Journal articles on the topic 'Sorghum – Seedlings – Evaluation'

Abstract Foliar treatments of 2 organophosphates and imidachloprid (Confidor) were evaluated for yellow sugarcane aphid (YSA) and greenbug (GB) control in a research greenhouse at Texas A&M University. Hybrid grain sorghum seedlings (ATx399 × RTx430) were grown in 110-mm germination pots containing a prepared soil mixture composed of peat, vermiculite, and periite in a 2:1:1 ratio, respectively. Four days after plant emergence and 3 d prior to insecticide applications, each seedling plant was infested with 10-20 YSA or GB. There were 5 singleseedling replications for each treatment. Insecticides were applied by using a CO2-pressurized backpack sprayer, through TX-3 hollow-cone nozzles at 35 psi, producing a finished spray volume of 5.6 gpa. Pre-treatment counts of YSA and GB were made the day of insecticide application; post-treatment counts of aphids were made 1, 2, and 3 DAT. Percent control was calculated by using Abbott’s (1925) formula. Data were statistically analyzed by using ANOVA and LSD.

Abstract The invasive sugarcane aphid, Melanaphis sacchari (Zehntner), is a devastating new pest of grain sorghum. Studies were conducted utilizing an integrated approach of four management tactics: planting date, insecticidal seed treatment, a foliar-applied insecticide, and plant resistance. Experiments were conducted in 2016 and 2017 at Griffin, Tifton, and Plains Georgia, and in 2016 in Texas, Alabama, and Oklahoma, United States. Early planting was effective in reducing damage and increasing yields when compared to the late planting. Use of a resistant variety reduced cumulative aphid-days, plant injury and usually prevented significant yield loss. Foliar application of flupyradifurone when aphids reached an economic threshold, was an effective management tactic preventing aphid injury and yield loss. Use of clothianidin seed treatment also reduced aphid injury and yield loss of the susceptible hybrid but generally did not prevent injury and yield loss of the resistant hybrid. We conclude that an earlier planting date coupled with a resistant variety and judicious use of an efficacious foliar-applied insecticide can effectively manage sugarcane aphid on grain sorghum. An insecticide seed treatment also may be useful to reduce the risk of sugarcane aphid damage to seedlings of susceptible hybrids.

Abstract The effectiveness of imidacloprid-treated sorghum seed for control of yellow sugarcane aphid was evaluated in a re-search greenhouse at Texas A&M University. Seed treated with 1, 2, 3, and 4 oz (AI)/cwt of imidacloprid was sown in 110-mm germination pots containing a prepared soil mixture of peat, vermiculite, and perlite in a 2:1:1 ratio, respectively. There were 10 single-seedling replications for each rate of imidacloprid. Plants were infested 3, 10, and 31 d after emergence (DAE) with 10, 15, and =21 yellow sugarcane aphids, respectively. An initial count of yellow sugarcane aphids was made 4 h after plant infestation (HAI). Subsequent counts of yellow sugarcane aphids were made 1,3,5, and 7 d (and 14 d for those infested 31 DAE) after infestation (DAI). Percent control was calculated by using the Henderson and Tilton (1955) formula. Data were analyzed statistically by using ANOVA and LSD.

Several plant introductions (PIs) and cultivars have been classified as partially resistant (PR) to sudden death syndrome. However, little is known about the nature of resistance to this disease. Seedlings of two PR PIs and two susceptible cultivars were inoculated with Fusarium solani f. sp. glycines in aeroponic chambers. Plants were inoculated by taping two sorghum seeds infested with F. solani f. sp. glycines to the main root. Foliar symptoms of the susceptible cultivars were higher than those on the PR PIs and were associated with lower root and plant dry weight. Root lesion lengths of the four soybean lines differed (P < 0.05), but did not correlate with foliar disease or any other variable. To better understand the resistance mechanism by distinguishing between root and plant resistance, three partially resistant PIs (PI 520.733, PI 567.374, and PI 567.650B) and one susceptible soybean cultivar (GL3302) were compared using different grafting combinations in aeroponic chambers. Results of sudden death syndrome evaluation indicated that resistance is conditioned by both the scion and the rootstock. All three PIs evaluated had resistance associated with the scion; resistance in PI 567.650B also was associated with the rootstock. Although the PR PIs used appear to have little or no root resistance, an aeroponic system and grafting may help identify new sources of resistance to F. solani f. sp. glycines with root- or whole-plant resistance.

