https://breeding.tabrizu.ac.ir/ Journal of Plant Physiology and Breeding en daily 1 Fri, 01 May 2026 00:00:00 +0330 Fri, 01 May 2026 00:00:00 +0330 https://breeding.tabrizu.ac.ir/article_21330.html Objective: Heat stress disrupts the photosynthetic machinery and shortens developmental phases, leading to yield loss in cereals. This study investigated the potential of rice bran-coated urea (RBCU) to ameliorate heat-induced constraints on growth, phenology, and dry matter partitioning in proso millet (Panicum miliaceum L.).Methods: A two-year field experiment evaluated uncoated urea (UCU), RBCU, gypsum-coated urea (GCU), and cement-coated urea (CCU) at four nitrogen rates (0, 60, 80, and 120 kg urea ha-¹) under optimal (spring) and heat stress (summer) conditions. The experiment was conducted as a split-plot factorial arrangment based on a randomized complete block design with three replications. The main plots included planting season (spring and summer seasons), while the subplots consisted of the factorial combination of coating type and urea-N rate. In this study, several traits, including days to heading, days to physiological maturity, chlorophyll a, total carotenoids, leaf area, panicle length, biomass, grain yield, and harvest index, were measured.Results: The results indicated that RBCU at 80 kg urea ha-¹ generally ranked among the best-performing treatments, particularly under summer conditions. Under summer heat stress, RBCU maintained significantly higher chlorophyll a and carotenoid contents, increasing chlorophyll a and carotenoids by 25.4% and nearly twofold, respectively, compared with the stressed UCU control. It concurrently improved canopy architecture, increasing leaf area and panicle length by 14.9% and 15.2%, respectively. RBCU also modulated crop phenology by delaying heading by 11.5%, and was associated with an improved dry matter partitioning efficiency, reflected in a higher harvest index. It increased total biomass by 17.3% and, most importantly, enhanced the harvest index by 6.3% under severe stress, indicating a more efficient allocation of assimilates to grains. Consequently, grain yield with RBCU at 80 kg urea ha-¹ was 17.5% higher than that with UCU under summer conditions.Conclusion: RBCU was associated with improved physiological performance and higher yield under summer heat conditions, likely through coordinated effects on canopy traits, phenology, and harvest index. https://breeding.tabrizu.ac.ir/article_21331.html Objective: Sugar beet is primarily cultivated from seeds, and one of its main challenges is the low germination rate caused by seed dormancy due to seed coat coverage. Seed priming is an effective method to overcome dormancy and enhance both germination percentage and speed. However, storing primed seeds reduces their longevity and accelerates deterioration. Therefore, determining the duration of priming effects during ambient storage is important. This study aimed to improve germination and seed vigor of sugar beet seeds and evaluate the storability of primed seeds.Methods: The experiment was conducted in 2025 at the Seed Science and Technology Laboratory of Hamyaran Keshavarz Company in Zarand, Kerman, Iran. The experimental design was a completely randomized design with seven priming treatments (0.2% nano-urea for 1 hour, 0.3% seaweed extract for 1 hour, 20 ppm gibberellic acid for 24 hours, hydroelectropriming with a current of 15 V for 2 minutes, hydropriming for 12 hours, electropriming with a current of 20 V for 2 minutes, and 20 ppm gibberellic acid for 1 hour), along with the control treatment, each replicated four times with 100 seeds per replication.Results: Nano-urea (0.2%), hydroelectropriming (15 V for 2 minutes), and seaweed extract (0.3%) had the largest positive effect on germination and seed vigor. The beneficial effects of priming significantly declined during storage, affecting germination, seed vigor, and the activities of antioxidant enzymes, such as catalase, superoxide dismutase, and peroxidase. Hydroelectropriming and nano-urea demonstrated the best seed viability retention over three months of storage.Conclusion: Hydroelectropriming (15 V, 2 min) and nano-urea priming (0.2%, 1 h), as innovative and environmentally friendly methods, are recommended to maximize germination and vigor while preserving seed storability for three months, supporting sustainable sugar beet production. https://breeding.tabrizu.ac.ir/article_21345.html Objective: Drought stress has destructive effects on the growth and performance of crops. The application of superabsorbent polymer can provide water and some nutrients to crops during the growth period. This experiment aimed to evaluate the effect of hydrogel polymer and drought stress on the characteristics of maize (variety MV 524 Maxima).Methods: The experiment was conducted as a split-plot design based on a randomized complete block design with three replications. The drought stress levels, 60 mm (control), 120 mm, and 180 mm, based on evaporation from the evaporation pan, were assigned to the main plots. The levels of hydrogel polymer, 0 (control), 75, 150, and 225 kg/ha were arranged in subplots.  