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1
CLOUTIER, Y., L. PELLETIER, and R. MICHAUD. "DEVELOPMENT OF A TEST FOR FREEZING TOLERANCE IN YOUNG ALFALFA SEEDLINGS." Canadian Journal of Plant Science 70, no. 1 (1990): 307–10. http://dx.doi.org/10.4141/cjps90-036.
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An experiment was conducted to study the effects of seedling age on their ability to harden, and to determine whether cultivar × seedling age interaction could be identified for frost resistance. In the present study, 6- to 24-d-old alfalfa (Medicago sativa L.) seedlings were significantly more freezing-tolerant after cold-hardening than unhardened controls. Cold-hardened seedlings of age varying from 8 to 24 d were hardier than 6-d-old seedlings. No cultivar × seedling age interaction was found. The best separation of the cultivars occurred between 18 and 24 d. These findings provide additional information towards the development of a rapid and reliable test for estimating freezing tolerance in alfalfa.Key words: Freezing test, alfalfa, cold hardiness, seedlings
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Smith, Albert E. "The Potential Allelopathic Characteristics of Bitter Sneezeweed (Helenium amarum)." Weed Science 37, no. 5 (1989): 665–69. http://dx.doi.org/10.1017/s004317450007260x.
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Research was conducted to determine the potential for allelopathy to occur in pastures infested with bitter sneezeweed. Aqueous extracts of bitter sneezeweed leaves reduced alfalfa and Italian ryegrass seedling growth as much as 50% at concentrations of 0.5% (w/v). Leaf extracts were more phytotoxic than either stem or root extracts and seedling growth was reduced more than seed germination. Bitter sneezeweed tissue mixed in potting soil at concentrations as low as 0.3% w/w reduced alfalfa seedling numbers by 43%, plant height by 26%, and foliage dry matter production by 54% compared to plants cultured in soil without bitter sneezeweed leaf tissue. The potential concentration of bitter sneezeweed leaf material in soil in the pasture ecosystem was determined to be 0.5% w/v in the liquid phase and 0.2% w/w in the solid phase. Alfalfa seedling growth was reduced by 70% when germinating seed were placed under a bell jar with a potted mature bitter sneezeweed plant compared to control seedlings. A potential exists for bitter sneezeweed interference with developing alfalfa and Italian ryegrass seedlings following fall interseeding into pastures infested with bitter sneezeweed.
3
SIMONS, R. G. "RELATIONSHIPS BETWEEN SEEDLING TRAITS AND MATURE PLANT YIELD IN ALFALFA." Canadian Journal of Plant Science 70, no. 1 (1990): 209–13. http://dx.doi.org/10.4141/cjps90-023.
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To compare some seedling traits with the yield of alfalfa plants when grown as a crop stand, 1000 individually weighed seeds of Beaver alfalfa (Medicago sativa L.) were germinated in a growth chamber in a greenhouse mix containing soil. The dates of emergence and expansion of the first trifoliolate leaf, the weight of the first trifoliolate leaf, and the height, shoot number, leaf number and yield 10 wk after seeding were all correlated with each other. The seedlings were transplanted in late summer in to a 15 × 15-cm grid in the field, simulating a crop stand. Individual plant yields were determined in each of the two succeeding years. The number of shoots present at the first harvest was determined in the seedling year. There was no difference in the mean weight of seeds which emerged and those which did not. The mature plant traits were all strongly correlated with each other (P > 0.001). Although the seed weight and seedling traits had low correlations with mature plant traits (r < 0.25), the top 10% of seedlings on the basis of the date of first trifoliolate leaf expansion or seedling yield exceeded the population (averaged over the two years) by more than 31 and 41% respectively.Key words: Alfalfa, Medicago, seedling, selection, yield
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Linscott, Dean L., and Richard H. Vaughan. "Fenoxaprop for Annual Foxtail (Setariasp.) Control in Seedling Perennial Forages." Weed Technology 4, no. 3 (1990): 560–64. http://dx.doi.org/10.1017/s0890037x00025975.
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Seedling timothy tolerated fenoxaprop at 0.09 kg ai ha-1whereas seedling orchardgrass tolerated applications as high as 0.13 kg ai ha-1. Several fenoxaprop treatments increased perennial grass yields the year following establishment. Fenoxaprop appears to solve annual foxtail problems in new plantings of orchardgrass or timothy seeded alone. Over a 2-yr period, alfalfa yields in on alfalfa-grass mixture were maintained or increased from fenoxaprop applied the seedling year. In the mixtures, timothy yield declined in relation to fenoxaprop applied, but orchardgrass did not. Use of fenoxaprop on seedling alfalfa-timothy or alfalfa-orchardgrass mixtures is questionable.
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Hwang, S. F., B. D. Gossen, G. D. Turnbull, K. F. Chang, and R. J. Howard. "Seedbed preparation, timing of seeding, fertility and root pathogens affect establishment and yield of alfalfa." Canadian Journal of Plant Science 82, no. 2 (2002): 371–81. http://dx.doi.org/10.4141/p01-121.
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Invasion by grasses and weedy species occurs when plant density in alfalfa fields falls below critical levels. Several soil-borne fungal pathogens can reduce stand density in alfalfa by impeding seedling establishment and by killing older plants weakened by other stresses. Surveys of alfalfa fields were conducted in 1997, and pathogenic fungi from rotted roots were isolated and identified. Isolates of selected pathogens were applied with the seed in field trials to assess the impact of fertilizer and seeding system (conventional vs. sod-seeding, spring vs. dormant-fall seeding) on seedling emergence and subsequent productivity when disease pressure was high. The impact of various fungicide seed treatments was also assessed. Seed treatment improved seedling emergence and initial forage productivity in one of three trials; however, it had little effect on long-term forage yield. Addition of sulphur fertilizer had little effect on seedling emergence or survival, but improved forage productivity at all three trial sites. Sod-seeded plots suffered more winterkill and were less vigorous than plots seeded into a tilled seedbed. Seedling emergence was lower when seedlings were planted in the fall than in the spring. However, fall-seeded treatments showed a less adverse response to inoculum treatments and, in some cases, these seedlings were able to take advantage of early-season moisture to produce higher yields than their spring-seeded counterparts. Key words: Medicago, Fusarium, Pythium, Phoma, fungicide, seed treatment, fertilizer, tillage
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Samac, Deborah A., Samuel Schraber, and Stuart Barclay. "A Mineral Seed Coating for Control of Seedling Diseases of Alfalfa Suitable for Organic Production Systems." Plant Disease 99, no. 5 (2015): 614–20. http://dx.doi.org/10.1094/pdis-03-14-0240-re.
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Most alfalfa seed is treated with the fungicide mefenoxam (Apron XL) for control of soilborne seedling diseases caused by Phytophthora medicaginis and Pythium spp. However, Apron XL is not active against Aphanomyces euteiches, the causal agent of Aphanomyces root rot (ARR), an important component of the alfalfa seedling root rot complex. Moreover, Apron XL-treated seed cannot be used in organic production systems. A seed coating using aluminosilicate (natural zeolite) at a rate of 0.33 g of zeolite per gram of alfalfa seed was tested as an alfalfa seed treatment. Inoculated growth chamber trials were conducted to determine the percentage of seedlings protected from Phytophthora root rot (PRR) and ARR. The mineral seed coating resulted in significantly greater control of PRR, with a mean of 89% healthy seedlings (disease score of 1 or 2 on a 1-to-5 scale) compared with the Apron XL treatment, with a mean of 38% healthy seedlings, or the control treatment, with 15% healthy seedlings. The mineral seed coating also resulted in significantly greater protection against ARR, with 67% healthy seedlings compared with 3 and 2% healthy seedlings with the Apron XL and control treatments, respectively. The coated seed were used for in vitro assays with Pythium ultimum and P. paroecandrum to test for protection from seed rot and damping off. The mineral seed coating resulted in a significantly greater percentage of healthy seedlings compared with the Apron XL and control treatments. In growth chamber assays with naturally infested field soils with a range of disease pressure, the mineral seed coating resulted in a similar or greater percentage of healthy plants than the Apron XL treatment. The mineral coating had no effect on in vitro growth of Sinorhizobium meliloti, and nodule numbers were similar on roots from mineral-coated and untreated seed. These experiments indicate that the zeolite seed coating is a promising means of controlling seedling diseases in alfalfa production systems.
