Unravelling The Morpho-Physiological Characteristics Of Soybean Genotypes Under Drought Stress In Controlled Glass House Conditions

Abstract

Ensuring global food security is one of the foremost challenges of the current human epoch. Addressing this imperative necessitates the development of novel soybean varieties, as well as the genetic enhancement of existing germplasm, with improved resistance and tolerance to both biotic and abiotic stresses. To investigate this aspect, eight soybean genotypes (G1–G8) along with two reference checks (NARC-Soy-2021 and NARC-Golden Soy) were evaluated. The experiment was conducted under controlled glasshouse conditions, with regulated temperature and water levels, employing a completely randomized block design with three replications consisting of one control and two drought stress treatments. Data were collected for a comprehensive set of traits, including germination potential (%), seedling height (cm), number of leaves, shoot length (cm), root length (cm), total seedling length (cm), seedling vigor index, shoot fresh weight (g), shoot dry weight (g), root fresh weight (g), root dry weight (g), number of secondary roots, chlorophyll content (µmol cm⁻²), membrane thermo-stability (%), and membrane injury (%). Statistical analyses included analysis of variance (ANOVA), principal component analysis (PCA), and correlation heat mapping to determine trait significance and interrelationships. The analyses revealed substantial variation among genotypes across most parameters, highlighting their potential for genetic improvement and suitability for incorporation into future breeding programs. PCA identified two major components explaining the majority of variation, with shoot length showing the highest loading in PC1, while membrane injury contributed most strongly to PC2. The findings provide critical insights into the physiological and morphological mechanisms underlying drought tolerance in soybean. This study establishes a valuable foundation for the development of resilient cultivars, thereby contributing to the mitigation of water-deficit stress in soybean production and enhancing long-term food security.