Effect of drought stress on the biochemical characteristics of grain sorghum cultivars in summer cultivation

Selection of cultivars adapted to drought stress conditions in each region plays an important role in achieving production potential in that region. For this purpose, the effect of drought stress through the irrigation cycle after ۸۰ (control), ۱۱۰ (mild stress), ۱۴۰ (relatively severe stress) and ۱۷۰ (severe stress) mm of evaporation from the class A evaporation pan on four grain sorghum cultivars, Sepideh, Kimia, Payam and KGS۳۲, was investigated in summer cultivation in Khorramabad, Lorestan. The results showed that the amount of photosynthetic pigments (chlorophyll a, chlorophyll b and total chlorophyll, ratio of chlorophyll a/b, carotene and xanthophyll) and the amount of starch, protein, sodium and the ratio of sodium to potassium decreased with the intensification of drought stress, but the amount of nitrate, proline and potassium increased in the sorghum shoot. Intensification of drought stress was accompanied by the suppression of catalase, which caused the antioxidant defense mechanism to work through increasing peroxidase production. The highest amounts of non-structural soluble sugars, peroxidase and proline in the aerial part were obtained from KGS۲۳ and Payam cultivars under severe drought stress conditions, while the highest amount of starch under normal irrigation conditions was obtained from the Sepideh variety, as were the highest amounts of catalase and total protein in the aerial part under normal conditions. Watering was observed in Payam and KGS۲۳ cultivars. The trend of grain yield changes of all grain sorghum cultivars under the influence of drought stress followed a significant and negative linear relationship, but the changes of peroxidase and proline with increasing drought stress had a significant and positive linear relationship. In general, grain sorghum cultivars KGS۲۳ and Sepideh have different drought stress tolerance mechanisms and can be recommended for normal and stressful conditions in the temperate region of Khorramabad.

Keywords:

Antioxidant , Irrigation regime , Micronutrient elements , Osmotic adjustment , Photosynthetic pigments , Seed yield , آنتی اکسیدان , تنظیم اسمزی , دور آبیاری , رنگیزه های فتوسنتزی , عملکرد دانه , عناصر ریزمغذی