Effect of drought stress on some seed characteristics of two bread wheat cultivars with two different qualities

Stress is the result of abnormal processes that are formed under the influence of one or a combination of environmental and biological factors. Plants are naturally affected by a wide range of living and non-living stresses. Exposure to stress during the growing season indirectly affects the crop and Gross Domestic Product (GDP). Almost half of all human food needs, especially in Asia, are met directly from cereals. More than a third of the world's population gets their daily calories and protein from wheat products, and It is a cheap source of energy, especially for the people of the Third World. Starch is the most important final product of wheat growth and development, and changes in starch content are indicative of a variety of plant growth processes.

In this study, two bread wheat cultivars named Navid with medium to poor bakery quality and Pishtaz with high bakery quality were selected. Two wheat cultivars were cultivated in the field. Both cultivars had control and drought stress treatment. The design was performed in the form of randomized complete blocks with three replications. Seeds were harvested 35 days after pollination. Morphological parameters, germination percentage, A, B and C granules were separated and the granules were examined by light microscopy. The composition of starch in wheat has a decisive effect on grain quality, flour processing and yield.

Drought caused a significant reduction in thousand seed weight in both Pishtaz and Navid cultivars. However, for spike length and germination percentage, only in Navid cultivar, which had poor bakery quality, the spike length was significantly reduced at the probability level of 1%. Also, drought stress in both cultivars had no significant effect on the amount of starch at the probability level of 1%.

Drought stress caused a significant reduction in thousand seed weight in both wheat cultivars with different qualities, but it did not affect the amount of starch in any of the cultivars. In contrast, the trait of spike length and germination percentage caused a decrease in poor quality cultivars.