Phenotypic Characterization of Growth and Yield Parameters of Selected Grain Forage Sorghum Accessions for Drought Tolerance

Abstract Sorghum is a vital cereal crop recognized for its resilience under marginal soil and stress conditions. To identify high-yielding, climate-resilient accessions for breeding, this study implemented a two-stage, dual-year approach that is rarely reported in grain forage sorghum research. First, 26 accessions alongside BARI Jowar-1 were evaluated under well-watered conditions to assess genetic diversity in agronomic traits. Significant variability was observed among accessions for agronomic traits, including days to flowering, days to maturity, plant height, panicle length (PL), grain yield per plant (GY), grain size, number of grains per panicle (GP), and thousand grain weight (TGW). High broad-sense heritability and genetic advance were noted for GY, GP, PL, GW, and TGW, indicating the potential for genetic improvement through selection. Multivariate analyses, including biplots, hierarchical heatmaps, and K-means clustering, identified BS-718, BS-746, and BS-749 as high-yielding and early-maturing accessions suitable for further evaluation. In the second stage, these three accessions and BARI Jowar-1 were evaluated under 60% field capacity and well-watered conditions to assess physio-biochemical and yield responses under water-limited environment. Water stress significantly reduced photosynthetic gas exchange attributes, leaf water potential, relative water content (RWC), photosynthetic pigments, PL, and grain yield across all accessions while increasing intercellular CO 2 concentration and leaf temperature. The magnitude of these reductions varied, with BARI Jowar-1 exhibiting the highest sensitivity and pronounced declines across measured traits, whereas BS-718 maintained higher RWC, pigment stability, gas exchange efficiency, and yield under drought condition, confirming its superior drought resilience. This integrated framework combining broad phenotypic screening with targeted physiological validation provides novel insights into sorghum variability and identifies BS-718 as a promising resource for developing drought-tolerant, high-yielding sorghum varieties. Further field trials and molecular characterization of these high-performing germplasms are warranted to facilitate the development of high-yielding, climate-resilient sorghum varieties.