Vol. 10, Issue 5 (2021)

Author(s):
Gowsiga S, M Djanaguiraman, N Thavaprakaash, Jeyakumar P and Govindaraj M

Abstract:
Sorghum [Sorghum bicolor (L.) Moench] is an important dryland cereal grown in arid and semi-arid regions to achieve food and nutritional security. The major problem associated with arid and semi-arid regions of the world is drought stress, limiting the sorghum yield. Therefore, one of the approaches to increase sorghum productivity in dryland agriculture is understanding the mechanism of drought tolerance. Therefore, the present study was conducted to (i) quantify the diurnal variation in transpiration rate of sorghum genotype differing in root angle and (ii) quantify the effect of progressive soil drying on leaf physiological traits. Two sorghum lines, IS13540 and IS23143, were grown under fully irrigated conditions up to the six-leaf stage; after that, the plants are subjected to progressive soil drying conditions for four days to understand the mechanism of drought tolerance. Between the lines, the line IS13540 had a lower transpiration rate than IS23143 from the start of drying to progressive soil drying. The results indicated that a higher fraction of transpirable soil moisture (FTSW) threshold value (0.622) was observed for the line IS13540 than for IS23143 (0.531). In contrast, a lower stomatal conductance and higher photosynthetic rate were observed in line IS13540 than IS23143. Overall, it is evident that the line IS13540 is more tolerant to drought than IS23143, as evidenced by a lower transpiration rate and higher photosynthetic rate.