R. L. Geneve. "Morphological Development of Pawpaw [Asimina triloba (L.) Dunal] during Seed Germination and Seedling Emergence." HortScience 31, no. 4 (August 1996): 633c—633. http://dx.doi.org/10.21273/hortsci.31.4.633c.
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Little scientific information is available describing morphological development of pawpaw during seed germination. To provide this information, a study was designed to outline important developmental stages and describe seedling characteristics within each stage. Stratified pawpaw seeds were sown in vermiculite and germinated at 25°C in a growth chamber. Ten seedlings were randomly chosen and destructively harvested at 5-day intervals starting at radicle protrusion. Length (mm), fresh and dry weight, and percentage of total dry weight were determined for seedling components. Pawpaw seeds have a small rudimentary embryo with all food reserves stored in a ruminate endosperm. Dry weight measurements showed a dramatic reallocation of reserves from the storage tissue to developing seedling parts. Initial embryo length was less than 3 mm, but within 70 days seedlings exceeded 350 mm. Twelve days after planting, simultaneous radicle and cotyledon growth occurred (3.4 and 3.0 mm, respectively), but neither hypocotyl nor epicotyl was visible. Radicle protrusion was observed at 15 days with radicle, cotyledon and hypocotyl lengths increasing to 4.4, 4.0, and 3.2 mm, respectively. Endosperm comprised 99.1% of total dry weight at this stage. The hypocotyl hook emerged after 30 days and endosperm comprised 76.1% of total dry weight. Cotyledons reached maximum length (29.0 mm) at day 40 and the epicotyl was discernible. At 55 days, the seed coat containing cotyledons and residual endosperm abscised and the average radicle, hypocotyl and epicotyl lengths were 182.0, 61.1, and 7.3 mm, respectively. It is suggested that the cotyledons primary function is absorption of food reserves from the endosperm for transfer to the developing seedling.
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Yang, Senshan, Joanne Logan, and David L. Coffey. "EFFECTS OF TEMPERATURE REGIMES ON TOMATO SEEDLING DEVELOPMENT." HortScience 27, no. 11 (November 1992): 1171a—1171. http://dx.doi.org/10.21273/hortsci.27.11.1171a.
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To investigate effects of temperatures in the preceding developmental stage on the following developmental stage, `Sunny' tomatoes were seeded in the greenhouse at six dates and three temperature levels. Plants were rotated among temperature levels so that all plants received approximately the same temperature accumulation at the time of field transplanting. Developmental stages defined were: emergence, 1st, 2nd, 3rd, 4th, 5th, and 6th leaf appearance. Temperature and solar radiation were recorded hourly. Results indicated a significant effect of temperature in the preceding stage on the following stage. Coefficients of variation (CV) in growing degree days (GDD) calculated from the 1st to the ith stage were significantly smaller than those calculated from the (i-1)th to ith stage. When Ri, defined as the reciprocal of the number of days from the 1st to the ith stage, was regressed to Ri-1 and the daily average temperature was regressed from the (i-1)th to the ith stage, all coefficients of Ri-1 were significant at the 1% level. This model was superior to one in which Ri was regressed to the daily average temperature from the 1st to the ith stage.
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Milus, Eugene A., Kevin D. Lee, and Gina Brown-Guedira. "Characterization of Stripe Rust Resistance in Wheat Lines with Resistance Gene Yr17 and Implications for Evaluating Resistance and Virulence." Phytopathology® 105, no. 8 (August 2015): 1123–30. http://dx.doi.org/10.1094/phyto-11-14-0304-r.
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Stripe rust, caused by Puccinia striiformis f. sp. tritici, has been the most important foliar wheat disease in south central United States since 2000 when a new strain of the pathogen emerged. The resistance gene Yr17 was used by many breeding programs to develop resistant cultivars. Although Yr17 was classified as a seedling (all-stage) resistance gene conferring a low infection type, seedlings with Yr17 frequently had intermediate to high infection types when inoculated with isolates that caused little or no disease on adult plants of the same wheat lines. The objectives of this study were to determine how to best evaluate Yr17 resistance in wheat lines and to determine which factors made seedling tests involving Yr17 so variable. Stripe rust reactions on wheat seedlings with Yr17 were influenced by temperature, wheat genotype, pathogen isolate, and the leaf (first or second) used to assess the seedling reaction. The most critical factors for accurately evaluating Yr17 reactions at the seedling stage were to avoid night temperatures below 12°C, to use the first leaf to assess the seedling reaction, to use multiple differentials with Yr17 and known avirulent, partially virulent and virulent isolates as controls, and to recognize that intermediate infection types likely represent a level of partial virulence in the pathogen that is insufficient to cause disease on adult plants in the field.
