Genotype × Environment Interactions for Qualitative Traits in Brinjal (Solanum melongena L.): Differential Phenotypic Plasticity and Stability in Inbreds and Hybrids across Summer and Kharif Seasons

Abstract

Brinjal (Solanum melongena L.), an important solanaceous vegetable, shows high phenotypic plasticity, making it a valuable model for studying genotype × environment (G×E) interactions. Sixty-eight diverse brinjal genotypes (22 inbred lines and 46 F₁ hybrids) were evaluated at ICAR–Indian Institute of Vegetable Research, Varanasi, India, during the summer (March–June) and kharif (July–October) seasons of 2024–25 to assess seasonal phenotypic plasticity and stability of seven qualitative morphological traits under contrasting environments. The experiment was laid out as a Randomized Complete Block Design (RCBD) with three replications per genotype in each season. Data were analysed using chi-square, McNemar’s, Stuart-Maxwell tests, and two-way ANOVA. Out of the 68 genotypes, 57.4% (39) exhibited complete phenotypic stability across both seasons, with inbred lines (59.1%, 13/22) slightly more stable than hybrids (56.5%, 26/46). Growth habit was the most plastic trait (23.5% genotypes changed), followed by fruit colour (17.6%) and fruit shape (13.2%), whereas calyx colour, fruit flesh colour, leaf vein colour, and leaf spininess remained invariant. Kharif conditions favoured erect growth habit, darker fruit pigmentation, and rounder fruit shape. Hybrids displayed greater plasticity for growth habit and fruit shape, while inbreds were more responsive for fruit colour. Highly significant G×E interactions were detected for growth habit (p = 0.0012) and fruit colour (p = 0.003). Thirty-nine genotypes showing complete stability across seasons, including 12 inbreds and 27 hybrids (listed in the manuscript), are recommended as promising parental material for breeding season-independent, climate-resilient brinjal cultivars and for direct commercial cultivation where consistent morphological expression and market preference are essential. These findings highlight the critical role of phenotypic plasticity and stability in developing adaptable brinjal varieties for variable and changing climatic conditions.