Trait phenotyping in an ancient Indian landrace of wheat Triticum sphaerococcum under optimum, terminal heat stress and deficit irrigation conditions

An ancient landrace of wheat Triticum sphaerococcum Perc. has been characterized for agronomic and physiological traits under timely sown-irrigated (TS-IR), timely sown restricted irrigation (TS-RI), and irrigated late sown conditions (IR-LS) in the winter season of 2021-22. A total of 116 accessions were collected from major gene banks across the world and examined, along with 20 bread wheat cultivars. The assessed genotypes revealed a considerable degree of variance for the trait under study. Average grain yields for the T. sphaerococcum accessions were 33.29 q/ha in TS-IR, 28.95 q/ha in TS-RI, and 26.15 q/ha in LS-IR. The extent of grain yield decline is lesser than that of bread wheat. This indicates that these species can withstand conditions of limited irrigation and extreme heat. T. sphaerococcum accessions had lower yield than bread wheat, although accessions like TS 49, TS5, TS6, TS17, TS27, and TS 61 have higher yield (> 35 q/ha) under stress conditions. Under the TS-RI trial, 25 accessions of T. sphaerococcum achieved significantly greater yields when compared to one of the well-known drought-tolerant cultivars, C 306 (29.2 q/ha). Grain yield under TS-RI and LS-IR trial exhibits substantial negative association with canopy temperature at physiological maturity (- 0.63*, and - 0.74***), and strong positive correlation with TGW (0.83*** and 0.82***), GRPS (0.67***, and 0.92***). This demonstrates that the greater grain yield can be attributed to the T. sphaerococcum accessions' ability to keep their canopies cooler in the face of heat stress. Thus, the introduction of ancient wheat in wheat cross breeding programme will increase genetic diversity and diversify current cultivars.