SEED PRIMING AND EXOGENOUS APPLICATION OF SALICYLIC ACID ENHANCE GROWTH AND PRODUCTIVITY OF OKRA (Abelmoschus esculentus L.) BY REGULATING PHOTOSYNTHETIC ATTRIBUTES

Low and uneven germination is a serious problem for the successful production of okra seedlings. Priming of seeds as well as supplementation of different plant growth regulators exhibited better response in successful seedling production which eventually results in higher yield. Therefore, the present study was conducted to evaluate the effects of seed priming and exogenous application of salicylic acid (SA) on okra seed germination and plant development. The okra seeds were primed by 1 mM and 2 mM of SA for 60 minutes whereas the seeds were washed several times with distilled water for the control treatment. Similar doses of SA have been exogenously sprayed to the 12 days okra seedlings for 4 days. The results of the study revealed that seed priming with SA enhanced germination percentage (GP), increased coleoptile length and weight, shoot and root length, and seed vigor index (SVI). Similarly, exogenous application of 1 mM SA increased relative water content (RWC), contents of chlorophyll a, chlorophyll b, total chlorophyll while a higher dose of SA (2 mM) degraded the leaf pigments. Supplementation of SA altered photosynthetic attributes, net photosynthetic (Pn) and transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE). Moreover, SA treatment reduced the time duration of flower bud initiation and days to first flowering and enhanced the yield per plant. The results of this study indicated that seed priming and exogenous application of SA enhanced germination and okra productivity by regulating RWC and photosynthetic attributes where 1 mM SA is more effective compared to 2 mM SA.

Phenotypic Evaluation and Genetic Analysis of Seedling Emergence in a Global Collection of Wheat Genotypes (Triticum aestivum L.) Under Limited Water Availability

The challenge in establishing an early-sown wheat crop in southern Australia is the need for consistently high seedling emergence when sowing deep in subsoil moisture (>10 cm) or into dry top-soil (4 cm). However, the latter is strongly reliant on a minimum soil water availability to ensure successful seedling emergence. This study aimed to: (1) evaluate 233 Australian and selected international wheat genotypes for consistently high seedling emergence under limited soil water availability when sown in 4 cm of top-soil in field and glasshouse (GH) studies; (2) ascertain genetic loci associated with phenotypic variation using a genome-wide association study (GWAS); and (3) compare across loci for traits controlling coleoptile characteristics, germination, dormancy, and pre-harvest sprouting. Despite significant (P < 0.001) environment and genotype-by-environment interactions within and between field and GH experiments, eight genotypes that included five cultivars, two landraces, and one inbred line had consistently high seedling emergence (mean value > 85%) across nine environments. Moreover, 21 environment-specific quantitative trait loci (QTL) were detected in GWAS analysis on chromosomes 1B, 1D, 2B, 3A, 3B, 4A, 4B, 5B, 5D, and 7D, indicating complex genetic inheritance controlling seedling emergence. We aligned QTL for known traits and individual genes onto the reference genome of wheat and identified 16 QTL for seedling emergence in linkage disequilibrium with coleoptile length, width, and cross-sectional area, pre-harvest sprouting and dormancy, germination, seed longevity, and anthocyanin development. Therefore, it appears that seedling emergence is controlled by multifaceted networks of interrelated genes and traits regulated by different environmental cues.

Phenotyping and Identification of Reduced Height (Rht) Alleles (Rht-B1b and Rht-D1b) in a Nepali Spring Wheat (Triticum aestivum L.) Diversity Panel to Enable Seedling Vigor Selection

Nepal is facing more intense early-season drought stress associated with climate change. The introgression of reduced height (Rht) alleles to enable stem dwarfism in bread wheat (Triticum aestivum L.) inadvertently reduced coleoptile length and growth plasticity in seedlings, making improved varieties less suitable for deep seeding; these alleles may have also reduced seedling root length. Therefore, with the long-term objective of breeding wheat for early-season drought stress, a Nepali spring wheat panel was evaluated to assess allelic variation at the most common dwarfing-associated loci (Rht-B1, Rht-D1) and their impact on coleoptile/seedling root traits, and to identify accessions with longer and/or more GA-responsive coleoptiles as parents for future breeding. Here, Kompetitive Allele Specific PCR (KASP) was used to genotype accessions. The panel was phenotyped using the cigar-roll method in the presence/absence of GA3. Plant height was measured under field conditions. The results showed that Nepali landraces had a significantly higher frequency of the non-dwarfing allele Rht-B1a. The dwarfing alleles Rht-B1b and Rht-D1b had negative effects on coleoptile length but positive effects on the length of the longest seedling root. However, 40 potential semi-dwarf accessions (possessing Rht-B1b and/or Rht-D1b alleles) with long and/or more plastic coleoptiles suited for deep sowing were identified. This included 12 accessions that exhibited significant changes in coleoptile length in response to GA3 treatment.

