The effects of drought stress on the yield and some biochemical characteristics of four Maize hybrids in the gorgan climate coditions

In order to evaluate the effects of drought stress on the yield and some biochemical characteristics of four Maiz hybrids in the Gorgan conditions, an experiment was conducted as a split split plot based on a randomized complete block design with three replicaitons during 2022. The main factor was drought stress at four levels (100, 75, 50 and 25% of water use) and the secondary factor was four maize hybrids (SC703, SC704, ZP548, BK50). The results of analysis of variance showed that the effects of drought stress and hybrid on all traits was significant (chlorophyll a, chlorophyll b, total chlorophyll (a+b), carotenoid, soluble sugar, proline, number of rows, number of seed in rows, thousand seed weight and grain yield). On the other hand, the interaction effects of drought stress × hybrid were also significant on all traits except proline and the number of rows. The results of mean comparison showed that the highest amount of proline (9.91 mol/g-1) and soluble sugar (30.2 mg/g-1) was obtained from the 25% water requirement. With increasing drought stress, the amount of chlorophyll a, chlorophyll b, total chlorophyll (a+b) and carotenoids decreased. Also, the highest seed yield (8450 kg/ha-1) was observed in hybrid Zp548 from 100% water requirement, but with 75% of water use (7934.3 kg/ ha-1) was in the same statistical group. At other levels of drought treatments, the highest seed yield was obtained from hybrid Zp548. Therefore, treatment of 75% water use and Sowing of ZP548 hybrid in Gorgan region is recommended.