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
