Evaluating the Effect of Seed Treatment with Hydrogen Peroxide on Anatomical and Physiological Characteristics of Wheat under Dry Condition

Introduction Water deficit is the major abiotic factor limiting plant growth and crop productivity around the world. In all agricultural regions, yields of rain-fed crops are periodically reduced by drought. Among various strategies, pre-sowing treatment and priming of seeds are easy, low cost, low risk and effective approaches to overcome the environmental stress problems. Various priming strategies include osmopriming, halopriming, hormonal priming or hydropriming, etc. Hydrogen peroxide, a stress signal molecule, was evaluated as seed treatment to produce the metabolic changes, which could lead to improved drought tolerance in wheat. The interaction of signals conferring stress tolerance in accomplishing better crop growth and yield is a priority area of research. Here we report some anatomical, physiological and biochemical changes induced by Hydrogen peroxide during seed treatment and their involvement in conferring drought tolerance upon wheat. Materials and Methods A field study was conducted out at the research farm of agricultural collage of Ilam university during 2014-2015 cropping season. This study was aimed to investigate the priming seed with hydrogen peroxide on two wheat genotypes (Cross Sabalan (bread wheat) and Saji (durum wheat)), under dryland farming system condition. Experimental design was factorial, arranged in randomized complete block, with three replications. Two main factors were wheat genotypes and four soaking treatments of seeds with different concentration (zero, 25, 50 and 80 Mm) of Hydrogen Peroxide. Seeds of each genotype were sown at 6 rows of 3 m length with lines space of 20 cm in depth 5 cm. At heading stage physiological traits were measured on selected leaves and then samples were taken to determine leaf area, Leaf rolling, number and length of Stomata on the epidermis, RWC, electrolyte leakage, photosynthetic pigments concentrations (Chla, b and carotenoid) and antioxidant enzyme contents (catalase, ascorbate peroxidase) and at tillering stage Anatomical traits (mesophyll area, bundle sheet area, upper and lower epidermis cells layer and both length and area of xylem and phloem vessels)were measured using image analysis technique by Dino-eyeanalysis software. Data were analyzed based on experimental design model. Means comparison was performed based on LSD test (P≤0.05). All calculations were performed using SAS (version 9.1) software. Results and Discussion All studied parameters, anatomical, physiological and grain yield, of genotypes were significantly affected by priming seeds with hydrogen peroxide. Positive changes in anatomical and physiological traits in response to hydrogen peroxide increased grain yield in both experimental genotypes. Priming of seeds with hydrogen peroxide produced plants with higher relative water contents, photosynthetic pigments concentrations (Chla, b and carotenoid) and antioxidant enzyme contents (catalase, ascorbate peroxidase) comparing with non -primed seeds. Plants of hydrogen peroxide primed seeds produced higher leaf area, stomata length, fresh and dry weights, and lower rate of electrolyte leakage and leaf rolling comparing to non-primed seeds. Priming seeds with hydrogen peroxide increased mesophyll area, bundle sheet area, upper and lower epidermis cells layer and both length and area of xylem and phloem vessels. Anatomical changing due to hydrogen peroxide priming in enhanced growth and yield of both genotypes was positive since primed plants with hydrogen peroxide had produced higher grain yield compared to non-primed plants. Overall, priming seeds with hydrogen peroxide improved grain yield of both wheat genotypes, especially grain yield of bread wheat Cross Sabalan cultivar. Conclusions The anatomical and physiological characteristics improved in dry conditions and lack of available water to the plant is essential for achieving high yield. The results showed that the concentration of 80 Mm hydrogen peroxide as a pre-treatment seed through positive effects on physiological and anatomical features could increase the yield of Saji and cross Sabalan under rain-fed conditions