Abstract
The present study compared six near-isogenic lines from different backgrounds, varying in Rht (reduced height) alleles for gibberellin (GA) response, for heat and drought tolerance. Various temperature (day/night: 20/12 °C to 39/31 °C), and irrigation (100% field capacity and no irrigation) treatments were imposed at booting stage. Results depicted a 50% reduction in grain yield at 36.7 °C with irrigation and at 31.2 °C without irrigation. Number of grains per spike was severely reduced over 26 °C for water-stressed plants while irrigated plants did not show any significant reduction up to 34 °C. Ear numbers per pot and spikelets per spike were unaffected by irrigation till 33 °C. In Mercia, grain nitrogen, sulphur, and Hagberg falling number (HFN) were significantly higher for severe dwarfs (Rht-D1c and Rht-12), however, in Maris Widgeon, rht (tall) recorded higher nitrogen and sulphur concentration while Rht-B1b presented the maximum sedimentation of sodium dodecyl sulphate (SDS). The SDS was higher in Maris Widgeon while HFN were superior in Mercia. Conclusively, the present study demonstrated that heat and drought stresses severely reduced the grain yield while improved grain quality traits. The GA-insensitive semi dwarf Rht-B1b was the most promising genotype for grain yield and HFN under combined drought and heat stresses.
•We studied the effect of GA-Sensitive Rht alleles on tolerance to heat and drought stresses.•Temperature >30 °C during booting reduced grain yield particularly under drought.•The semi-dwarfing alleles Rht-B1b recorded higher yield in the Mercia background.•Extreme dwarfism was associated with reduced grain weight and yield.•Severe dwarf Rht-D1c had higher HFN and lower SDS.