Phenotypic screening of brinjal genotypes for excess moisture stress tolerance during reproductive growth

Abstract

The growth, physiology and yield stability of eggplants (Solanum melongena L.) are significantly impacted by excessive moisture stress during the reproductive stage, especially in humid and poorly drained settings. The goal of the current study was to categorise brinjal genotypes by their response patterns and to identify key phenotypic features associated with resistance to excess moisture stress. A completely randomized design (CRD) was used to assess 40 genetically distinct brinjal genotypes under controlled polyhouse conditions. At the onset of flowering, excess moisture stress was imposed for six consecutive days by maintaining continuous waterlogging with approximately 5 cm standing water above the soil surface, whereas control plants were irrigated to near field capacity without water stagnation. Leaf area (LA), number of leaves per plant (NL), root characteristics, total biomass (TB), Soil and plant analyser development (SPAD), chlorophyll content, canopy temperature (CT) and tolerance score were among the morphological and physiological characteristics recorded. Tolerance score showed a strong negative correlation with CT and positive correlations with LA, root length (RL), root volume (RV), root dry weight (RDW), NL and TB, as indicated by the correlation analysis. 83.6 % of the total phenotypic variance was explained by the first four principal components (PCs) in principal component analysis (PCA), with PC1 primarily reflecting an integrated growth vigour and tolerance axis. Divergent tolerance strategies were reflected in the classification of genotypes into susceptible (S), moderately tolerant (MT) and tolerant (T) groups using hierarchical cluster analysis. Under stress, T genotypes showed improved growth maintenance, strong root systems, advantageous physiological characteristics and reduced CT. Overall, the study provides reliable indirect selection criteria for breeding programs aimed at enhancing stress resistance and shows that coordinated morphological and physiological features, rather than a single attribute, govern tolerance to excess moisture stress in brinjal.