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Fischer, Albert J., Jean H. Dawson, and Arnold P. Appleby. "Interference of Annual Weeds in Seedling Alfalfa (Medicago sativa)." Weed Science 36, no. 5 (1988): 583–88. http://dx.doi.org/10.1017/s0043174500075445.
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Barnyardgrass [Echinochloa crus-galli(L.) Beauv. #4ECHCG] and pigweeds (mixture ofAmaranthus retroflexusL. # AMARE andA. powelliiS. Wats. # AMAPO) seeded separately with alfalfa (Medicago sativaL.) in mid-August suppressed alfalfa severely before frost killed them in October and November. Some alfalfa was killed, and yield of alfalfa forage was reduced in each of three harvests the following year. These weeds did not harm alfalfa seeded in mid-September. Downy brome (Bromus tectorumL. # BROTE) and tumble mustard (Sisymbrium altissimumL. # SSYAL) suppressed alfalfa seeded in August and September. They reduced alfalfa stands and reduced yield of alfalfa forage in each of three harvests the following year. Alfalfa seeded August 27 and allowed to compete with a mixture of these species for various periods was injured most by weeds that emerged with the alfalfa and remained uncontrolled until forage harvest in May. These weeds did not reduce alfalfa yields if removed by 36 days after alfalfa emergence. Thereafter, yield decreased as the period of weed interference increased. Interference was most damaging in early spring, when growth of winter annual weeds was rapid and vigorous. Weeds seeded 65 or more days after alfalfa emergence did not reduce alfalfa yields but sometimes produced enough biomass to reduce the quality of the first-cutting alfalfa hay.
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Kesoju, Sandya R., Rick A. Boydston, and Stephanie L. Greene. "Effect of Synthetic Auxin Herbicides on Seed Development and Viability in Genetically Engineered Glyphosate-Resistant Alfalfa." Weed Technology 30, no. 4 (2016): 860–68. http://dx.doi.org/10.1614/wt-d-16-00045.1.
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Feral populations of cultivated crops have the potential to function as bridges and reservoirs that contribute to the unwanted movement of novel genetically engineered (GE) traits. Recognizing that feral alfalfa has the potential to lower genetic purity in alfalfa seed production fields when it is growing in the vicinity of foraging pollinators in alfalfa seed fields, industry has established production standards to control feral plants. However, with the commercialization of GE glyphosate-resistant (GR) alfalfa and the need to support the coexistence of both GE and conventional production, effective methods to control transgenic feral alfalfa need to be developed. Therefore, a study was conducted in 2012, 2013, and 2014 to determine the effect of several synthetic auxin herbicides on seed development in GR alfalfa. GR alfalfa, var. Genuity (R44BD16), was treated with dicamba, 2,4-D, triclopyr, and aminopyralid when alfalfa plants contained green seed pods. Two weeks after herbicide application, plants were harvested, air dried, and seed yield, seed germination, and seedling emergence from the soil were determined. In 2013, dicamba, triclopyr, and 2,4-D decreased alfalfa seed yield per plant compared wih nontreated plants, whereas in 2014, all four herbicides decreased alfalfa seed yield per plant 24 to 49% (by weight) compared with nontreated plants. The same trend was evident in 2012, but seed yield was variable and was not significantly different among treatments. Seed germination averaged 43, 50, and 72% in 2012, 2013, and 2014, respectively, and was not affected by the four herbicides applied at early pod-fill stage. However, seeds harvested from plants treated with dicamba, 2,4-D, and triclopyr often produced deformed and abnormal seedlings, and when planted in soil, frequently failed to emerge. The combined effects of dicamba, 2,4-D, and triclopyr in reducing seed yield, seedling emergence, and seedling growth could contribute to managing feral alfalfa populations.
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Ells, James E., and Ann E. McSay. "Allelopathic Effects of Alfalfa Plant Residues on Emergence and Growth of Cucumber Seedlings." HortScience 26, no. 4 (1991): 368–70. http://dx.doi.org/10.21273/hortsci.26.4.368.
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Growth chamber tests demonstrated that alfalfa (Medicago sativa L.) residue is toxic to cucumber (Cucumis sativus L.) seed germination and seedling growth. Ground alfalfa roots at 0.5% (w/w, dry weight) inhibited germination when added to the growing medium. Alfalfa roots at 0.5% were also toxic to pregerminated cucumber seed. However, cucumber seedlings grew normally if this same medium was watered and incubated for >1 day before planting. Alfalfa particle size in media influenced cucumber performance, with the intermediate size (1 to 2 mm) being lethal to cucumbers.
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Tonks, Dennis, Larry S. Jeffery, and Bruce L. Webb. "Response of Seedling Alfalfa (Medicago sativa) to Four Postemergence Herbicides." Weed Technology 5, no. 4 (1991): 736–38. http://dx.doi.org/10.1017/s0890037x00033777.
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Response of seedling alfalfa to four herbicides applied at the 2nd, 4th, and 8th trifoliate leaf stages was evaluated in 1988 and 1989. There was no interaction between the herbicides and alfalfa growth stages at the time of herbicide application in either year. Bentazon did not reduce alfalfa height or yield of the first cutting in either year. The dimethylamine salt of 2,4-DB and bromoxynil reduced first-cutting alfalfa yield in 1988 and 1989, respectively, and the butoxyethanol ester of 2,4-DB reduced first-cutting alfalfa yield both years. Each herbicide affected one or more measurements of alfalfa quality in at least one year.
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TOUCHETTE, R., G. D. LEROUX, and J. M. DESCHÊNES. "ALLELOPATHIC ACTIVITY OF QUACKGRASS (Agropyron repens) EXTRACTS AND RESIDUES ON ALFALFA (Medicago sativa)." Canadian Journal of Plant Science 68, no. 3 (1988): 785–92. http://dx.doi.org/10.4141/cjps88-091.
