EFFECT OF DROUGHT STRESS AND GIBBERELLIC ACID ON MORPHOPHYSIOLOGICAL PARAMETERS AND YIELD OF WHEAT

Abstract

Drought stress is a major problem in wheat production but it could be managed by using various exogenous protectants. In the first experiment drought stress was imposed on various growth stages of wheat and to alleviate it GA was applied. Drought stress reduced plant height 16.42%, 22.06 % tiller and 36.10% biomass. The 28.31% spikelets spike -1 , 33.25% grains spike -1 , 35.17% 1000-grain weight, 45.40% grain yield, 36.43% biological yield and 13.14% harvest index was reduced due to drought stress but GA had played a role to reduce the damage of drought stress and in most of the cases it increased the growth and yield than no gibberellic acid. For growth CRI stage was most critical and for yield flowering and grain development stage was more sensitive to drought though GA treated plants showed less damage at CRI stage. In the second experiment, combined effect of GA and drought stress after 48h and 72h was studied. MDA, H 2 O , proline content was increased and CAT, APX was reduced in drought stress. GA played a role to restore not only these but also AsA, GSH/GSSG ratio, MDHAR, DHAR activity was restored by GA. GA significantly worked on glyoxalase system. Under drought stress MG activity was increased but GA stimulated Gly I and Gly II activity to protect the wheat seedlings. So, the present study concluded that the severity of drought stress on wheat depends on the growth stage and it increased with the enhancement of duration of stress whereas GA helped wheat seedlings by upregulating of antioxidant defense mechanism and glyoxalase system