Phenotyping sorghum for maturation period, harvest index, and associated traits

Abstract Background: Sorghum is a climate-resilient crop and is a key food, feed, and industrial raw material source. Dwindling yields associated with recurrent drought and short rain seasons necessitate the development of early-maturing and high-harvest index sorghum varieties for sustainable production and livelihoods. This study aimed to phenotype sorghum for maturity period, harvest index, and associated traits to guide production and select complementary parents for breeding population development with desirable product profiles. Methods: One hundred and six genetically diverse sorghum genotypes were evaluated during the 2023/2024 and 2024/2025 growing seasons using a 10 × 11 alpha lattice design. Significant ( p < 0.001) genotype-by-season interaction and genotype effects were detected for days to 50% anthesis (DTA), grain filling period (GFP), days to 75% maturity (DTM), plant height (PH), shoot biomass (SB), number of productive tillers (NPT), grain yield (GY), and harvest index (HI). Results: The study selected early-maturing genotypes, such as AS232, AS603, ACCI-S-108, and ACCI-S-118, with maturity periods of 133.2, 136, 136.75, and 137.5 days, respectively. Relatively higher harvest indices were recorded for genotypes AS232, AS352, AS229, and AS619, with mean values of 41.74, 41.04, 40.54, and 38.98%, in that order. Two principal components were identified, explaining the genetic variations of the test genotypes for the maturity period and harvest index component traits. The assessed sorghum genotypes were resolved into three maturity groups: early (16% of the test genotypes, 133–142 DTM), intermediate (69%, 143–161 DTM), and late (15%, 161–183 DTM). Three HI groups were discerned, including high HI (16.98% of the evaluated genotypes with HI 35.63–41.74%), intermediate HI (64.15% with 22.27–35.16%), and low HI (18.87% with 14.47–21.16%). The days to maturity showed significant ( p < 0.001) positive correlations with DTA ( r = 0.75), SB ( r = 0.42), and a negative association with HI ( r = −0.47). Furthermore, HI exhibited a significant ( p < 0.001) negative relationship with DTA ( r = −0.39) and SB ( r = −0.56). Conclusion: The selected early-maturing and high HI genotypes are recommended for grain production and breeding, aiming at low-moisture agro-ecologies.