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Experiments were conducted to characterize the allelopathic activity of quackgrass on alfalfa. Both percent germination and seedling length of alfalfa were recorded to evaluate the toxicity of aqueous extracts from rhizomes or shoots of field-grown quackgrass harvested at three stages of growth in 1984 and 1985. The length of alfalfa seedlings was more sensitive to extracts than was percentage of germination. Aqueous solutions simulating levels of salinity, cyanide content and osmotic pressure equivalent to those found in quackgrass extracts did not affect the growth of alfalfa seedlings. Only quackgrass extracts were phytotoxic to alfalfa. Similar results with hot and cold extraction procedures demonstrated that temperature did not influence the release of water-soluble toxins. Shoot extracts were generally more toxic than were rhizome extracts. Shoot extracts were more inhibitory to alfalfa seedlings when quackgrass was harvested at the vegetative stage than at later stages. Rhizome extracts did not influence the germination of alfalfa, whereas shoot extracts of vegetative quackgrass did in 1985 but not in 1984. The tolerance of alfalfa to rhizome and shoot extracts differed among eight alfalfa varieties. Incorporation of rhizome and shoot residues into the soil caused a similar level of yield reduction, whereas peat moss residues did not influence alfalfa yield. When quackgrass residues were incorporated into soil at various times before seeding, the yields of alfalfa were progressively reduced as the period of incubation was shortened. The incorporation of peat moss did not reduce the yield of alfalfa at any periods.Key words: Allelopathy, quackgrass, alfalfa, aqueous extracts, plant residues, Agropyron repens
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Girousse, C., R. Bournoville, and I. Badenhausser. "Evaluation of alfalfa resistance to the pea aphid, Acyrtosiphon pisum [Homoptera : Aphididae] – Methodological aspects to improve a standardized speedling test." Phytoprotection 79, no. 3 (2005): 139–48. http://dx.doi.org/10.7202/706142ar.
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This study proposes a guide for the design of experiments to test alfalfa (Medicago sativa) for resistance to pea aphid infestation (Acyrthosiphon pisum). This test was conducted in controlled conditions on alfalfa seedlings. For the infestation, aphid population maintained on alfalfa was found to be more efficient than an aphid population reared on broad bean. When comparing alfalfa cultivars, a non-choice test gave the same results as a choice test, that was more difficult to perform. When infesting a unit of 54 seedlings at the cotyledon stage on the 1st and 5th day of the experiment, 360 mg compared with 180 mg and 540 mg aphids, led to the best compromise between levels of infestation and aphid stock culture availability. Infestation was stopped when more than 60% of susceptible cultivar seedlings were wilted or dead. Under these conditions, we calculated the number of replicates necessary to obtain a fixed level of difference. Six units per cultivar would distinguish between cultivars differing from 20% in their seedling mortality.
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Assadian, N. Waissman, and S. Miyamoto. "Salt Effects on Alfalfa Seedling Emergence 1." Agronomy Journal 79, no. 4 (1987): 710–14. http://dx.doi.org/10.2134/agronj1987.00021962007900040026x.
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CUI, YUE, DA LIU, and JINRU CHEN. "Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli on Vegetable Seeds Contaminated by Direct Contact with Artificially Inoculated Soil during Germination." Journal of Food Protection 83, no. 7 (2020): 1218–26. http://dx.doi.org/10.4315/jfp-20-021.
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ABSTRACT Contaminated vegetable seeds have been identified as a potential source of foodborne bacterial pathogens. This study was undertaken to observe the behavior of Salmonella and enterohemorrhagic Escherichia coli (EHEC) on vegetable seeds, contaminated by direct contact with artificially inoculated soil, during germination. Sterile sandy soil inoculated with lyophilized cells of four individual strains of Salmonella or EHEC (three O157:H7 strains and one O104:H4 strain) was mixed with sanitized seeds (2 g) of alfalfa, fenugreek, lettuce, and tomato at 20°C for 1 h. The contaminated seeds were germinated on 1% water agar at 25°C for 9 days in the dark. Populations of Salmonella and EHEC on various tissues (seed coat, root, cotyledon, and stem, etc.) of sprouts and seedlings were determined every other day over the germination period. Overall, 70.4 and 72.4% of collected tissue samples (n = 544) tested positive for Salmonella and EHEC, respectively. In general, the mean populations of Salmonella and EHEC on sprout and seedling tissues increased with the prolongation of germination time. Seed coats had the highest bacterial counts (4.00 to 4.06 log CFU/0.01 g), followed by the root (3.36 to 3.38 log CFU/0.01 g), cotyledon (3.13 to 3.38 log CFU/0.01 g), and stem tissues (2.67 to 2.84 log CFU/0.01 g). On average, tissue sections of fenugreek sprouts and lettuce seedlings had significantly higher (P &lt; 0.05) numbers of Salmonella and EHEC cells than that of alfalfa sprouts and tomato seedlings. Data suggest that the growth and dissemination of Salmonella and EHEC cells on alfalfa, fenugreek, lettuce, and tomato sprout and seedling tissues are influenced by the type of vegetable seeds and sprout and seedling tissues involved. The study provides useful information on the fate of two important foodborne bacterial pathogens on selected vegetable seeds, contaminated by direct contact with inoculated soil, during the germination process. HIGHLIGHTS
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Malik, Najib, and John Waddington. "Alfalfa (Medicago sativa) Seed Yield Response to Herbicides." Weed Technology 4, no. 1 (1990): 63–67. http://dx.doi.org/10.1017/s0890037x00024994.
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Seedling alfalfa was injured by chlorsulfuron and sethoxydim plus 2,4-DB but recovered the following year as alfalfa seed yields were comparable to the hand-weeded control. Fluazifopbutyl and flamprop-methyl (active isomer) at 0.5 kg/ha did not affect seedling alfalfa adversely; however, seed yields were lower the following year compared to those treated at the 0.25-kg/ha rate. In established alfalfa, sethoxydim alone or with 2,4-DB applied annually did not affect seed yields adversely. However, 2,4-DB alone reduced seed yields in 2 of 5 yr. Alfalfa tolerated chlorsulfuron at 0.015 kg/ha but was damaged at the 0.03-kg/ha rate. Initial injury and later recovery without adverse effects on seed yield also were observed following annual treatments with bromoxynil, MCPA plus 2,4-DB and bentazon plus 2,4-DB.
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Schellenberg, Michael P., John Waddington, and Jane R. King. "Sod-seeding alfalfa in spring into established crested wheatgrass in southwest Saskatchewan." Canadian Journal of Plant Science 74, no. 2 (1994): 293–301. http://dx.doi.org/10.4141/cjps94-057.
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Five experiments were started over a 3-yr period to examine the width of a strip of established crested wheatgrass (Agropyron desertorum (Fisch.) Schult.) that should be killed for reliable establishment of alfalfa (Medicago sativa L.) by sod-seeding in semiarid southwestern Saskatchewan. The value of pruning the grass roots along the edges of the killed area for alfalfa establishment was also examined. When alfalfa seeds were sown in a single row in strips of dead crested wheatgrass, alfalfa establishment improved as the width of the dead strip increased up to 75 cm, the maximum used, because of less competition for moisture and light. Pruning grass roots did not improve alfalfa establishment. Killing the crested wheatgrass in a strip wider than 50 cm favoured weed growth. Annual and biennial weeds were present only in the establishment year, but perennials persisted for the duration of the experiments. Yields of Rangelander, a creeping-rooted alfalfa of mixed ssp. sativa (L.) Lesins & Lesins and ssp. falcata (L.) Arcangeli parentage, and SCMf3713, a tap-rooted ssp. falcata were similar in the seedling and the following year. Etiolated growth of established plants revealed that SCMf3713 had a more persistent recovery characteristic which probably confers survival ability in severe environments. Killing the resident crested wheatgrass benefitted alfalfa establishment, as measured by seedling numbers, growth, seedling and first harvest year yields, and root reserves. Key words: Crested wheatgrass, sod-seeding, alfalfa, Agropyron desertorum, Medicago sativa
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Reichard, S. L., R. M. Sulc, L. H. Rhodes, and M. M. Loux. "Effects of Herbicides on Sclerotinia Crown and Stem Rot of Alfalfa." Plant Disease 81, no. 7 (1997): 787–90. http://dx.doi.org/10.1094/pdis.1997.81.7.787.