Hydrogels were mixed and applied at a depth of 20-30 cm in the soil. Samples were taken from young leaves at the seed-filling stage to measure photosynthetic pigments and antioxidant enzymes activity. Also, at maturity, mineral elements (nitrogen, phosphorus, and potassium) in the grains, biomass, grain yield, and yield components, including 1000-kernel weight, number of kernels per row, number of kernel rows per ear, and plant height were measured.Results: Drought stress reduced photosynthetic pigments (chlorophyll “a”, chlorophyll “b” and carotenoids), N, P, and K content in the grains, the number of kernels per row, number of kernel rows per ear, and 1000-kernel weight. Also, drought stress increased the activities of catalase (CAT) and glutathione peroxidase (GPX). The application of hydrogel polymer had a positive effect on maize plants and at all drought levels, the highest grain yield, biomass, and number of kernels per row were obtained with the highest amount of hydrogel polymer (225 kg/ha). However, hydrogel polymer decreased CAT activity and anthocyanin content, but it did not change the number of kernel rows, 1000-kernel weight, ion content in the grains, GPX activity, chlorophyll “a” and “b”, and carotenoids in the maize leaves.Conclusion: The results indicated that the application of 225 kg/ha hydrogel polymer had a beneficial effect on maize and mitigated the harmful effects of drought stress. https://breeding.tabrizu.ac.ir/article_21346.html Objective: Snapdragon (Antirrhinum majus), a perennial species in the Scrophulariaceae family, is valued for its colorful flowers and ornamental appeal. This study aimed to evaluate the effects of chitosan‑coated iron oxide nanoparticles (chitosan‑coated IONPs) and silver nanoparticles (AgNPs) on key morphological and biochemical characteristics of this species.Methods: The experiment was conducted under greenhouse conditions as a factorial arrangement in a completely randomized design with four replications. Factors included four concentrations of chitosan‑coated IONPs (0, 50, 100, and 150 µM) and four concentrations of AgNPs (0, 50, 100, and 150 mg·L⁻¹). Measured traits encompassed stem diameter, fresh weight of aerial parts, number of lateral branches, plant height, flower number and diameter, total sugars, total flavonoids, total phenolic content, antioxidant capacity [1,1‑diphenyl‑2‑picrylhydrazyl (DPPH)], stomatal conductance, and chlorophyll fluorescence indices (F0, Fm, Fv, Fv/F₀, and Fv/Fm).Results: The combined application of chitosan‑coated IONPs and AgNPs significantly enhanced vegetative growth, floral attributes, and most physiological indicators. The greatest improvements in fresh weight, plant height, and number of lateral branches were achieved with 100 µM chitosan‑coated IONPs + 50 mg/L AgNPs. The Fv/F₀ and Fv/Fm ratios were enhanced by the combination of 150 µM chitosan-coated IONPs + 150 mg/L AgNPs. Significant interaction effects were observed for total sugars, total flavonoids, and DPPH activity, with the 100 µM chitosan‑coated IONPs + 100 mg/L AgNPs treatment showing the most pronounced improvements. Total phenolic content also increased under combined nanoparticle treatments, indicating activation of the antioxidant defense system.Conclusion: Overall, single or combined applications of chitosan‑coated IONPs and AgNPs improved growth performance, flowering, and antioxidant responses in snapdragon. These findings highlight the potential of nanoparticle‑based strategies for sustainable, high‑quality ornamental plant production. Future research should focus on refining optimal nanoparticle concentrations and assessing their long‑term impacts. https://breeding.tabrizu.ac.ir/article_21363.html Objective: One of the most important factors limiting the yield of a crop, including barley, is water-deficit stress during critical stages of growth. Water-deficit stress reduces barley yield and associated traits, compared to optimal conditions. Previous studies have reported that drought stress significantly increases the activity of antioxidant enzymes. This study aimed to identify water-deficit-stress-tolerant barley genotypes by assessing some morphological and enzymatic traits.Methods: In this study, the tolerance of 18 barley genotypes to water-deficit stress was evaluated based on some morphological and enzymatic traits. Two field experiments were conducted in a randomized complete block design with three replications: one under optimal irrigation and the other under limited irrigation, where water was withheld at the 50% flowering stage (Zadok’s 10.5.2). Subsequently, some enzymatic and agronomic characteristics