Studies on genetic variability, correlation and path analysis in lettuce (Lactuca sativa L.) under protected conditions

Twenty-eight genotypes of lettuce including check cultivars viz., Simpson Black Seeded and Great Lakes were grown in a RCBD with three replications during Rabi 2011-12 and 2012-13 at Vegetable Experimental Research Farm, Nauni, Solan H.P. to estimate the parameters of genetic variability, correlation and path analysis undernaturally ventilated polyhouse. Analysis of variance showed highly significant differences among genotypes for all the characters under study. Variability revealed that phenotypic co-efficient of variation (PCV) in general were higher than the corresponding genotypic co-efficient of variation (GCV) for all the characters. High co-efficient of variability were found for heading percentage (37.00% and 36.01%), incidence of sclerotinia rot (63.49% and 61.475%), gray mould (90.13% and 88.08%) and yield per plot (39.55% and 33.09%) indicated wider range of variation and offer better scope for improvement through selection. High heritability estimates coupled with moderate genetic gain were observed for yield and other horticultural traits. Correlation study indicated that yield per plot was positively correlated with gross and net head weight, seed germination, seed vigour index-I & II, 1000-seeds weight and also showed maximum direct effects towards yield per plot. The path co-efficient analysis revealed that net head weight has maximum positive direct effect on yield per plot followed by gross head weight, days to marketable maturity, seed germination, 1000-seeds weight, head shape index and incidence of sclerotinia rot. While, negative direct effect of number of non-wrapper leaves and incidence of gray mould was observed on yield. The new multicoloured cultivars indigenous and exotic mostly procured from CGN, Netherlands , identified for commercial cultivation under protected conditions in the mid hills of North Western Himalayas, may act as a substitute to the old cultivars with good quality and higher yielding potential.