Phenotyping for stem reserve mobilization efficiency under heat, drought and combined stress along with defoliation in wheat (Triticum aestivum)

The present study was conducted to determine genotypic variations for stem reserve mobilization efficiency in wheat (Triticum aestivum L.) under drought, heat and combined stresses along with defoliation. Genotypes (43) were evaluated under 4 field conditions namely, timely sown irrigated (control), timely sown rainfed (drought), delayed sown irrigated (heat) and delayed sown rainfed (combined heat and drought) by cutting off all leaf blades (defoliation) at 12 days after anthesis. The traits recorded were stem reserve mobilization efficiency (SRE), harvest index (HI), grain weight (GW) and specific weight (Sp. wt). In timely sown and delayed sown environment condition the average maximum temperature was 24.7 degrees C and 30.4 degrees C during flowering to maturity stage respectively. The average soil moisture under control, drought, heat and combined stress was 14.46, 6.68, 16.87 and 7.78% respectively. SRE was found significantly higher under drought stress followed by combined stress, control and heat stress. The correlation analysis revealed Sp. wt at 12 DAA was highly positively correlated with the GW. The trait SRE was highly positively correlated with HI. Combined analysis for all stresses showed that HD 4728, Duram 1, Chiriya 3, HD 2851, HD 2329, DBW 43 had highest and Hindi 62, WL 711, GCP 23, HD 2967, GCP 2, Kalyansona had lowest SRE. Genotypes were also grouped into different clusters based on their SRE. The genotypes with higher SRE can be used in breeding programmes or directly used as cultivars under drought, heat and combined stress conditions.