Arfang Badji

This study aimed to evaluate the effects of different nitrogen sources on sesame (Sesamum indicum L.) growth, yield, and physiological parameters to identify optimal fertilization strategies for maximizing production. Sesame is a valuable seed plant known for its oil, protein, and antioxidant content. A two-season field experiment (2021 and 2022) was conducted to investigate the impact of eight nitrogen sources, applied at 126 kg N/ha, including two organic sources (urea and thiourea), four nitrate salts (sodium, potassium, calcium, and magnesium nitrates), and two ammonium salts (sulfate and citrate). The experiment followed a completely randomized block design with three replicates. Among the nitrogen sources, urea exhibited superior performance in promoting vegetative growth, nitrogenous compounds, and seed yield. K nitrate emerged as the leading source for enhancing K⁺ and NO₃⁻ concentrations, capsules number, and oil content. Implementing Na nitrate increased catalase and ascorbate peroxidase activities, while urea enhanced glutathione reductase activity, and Mg nitrate stimulated glutathione-S-transferase activity. Moreover, Mg nitrate demonstrated the highest efficacy in improving Chl b levels and photosystem II photochemical efficiency. Consequently, K nitrate and urea can be considered optimal fertilizers for maximizing sesame production. Although urea resulted in the greatest vegetative growth of sesame, ammonium salts (citrate and sulfate) exhibited the second-highest effectiveness in enhancing most of the evaluated parameters. Compared to the least effective nitrogen source, urea significantly increased Chl b (57.1% vs. K nitrate), carotenoids (58.8% vs. Mg nitrate), amino acids (31.6% vs. K nitrate), nitrogen content (208.8% vs. ammonium citrate), seed yield (62.8% vs. thiourea), and oil production (41.1% vs. ammonium citrate). These results demonstrate that urea and K nitrate are optimal nitrogen sources for maximizing sesame growth and yield, providing farmers with targeted fertilization strategies to enhance productivity and sustainable nutrient management.

Trehalose serves as a crucial osmolyte and plays a significant role in stress tolerance. The influence of exogenously added trehalose (1 and 5 mM) in alleviating the chromium (Cr; 0.5 mM) stress-induced decline in growth, photosynthesis, mineral uptake, antioxidant system and nitrate reductase activity in Vigna radiata was studied. Chromium (Cr) significantly declined shoot height (39.33%), shoot fresh weight (35.54%), shoot dry weight (36.79%), total chlorophylls (50.70%), carotenoids (29.96%), photosynthesis (33.97%), net intercellular CO₂ (26.86%), transpiration rate (36.77%), the content of N (35.04%), P (35.77%), K (31.33%), S (23.91%), Mg (32.74%), and Ca (29.67%). However, the application of trehalose considerably alleviated the decline. Application of trehalose at both concentrations significantly reduced hydrogen peroxide accumulation, lipid peroxidation and electrolyte leakage, which were increased due to Cr stress. Application of trehalose significantly mitigated the Cr-induced oxidative damage by up-regulating the activity of reactive oxygen species (ROS) scavenging enzymes, including superoxide dismutase (182.03%), catalase (125.40%), ascorbate peroxidase (72.86%), and glutathione reductase (68.39%). Besides this, applied trehalose proved effective in enhancing ascorbate (24.29%) and reducing glutathione content (34.40%). In addition, also alleviated the decline in ascorbate by Cr stress to significant levels. The activity of nitrate reductase enhanced significantly (28.52%) due to trehalose activity and declined due to Cr stress (34.15%). Exogenous application of trehalose significantly improved the content of osmolytes, including proline, glycine betaine, sugars and total phenols under normal and Cr stress conditions. Furthermore, Trehalose significantly increased the content of key mineral elements and alleviated the decline induced by Cr to considerable levels.

Soybean is a high oil and protein-rich legume with several production constraints. Globally, several fungi, viruses, nematodes, and bacteria cause significant yield losses in soybean. Coniothyrium glycines (CG), the causal pathogen for red leaf blotch disease, is the least researched and causes severe damage to soybean. The identification of resistant soybean genotypes and mapping of genomic regions associated with resistance to CG is critical for developing improved cultivars for sustainable soybean production. This study used single nucleotide polymorphism (SNP) markers generated from a Diversity Arrays Technology (DArT) platform to conduct a genome-wide association (GWAS) analysis of resistance to CG using 279 soybean genotypes grown in three environments. A total of 6395 SNPs was used to perform the GWAS applying a multilocus model Fixed and random model Circulating Probability Unification (FarmCPU) with correction of the population structure and a statistical test p-value threshold of 5%. A total of 19 significant marker–trait associations for resistance to CG were identified on chromosomes 1, 5, 6, 9, 10, 12, 13, 15, 16, 17, 19, and 20. Approximately 113 putative genes associated with significant markers for resistance to red leaf blotch disease were identified across soybean genome. Positional candidate genes associated with significant SNP loci-encoding proteins involved in plant defense responses and that could be associated with soybean defenses against CG infection were identified. The results of this study provide valuable insight for further dissection of the genetic architecture of resistance to CG in soybean. They also highlight SNP variants and genes useful for genomics-informed selection decisions in the breeding process for improving resistance traits in soybean.