Exploring genotypic diversity in sorghum breeding lines for water‐saving traits to enhance drought adaptation during the post‐rainy season

Abstract

AbstractSorghum [Sorghum bicolor (L.) Moench], a crucial staple crop in South Asia and sub‐Saharan Africa, faces challenges amid increasing climate variability. Post‐rainy sorghum serves as a dominant food and fodder crop in India. Aligned with International Crops Research Institute for the Semi‐Arid Tropics's post‐rainy sorghum product profile, this research extensively characterizes sorghum lines, emphasizing the traits vital for post‐rainy drought adaptation in hybrid parents. We examined genotypic differences and trait correlations in 25 sorghum hybrid parents and varieties (B line for seed parent, R line for restorer, and check for varieties) through atmospheric and soil drought experiments. Results from atmospheric drought experiments revealed significant variation in transpiration rate (TR) under high vapor pressure deficit (VPD), with certain lines showing limited TR (BTX623 and ICSR 21002), while others exhibited high TR. In soil drought experiments, transpiration decline occurred at fractions of transpirable soil water ranging between 0.38 (ICSR 174) and 0.65 (40162 and ICSR 21005). R lines consistently displayed superior plant growth, water use, and biomass compared to B lines. Transpiration efficiency (TE) and total biomass showed positive correlations (r2 = 0.69) in well‐watered and (r2 = 0.45) in water‐stressed conditions. Most R lines displayed higher biomass and TE. Genotypes exhibiting enhanced vigor and limited TR in high VPD conditions and high TE hold potential for enhancing drought adaptation in post‐rainy sorghum. Notably, genotypes with higher biomass, lower TR, and increased TE within both R and B line groups represent valuable genetic resources for enhancing sorghum crops, post‐rainy sorghum adaptation to water deficit.