Abstract
Low night temperatures during the November-December flowering stage significantly impact sorghum production in semi-arid regions of India, particularly during critical growth stages. To address this issue, a randomized complete block design experiment was conducted at ICRISAT, India, to characterize 16 sorghum genotypes, including nine varieties and seven hybrid parental lines, across controlled environment research facilities and precision experimental fields, with three replications for each genotype. The study found B line 296B and R line ICSR 93034 to be the most susceptible to cold treatments, while B lines 104B, ICSB52, and 185B showed better tolerance. Popular post-rainy sorghum cultivars and a line from Russia demonstrated cold tolerance, exhibiting higher values for pollen viability, panicle harvest index (PHI), and grain yield with minimal deviation between cold and control treatments. Treatment 2 (25°C/5°C) had the most detrimental effects, with the lowest values for pollen viability, PHI, and grain yield. Significant positive correlations were found between PHI (r = 0.67, p ≤ 0.01) and pollen viability (r = 0.50, p ≤ 0.01) with grain yield, indicating PHI's efficacy as a phenotypic indicator for cold tolerance. In field experiments, genotypes and date of sowing (DOS) significantly affected all studied traits, except plant height, with mean PHI, panicle weight, and grain yield notably reduced with the second DOS (8th November), highlighting the impact of cold on sorghum genotypes.