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This study was conducted to determine whether herbicides and adjuvants registered for poste-mergence use in alfalfa have an effect on Sclerotinia crown and stem rot (SCSR). In a controlled environment, disease severity index (DSI) of alfalfa seedlings was reduced by pronamide and 2,4-DB compared with the untreated control, whereas bromoxynil and 13% sethoxydim + petroleum-based adjuvant (PBA) increased DSI. In the field, disease severity in all herbicide treatments was similar to that in untreated alfalfa. In a second controlled-environment study, pronamide and 2,4-DB reduced DSI compared with the no herbicide control when seedlings were inoculated 1 day after herbicide application, but this protective effect was not observed when seedlings were inoculated 8 days or longer after herbicide application. The results demonstrate that several herbicides are capable of suppressing or enhancing SCSR severity in a controlled environment if seedling inoculation occurs soon after herbicide application; however, the residual effect of these herbicides on SCSR appeared to be much shorter than the 4- to 6-week infection period occurring in the field.
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Wilson, Robert G. "Weed Control in Irrigated Seedling Alfalfa (Medicago sativa)." Weed Science 34, no. 3 (1986): 423–26. http://dx.doi.org/10.1017/s0043174500067114.
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Spring-applied herbicides were evaluated in the field in 1982 through 1984 in western Nebraska for selective weed control in irrigated seedling alfalfa (Medicago sativaL. ‘Appollo’). Weed densities were least in plots treated preplant with benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine] in combination with postemergence applications of 2,4-DB [4-(2,4-dichlorophenoxy) butyric acid]. Combinations of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} with bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and fluazifop-butyl {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} with bromoxynil provided less grass control than sethoxydim or fluazifop-butyl applied alone. Annual weeds did not reduce alfalfa stand density.
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Hagood, Edward S. "Herbicide Treatments for No-Till Alfalfa, Medicago sativa L., Establishment in Sod." Weed Technology 2, no. 3 (1988): 327–32. http://dx.doi.org/10.1017/s0890037x00030682.
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Field experiments were established to evaluate the effect of herbicide treatments on control of tall fescue before spring or fall no-till alfalfa planting and to determine the effect of fescue control on alfalfa seedling establishment, forage yield, and forage quality. No treatment provided significantly greater tall fescue control than the standard two applications of paraquat at 13- to 21-day intervals. Fescue control values with this treatment ranged from 86 to 99% over experiments and were associated with maximum values for alfalfa ground-cover and alfalfa yield percentage parameters, 52 to 83% and 64 to 96%, respectively. Glyphosate and SC-0224 at 2.2 kg/ha and greater generally gave tall fescue control equivalent to the paraquat treatment in both spring and fall seedings as did sethoxydim at 0.6 kg/ha in spring seedings. Applications of fluazifop or HOE-0661 did not result in satisfactory tall fescue control or alfalfa establishment. Adding nonionic surfactant to glyphosate or SC-0224 did not increase tall fescue control. There was a direct linear relationship between tall fescue control and both alfalfa seedling establishment and yield percentage.
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Kells, James J., Richard H. Leep, Milo B. Tesar, Richard A. Leavitt, and John Cudnohufsky. "Effect of Atrazine and Tillage on Alfalfa (Medicago sativa) Establishment in Corn (Zeaways)-AlfaIfa Rotation." Weed Technology 4, no. 2 (1990): 360–65. http://dx.doi.org/10.1017/s0890037x00025549.
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The effect of atrazine rate and subsequent tillage on seedling alfalfa injury from atrazine carry-over was examined at two locations in Michigan. Atrazine concentration and alfalfa injury 1 yr after treatment were greater in the northern location than in the central Michigan location. At both locations, alfalfa injury was significantly greater under no-tillage than moldboard plowing. With no-tillage, alfalfa was injured more in the area between the previous corn rows than within the rows. Analysis of soil samples collected from within corn rows and between rows showed higher atrazine concentration between the corn rows.
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Forney, D. Raymond, Chester L. Foy, and Dale D. Wolf. "Weed Suppression in No-Till Alfalfa (Medicago sativa) by Prior Cropping of Summer-Annual Forage Grasses." Weed Science 33, no. 4 (1985): 490–97. http://dx.doi.org/10.1017/s0043174500082710.
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A sorghum-sudangrass hybrid [Sorghum bicolor(L.) Moench. xSorghum sudanense(P.) Stapf. ‘DEKALB SX17+’] (SSH) and foxtail millet [Setaria italica(L.) Beauv.] (FM) were evaluated for their effects on weed populations when grown for forage and as land conditioners prior to late-summer, no-till planting of alfalfa (Medicago sativaL. ‘Arc’). Both grasses established well in no-till situations, except for FM when excessive mulch impeded seed placement or seedling summer-annual weeds were not destroyed at planting time. SSH was the better competitor; after both were planted into a dense stand of seedling summer-annual weeds, SSH outyielded the weeds while FM did not. Both grasses suppressed weeds and enhanced subsequent alfalfa establishment. Obtaining adequate alfalfa stands was not a problem in no-till seedings: seedling populations often exceeded 300/m23 to 6 weeks after planting. Lack of adequate weed control was associated with stand losses in which disease was also a factor. Biennial and perennial broadleaf species were the predominant weeds. Prior cropping of SSH or FM is a valuable option for growers wishing to establish alfalfa without tillage, particularly when summer forage is useful.
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Ratcliffe, Roger H., and James H. Elgin. "A Seedling Test to Select for Alfalfa Weevil (Coleoptera: Curculionidae) Resistance in Alfalfa." Journal of Economic Entomology 80, no. 4 (1987): 975–78. http://dx.doi.org/10.1093/jee/80.4.975.
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Bell, Carl E., and Juan N. Guerrero. "Sheep grazing effectively controls weeds in seedling alfalfa." California Agriculture 51, no. 2 (1997): 19–23. http://dx.doi.org/10.3733/ca.v051n02p19.
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Dornbos, David L., Gayland F. Spencer, and Roger W. Miller. "Medicarpin Delays Alfalfa Seed Germination and Seedling Growth." Crop Science 30, no. 1 (1990): 162–66. http://dx.doi.org/10.2135/cropsci1990.0011183x003000010035x.
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Blanchar, R. W., and D. S. Lipton. "The pe and pH Alfalfa Seedling Rhizospheres 1." Agronomy Journal 78, no. 1 (1986): 216–18. http://dx.doi.org/10.2134/agronj1986.00021962007800010044x.
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Mahawar*, Pratibha, and Azra Akhtar. "Impact of dye effluent on growth and chlorophyll content of Alfalfa (Medicago sativa l.)." Annals of Plant Sciences 5, no. 10 (2016): 1432. http://dx.doi.org/10.21746/aps.2016.10.002.
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The textile industry plays an important role in the world economy as well as in our daily life time, it consumes large quantity of water and generates huge amount of waste water. The chemical reagents used in the textile sector are diverse in chemical composition ranging from inorganic to organic molecules. The presence of these chemicals will show detrimental effects on the germination process and growth of seedlings. Present research work has been carried out to study the impact of effluent at different concentrations (20%, 40%, 60%, 80%, 100%) on seed germination and seedling growth of Medicago sativa. On the 14th day of seedling growth, maximum root and shoot length were observed at 20% concentration of effluent i.e. 5.4cm (root length) and 5.1cm (shoot length) which increased 3.8% and 4.0% respectively in comparison to control. At high concentrations of treatment levels root length was decreased 2.04%, 19.2%, 26.5%, 51.0% respectively and shoot length was decreased 3.84%, 17.3%, 26.9%, 44.2% respectively at 40%, 60%, 80% and 100% treatment levels in comparison to control (4.9cm and 5.2cm respectively). Same trend was observed during estimation of dry weight and chlorophyll contents. Inhibition of seedling germination and seedling growth at higher concentrations of effluent may be due to high level of dissolved solids which inhance the salinity. The present study concluded that the dyeing effluent waste significantly influence growth parameters of Medicago sativa.
