Unveiling mechanisms of resistance for leafhopper, Amrasca biguttula biguttula Ishida in okra genotypes

Amrasca biguttula biguttula Ishida is the major biotic constraint in okra cultivation that cause considerable economic loss. Screening of okra (Abelmoschus esculentus) genotypes is important to develop leafhopper-resistant high-yielding cultivars for improving crop yield. To categorize leafhopper-resistant okra genotypes, we used a comprehensive collection of morphological and biochemical parameters with multivariate analysis in this study. Plant morphological and biochemical parameters were estimated by collection of leaves from different okra genotypes with three replicates during peak leafhopper infestation period and assay were performed based on specific standard protocols. Completely randomized block design was deployed and significant variations in plant morphometrics, biochemicals, and leafhopper population were recorded from each genotype screened. In the present study the morphological parameter viz., the shortest plant height was observed in resistant genotype AE 23 (17.21 cm) and the tallest plant height was recorded in the susceptible genotype AE 26 (63.22 cm) followed by Pusa Sawani (63.07 cm). The maximum leaf area of 132.24 cm² was recorded in AE 15 genotype. Biochemical data reveals that, protein content was highest in susceptible genotype AE26 (11.01 mg/g), followed by Pusa Sawani (10.72 mg/g), and the lowest in the resistant genotype AE65 (4.72 mg/g) followed by AE27 (5.54 mg/g). While phenol, OD phenol, surface wax content were maximum in identified moderately resistant genotypes. The Kaiser Criterion or eigenvalue is greater than one for the first four principal components with the cumulative percentage of variance of 78.48 percent. Principal component analysis simplified the understanding of the interactions among leafhopper and biophysical and biochemical characteristics. The genotypes AE65, AE23, AE 27, No.315, and AE4 expressed resistance in terms of higher total phenol, ortho dihydroxy phenols, tissue toughness, and surface wax contents. Our visual observations on the growth and development of okra genotypes under leafhopper pressure were represented by principal component analysis which makes it reliable. Therefore, the identified jassid-resistant okra genotypes could be further utilized as a source of appropriate donor parents in the breeding of leafhopper-resistant okra varieties.