Physiological responses of doubled haploid wheat lines differing in grain yield under rainfed and irrigated environments.
Sangha J.S., et al. (2021). Physiological responses of doubled haploid wheat lines differing in grain yield under rainfed and irrigated environments. Canadian Society of Plant Biologists annual meeting, 7-10 June 2021, Saskatoon, SK.
Understanding the physiological mechanisms contributing to high grain yield is important for early generation selection in breeding, either by directly measuring physiological traits or by selecting for markers to those traits. A six year study of a doubled haploid (DH) bread wheat population “B0767&” (Carberry/ AC Cadillac) in the field showed significant grain yield variation under rainfed and irrigated conditions. Four DH lines with contrasting grain yield were further investigated in the field and greenhouse for various physiological mechanisms associated with water stress response. Analysis of flag leaf stomatal traits from two independent experiments revealed significantly low stomatal density (p< 0.05) and conductance (gs) (p<0.05) in the high yielding line ‘B0767&AG075’ (registered as AAC Goodwin) and ‘B0767&AX125’ under water stress but not under irrigation. The lines B0767&AG075 and ‘B0767&AX125’ also showed a high ∆13C/δ18O ratio, a cooler canopy, and higher NDVI compared to the lines B0767&AD028 and B0767&AH156 with low grain yield. Greenhouse studies for gas exchange parameters, the maximum rate of carboxylation (Vcmax), photosynthetic electron transport rate (J), dark respiration (Rd), and mesophyll conductance (gm) showed contrasting reaction of these DH lines during water stress. Taken together, our results suggest that diverse physiological mechanisms and traits related to carbon fixation contribute to the grain yield variation in DH lines during water stress. The DH lines such as ‘AAC Goodwin’ with high yield potential and contrasting physiological mechanisms hold great promise to develop wheat germplasm for dryland environments.