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May, W. E., H. A. Loeppky, D. C. Murrell, C. D. Myhre, and J. J. Soroka. "Preharvest glyphosate in alfalfa for seed production: Effect on alfalfa seed yield and quality." Canadian Journal of Plant Science 83, no. 1 (2003): 189–97. http://dx.doi.org/10.4141/p01-196.
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Preharvest applications of glyphosate have been shown to be effective in controlling Canada thistle in annual crops, but may reduce alfalfa seed yield depending on time and rate of application. The objective of this study was to determine the effect of preharvest applications of glyphosate on subsequent alfalfa seed yield and quality. The effects of timing, 1, 26, 51 and 76% alfalfa seed pod maturity, and rate, 0, 440, 880, 1320, and 1760 g a.i. ha-1, of a preharvest application of glyphosate on alfalfa seed yield and quality in the year of application, and regrowth and seed yield in the following year were determined. The rate of glyphosate applied did not affect seed yield in the application year; however, in the following year, growth and seed yield were reduced as rates increased. Delaying the application of glyphosate increased seed yields in the application year, but decreased alfalfa regrowth and flowering the following year. Germination and seedling emergence were not affected by the rate or timing of the glyphosate. A preharvest application of glyphosate at 1760 g a.i. ha-1 at 76% pod maturity is a viable option in the last year of seed production. Key words: Alfalfa (Medicago sativa L.), glyphosate, abnormal seeds, seed quality, and seedling vigour
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Miralles, Pola, Errin Johnson, Tamara L. Church, and Andrew T. Harris. "Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake." Journal of The Royal Society Interface 9, no. 77 (2012): 3514–27. http://dx.doi.org/10.1098/rsif.2012.0535.
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Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l −1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe 3 O 4 -functionalized CNTs were prepared and studied using energy-filter mapping of Fe 3 O 4 . CNTs bearing Fe 3 O 4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.
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Ells, James E., Ann E. MeSay, and Stephen M. Workman. "Toxic Effects of Manure, Alfalfa, and Ammonia on Emergence and Growth of Cucumber Seedlings." HortScience 26, no. 4 (1991): 380–83. http://dx.doi.org/10.21273/hortsci.26.4.380.
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Chopped alfalfa (Medicago sativa L.), alfalfa hay extract, and ammonium hydroxide produced free ammonia in media and inhibited both germination and seedling growth of cucumber (Cucumis sativus L.). Toxic levels of ammonia were not produced by the quantities of manure added to the media. Alfalfa extract enhanced cucumber seedling growth in sand medium while inhibiting growth in sand-soil media. This difference is attributed to a reduced level of microbial activity in the sand. With higher levels of microbial activity, rapid decomposition of the extract may have resulted in a burst of ammonia evolution that proved damaging to cucumbers. The natural buffering capacity of the soil medium apparently mitigated the effects of the ammonia. Ammonium hydroxide, which did not depend on microbiological activity to release ammonia, proved lethal to cucumbers grown in sand. A diminished effect on growth was observed as the cation exchange capacity of the medium increased. Because high levels of alfalfa hay and ammonium hydroxide were required to produce toxic levels of ammonia in soil, it is unlikely that cucumbers would be harmed under normal field usage of alfalfa hay.
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Pino, J., F. X. Sans, and R. M. Masalles. "Effects of intrinsic and environmental factors on seedling survival of Rumex obtusifolius in Mediterranean alfalfa crops." Canadian Journal of Botany 75, no. 6 (1997): 939–45. http://dx.doi.org/10.1139/b97-104.
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This paper focusses on the survivorship pattern of seedlings of Rumex obtusifolius L. in the irrigated alfalfa crops (Medicago sativa L.) in central Catalonia (NE Spain). The relationship between this pattern and seasonal environmental change was evaluated by monitoring seedling cohorts that had germinated at different times of the year for 31 months. Paired comparisons of cohort survivorship curves were performed over their life-spans and for their coexistence period, using Peto and Peto's log rank test. The significance of intrinsic variables such as age and size in determining seedling survival was tested using hierarchical log-linear analysis applied on a three-way contingency table and by means of Goodman and Kruskal's association coefficients. Results showed that seedling cohorts emerging at different times in the year exhibited a similar Deevey type III survivorship pattern. Therefore, survivorship was scarcely affected by seasonal environmental variation. However, since age had little effect on seedling survival compared with size, this age-specific survivorship pattern was, in fact, a consequence of both size-dependent mortality and changes in size distribution with age. In the first weeks of life, cohort size distribution was greatly skewed to the smallest classes, with the highest mortality rates, and therefore the risk of death in the cohort was high. Afterwards, the frequency of the largest size classes increased with age, thus reducing the risk of death of the cohort. Key words: Rumex obtusifolius, seedling survivorship pattern, size versus age dependency, survival analysis.
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Berg, Laurine E., Susan S. Miller, Melinda R. Dornbusch, and Deborah A. Samac. "Seed Rot and Damping-off of Alfalfa in Minnesota Caused by Pythium and Fusarium Species." Plant Disease 101, no. 11 (2017): 1860–67. http://dx.doi.org/10.1094/pdis-02-17-0185-re.
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Globally, 15 Pythium species have been found to cause damping-off and seed rot of alfalfa, although surveys of species causing disease on alfalfa in the midwestern United States are lacking. Pathogens were isolated by a seedling baiting technique from soil samples of five alfalfa fields in Minnesota with high levels of damping-off. Of the 149 organisms isolated, 93 (62%) were identified as Pythium spp. and 43 (29%) were identified as Fusarium species. Pythium sylvaticum, P. irregulare, and P. ultimum var. ultimum were aggressive pathogens on germinating alfalfa seedlings. Strains of seven Pythium spp. pathogenic on soybean and corn were also pathogenic on alfalfa. The majority of the Fusarium isolates were identified as F. solani and F. oxysporum with a low number of F. redolens and F. incarnatum-equiseti. The F. oxysporum and F. incarnatum-equiseti strains were the most aggressive in causing seed and root rot. Pythium strains were sensitive to Apron XL (mefenoxam) and pyraclostrobin in vitro but efficacy varied when the fungicides were applied as a seed treatment. Seed treatments with Apron XL were more effective than treatments with Stamina against Pythium. The presence of aggressive, broad-host-range pathogens causing seed rot and damping-off suggests that new strategies are needed for managing this disease in alfalfa production systems.
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Ashrafi, Ensieh, Morteza Zahedi, and Jamshid Razmjoo. "Effects of salt stress on lipid peroxidation and antioxidative enzymes of alfalfa (Medicago sativa L.) cultivars." Bangladesh Journal of Botany 43, no. 2 (2015): 191–96. http://dx.doi.org/10.3329/bjb.v43i2.21672.
