Genetic analysis of shade tolerance in chilli (Capsicum spp.)

Abstract

Investigation on 'Genetic analysis of shade tolerance in chilli (Capsicum spp.)' was carried out in the Department ofOlericulture, College of Agriculture, Vellayani, during 1997 - 2000 with the objective of identifying superior genotype(s) of chilli to yield better under shade and to analyse the physiological, anatomical, biochemical and genetic basis of shade tolerance. Seventy genotypes of chilli belonging to C. annuum, C. Jrutescens and C. chinense collected from different parts of the country were initially evaluated under 25, 50 and 75 per cent shade in comparison with open condition for shade tolerance and yield. Plant height, internodal length, stem girth, leaf area, petiole length, days to first flower, node to first flower, height of node to first flower, fruits per plant, fruit length, fruit girth, fruit weight, yield and incidence of mite were found significantly different both among the genotypes and between different shade levels. High heritability combined with high GCV and expected genetic advance was observed for fruits per plant, fruit weight, fruit length, fruit girth, leaf area and yield under shade indicating the possibility of improvement of these characters through selection. A positive correlation was observed for fruits per plant, fruit length and fruit weight with yield at genotypic and phenotypic levels. CA 38 of C. annuum, CF 51 of c. Jrutescens and CC 63 of C. chinense were identified as shade tolerant and CA 39 of C. annuum, CF 46 of C. Jrutescens and CC 66 of C. chinense as shade susceptible genotypes. The shade tolerant genotypes were found to be superior in maintaining higher LAl, SLW, CGR, RGR and NAR under shade than shade susceptible ones. Genotypes grown under open had thicker leaves with more stomates per unit area. Anatomical attributes viz., upper and lower epidermal cells, palisade and spongy mesophyll cells and vascular bundle thickness were maximum in open. The increase in chlorophyll ~, h and total chlorophyll under shade was prominent in shade tolerant genotypes than that of susceptible ones. A decreasing trend was observed in chlorophyll ~ / h ratio in all the genotypes due to prominent increase of chlorophyll h fraction. The shade tolerant genotypes were found to maintain higher proline and total phenol content under shade compared to shade susceptible genotypes. Capsaicin, oleoresin and ascorbic acid content did not vary significantly due to shade. Under open condition the genotypes recorded higher carotenoid content. A polygenic system of inheritance with non-allelic interaction was revealed in shade tolerance. Duplicate type of epistasis with additive, additive x additive, dominance and dominance x dominance components of genetic variances could observe.