Priming is a natural phenomenon that pre-conditions plants for enhanced defence against a wide range of pathogens. It represents a complementary strategy, or sustainable alternative that can provide protection against disease. However, a comprehensive functional and mechanistic understanding of the various layers of priming events is still limited. A non-targeted metabolomics approach was used to investigate metabolic changes in plant growth-promoting rhizobacteria (PGPR)-primed Sorghum bicolor seedlings infected with the anthracnose-causing fungal pathogen, Colletotrichum sublineolum, with a focus on the post-challenge primed state phase. At the 4-leaf growth stage, the plants were treated with a strain of Paenibacillus alvei at 108 cfu mL−1. Following a 24 h PGPR application, the plants were inoculated with a C. sublineolum spore suspension (106 spores mL−1), and the infection monitored over time: 1, 3, 5, 7 and 9 days post-inoculation. Non-infected plants served as negative controls. Intracellular metabolites from both inoculated and non-inoculated plants were extracted with 80% methanol-water. The extracts were chromatographically and spectrometrically analysed on an ultra-high performance liquid chromatography (UHPLC) system coupled to high-definition mass spectrometry. The acquired multidimensional data were processed to create data matrices for chemometric modelling. The computed models indicated time-related metabolic perturbations that reflect primed responses to the fungal infection. Evaluation of orthogonal projection to latent structure-discriminant analysis (OPLS-DA) loading shared and unique structures (SUS)-plots uncovered the differential stronger defence responses against the fungal infection observed in primed plants. These involved enhanced levels of amino acids (tyrosine, tryptophan), phytohormones (jasmonic acid and salicylic acid conjugates, and zeatin), and defence-related components of the lipidome. Furthermore, other defence responses in both naïve and primed plants were characterised by a complex mobilisation of phenolic compounds and de novo biosynthesis of the flavones, apigenin and luteolin and the 3-deoxyanthocyanidin phytoalexins, apigeninidin and luteolinidin, as well as some related conjugates.

Seeds of maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench.] were submitted to different osmotic potential levels induced by polyethylene glycol (PEG) with the objective of evaluating the effects of drought stress on seed germination and early seedling growth. Seeds were arranged in paper rolls and soaked in PEG solutions prepared with osmotic potentials 0.0 (control), -0.2, -0.4, and -0.8 MPa and kept into a seed germinator, at 25 &deg;C for 18 days. A completely randomized design in a 2 &times; 4 factorial scheme with four replications of 50 seeds each was used. The results showed that by increasing of the osmotic potential level, germinated seed number, germination rate index, root and shoot length, shoot and root dry matter, and seedling vigor index (SVI) decreased, while mean germination time (MGT) and root: shoot ratio (RSR) increased in both crops. Additionally, the maize was more susceptible than sorghum to drought stress, with germination response declining more rapidly with decreasing osmotic potential. Sorghum crop tolerates water stress of up to -0.2 MPa, without reducing germination of the seeds; however, the growth of shoots and roots are inhibited. Drought stress limits the process of seed germination and early growth of maize seedlings.

Boron (B) deficiency is commonly found in tropical crops, among which sorghum stands out for its limited yield under B shortage. However, as a micronutrient, the range between its adequate and toxic levels is narrow, thus fertilization should be cautiously applied. Our goal was to evaluate the physiological and physical quality, as well as early performance, of grain sorghum seedlings under different B doses applied via seeds. Treatments consisted of six doses of boric acid (0.0, 2.5, 5.0, 7.5, 10.0, and 12.5 g Kg-1 seeds) plus a control (uncoated seeds). Boron doses were applied to seeds by coating, in which dolomitic limestone and glue were used for pellet formation. Coated seeds were assessed for physical, physiological, and nutritional characteristics in the laboratory, and early seedling performance was evaluated in a greenhouse. Seed tests were carried out in a fully randomized design, while seedling evaluations were carried out in a randomized block design. Boron application to seeds had no significant effect on seed physical characteristics, despite increases in coated seed sizes. Boron doses had a negative effect on the length and dry mass accumulation of both plant shoot and root. Seed-applied B accumulated mainly in roots and significantly interfered with Ca and Mg accumulations in sorghum seeds, shoots, and roots.

SUMMARYTwelve sorghum lines resistant to sorghum shoot fly were evaluated for their combining ability for shoot fly resistance and traits associated with resistance, using three male sterile lines in two environments. Using a completely randomized block design with three replications, 36 hybrids and 15 parental genotypes were raised. Considerable genetic variation was observed for all the traits studied. Non-additive gene effects played an important role in governing glossiness, seedling vigour and proportion of plants with deadhearts. For trichome density, both additive and non-additive gene actions were important. Among the lines evaluated, those identified to be good combiners were SFCR 1047 for seedling vigour, deadheart proportion and trichome density, RSE 03 for glossiness, deadheart proportion at 21 DAE and trichome density, and SPSFR 94032 for seedling vigour and shoot fly eggs per plant. Genetic diversity and cluster analysis grouped the 15 parents (12 resistant and 3 susceptible parents) into five clusters. Utilization of the resistant lines belonging to different clusters in improving shoot fly resistance in sorghum is discussed.

