Abstract

Drought stress reduces photosynthesis during the grain-filling period. Hence, the remobilization of culm reserves becomes an essential attribute for grain filling and yield in wheat under post-anthesis stress. To evaluate the contribution of culm reserve towards the drought tolerance in wheat, a pot experiment was conducted at the Net House, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh, from November 2018 to March 2019. The experiment consisted of two factors: (a) four cultivars viz. BARI Gom21, BARI Gom22, BARI Gom30 and BARI Gom33; and (b) stress i.e., control and drought. Each treatment was replicated thrice following Completely Randomized Design. Drought stress was imposed by manipulating the irrigation during the grain-filling period. Results revealed that the highest yield was obtained in BARI Gom33 (7.97 g/pot). It also showed statistically similar biomass yield under both control and stress conditions. Furthermore, leaf greenness was the highest in BARI Gom33 under control (43.38) and stress (41.36) conditions, while grain filling rate and maximum grain weight were in both BARI Gom33 and BARI Gom30. All cultivars showed an increasing pattern in changes in spike dry weight, but culms and leaves exhibited a decreasing trend. The amount of remobilized culm water-soluble carbohydrates (WSCs) varied from 19.80 to 204.6 and 6.950 to 117.3 mg/g under control and drought conditions, respectively. The contribution of culm WSCs to grain yield was comparatively higher in BARI Gom30 and BARI Gom33 than the others, which varied from 5.423 to 22.66% and 4.517 to 17.86% of the total grain weight under control and drought stress, respectively. Thus, BARI Gom30 and BARI Gom33 appeared to be relatively drought tolerant over the rest two because of their higher current assimilation and culm reserves that contribute to the grain weight.