were measured, including catalase (CAT) and peroxidase (POD) activity, 1000-grain weight, number of tillers, spike length, number of grains per spike, plant height, biomass, and grain yield. For the measured traits, genetic coefficient of variation, phenotypic coefficient of variation, and heritability were estimated. Also, cluster analysis was conducted to group genotypes under both water-deficit stress and normal conditions. In addition, the stress tolerance index (STI) was calculated to identify water-deficit-stress tolerant genotypes.Results: There were significant differences among the barley genotypes for all traits, except for POD and CAT. Also, water-deficit stress significantly affected plant height, biomass, grain yield, peroxidase, and catalase. However, the interaction between genotypes and irrigation conditions was significant only for grain yield and biomass. According to the analysis of variance, the estimates of genetic coefficients of variation, and cluster analyses, there was appreciable variation among the barley genotypes for most of the traits measured in this experiment. Genotypes 12, 17, and 10 exhibited a higher grain yield in both normal and water-deficit stress conditions, and also the highest STI values among the genotypes. Enzyme activity analysis suggested that CAT is a more reliable indicator than POD for alleviating the adverse effects of water-deficit stress. Also, CAT exhibited a higher genetic coefficient of variation and higher heritability than POD under both conditions. The number of grains per spike showed noticeably higher heritability values than grain yield under both normal and water-deficit stress conditions. Also, a high heritability was observed for1000-grain weight under stress conditions. Thus, indirect selection for grain yield through the number of grains per spike and 1000-grain weight may be useful in segregating generations under water-deficit stress conditions, and through the number of grains per spike under normal conditions.Conclusion: Genotypes 12, 17, and 10, with higher grain yield under normal and water-deficit stress conditions, and the highest STI values, can be recommended for future evaluation in breeding programs for drought tolerance. https://breeding.tabrizu.ac.ir/article_21803.html Objective: Colocynth (Citrullus colocynthis L. Schrad.) is an important medicinal and oilseed species adapted to arid and semi-arid environments. This study aimed to characterize the morphological and phytochemical diversity among Iranian C. colocynthis accessions and identify superior genotypes with desirable yield and nutritional traits. Methods: Seventeen accessions, collected from different geographical regions of Iran, were evaluated under field conditions using a randomized complete block design with three replications. Morphological traits related to fruit and seed characteristics, along with phytochemical attributes- including fatty acid composition, total phenolic content, and carotenoid concentrations- were analyzed using several statistical methods, including analysis of variance, principal component analysis, and hierarchical clustering. Correlation coefficients among the morphological and phytochemical characteristics were also computed. Results: Significant variation was observed among the colocynth accessions for all of the evaluated traits, indicating substantial genetic diversity within the Iranian colocynth germplasm. The Jiroft, Khorasgan 5, Arak, and Orzoeeh accessions exhibited superior performance for fruit yield, and fruit number. Seed oil analysis revealed the predominance of unsaturated fatty acids, particularly linoleic acid, with the highest concentration detected in the Orzoeeh accession (73%), followed by Arak (72%), Hormozgan (72%), Jiroft (71%), and Khorasgan 5 (71%). Higher total phenolic content was observed in the Kerman and Yazd accessions, while the Ahvaz, Jiroft, and Arak accessions exhibited higher total carotenoid levels, suggesting a higher antioxidant potential and adaptation to environmental stress conditions. Principal component and cluster analyses confirmed the divergence among the colocynth accessions and differentiated them based on combined agronomic and phytochemical characteristics. Conclusion: This study represents one of the first evaluations integrating the morphological and phytochemical characteristics of Iranian colocynth germplasm. The results demonstrate substantial genetic diversity within Iranian colocynth germplasm for morphological and phytochemical characteristics. The high proportion of unsaturated fatty acids, particularly linoleic acid, further emphasizes the nutritional and pharmaceutical value of this germplasm. The identified superior accessions may serve as valuable genetic resources for breeding programs targeting drought tolerance, medicinal quality, antioxidant capacity, and seed oil improvement under arid climatic conditions.