Tylenchorhynchus ewingi, a stunt nematode, causes severe injury to slash pine seedlings and has been recently associated with stunting and chlorosis of loblolly pine seedlings at some forest tree nurseries in southern USA. Experiments confirmed that loblolly pine is a host for T. ewingi, and that the nematode is capable of causing severe damage to root systems. Initial population densities as low as 60 nematodes (100 cm3 soil)−1 were sufficient to damage the root systems of loblolly pine seedlings. Populations of T. ewingi increased on pine from two- to 16-fold, depending on the initial population density. Evaluations of various cover crops used in southern forest tree nurseries indicated that legumes, rye and several varieties of sorghum were excellent hosts for T. ewingi. Other small grains such as ryegrass, oats and wheat were poorer hosts. A cultivar of pearl millet was a non-host for T. ewingi, and a cultivar of brown top millet appeared to be either a very poor host or a non-host. Nurseries that have seedling production losses caused by T. ewingi should consider rotating with non-host cover crops such as pearl millet or leaving fields fallow as part of their pest management programme.

Sorghum is a multipurpose crop cultivated in over 100 countries, but its productivity is constrained by several biotic and abiotic stresses. Therefore, sorghum improvement programs largely focus on developing high-yielding cultivars with multiple traits including stress resistance, bioenergy and nutritional quality. This study was undertaken to meet breeders’ needs to develop such cultivars and identify diverse germplasm sources with multiple traits. The 242 sorghum mini core accessions were evaluated for agronomic traits (yield, maturity, 100-seed weight) in two post-rainy seasons under optimally irrigated and drought conditions and identified 21 accessions as a sources for agronomic traits. The evaluation of mini core revealed 70 accessions resistant to biotic stress, 12 to abiotic stress, 13 for bioenergy traits and 27 for nutritional traits. The 13,390 single nucleotide polymorphism markers on mini core were used to identify genetically diverse accessions with desirable agronomic traits: IS 23684 (nutrition traits, diseases, insect pests), IS 1212 (earliness, nutrition traits, drought, seedling vigor, diseases), IS 5094 (yield, drought, diseases, insect pests), IS 473 (earliness, diseases), IS 4698 (yield, Brix %, insect pests) and IS 23891 (greater seed weight, yield, Brix %, drought, diseases). These are useful genetic resources that meet breeders needs to develop agronomically superior sorghum cultivars with desirable combinations of multiple traits and a broad genetic base.

In recent years, the use of plants for clean-up and recovery (phytoremediation) has been studied and used in many countries of the world. In this study, E-Tian sweet sorghum (ET) and BT x 623 (BT) sorghum were treated with heavy metal cadmium at 5 concentrations (0, 5, 10, 25, 50 mg/kg). The growth of plant; absorption, accumulation of cadmium (Cd) heavy metals in plant parts at the seedling stage have been identified and assessed. The results showed that Cd affected the height and number of leaves of the plant. Especially, Cd accumulation in the plant decreased in sequence: root, stem, leaf. When comparing the heavy metals accumulation in the two cultivars, the results showed that the BT cultivar had higher Cd uptake and accumulation potential than ET. Therefore, BT can be used for phytoremediation of heavy metals in soil but not for providing food and feed.

SummarySeeds of 50 sorghum genotypes were tested for emergence after imbibition in water for different times followed by up to 30 days of drying. The emergence of a large number of sorghum genotypes was then tested after 40 h imbibition in water followed by 10 h drying. Genotypes selected as resistant to 45 hours imbibition and 10 days drying regained turgor in the radicle and plumule when exposed to imbibition and drying injury. Genotypes showed significant difference both for emergence and seedling dry weight after exposure to this stress. The genotypes resistant to imbibition injury and drying had a specific protein of 33.0 KDa which was absent from those which were susceptible to such stress.La adaptación del sorgo a la siembra seca

Kapanigowda, M., H., Perumal, R., Aiken, R. M., Herald, T. J., Bean, S. R. and Little, C. R. 2013. Analyses of sorghum [ Sorghum bicolor (L.) Moench] lines and hybrids in response to early-season planting and cool conditions. Can. J. Plant Sci. 93: 773–784. Early-season cold tolerance in sorghum contributes to emergence, seedling establishment, and early vegetative growth, and reduces damping-off diseases under chilling conditions. The objectives of this study were to identify cold-tolerant sources and to evaluate and optimize rapid screening techniques under a controlled environment. Field studies involving 48 genotypes, representing phases of the hybrid development process (landraces, elite and advanced breeding lines, recombinant inbred lines (RILs) and hybrids were conducted with early and normal planting dates in 2011 at Hays and Colby, Kansas. Studies under controlled environments were conducted at both locations using 18 genotypes that differ for emergence index (EI) and 30 d after emergence (DAE) shoot biomass based on field studies during 2011. Significant differences among the genotypes were recorded for all seedling traits (emergence percentage, EI, shoot biomass, plant height, and leaf number measured 30 DAE), and agronomic traits (days to 50% flowering, panicle exsertion, panicle length, and plant height at maturity). Eight advanced breeding lines: ARCH10731, ARCH10732, ARCH10736, ARCH10737, ARCH10738, ARCH10739, ARCH10744 and ARCH10749 and one RIL (RTx430/SQR-2) were found to be potential sources of cold tolerance with early EI, higher biomass and relatively early flowering. These genotypes are free from tannin, which helps to increase the feed grain efficiency of livestock, and hence were selected for test hybrid evaluation to assess fertility status, combining ability and yield performance. Significant correlation was observed between EI and biomass during early planting, which indicated that late-emerging genotypes produced greater biomass (30 DAE) compared with early-emerged genotypes. Significant correlation between growth chamber and field study for EI offers a potential and fast preliminary high-throughput screening technique for identification of cold-tolerant sorghum.

