Morphological basis of resistance to yellow mite, Polyphagotarsonemus latus and thrips, Scirtothrips dorsalis in chilli genotypes

Abstract

To investigate the morphological factors contributing to resistance to yellow mite, Polyphagotarsonemus latus and thrips, Scirtothrips dorsalis in chilli, an analysis was conducted on 15 chilli genotypes, examining various traitsviz. trichome density, length, and angle, along with leaf thickness, length, breadth, and area. Among the genotypes, SL-696 exhibited the highest trichome density (87.67/0.75mm²), while IS-267 displayed the lowest density (19/0.75mm²), and C-142 lacked trichomes altogether. In terms of trichome length, SR-4611 had the maximum (5.02 µm), contrasting with PUP-661, which had the minimum length (1.16 µm). PCH-757 featured the highest trichome angle (44.47°), while AC-105° showed the lowest angle. C-142 demonstrated the greatest leaf thickness (264.67 µm), whereas SL-466 exhibited the smallest thickness (79.60 µm). PUP-661 displayed the highest values for leaf length (9.10 cm), breadth (3.93 cm), and area (148.19 cm²), with PP-418 exhibiting the minimum values for length (3.87 cm), breadth (1.40 cm), and leaf area (44.03 cm²). Analyses of correlations between damage score/LCI and various morphological leaf traits indicated weak, negative, yet nonsignificant associations with trichome density, length, angle, and leaf thickness. Conversely, leaf area demonstrated a weak positive but nonsignificant correlation with the damage score.