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Fan, Jing, and Li Ping Chen. "Comparative Environmental Analysis of the Effects of Different Salinity Levels on Growth and Physiological Status of Nipponbare Rice." Advanced Materials Research 908 (March 2014): 416–20. http://dx.doi.org/10.4028/www.scientific.net/amr.908.416.
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Salinity is a major environmental constraint limiting crop growth and yield in worldwide. This paper compared the salt induced damages to Nipponbare rice at germination and seedling stages. All rice samples were treated with four levels of salinity, growth and physiological status were then measured. Dose-dependent changes in rice growth parameters and peroxidase activity were observed. The growth parameters including germination percentages, germination indexes, root numbers, root lengths, shoot lengths and fresh weights decreased significantly at germination and early seedling stages when treated with NaCl greater than 100 mM. However, 100 mM NaCl was not enough to bring significant change of enzyme activity between the salt treated and untreated rice at late seedling stage, this suggests that rice at late seedling stage has stronger self-adjustment ability and more resistant to salt toxicity than that at early seedling stage. More serious inhibition of roots growth was also observed than that of shoots under salt stresses. This work is helpful for the development of protection strategy for rice production in saline areas.
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Houle, Gilles. "Environmental filters and seedling recruitment on a coastal dune in subarctic Quebec (Canada)." Canadian Journal of Botany 74, no. 9 (September 1, 1996): 1507–13. http://dx.doi.org/10.1139/b96-181.
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One important factor that often determines the presence of a plant species on a site is propagule availability. Afterwards, abiotic and biotic factors act as a series of filters operating sequentially from the seed to the adult stage, determining the pattern of recruitment. By comparing the spatial pattern of emerging seedlings to those of seed availability and of surviving seedlings, one can determine the relative importance of the environmental filters acting on the seed germination and the seedling establishment phases. On a coastal dune system in subarctic Quebec (Canada), sand accumulation, salt spray, and substrate physicochemistry, all affecting microsite quality for seeds and seedlings, vary along a short topographical gradient. My goal was to determine whether or not conditions changing along this gradient differentially affect the initial stages of population recruitment of two perennial herbaceous species for which adults are segregated along the gradient: Honckenya peploides and Elymus mollis. The spatial pattern of seeds in the seed bank and that of emerging seedlings were not related to one another for either Honckenya or Elymus. However, patterns of surviving seedlings were spatially correlated with those of emerging seedlings. Seed and seedling mortality were not density dependent; they were both spatially variable, although not clinal. These results suggest that the environmental filters acting on the germination stage are those that determine the spatial patterns of recruitment. Spatial segregation along the flank of the foredune between adults of the two species studied thus seems to be maintained in part (and maybe reinforced) by low seed mobility, or low seed retention, and the availability of suitable microsites for seed germination. Population progression towards the upper beach seems to depend mostly on seedling establishment for Honckenya but on clonal growth for Elymus. Keywords: Elymus mollis, Honckenya peploides, Hudson Bay, partial Mantel test, spatial segregation, Whapmagoostui-Kuujjuaraapik.
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Rehman, Shoaib Ur, Muhammad Bilal, Rashid Mehmood Rana, Muhammad Naveed Tahir, Muhammad Kausar Nawaz Shah, Habtamu Ayalew, and Guijun Yan. "Cell membrane stability and chlorophyll content variation in wheat (Triticum aestivum) genotypes under conditions of heat and drought." Crop and Pasture Science 67, no. 7 (2016): 712. http://dx.doi.org/10.1071/cp15385.
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Heat and drought are among the major obstacles confronting crop production under climate change. The present study was conducted to evaluate 50 diverse wheat genotypes for cell membrane stability (CMS) and chlorophyll content at seedling and anthesis stages under heat and drought stress conditions, to understand the effect of the two abiotic factors and to find promising genotypes for future breeding. Experiments were conducted in the glasshouse (seedling stage) and the field (anthesis stage). Analysis of variance showed significant variation (P ≤ 0.05) for all of the traits at seedling and anthesis stages. High levels of broad-sense heritability and genetic advance at 5% selection intensity indicated the presence of a high genetic component of variation and potential for genetic improvement through selection among the existing genetic variation. CMS showed a significant positive correlation with 1000-grain weight (TGW) under heat and drought conditions at both seedling and anthesis stages. Chlorophyll a/b ratio at seedling stage exhibited a significant negative correlation (r = –0.39, P < 0.05) with TGW under heat stress. Total chlorophyll content was significantly (r = 0.42, P < 0.05) correlated with TGW under heat stress at anthesis. Genotypes ETAD248 and ETAD7 showed the highest CMS and TGW values, whereas their chlorophyll a/b values were lowest, at both seedling and anthesis stages under heat and drought stress conditions. Higher CMS and total chlorophyll content, and lower chlorophyll a/b, were found to be useful indicators to identify genotypes with high TGW under heat and drought stress conditions. This study indicated the possibility of using seedling resistance as an indicator for later stage response in breeding for heat and drought resistance. The resistant genotypes identified can be used as potential germplasm in breeding programs.