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The effect of salt stress on enzyme activities of nine alfalfa cultivars at germination and seedling stage was studied. The activities of SOD, GR, POX and APOX were higher in salt tolerant and lower in salt sensitive cultivars. Results of the effect of salt stress on the SOD, GR, POX, APOX activities and MDA content may be used to select salt tolerance cultivars at the germination and seedling stages. SOD, GR, POX, APOX and MDA may play an important role in salt tolerant mechanisms in alfalfa. DOI: http://dx.doi.org/10.3329/bjb.v43i2.21672 Bangladesh J. Bot. 43(2): 191-196, 2014 (September)
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Cudney, David W., Steve B. Orloff, and Carol J. Adams. "Improving Weed Control with 2,4-DB Amine in Seedling Alfalfa (Medicago Sativa)." Weed Technology 7, no. 2 (1993): 465–70. http://dx.doi.org/10.1017/s0890037x00027895.
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2,4-DB ester had been widely used for winter annual broadleaf weed control in seedling alfalfa in the western United States, but was replaced commercially by the amine formulation in 1990. Field studies conducted in the high desert region of southern California confirmed previous reports that 2,4-DB amine is not as effective as the ester formulation. Two methods were found to improve the weed control performance of 2,4-DB amine: 1) application at earlier alfalfa growth stages and 2) the addition of adjuvant. Applications made at the three-trifoliate leaf stage of the alfalfa were more than three times as effective as applications made at the eight-trifoliate leaf stage. When adjuvants were added to the amine formulation, weed control was improved 50 to 97%.
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Peregrine, Esther K., and Robert F. Norris. "Environmental Modification of Seedling Alfalfa,Medicago sativa, Tolerance to Bromoxynil." Weed Science 36, no. 5 (1988): 671–77. http://dx.doi.org/10.1017/s0043174500075603.
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Seedling alfalfa exhibited increased phytotoxicity from bromoxynil when applications were made with temperatures greater than 28 C both in controlled environments and in the field. Treatments applied in the morning were more phytotoxic than treatments made in the late afternoon. In laboratory experiments, inhibition of oxygen evolution occurred within 1 h after treatment. The amount of permanent damage sustained was dependent on the rate of bromoxynil and the length of time the alfalfa was exposed to light or darkness immediately after spraying. Bromoxynil treatments in cool weather and/or in the late afternoon should minimize injury to the crop.
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Goplen, Jared J., Craig C. Sheaffer, Roger L. Becker, et al. "Seedbank Depletion and Emergence Patterns of Giant Ragweed (Ambrosia trifida) in Minnesota Cropping Systems." Weed Science 65, no. 1 (2016): 52–60. http://dx.doi.org/10.1614/ws-d-16-00084.1.
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In the midwestern United States, biotypes of giant ragweed resistant to multiple herbicide biochemical sites of action have been identified. Weeds with resistance to multiple herbicides reduce the utility of existing herbicides and necessitate the development of alternative weed control strategies. In two experiments in southeastern Minnesota, we determined the effect of six 3 yr crop-rotation systems containing corn, soybean, wheat, and alfalfa on giant ragweed seedbank depletion and emergence patterns. The six crop-rotation systems included continuous corn, soybean–corn–corn, corn–soybean–corn, soybean–wheat–corn, soybean–alfalfa–corn, and alfalfa–alfalfa–corn. The crop-rotation system had no effect on the amount of seedbank depletion when a zero-weed threshold was maintained, with an average of 96% of the giant ragweed seedbank being depleted within 2 yr. Seedbank depletion occurred primarily through seedling emergence in all crop-rotation systems. However, seedling emergence tended to account for more of the seedbank depletion in rotations containing only corn or soybean compared with rotations with wheat or alfalfa. Giant ragweed emerged early across all treatments, with on average 90% emergence occurring by June 4. Duration of emergence was slightly longer in established alfalfa compared with other cropping systems. These results indicate that corn and soybean rotations are more conducive to giant ragweed emergence than rotations including wheat and alfalfa, and that adopting a zero-weed threshold is a viable approach to depleting the weed seedbank in all crop-rotation systems.
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Lopez‐Jurado, G., and D. B. Hannaway. "Sulfur nutrition effects on dinitrogen fixation of seedling alfalfa." Journal of Plant Nutrition 8, no. 12 (1985): 1103–21. http://dx.doi.org/10.1080/01904168509363410.
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Holub, E. B. "Specificity of Resistance to Aphanomyces euteiches in Seedling Alfalfa." Plant Disease 74, no. 2 (1990): 164. http://dx.doi.org/10.1094/pd-74-0164.
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Acharya, S. N., and H. Steppuhn. "Bridgeview alfalfa." Canadian Journal of Plant Science 92, no. 1 (2012): 203–6. http://dx.doi.org/10.4141/cjps2011-114.
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Acharya, S. N. and Steppuhn, H. 2012. Bridgeview alfalfa. Can. J. Plant Sci. 92: 203–206. Bridgeview salt tolerant alfalfa (Medicago sativa L.) was developed by the Agriculture and Agri-Food Canada Research Centre, Lethbridge, Alberta in cooperation with the salt laboratory at Semiarid Prairie Agricultural Research Centre, Swift Current, Saskatchewan. This synthetic cultivar, tested as SC-A101 in the Western Forage Testing System (WFTest), was developed for improved seedling vigor and high forage yield under saline conditions. This cultivar yielded about 1% better than Beaver check in the WFTest over 36 location years. The pedigree of this cultivar consists of saline tolerant selections from Apica, AC Blue J, Barrier, Beaver, Heinrichs, Rangelander and Roamer alfalfa. This cultivar produced higher dry matter yield than Beaver in the third year of a test conducted in a naturally saline seep area in Vauxhall, AB. SC-A101 was found to perform significantly higher emergence, survival and biomass production than Rangelander alfalfa in an indoor test at salt levels higher than 16 dS m−8. Bridgeview was registered by CFIA on 2011 May 16 (Reg. No. 7018) and was licensed to SeCan for seed multiplication and distribution. This cultivar is well suited for hay production in western Canada.
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Ren, Lei, and Yuguang Bai. "Smoke originating from different plants has various effects on germination and seedling growth of species in Fescue Prairie." Botany 94, no. 12 (2016): 1141–50. http://dx.doi.org/10.1139/cjb-2016-0185.
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Little is known about how smoke, an important germination cue, influences seed regeneration of species in Fescue Prairies. Whether germination and seedling growth responses vary with smoke produced from different materials is still ambiguous. In this study, seeds of four forbs from a Fescue Prairie were primed in serial dilutions of aqueous smoke solutions produced from alfalfa (Medicago sativa L.), prairie hay (Festuca hallii (Vasey) Piper), and wheat straw (Triticum aestivum L.), and incubated at 10–0 °C or 25–15 °C in a 12 h light – 12 h dark cycle or 24 h darkness for 49 d. Nonprimed seeds and those primed in distilled water were used as controls. Germination and radical length of Conyza canadensis (L.) Cronquist increased after priming in concentrated smoke-solutions derived from alfalfa, but decreased after priming in the same concentrated smoke solutions made from prairie hay and wheat straw at 25–15 °C in 24 h darkness. Smoke substituted for light improved germination of Artemisia ludoviciana Nutt. Our results indicate that the effect of smoke on seed germination and seedling growth was temperature- and light-dependent. It appears that smoke produced from alfalfa had different compounds that, in turn, had different germination and seedling growth responses as compared with the smoke produced from prairie hay and wheat straw.
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Malvick, D. "Aphanomyces euteiches Race 2 in Central Illinois Alfalfa Fields." Plant Disease 86, no. 5 (2002): 560. http://dx.doi.org/10.1094/pdis.2002.86.5.560a.