Interferences of Inorganic Arsenic (III & V) on Growth and Development of Rice (Oryza sativa L.) With Special Emphasis on Root and Coleoptile Growth

A short-term phytotoxicity experiment was conducted on four varieties of rice (Oryza sativa L.) under the influence of arsenic (III & V) to evaluate the impact on root and coleoptiles growth. Four varieties (GB-1, IET-4786, IET-4094, and MTU-1010) of rice were undertaken for this study with different concentrations (0, 5, 10, 25 and 50 mg/L) of arsenic (III & V). Germination along with mean daily germination (MDG), length of root and coleoptile, water holding capacity of root and coleoptiles, fresh and dry weight, arsenic accumulation, MDA and root ion leakage were evaluated. Results highlighted that the percent germination of IET-4094 and MTU-1010 varieties of rice seed over control decreased significantly (p < 0.05) with increasing concentration of both arsenite and arsenate. However, the percent germination of GB-I and IET-4786 dose not affected on the different concentration of both arsenate and arsenite. The root and coleoptile length of all the four varieties showed remarkable decreasing trend over control with increasing concentration of both arsenite and arsenate. However, more pronounced effects were observed for arsenite than arsenate. Similarly, biomass of shoot is less affected than root under different concentration of arsenite and arsenate. The variety IET-4786 and MTU-1010, accumulated lower level of arsenic and variety GB-1 accumulate higher level of MDA level in root under both arsenite and arsenate treatments. Therefore, it can be concluded that the variety IET-4786 and MTU-1010 are the suitable varieties towards phytoremediation of both arsenite and arsenate. Moreover, farmers of arsenic contaminated area are recommended to cultivate IET-4786 and MTU-1010 varieties.

Drought Resistance Loci in Recombinant Lines of Iranian Oryza sativa L. in Germination Stage

In order to locate control genes related to Oryza sativa L. traits at the germination stage under normal conditions and at drought stress levels (−4.5 and −9.0 bar), we evaluated 120 F8 generation offspring from the cross between two cultivars Neda × Ahlemitarum in a factorial experiment in a completely randomized block design with three replications in 2013 in the botanical laboratory of Gonbad Kavous University. A linkage map was prepared using 90 Simple Sequence Repeats (SSR) markers and 28 Inter Simple Sequence Repeats (ISSR), and 6 iPBS and 9 IRAP markers (265 polymorphic alleles). The results of the analysis of variance showed that all of the evaluated traits had a significant difference at the probability level of 1%. Hence, it can be noted that the desired genetic diversity can be found between genotypes. The results of the stepwise regression analysis for the germination percentage as a dependent variable and other traits as independent variables in the studied treatments showed that under normal conditions, there was variable coleoptile length, but under drought stress of −4.5 and −9.0 bar, the variable plumule dry weight entered the model. In this study, the markers included in RM1-RM490 and ISSR2-3-RM133 of chromosomes 1 and 6 of Oryza sativa were identified as the main regulators of traits associated with Oryza sativa drought resistance. In particular, they present the quantitative trait loci (QTL) that control the first stages of germination of Oryza sativa in water stress conditions.

Optimization of a Pre-Sowing Treatment of Corn Seeds with Low-Frequency Pulse Electric Field to Improve the Germination and Development of Seedlings

Corn is one of the key forage crops in agriculture. However, corn production in Russia still remains behind of its demand, so the search and development of technologies allowing to improve its yield are very relevant. Pre-sowing treatment of seeds of corn and other crops with physical fields provides stimulation of the growth and development of plants, but its efficiency depends on some parameters including duration of such treatment. The laboratory evaluation of the effect of a pre-planting treatment of corn seeds with low-frequency pulse electric field for 1–9 h on their germination, average lengths of the coleoptile and radicle root, and the number of seminal roots made it possible to determine the optimum exposure time (4 h) providing a significant improvement of germination (+26.7% of the control) and increase in the coleoptile length (+21.2% of the control). The maximum negative effect was revealed for a 5-h exposure; it resulted in a significant reduction of the coleoptile and radicle root lengths (421.7 and 16.3% of the control, respectively), as well as the reduction of the average number of seminal roots (4.8% of the control).