Loss of function mutations in waxy, encoding granule bound starch synthase (GBSS) that synthesizes amylose, results in starch granules containing mostly amylopectin. Low amylose grain with altered starch properties has increased usability for feed, food, and grain-based ethanol. In sorghum, two classes of waxy (wx) alleles had been characterized for absence or presence of GBSS: wxa (GBSS−) and wxb (GBSS+, with reduced activity). Field-grown grain of wild-type; waxy, GBSS−; and waxy, GBSS+ plant introduction accessions were screened for fungal infection. Overall, results showed that waxy grains were not more susceptible than wild-type. GBSS− and wild-type grain had similar infection levels. However, height was a factor with waxy, GBSS+ lines: short accessions (wxb allele) were more susceptible than tall accessions (undescribed allele). In greenhouse experiments, grain from accessions and near-isogenic wxa, wxb, and wild-type lines were inoculated with Alternaria sp., Fusarium thapsinum, and Curvularia sorghina to analyze germination and seedling fitness. As a group, waxy lines were not more susceptible to these pathogens than wild-type, supporting field evaluations. After C. sorghina and F. thapsinum inoculations most waxy and wild-type lines had reduced emergence, survival, and seedling weights. These results are valuable for developing waxy hybrids with resistance to grain-infecting fungi.

We are evaluating the severity of apple replant disease (ARD)-characterized by stunted tree growth in replanted orchards, attributed to root pathogens and/or edaphic conditions-and testing preplant soil treatments for control of this wide-spread problem. Soil samples were collected during 1996–98 at 17 orchards in New York's major fruit growing regions and plant-parasitic nematodes and nutrient availability were quantified. Apple seedlings and potted trees on M.9 rootstocks were grown in fumigated and non-fumigated soil samples as a diagnostic bioassay for ARD severity. Factorial combinations of metam sodium, consecutive cover crops of Brassica juncea `Forge' and Sorghum sudanense `Trudan 8', and fertilizer/lime amendments were applied as preplant treatments at each orchard, 9 to 12 months before trees were replanted. Diagnostic bioassays indicated severe ARD at more than half the sites, and nematodes were not a major factor. Responses to preplant soil treatments were highly variable across the 17 farms. The best tree growth and yields followed preplant metam sodium at some sites, Brassica juncea and Sorghum sudanense at others, or fertilizer amendments at a few others. Tree responses to combined preplant soil treatments were often additive, and greater at irrigated sites. Comparisons of preplant diagnostic bioassay results with subsequent tree responses to metam sodium at the 17 orchards indicated that diagnostic tests predicted from 7% to 75% of tree growth response to soil fumigation, varying substantially across years and sites. It appeared that ARD was variable and site specific in New York orchards, and could not be controlled effectively with a uniform preplant soil treatment across our major fruit-growing regions.

Salinity is among the most severe and widespread environmental constrains to global crop production, especially in arid and semi-arid climates and negatively affecting productivity of salt sensitive crop species. Breeding and selection of salt tolerant crop varieties is therefore necessary for sustainable plant productivity. Given that germination and seeding phases are the most critical phase in the plant life cycle, this study aimed to evaluate seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt tolerant sorghum varieties [Gadam, Sc Sila and Serena] which are adaptated to various agroecological regions. Salinity stress was applied by addition of NaCl at three different levels of stress [100, 200 and 300 mM NaCl], while plants irrigated with water were used as control. Evaluation of tolerance was performed on the basis of germination percentage, shoot and seed water absorbance, shoot and root length, leave water content, seedling total chlorophyll content and morphologic abnormality. Our results showed that salinity stress significantly impacts all features associated with germination and early development of seedlings. Our results indicated that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the variety used and level of salinity stress applied. Among the tested sorghum varieties, Gadam was established to the most salt tolerant variety, suggesting its potential use for cultivation under salinity stress conditions as well as its suitability for use as germplasm material in future sorghum breeding programmes. For a greater insight into comprehensive mechanisms of salinity tolerance in sorghum, we suggest further research on genomic and molecular analysis.