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Approximately 260,000 ha of alfalfa is grown in Illinois. Two soil samples were collected randomly from slowly drained thin patches in each of four established alfalfa fields near Urbana in 2001. Plants in the thin patches were asymptomatic. Aphanomyces euteiches Drechs. was baited from the soil with cv. Saranac alfalfa seedlings and was isolated from 3- to 4-week-old infected seedlings using a medium containing metalaxyl and benomyl (1,2). It is difficult to isolate A. euteiches from field-grown roots. One to seven isolates were obtained per field, and all were identified as A. euteiches based on morphology (1,2). A. euteiches (races R1 and R2) causes root rot of alfalfa in slowly drained fields in Iowa, Kentucky, and Wisconsin (1,2). The race of 13 isolates was determined in tests repeated once with alfalfa populations Saranac (susceptible to R1 and R2), WAPH-1 (resistant only to R1), and WAPH-5 (resistant to R1 and R2) (1). Twelve 7-day-old seedlings in each of three pots per population were inoculated with 103 zoospores per seedling in a growth chamber (25°C). A disease index (DI) was determined 12 days later by scoring plants on a 1 to 5 scale, where 5 is a dead plant (1). Race was based on DI, R1: DI ≥3 for Saranac and <3 for WAPH-1, and R2: DI > 3 for Saranac and WAPH-1. The DI was 1.0 for noninoculated plants. All isolates were R2; the DI was >3.0 for inoculated Saranac and WAPH-1 and <3.0 for WAPH-5. To our knowledge, this is the first report of A. euteiches races in Illinois, and this pathogen was reported previously only from northwest Illinois. Control of Aphanomyces root rot is based on resistance; however, few alfalfa cultivars are resistant to R2. References: (1) D. Malvick and C. Grau. Plant Dis. 85:740, 2001. (2) G. Munkvold and W. Carlton. Plant Dis. 79:1251,1995.
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Favero, Daniela, Simone Meredith Scheffer-Basso, and Cerci Maria Carneiro. "Morphological development of Alfagraze cultivar and Crioula alfalfa populations selected at the seedling stage." Revista Brasileira de Zootecnia 38, no. 4 (2009): 605–10. http://dx.doi.org/10.1590/s1516-35982009000400003.
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The objective of this study was to compare two populations of Crioula alfalfa cultivars, selected by the length of the seedling second internode (Crioula-LI, long internode = 2.5 cm; Crioula-SI, short internode = 1.5 cm) with Alfagraze cultivar in order to verify the seedling morphology value for the selection of more prostrate plants. The plants were grown individually in pots in a semi-protected environment and harvested at 74, 104, 134, 164, 194 and 224 days. Crioula populations varied in terms of height, leaf area, root volume, dry matter yield, and the Crioula-LI population outnumbered that of Crioula-SI. For height, length of internode and primary stem, Alfagraze (45.1 cm, 2.1 cm and 16.7 cm) was similar to Crioula-SI (37.6 cm, 2.3 cm and 18.2 cm); however, the leaf area (2.028 cm²) and dry matter yield (20.3 g) did not differ from those of Crioula-LI (2.021 cm², 21 g). The Alfagraze cultivar surpassed the Crioula population in terms of procumbency, crown diameter and crown stem number. At the flowering stage, the Crioula-LI cultivar had total stem number (61/plant) higher than Alfagraze (47/plant) and Crioula-SI (41/plant) cultivars. The length of the seedling internode is a promising marker for the selection of alfalfa, being a predictive factor for plant height, stem number, root volume and leaf area, and can be useful in the alfalfa breeding.
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Hancock, J. G. "Seedling and Rootlet Diseases of Forage Alfalfa Caused byPythium irregulare." Plant Disease 75, no. 7 (1991): 691. http://dx.doi.org/10.1094/pd-75-0691.
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Teutsch, Christopher D., and R. Mark Sulc. "Influence of Seedling Growth Stage on Flooding Injury in Alfalfa." Agronomy Journal 89, no. 6 (1997): 970–75. http://dx.doi.org/10.2134/agronj1997.00021962008900060020x.
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Waddington, John, and Marvin C. Snoop. "Using small tubes to measure root elongation of newly germinated alfalfa seedlings in relation to moisture." Canadian Journal of Plant Science 74, no. 2 (1994): 215–19. http://dx.doi.org/10.4141/cjps94-045.
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A method of growing newly germinated seedlings in small tubes was developed to enable the study of early root elongation. Three newly germinated alfalfa (Medicago sativa L.) seeds were placed in tubes of various diameters and volumes filled with sand at several moisture tensions, and the tubes were sealed to prevent moisture loss. For the first 4 d, roots elongated at approximately 8 mm d−1 in polyvinyl chloride plastic tubes holding 60 mL of sand with a moisture tension of 100 kPa or less. After the initial 4 d, root elongation continued at a slower rate, and branch roots developed before termination of the experiments at 12 d after germination. At a moisture tension of 300 kPa, root elongation was markedly less than at 100 kPa, and was zero at moisture tensions of 500 kPa or greater. In round-bottom glass tubes, root elongation rate was significantly slower in a sand volume of 23 mL than in 65 mL, and there was evidence of slower seedling development as the diameter of the tubes was reduced from 20 to 15 mm. Wax plus masking tape or nylon tape were equally effective in sealing the sides of tubes formed from the two halves of a plastic pipe previously cut lengthwise. A plastic cap plus wax was significantly better than plastic film for sealing the bottom ends of plastic tubes. Neither aeration nor replacement of water with a dilute nutrient solution had an effect on root elongation of young seedlings. Key words: Alfalfa, seedling, root elongation, moisture stress, Medicago sativa
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Barta, A. L., R. M. Sulc, M. J. Ogle, and R. B. Hammond. "Interaction Between Flooding or Drought Stress and Potato Leafhopper Injury in Alfalfa." Plant Health Progress 3, no. 1 (2002): 10. http://dx.doi.org/10.1094/php-2002-0502-01-rs.
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Potato leafhopper is a predominant biotic stress in alfalfa production, whereas drought and flooding are frequent abiotic stresses. Controlled environment studies were conducted to examine the interaction between flooding or drought stress and potato leafhopper (PLH, Empoasca fabae [Harris]) feeding damage on seedlings of two cultivars of alfalfa (Medicago sativa L): one susceptible to PLH, one resistant to PLH. Flooding treatments reduced shoot dry matter accumulation approximately 50% in the absence of PLH in both cultivars and significantly reduced root dry matter in one cultivar. Drought stress significantly reduced shoot dry matter and increased root dry matter. PLH feeding combined with either flooding or drought stress reduced root dry matter accumulation but not shoot dry matter. Flooding injury and PLH feeding injury showed an additive negative response for root dry matter accumulation. Flooded and non-stressed plants accumulated less root total non-structural carbohydrates (TNC) when subjected to PLH feeding. Responses of the two cultivars were similar across all biotic and abiotic treatments. The results clearly show that the most damaging physiological response of seedling alfalfa to PLH feeding is a sharp decline in root growth and TNC accumulation. This suggests that seedlings that have experienced even minor root waterlogging damage may be especially susceptible to damage by PLH feeding. Accepted for publication 23 April 2002. Published 2 May 2002.
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Miller, Amanda J., Vagner M. Leite, Linda M. Hall, and Edward W. Bork. "Forage Legume Establishment under Exposure to Progressive Declines in Aminocyclopyrachlor and Aminopyralid in Temperate Pastures." Agronomy 10, no. 3 (2020): 392. http://dx.doi.org/10.3390/agronomy10030392.