Comparison of Single-Trait and Multi-Trait Genome-Wide Association Models and Inclusion of Correlated Traits in the Dissection of the Genetic Architecture of a Complex Trait in a Breeding Program

Traits with an unknown genetic architecture make it difficult to create a useful bi-parental mapping population to characterize the genetic basis of the trait due to a combination of complex and pleiotropic effects. Seedling emergence of wheat (Triticum aestivum L.) from deep planting is a vital factor affecting stand establishment and grain yield, has a poorly understood genetic architecture, and is historically correlated with coleoptile length. The creation of bi-parental mapping populations can be overcome by using genome-wide association studies (GWAS). This study aimed to dissect the genetic architecture of seedling emergence while accounting for correlated traits using one multi-trait GWAS model (MT-GWAS) and three single-trait GWAS models (ST-GWAS) with the inclusion of covariates for correlated traits. The ST-GWAS models included one single locus model (MLM), and two multiple loci models (FarmCPU and BLINK). We conducted the GWAS using two populations, the first consisting of 473 varieties from a diverse association mapping panel (DP) phenotyped from 2015-2019, and the other population used as a validation population consisting of 279 breeding lines (BL) phenotyped in 2015 in Lind, WA, with 40,368 markers. We also compared the inclusion of coleoptile length and markers associated with reduced height as covariates in our ST-GWAS models for the DP. ST-GWAS found 107 significant markers across 19 chromosomes, while MT-GWAS found 82 significant markers across 14 chromosomes. MT-GWAS models were able to identify large-effect markers on chromosome 5A. FarmCPU and BLINK models were able to identify many small effect markers, and the inclusion of covariates helped to identify the large effect markers on chromosome 5A. Therefore, by using multi-locus models combined with pleiotropic covariates, breeding programs can uncover the complex nature of traits to help identify candidate genes and the underlying architecture of a trait, such as seedling emergence of deep-sown winter wheat.

Effect of pesticide treatment of spring wheat plots on seed yields

Introduction. High-quality varietal seeds, which can ensure a gain of 0.2–0.4 t/ha in the yields from their offspring, is one of the most important and cost-effective means to increase the gross grain collection of grain. Purpose. To study productive capacities of spring wheat seeds depending on treatment of fields with fungicides and insecticides. Materials and methods. The following indicators were evaluated: swelling activity, germination energy, laboratory germinability, initial growth strength, coleoptile length and the number of radicles. Seed samples that after pesticide treatment had showed the best results were tested in field experiments for productive capacities. The experimental plot area was 10 m2, in six replications. Seeds were sown with a seeder SN-10Ts after soybean with a seeding rate of 5 million germinable seeds per hectare. Spring wheat seeds produced in the experimental plots, which were treated with fungicides Akula (0.6 L/ha) and Soligor 425 EC (0.6 L/ha) and insecticides Fas (0.15 L/ha) and Karate Zeon 050 CS (0.15 L/ha) in organogenesis stages VI, VIII and X, were evaluated for productive capacities. The study was carried out on varieties MIP Zlata, Bozhena, MIP Raiduzhna and Diana. Results and discussion. Over the study years, the gain in the yields of spring wheat varieties grown from seeds of fungicide-treated plants was 0.23–0.36 t/ha; the gain in the yields of spring wheat varieties grown from seeds of insecticide-treated plants was – 0.24-0.31 t/ha. Pesticide-treated parental plants produced seeds with increased productive capacities: when such seeds were sown, the field germinability increased by 3-5%, and the plant survival – by 5-7%. Conclusions. The results indicate that the treatment of vegetating plants of spring wheat varieties in seed plots with fungicides and insecticides is a reliable way to obtain seeds with high productive capacities

Germination of common winter wheat (Triticum aestivum L.) treated with unconventional preparations

The study was conducted in the laboratory of the Agricultural Institute of Shumen. The germination energy and germination of winter wheat variety Venka 1 are reported following the adopted methodology. The germination energy was recorded on the fourth day of the experiment, and the germination and measurement of the coleoptile – on the eighth day. 10 granules of the following homeopathic preparations are pre-dissolved in distilled water: Calcium sulfuricum 6 D, Thallium sulfuricum 6 D, Sulfur, Graphites 6 D, Selenium, Ferrum metallicum 10 D, Magneziun fluoratum 10 D, Arsenicum album 12 D, Causticum Hanenmanni 30 D, Zincum metalicum 30 D. The tested homeopathic preparations have no proven effect on the germination energy and germination of seeds in wheat variety Venka 1. The variants treated with the homeopathic preparations Thallium sulfuricum and Sulfur have been proven to exceed the standard one in terms of coleoptile length. Тhis work will serve as a basis the study of other homeopathic preparations to determine their impact on uniform germination and their aftereffect on plant growth.