Poor crop establishment is one of the major constraints to obtain the higher potential of rice, particularly in areas prone to environmental stresses. Therefore, present study was conducted to evaluate the effects of potassium nitrate on germination dynamics, seedling growth and associated physiological and biochemical events of two rice cultivars. For this purpose, various seed priming treatments were tested in lab and greenhouse. The percent concentrations of potassium nitrate were 0.25, 0.50, 0.75, 1.0 and 1.25 in both lab evaluation and greenhouse experiment. Non-primed seeds were maintained as a control for comparison. The results depicted that soaking rice seeds at higher concentrations of KNO3 could delay emergence time and final emergence (%) in both cultivars under lab and greenhouse conditions. Seed priming with 0.75% KNO3 significantly increased the stand establishment and seedling vigor attributes of both cultivars compared with other concentrations and naked rice seeds both in lab evaluation and greenhouse screening. Similarly, highest values for photosynthesis rate, evaporation rate and CO2 index were observed in experimental units receiving primed seeds with 0.75% KNO3 under greenhouse screening. Interestingly, no variance was observed among both rice cultivars. Overall, higher seed emergence, seedling vigor and associated biochemical attributes due to seed priming with 0.75% KNO3 was associated with decrease in alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDH) activities in lab and greenhouse screening. Keywords: Seed priming, potassium nitrate, seed quality, stand establishment, vigor Introduction Rice is an important cereal crop that serve as staple food for almost half of the world population (Chun et al. 2020; Zafar et al. 2020). Its germination is affected under various environmental stresses which causes poor yield (Zafar et al. 2015; Zafar et al. 2018). Poor germination is the problem often faced by different farmers of rice, especially when the seed is broadcasted in dry condition. Under unfavorable and harsh environmental condition, seed priming method is the best technique which help the seed to germinate easily. It enhances the germination chances and boost up the process (Ahmed et al., 2019), and is a cheaper solution to overcome poor stand establishment (Farooq et al., 2009; Harris et al., 1999). It has been reported that the seed priming is very helpful in improving germination rate of many crops i.e., rice, wheat, maize and canola (Basra et al., 2005). The germination percentage and dry weight of seedlings of safflower was increased by seed priming (Razaji et al., 2012). It has been reported that the inferior quality of wheat could also grow well after seed priming (Hussian et al., 2013). Increase in germination rate, uniformity in process, improved plant growth and yield, and better physiological performance are included in the beneficial aspects of seed priming (Farooq et al., 2007; Ruan et al., 2002). The seed priming principle is based on the behavior of seed towards water absorption; water is very important factor for seed germination and growth. The water intake of seed is divided into three phases. First phase includes the intake of water by seed and activation of enzymes. In 2nd phase, after activation of enzymes, several processes such as food deprivation, cell membrane restructuring and biosynthesis of starch occur to support seedling and root growth. In final phase, the growth of root and shoot organs i.e., radicle and plumule takes place (Bewley et al., 2013). There are three categories of seed priming techniques; (1) hydro-priming – priming with simple water, (2) solid-matrix priming – priming with solid organic material and (3) osmopriming – priming with priming solutions e.g., potassium nitrate (KNO3), potassium chloride (KCl) and polyethylene glycol (PEG) (McKersie, 2002; Mohammadi, 2009). PEG and KNO3 are commonly used in priming studies, but PEG is more expensive than KNO3. In a previous study, it was demonstrated that the osmopriming of seed of soybean with KNO3 at the concentration of 6 g/L increased the germination percentage and dry weight of seedling (Ahmadvand et al., 2012). Similarly, seed priming with 1.0% KNO3 for 24 h at 20°C enhance the germination rate and improved the physiological quality of soybean (Mohammadi, 2009). Moreover, it has also been reported that the seed priming could improve the protein synthesis during early growth of embryo (Xu et al., 2009). Here in this study, the aim was to evaluate the effect of seed priming with different concentrations of KNO3 (0.25%, 0.50%, 0.75%, 1.0% and 1.25% (w/v) KNO3 for 1 day at 25°C) on the stand establishment, seedling vigor, physiological and biochemical attributes of two rice cultivars. Materials and Methods Seed Source: Seed of Indica rice (Oryza sativa L.) cultivars viz., Basmati-515 and Basmati-385 were obtained from Rice Research Institute, Kala Shah Kaku, Punjab, Pakistan. The initial germination and seed moisture content prior to seed treatment was ˃80% and 12% respectively on dry weight basis. Seed Priming Treatments: Rice seeds were primed with 0.25%, 0.50%, 0.75%, 1.0% and 1.25% (w/v) KNO3 for 24 h at 25°C. Pre-weighed seeds (5g) were placed on two