Genetic variability and character association in lettuce (Lactuca sativa L.)
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Date
2007
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SKUAST Kashmir
Abstract
The present investigation was carried out at Experimental Farm, Division of Olericulture SKUAST-K, Shalimar during winter 2006 and summer 2007 to estimates variability, correlation, path coefficient and principal component analysis from 25 diverse lettuce genotypes. The experiment was laid out in Randomized Block Design with three replications. Observations were recorded on plant height, plant spread, number of leaves per plant, average leaf weight, leaf area, days to first picking, duration of picking, leaf yield per plant, dry matter content, vitamin C, carotenoids and minerals (Ca, P and K).
The analysis of variance revealed highly significant differences among genotypes for all the characters. Mean data revealed that the genotypes viz. LS-2, LS-17 and LC-24 were superior in both the season for yield and most of other traits. PCV was in general higher than GCV. Genotypic coefficient of variation (GCV) was high for number of leaves per plant, leaf yield per plant, vitamin C, carotenoids, and calcium in both the season winter and summer except plant spread, leaf size and duration of picking which recorded high genotypic coefficient of variations in winter only and moderate for average leaf weight, leaf size, phosphorus and potassium, while it was low for days to first picking and dry matter content in both the seasons. Heritability in broad sense was high for all the character except days to picking and duration of picking in winter as well as in summer. High heritability along with high genetic gain was found for number of leaves per plant, leaf yield per plant, vitamin C, carotenoids, calcium and potassium; high heritability with moderate genetic gain for plant height, average leaf weight, leaf size, duration of picking, dry matter content and phosphorus, while low heritability along with low genetic gain was found for days to first picking in both the seasons.
Leaf yield per plant was found to be positively and significantly correlated with plant height, plant spread, number of leaves per plant, average leaf weight, leaf area, and duration of picking, while it was negatively and significantly correlated with days to first picking and dry matter content in winter season. Same trend was also found in summer except plant height, duration of picking and vitamin C which was positively non-significantly correlated with leaf yield. Significant positive as well as negative correlation also existed among different characters. The maximum direct contribution to leaf yield on both season basis came from number of leaves per plant, average leaf weight, leaf area and carotenoids.
Principal component analysis revealed that first principal component (PC1) contributed 56.27% in pooled data, 60.22% in winter and 41.72% in summer of total variability amongst the 25 genotypes for seven quantitative traits. Maximum contribution to the PC1 in terms of loading was from plant spread (-0.450) followed by leaf yield per plant (-0.449) on pooled basis.
On the basis of principal component analysis scores (PCA scores) top five best genotypes were identified on the basis of seven characters viz., plant height, plant spread, number of leaves, average leaf weight, leaf area, days to first picking and leaf yield per plant and it was found that LS-2 in superior followed by Simpson, LS-17, SS-12 and SS-11 on pooled data, while LS-2, LS-17, LC-24, LC-4 and LC-9 during winter season and LS-2, DPHL-1, Simpson, SS-12 and LS-15 during summer season was found better.
Description
M.Sc Thesis submitted to SKUAST Kashmir
Keywords
Genetic variability, Character association, lettuce (Lactuca sativa L.), Olericulture/Vegetable Science