AMMI and GGE biplot analysis of yield under terminal heat tolerance in wheat

Wheat is an important cereal crop that helps to meet the food grain needs of people all over the world. Heat stress is one of the most significant abiotic stresses that wheat crops face during terminal growth stages in the wheat growing regions like India. It is very important to identify heat tolerant genotypes to be used as donors for breeding tolerant varieties.

Thirty-six wheat genotypes were evaluated under different sowing dates viz., Timely sown (TS), Late sown (LS) and very late sown (VLS), and the fourth was sown in the Temperature controlled phenotyping facility (TCPF) across two years. Genotypes were planted following lattice square design with two replications. Data was recorded for yield and yield contributing traits and analysed using selection indices as well AMMI and GGE biplot stability models.

Heat stress affected all the traits under different heat environments which ranged from 1.6% (Spikelet number) to 37.2% (grain yield). Regression analysis indicated that the thousand grains weight (R² = 0.50) contributed significantly towards grain yield under heat stress. Stress susceptibility index (SSI) found genotypes GW322, RAJ3765, Raj4037and MACS6145 as heat tolerant whereas, Stress Tolerance Index (STI) identified C306, HD2967, WH1080, WH730, DBW90, HD2932, DBW17, RAJ3765 as heat tolerant and high yielding. AMMI biplot analysis indicated stable genotypes DBW90, WH730, RAJ4083, CBW38, HD2932, NI5439, WR544, whereas GGE biplot analysis revealed stable genotypes NIAW34, NI5439, RAJ4083, DBW90, PBW590, Raj3765, HUW 510, WH730, HD2967 and UP2382.

Heat stress affects significantly all yield contributing traits. Thousand grain weight was the most important trait that can be used as a selection criterion for selecting tolerant lines. Based on selection indices and both AMMI and GGE analysis, genotype RAJ3765 was identified to be highly heat tolerant with good grain yield.