blotter papers in 9-cm diameter petri dishes saturated with appropriate concentration of osmotic solutions followed by covering of dishes with aluminum foil. Non-primed rice seeds were maintained as control for comparison. Seeds were stored at -4°C in paper bags, prior to experimentation. Experimental Site and Conditions: Lab experiment was conducted in the growth chamber of Seed Preservation Lab, National Agricultural Research Centre, Islamabad, Pakistan during September 2019 to October 2019. While, greenhouse experiment was conducted at the research station of National Agricultural Research Centre, Islamabad, Pakistan during September 2019 to November 2019. Well pulverized soil was collected from the field of research station and each plastic pot 35cm×25cm×15cm in size was filled with 6kg of soil. After leveling the soil surface in each pot, moisture was applied up to field capacity. In each pot, 40 seeds were equally sown on the soil surface in both experiments. Both experiments were laid out in a completely randomized design with four replications. For lab screening, all the trays were placed in the growth chamber with a constant temperature of 25°C and a light period of 12h. The relative humidity during the complete execution of lab experiment was maintained at 65%. For greenhouse experiment, all the trays were placed in greenhouse under natural environmental conditions. Moisture was applied to each try when declined. Stand Establishment: Emergence was recorded on daily basis until a constant was achieved. Final emergence (%) was taken at the end of experiment (AOSA, 1990). Mean emergence time (days) was recorded as per the equation of ISTA (2015). Seedling Vigor: Seedling length of five randomly selected from each treatment was measured with the help of measuring tape and averaged to get mean length. Similarly, fresh and dry weight of these plants was measured on a weighing balance. For dry weight, plants were dried at 70°C till constant weight in an oven (Zafar et al., 2015). Physiological Parameters: Measurements of CO2 index (µmol mol-1), net photosynthetic rate (µmol CO2 m-2 s-1) and evaporation rate (µmol H2O m-2 s-1) were made on a fully expanded leaf from top by using an open system LCA-4 ADC (USA) portable infrared gas analyzer. Biochemical Attributes: To determine the activities of alcohol dehydrogenase and pyruvate decarboxylase, seedling samples were ground and detected by an alcohol dehydrogenase assay kit and a pyruvate decarboxylase test kit. Statistical Analysis: The data from growth chamber and greenhouse experiments are presented as the mean value ± standard error of four replicates. By using Statistix 9.0, analysis of variance for all the treatments was performed. Graphical presentation of data was performed by using SigmaPlot 14.0. Results Lab Screening Stand Establishment: Seed priming treatments maximally improved the final emergence (%) of both rice cultivars under well-controlled conditions. Highest values for final emergence (%) were recorded in experimental units (Cultivar 1 (V1)=96%, Cultivar 2 (V2)=98%) receiving rice seed primed with 0.75% KNO3 as compared to control. Seed priming with 1% KNO3 was also proved to be beneficial in both cultivars (V1=89%, V2=90%) for improving final emergence (%). No variance in final emergence was observed among experimental units receiving rice seed primed 0.50% and 1% KNO3 in V2 cultivar (Fig. 1a). Similarly, minimum mean emergence time (MET) was recorded in rice seeds primed with 0.75% followed by 1% KNO3. Highest values for MET was recorded in control in both cultivars (Fig. 1b). Collectively, statistical analysis of data revealed that seed primed with KNO3 proved better in improving stand establishment of both rice cultivars as compared to control. Seedling Vigor: Seedling length of both rice cultivars is graphically presented in Fig. 2a and data revealed that maximum seedling vigor in both cultivars was achieved in rice seeds primed with 0.75% (V1=8.10cm, V2=8.24cm) followed by 1% (V1=7.88cm, V2=7.91cm) and 0.50% (V1=7.43cm, V2=7.69cm) KNO3 solutions as compared to control (V1=6.83cm, V2=6.71cm) (Fig. 2a). Seed priming with KNO3 also proved effective in improving the seedling fresh and dry weight, nonetheless effect of different cultivars was not pronounced. Plants in both cultivars raised from seeds treated with 0.75% KNO3 depicted highest values for seedling fresh (V1=34.45mg, V2=37.67mg) (Fig. 2b) and dry weight (V1=18.12mg, V2=19.01mg) as compared to other treatments and control (Fig. 2c). No apparent difference in seedling fresh and dry weight was observed among rice seed treated with 0.50% and 1.0% KNO3 in both cultivars. Greenhouse Screening Stand Establishment: A variable trend of primed and non-primed final emergence (%) was observed in both cultivars under greenhouse screening. Rice seed in both cultivars treated with 0.75% KNO3 steadily depicted highest values for final emergence (V1=95%, V2=98%), while an opposite drift was examined in control (V1=77%, V2=80%). Rice seeds treated with 1% KNO3 also proved to be successful in both cultivars (V1=88%, V2=91%) for improving final emergence (%) under greenhouse conditions. No variance in final emergence was observed among experimental units receiving