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Legumes such as alfalfa (Medicago sativa L.) and white clover (Trifolium repens L.) increase forage productivity and quality in northern temperate pastures, but require re-establishment following broadleaf weed control using herbicides. To quantify the residual effects of two herbicides (aminocyclopyrachlor and aminopyralid) on potential legume re-establishment we examined alfalfa and clover recruitment at two field sites over two years. Sites were over-seeded with alfalfa and clover to populate the seed bank, and then sprayed with herbicide, after which seedling densities were monitored in late summer and fall of the current growing season. Defoliation (via mowing) effects were also assessed to evaluate the role of vegetation competition on legume establishment. Herbicides were applied at recommended rates (1.0), and 0.5, 0.25, 0.125, 0.0625, and 0 times recommended field rates, emulating exponential herbicide degradation (one through four half-lives). Alfalfa and white clover seedling densities were negatively impacted by all rates of herbicide, with modestly greater negative impacts from aminopyralid than aminocyclopyrachlor, although responses to herbicides remained site and legume specific. Reductions in alfalfa and clover were particularly evident through the 0.25 (i.e., two half-life) herbicide rate, with reductions in alfalfa ranging from 78% to 95%, and in clover from 73% to 88%. Legume densities at the 0.125 (three half-life) rate were 39%–68% lower than those in nonsprayed control plots. Our results suggest that at least three half-lives of degradation must occur, and likely four or more, before these legumes can re-establish at densities acceptable for pasture production. These findings have implications for producers seeking to promptly re-establish forage legumes within pastures sprayed for broadleaf weed control in northern temperate regions.
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Chen, Zhao, Xin-long Cao, and Jun-peng Niu. "Effects of exogenous ascorbic acid on seed germination and seedling salt-tolerance of alfalfa." PLOS ONE 16, no. 4 (2021): e0250926. http://dx.doi.org/10.1371/journal.pone.0250926.
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Alfalfa (Medicago sativa L.) is an important legume crop for forage, agriculture, and environment in the world. Ascorbic acid (AsA) plays positive roles in plants. However, its effects on germination and salt-tolerance of alfalfa are unknown. The effects of AsA applications on seed germination and seedling salt-tolerance of alfalfa were investigated. The results revealed that 0.1 and 1 mmol L-1 of exogenous AsA increased germination, amylase, and protease, as well as seedling length, fresh weight (FW), dry weight (DW), and endogenous AsA both in the shoots and roots, except that 1 mmol L-1 AsA reduced the activities of α-amylase, β-amylase and protease on day 3. However, 10 and 100 mmol L-1 AsA inhibited these parameters and even caused serious rot. It indicates that 0.1 mmol L-1 AsA has the optimal effects, whereas 100 mmol L-1 AsA has the worst impacts. Another part of the results showed that 0.1 mmol L-1 AsA not only enhanced stem elongation, FW and DW, but also increased chlorophyll and carotenoids both under non-stress and 150 mmol L-1 NaCl stress. Furthermore, 0.1 mmol L-1 AsA mitigated the damages of membrane permeability, malondialdehyde, and excessive reactive oxygen species (ROS) and ions both in the shoots and roots under 150 mmol L-1 NaCl stress. Hence, 0.1 mmol L-1 AsA improves growth and induces salt-tolerance by inhibiting excessive ROS, down-regulating the ion toxicity and up-regulating the antioxidant system. The principal component analysis included two main components both in the shoots and roots, and it explained the results well. In summary, the optimum concentration of 0.1 mmol L-1 AsA can be implemented to improve the seed germination and seedling growth of alfalfa under salt stress.
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Barak, Jeri D., Lisa Gorski, Anita S. Liang, and Koh-Eun Narm. "Previously uncharacterized Salmonella enterica genes required for swarming play a role in seedling colonization." Microbiology 155, no. 11 (2009): 3701–9. http://dx.doi.org/10.1099/mic.0.032029-0.
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Incidences of bacterial foodborne illness caused by ingestion of fresh produce are rising. Instead of this being due to incidental contamination, the animal pathogen Salmonella enterica utilizes specific molecular mechanisms to attach to and colonize plants. This work characterizes two S. enterica genes of unknown function: a putative periplasmic protein, STM0278, and a putative protein with a hydrolase in the C-terminus, STM0650. STM0278 and STM0650 are important for seedling colonization but appear to have different roles during the process of colonization. Mutants of either STM0278 or STM0650 showed reduced colonization of alfalfa seedlings at 24 h, and the STM0278 mutant also showed reduced colonization at 48 h. Both genes were expressed in planta at 4 h following inoculation of 3-day-old seedlings and at 72 h after seed inoculation. This suggests that the role of STM0650 in seedling colonization is less important later in the process or is duplicated by other mechanisms. Mutants of STM0278 and STM0650 were defective in swarming. The STM0278 mutant failed to swarm in 24 h, while swarming of the STM0650 mutant was delayed. Addition of surfactant restored swarming of the STM0278 mutant, suggesting that STM0278 is involved in surfactant or osmotic agent production or deployment. Alfalfa seed exudates as the sole nutrient source were capable of perpetuating S. enterica swarming. Sequence analysis revealed sequences homologous to STM0278 and STM0650 in plant-associated bacteria, but none in Escherichia coli. Phylogenetic analysis of STM0650 showed similar sequences from diverse classes of plant-associated bacteria. Bacteria that preferentially colonize roots, including S. enterica, may use a similar hydrolase for swarming or biofilm production on plants. Multicellular behaviours by S. enterica appear central to plant colonization. S. enterica genes involved in plant colonization and survival outside of a host are most likely among the ‘function unknown’ genes of this bacterium.
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Cen, Huifang, Tingting Wang, Huayue Liu, Danyang Tian, and Yunwei Zhang. "Melatonin Application Improves Salt Tolerance of Alfalfa (Medicago sativa L.) by Enhancing Antioxidant Capacity." Plants 9, no. 2 (2020): 220. http://dx.doi.org/10.3390/plants9020220.
Full textAbstract:
Alfalfa (Medicago sativa L.) is an important and widely cultivated forage grass. The productivity and forage quality of alfalfa are severely affected by salt stress. Melatonin is a bioactive molecule with versatile physiological functions and plays important roles in response to various biotic and abiotic stresses. Melatonin has been proven efficient in improving alfalfa drought and waterlogging tolerance in recent studies. In our reports, we applied melatonin exogenously to explore the effects of melatonin on alfalfa growth and salt resistance. The results demonstrated that melatonin application promoted alfalfa seed germination and seedling growth, and reduced oxidative damage under salt stress. Further application research found that melatonin alleviated salt injury in alfalfa plants under salt stress. The electrolyte leakage, malondialdehyde (MDA) content and H2O2 content were significantly reduced, and the activities of catalase (CAT), peroxidase (POD), and Cu/Zn superoxide dismutase (Cu/Zn-SOD) were increased with melatonin pretreatment compared to control plants under salt stress with the upregulation of genes related to melatonin and antioxidant enzymes biosynthesis. Melatonin was also involved in reducing Na+ accumulation in alfalfa plants. Our study indicates that melatonin plays a primary role as an antioxidant in scavenging H2O2 and enhancing activities of antioxidant enzymes to improve the salt tolerance of alfalfa plants.
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Brouwer, D. J., S. H. Duke, and T. C. Osborn. "Comparison of Seedling and Cuttings for Evaluating Winter Hardiness in Alfalfa." Crop Science 38, no. 6 (1998): 1704–7. http://dx.doi.org/10.2135/cropsci1998.0011183x003800060047x.
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