THIOUREA-INDUCED DROUGHT STRESS TOLERANCE IN TWO CHICKPEA VARIETIES

Abstract

Drought stress is one of the major constraints for crop production around the world; hence, a number of mechanistic approaches are required to mitigate the negative impact of drought stress. Two chickpea varieties BARI Chola-7 and BARI Chola-9 were studied to understand the effect of drought stress and the protective role of thiourea (TU) in improving drought stress tolerance. The experiment was conducted at the Department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, from December 2019 to March 2020. The experiment consisted of sixteen treatments with four levels of drought stress: D 0 = no drought stress i.e. soil moisture at 100% field capacity (FC), D 1 = mild drought stress (25% depletiom from FC), D 2 = moderate drought stress (50% depletion from FC), D 3 = severe drought stress (75% depletion from FC) with and without 5 mM TU application. This study was carried out in a completely randomized design (CRD) with three replications. All the obtained data were subjected to one-way analysis of variance (ANOVA). In the current study, the highest reduction of plant height, root length, fresh weight and dry weight of shoot and root, number of branches plant −1 , RWC and chlorophyll (chl) content was found under severe drought stress in the two chickpea varieties compared to control. A sharp increase of malondialdehyde (MDA), H 2 O 2 and proline (Pro)

content was observed under mild, moderate and severe drought stress. However, foliar spray of TU mitigated the oxidative damages under drought stress as reflected in improved growth and physiological parameters under mild and moderately stressed plants of both the varieties. Ascorbate (AsA) content was decreased and glutathione (GSH) and glutathione disulfide (GSSG) content were increased under D 1 , D 2 and D 3 . Between the two varieties, BARI Chola-9 was more tolerant compared to BARI Chola-7. Besides, TU has proved its beneficial effect against drought stress by increasing MDA, H 2 O 2 and Pro

in mild and moderately stressed plants through modulating non-enzymatic antioxidants. Drought stress lowered the weight of 100seed,

seed yield plant −1 , stover yield plant −1 and biological yield plant , which were further improved by foliar spray of TU under mild and moderate drought stress of both the chickpea varieties. Noteworthy that BARI Chola-7 could not survive till maturity and plant death in two treatments (V 1 D 3 TU 0 and V 1 D 3 TU) occured finally. Those two treatments were not considered for measuring yield parameters under drought stress. Nonetheless, TU did not show any significant effect in improving stress-inducing damage under severe drought stress. However, the effect of TU was more promising in ameliorating oxidative stress under mild and moderately stressed plants of BARI Chola-9 compared to BARI Chola-7. Thus it was concluded that TU foliar spray improved morphological, physiological, biochemical and yield parameters under mild and moderate drought stress of chickpea. −1