rice seed primed 0.50% and 1% KNO3 in both cultivars (Fig. 3a). However, minimum mean emergence time (MET) was recorded in rice seeds primed with 0.75% followed by 1% KNO3 in both cultivars compared to other treatments and control. In addition, both cultivars showed highest values for MET in experimental units receiving control (Fig. 3b). Seedling Vigor: Statistical analysis of data pertaining to seedling vigor depicted that the effect of seed priming treatments was significant in both cultivars. However, both cultivars did not exhibit pronounced effect on seedling vigor. All priming treatments significantly improved the seedling length in both cultivars, whereas maximum seedling was achieved in rice seed primed with 0.75% (V1=7.90cm, V2=8.09cm) followed by 1% (V1=7.65cm, V2=7.74cm) KNO3 solutions. Furthermore, lowest vales for seedling length in both cultivars was observed in control (V1=6.41cm, V2=6.51cm) (Fig. 3a). Plants in both cultivars raised from seeds treated with 0.75% KNO3 depicted highest values for seedling fresh (V1=33.45mg, V2=36.54mg) (Fig. 3b) and dry weight (V1=16.78mg, V2=19.99mg) as compared to other treatments and control (Fig. 3c). Overall, statistical analysis of data revealed that seed priming with 0.75% KNO3 proved successful in improving seedling vigor of both rice cultivars as compared to other treatments and control. Physiological and Biochemical Attributes: Analysis of variance of data showed that seed priming treatments significantly improved the physiological and biochemical attributes of both cultivars, while effect of cultivars was not significant. Highest photosynthesis rate, evaporation rate and CO2 were observed in rice seeds treated with 0.75% KNO3, whereas lowest values were examined in non-treated control. Statistical analysis of data demonstrated that PDH and ADH activities were significantly influenced by seed priming treatments. Though all the seed priming treatments proved successful for improving the biochemical attributes however lowest values were observed in experimental units receiving rice seed treated with 0.75% KNO3 under greenhouse screening. Highest values for PDH and ADH activities were observed in control (Table 1). Figure 3. Effect of seed priming with KNO3 on stand establishment of two rice cultivars in greenhouse. V1=Basmati-515, V2=Basmati=385: T0=Control, T1=0.25% KNO3, T2=0.50% KNO3, T3=0.75% KNO3, T4=1.0% KNO3, T5=1.25% KNO3. Seedling Vigor: Statistical analysis of data pertaining to seedling vigor depicted that the effect of seed priming treatments was significant in both cultivars. However, both cultivars did not exhibit pronounced effect on seedling vigor. All priming treatments significantly improved the seedling length in both cultivars, whereas maximum seedling was achieved in rice seed primed with 0.75% (V1=7.90cm, V2=8.09cm) followed by 1% (V1=7.65cm, V2=7.74cm) KNO3 solutions. Furthermore, lowest vales for seedling length in both cultivars was observed in control (V1=6.41cm, V2=6.51cm) (Fig. 4a). Plants in both cultivars raised from seeds treated with 0.75% KNO3 depicted highest values for seedling fresh (V1=33.45mg, V2=36.54mg) (Fig. 4b) and dry weight (V1=16.78mg, V2=19.99mg) as compared to other treatments and control (Fig. 4c). Overall, statistical analysis of data revealed that seed priming with 0.75% KNO3 proved successful in improving seedling vigor of both rice cultivars as compared to other treatments and control. Figure 4. Seedling vigor attributes of two cultivars of rice under the influence of seed priming with KNO3 in greenhouse. V1=Basmati-515, V2=Basmati=385: T0=Control, T1=0.25% KNO3, T2=0.50% KNO3, T3=0.75% KNO3, T4=1.0% KNO3, T5=1.25% KNO3. Table 1. Variations in physiological and biochemical attributes of two rice cultivars under the influence of seed priming with KNO3 in lab. Cultivars Treatments Physiological attributes Biochemical attributes Photosynthesis rate (µmol CO2 m-2 s-1) Evaporation rate (µmol H2O m-2 s-1) CO2 index (µmol mol-1) Alcohol dehydrogenase (Ug-1 FW) Pyruvate decarboxylase (U g -1 FW) Basmati-515 T0 10.67±0.05 c 0.91±0.09 c 120.33±5.5 d 1.72±0.09 a 1.62±0.09 a T1 12.67±0.08 bc 1.09±0.09 bc 131.33±6.2 cd 1.44±0.07 ab 1.33±0.05 ab T2 14.83±0.06 abc 1.31±0.08 b 148.33±5.2 bc 1.29±0.06 bc 1.17±0.08 bc T3 17.67±0.04 a 1.72±0.06 a 172.00±5.3 a 1.11±0.08 c 1.02±0.04 c T4 15.83±0.06 ab 1.40±0.06 ab 154.33±4.8 ab 1.33±0.06 bc 1.24±0.07 bc T5 14.00±0.07 abc 1.33±0.08 b 142.67±4.8 bc 1.54±0.09 ab 1.43±0.06 ab LSD at p≤0.05 1.23 0.31 18.71 0.31 0.29 Basmati-385 T0 9.69±0.05 c 1.02±0.08 c 122.33±5.12 c 1.82±0.08 a 1.73±0.08 a T1 11.63±0.08 bc 1.19±0.06 bc 132.67±5.98 bc 1.51±0.09 abc 1.42±0.09 abc T2 13.89±0.06 abc 1.39±0.09 b 152.33±4.82 ab 1.40±0.08 bc 1.29±0.08 bc T3 16.64±0.04 a 1.81±0.05 a 174.00±5.83 a 1.22±0.05 c 1.10±0.05 c T4 14.88±0.06 ab 1.51±0.07 ab 155.33±4.89 ab 1.43±0.06 bc 1.31±0.06 bc T5 13.01±0.07 abc 1.40±0.05 b 144.00±5.01 bc 1.65±0.07 ab 1.56±0.07 ab LSD at p≤0.05 1.03 0.34 28.00 0.32 0.31 Discussion Osmopriming of seed by KNO3 affected the seed emergence and the speed of seed germination. Osmopriming induces the reduction in intake of water in phase-I of germination, causing prolonged duration of phase-2, resulting commencement of major event before the emergence