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Liptay, A., and A. E. Arevalo. "Plant mineral accumulation, use and transport during the life cycle of plants: A review." Canadian Journal of Plant Science 80, no. 1 (January 1, 2000): 29–38. http://dx.doi.org/10.4141/p99-014.
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Minerals accumulated during each stage of plant development are important, especially for the initial portion of subsequent stages of growth. For example, minerals acquired during seed ontogeny are largely responsible for the earliest stage of seedling growth. Without these minerals, seedling development would be arrested or impossible. Thus, even though the amount of minerals may be relatively small in the seed, their presence is absolutely essential. Similarly, although the mineral nutrient content of a seedling used as a transplant in establishing a crop in the field may seem rather minuscule, the importance to the initiation of development of the successive stage of growth is critical. Moreover, seedling-mineral content, plant performance and seed production can be improved by the selection of optimal cultural practices. This review examines acquisition, content and use of minerals in the various stages of plant development and growth as well as agricultural approaches to enhance mineral accumulation. Key words: Nutrient uptake, field crop establishment, seed mineral content, seed yield, crop growth
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Alemu, I. D., and D. S. Boke. "MORPHOLOGICAL CHARACTERIZATION OF COFFEE (Coffea arabica L.) LANDRACES AT SEEDLING STAGE COLLECTED FROM GUJI ZONES." Bangladesh Journal of Plant Breeding and Genetics 30, no. 2 (May 2, 2018): 09–18. http://dx.doi.org/10.3329/bjpbg.v30i2.34540.
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The present study was aimed to determine genetic diversity of Coffea arabica landraces based on morphological characteristics at seedling stage in Guji zones. Three kebeles and twenty-five farmers’ coffee landraces were selected based on availability of Coffea arabica landraces from each district by the guidance of Developmental Agency in the kebele. Coffea arabica seeds were collected and planted at kercha nursery sub-site in plastic pots arranged on randomized block design. Seedling characteristics were collected from one year old randomly selected four coffee seedlings from each plot. The results showed that there were significant variations (p<0.05) between and within Coffea arabica landraces of the district. The seedling height of Coffea arabica collected from Didiba local was highest (11.25) followed by Sorile local (11.17) whereas Ebala local was the least. Coffea arabica from Diqisa local (5.25) was the highest for leaf height followed by Didiba local (5.13), Harobora (5.00) and Wacufora local (5.00). Similarly, Wacufora local (2.05) and Didiba local (2.53) were the highest in leaf width. The Coffea arabica landrace of Qaqali local (6.25) and Harobora local (5.75) were the highest in number of paired leaves. Correlation between the characteristics of coffee seedling showed that seedling height was high and significantly correlated with leaf width (0.62**), number of paired leaves (0.58**), node number (0.57**) and leaf area (0.64**). Similarly, leaf height was high and significantly correlated with leaf width (0.72**) and leaf area (0.77**). Generally, the increase of leaf height increases the leaf width and leaf area. Existence of morphological variation of Coffea arabica at seedling stage was used to determine Coffea arabica diversity in this study area. Therefore, Coffea arabica landraces having high seedling height, leaf height, number of paired leaves and leaf area should get attention during selection for plantation. Additionally, farmers, conservationists and other concerned bodies should take action to conserve and keep the gene pool of these coffees. As a result, it opens the door for biotechnologists to characterize coffee at molecular level and breeder scan take action on it to release superior coffee varieties.
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Pedroza Carneiro, José Walter. "Stevia rebaudiana (Bert.) Bertoni: Stages of plant development." Canadian Journal of Plant Science 87, no. 4 (October 1, 2007): 861–65. http://dx.doi.org/10.4141/p06-040.
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Vegetative and reproductive codes were developed to describe seeds under germination, normal seedlings, seedling growth, plant growth and branching, plant regrowth, flower buds, crop flowering (anthesis), developing seeds, seed dispersion, and senescent plants as V0, V1.i, V2.i, V3.i.k, V4.i.k, R1.i, R2.i, R3.i, R4.i and R5.i, respectively. The numerical code attached to both capital letters indicates the stage, and the lower case letters i or k indicate a number or a percentage. Key words: Natural sweetener, plant regrowth, anthesis, seed, seedling, transplant