of radicle (Nonogaki and Nonogaki, 2016). This major event includes metabolic changes such as repair of DNA and increase in biosynthesis of RNA (Bray, 2017), and enhancement in the respiration process of seed (Singh et al., 2013). It indicates that the time of seed imbibition is very important for osmopriming. For the study of osmopriming of rice (Oryza sativa L.) seed with different levels of KNO3, therefore it is important to know about the emergence percentage and mean emergence time (MET). The results of present study indicate that the performance of osmopriming of both cultivars of rice with 0.75% KNO3 was appreciable in lab screening as well as greenhouse (Fig. 1 and 3). The pattern of seedling emergence (%) and MET was almost same in both cultivars as well as both sites (lab and greenhouse). The time of water intake by the seed during priming can very within the cultivars which can affect the performance of osmoticum (KNO3) (Kiers et al., 2008), but in our study the difference between the performance of both cultivars was non-significant. Emergence of the seed is the stage where it is determined that either the seedling will further grow or not. The emergence percentage is calculated from the number of emerged seedlings from number of primed seeds sown (International Seed Testing Association, 2015). The data shown in figure 1 and 3 depicts that the osmopriming of rice seed with 0.75% KNO3 is better than all other treatments in term of emergence percentage and MET. Our study is in correspondence with another study who revealed that emergence percentage of wheat seed was decreased with the increase in KNO3 concentration (Shafiei Abnavi and Ghobadi, 2012). This indicates that the KNO3 concentration above than a certain level may not be appropriate for cereals. Osmopriming with 1% KNO3 was found useful in term of emergence percentage in sorghum (Shehzad et al., 2012). Besides, soybean seed priming with 1% KNO3 for 1 day enhanced the emergence percentage as compared to untreated seeds, both in lab and field experiments (Mohammadi, 2009). Seedling vigor is the combine result of the emerged seeds in a wide range of biotic and abiotic factors (International Seed Testing Association, 2015). Seedling vigor is not a single measurable entity, but it is a sum of many growth parameters such as seedling length, seedling fresh weight and seedling dry weight (International Seed Testing Association, 2015). Maximum vigor was observed when seed priming with 0.75% KNO3 was done (Fig. 2 and 4). Our study is in line with another study in which seedling vigor of wheat was improved by the priming with KNO3 (Shafiei Abnavi and Ghobadi, 2012). Similar results were found in corn when the osmopriming of seed was done with 1% KNO3 (Hadinezhad et al., 2013). Our findings are similar with other studies, in which the shoot length of tomato and watermelon was increased by the osmopriming with KNO3 (Demir and Van De Venter, 1999; Mirabi & Hasanabadi, 2012). Seed priming with KNO3 can cause significant increase in seedling vigor of wheat crop as compared to hydro-priming or dry broadcasting (Basra et al., 2003). The growth and development of plant is based upon a process; photosynthesis. While its performance is mostly dependent on the opening/closing of stomata, causing decrease in photosynthetic rate, respiration rate and CO2 index (Shu et al., 2016). The results of present study revealed that the maximum photosynthesis rate, evaporation rate and CO2 index was observed in the rice seeds which were primed with 0.75% KNO3 (Table 1). Whereas the seedlings of control treatments showed inferior results as compared to other osmopriming treatments. Our study is in corroboration with another study in which the increased photosynthetic rate, respiration rate and CO2 index of cucumber seedlings as the result of seed priming with KNO3 was reported (Anwar et al., 2020). Photosynthesis rate of the seedlings has a positive correlation with the growth of seedling (Anwar et al., 2020). A previous study indicated that the leaf nitrogen and chlorophyll contents have a positive correlation, and can derive the photosynthesis rate being a key molecule for photosynthesis (De Castro et al., 2014). The results of present study revealed that the biochemical attributes e.g. alcohol dehydrogenase (Ug-1 FW) and pyruvate decarboxylase (Ug-1 FW) of rice were suppressed by osmopriming of seed with KNO3. Maximum suppression was observed in those seedlings who were treated with 0.75%% KNO3, while minimum suppression was seen in non-primed seedlings. A previous study expressed that seed priming with potassium nitrate (KNO3) improved the biochemical indices of Chicory (Cichorium intybus L.) (Dehkordi et al., 2012). Conclusion Good quality seed is always in demand by the farmers and seed industry. Therefore, present study was conducted to improve the rice seed quality by seed priming with KNO3. The results depicted that seed priming with 0.75% KNO3 proved successful in improving stand establishment, vigor and physiological attributes. The improved performance might by linked with better activities of ADH and PDH. Therefore, present research provides basis for further transcriptomics/metabolomics/proteomics basis of primed seeds with KNO3