RAMA KUMAR, P.V.VANAJA, THUTE2017-02-202017-02-202014http://krishikosh.egranth.ac.in/handle/1/5810001605D5103The present investigation was carried out during kharif 2013 at Agricultural College Farm, Bapatla to study the variability, heritability, expected genetic advance, combining ability, heterosis, character association and path coefficient analysis involving 50 F1s (fifteen parents i.e., ten lines  five testers) along with two checks in cotton for characters viz., plant height (cm), days to 50% flowering, number of monopodia per plant, number of sympodia per plant, relative water content (%), specific leaf weight (mg/cm2), number of bolls per plant, boll weight (g), seed index (g), lint index (g), ginning out turn (%), 2.5% span length (mm), micronaire value (10-6 g/inch), bundle strength (g/tex), uniformity ratio, seed cotton yield per plant (g), lint yield per plant (g) and fiber elongation (%). Analysis of variance revealed significant differences among the genotypes for all the characters indicating a high degree of variability in the material. The estimates of heritability and genetic advance as per cent of mean were high for the characters viz., number of monopodia per plant, specific leaf weight, number of bolls per plant and seed cotton yield per plant. High heritability coupled with moderate genetic advance as per cent of mean was observed for days to 50% flowering, relative water content, boll weight and seed index. Moderate heritability coupled with moderate genetic advance as per cent of mean was observed for plant height, lint index and number of sympodia per plant. While moderate heritability coupled with low genetic advance as per cent of mean was observed for ginning out turn, 2.5% span length, micronaire value, bundle strength, uniformity ratio, and fiber elongation. Moderate heritability combined with high genetic advance as per cent of mean was observed for lint yield per plant. The analysis of variance for combining ability revealed that lines, crosses and Line × Tester effects had significant amount of variability with in each of them for majority of the traits studied. The per cent contribution towards the total variance was maximum due to the interaction of lines and testers for the traits, plant height, days to 50% flowering, number of monopodia per plant, number of sympodia per plant, relative water content, specific leaf weight, number of bolls per plant, boll weight, seed index, lint index, ginning out turn, 2.5% span length, uniformity ratio, lint yield per plant and seed cotton yield per plant. The estimates of sca and gca variance also revealed the predominance of nonadditive gene action in the inheritance of plant height, days to 50% flowering, number of monopodia per plant, number of sympodia per plant, relative water content, specific leaf weight, boll weight, seed index, lint index, ginning out turn, 2.5% span length, micronaire value, uniformity ratio, lint yield per plant, fiber elongation and seed cotton yield per plant. While both additive and non-additive gene actions were predominant for number of bolls per plant and bundle strength. These gene actions were further confirmed by the ratios of gca variance to total genetic variance and the estimates of narrow sense heritability. Out of the ten lines tested, DDHH-46 recorded significant general combining ability effects in desirable direction for six characters viz., plant height, relative water content, number of bolls per plant, ginning out turn, lint yield per plant and seed cotton yield per plant followed by DDHH- 36 and DGHH-16. While the testers DGHH-116 and DGHH-136 recorded significant general combining effect for plant height, days to 50% flowering, relative water content, number of bolls per plant, seed cotton yield per plant and lint yield per plant. The perusal of sca effects revealed that the crosses DGHH-36 × DGHH-116, DGHH-11 × DGHH-116 and DGHH-36 × DGHH-145 expressed high sca effect with high per se performance for seed cotton yield. The gca effects of parents and sca effects of their hybrid combinations indicated that the crosses with high sca effects have resulted due to high × low, low × low and high × high gca combinations. Therefore, one can afford to include some low general combiners also along with good general combiners in heterosis breeding programmes. Heterosis studies revealed that crosses viz., DGHH-36 × DGHH-116, DGHH-11 × DGHH-116 and DGHH-36 × DGHH-145 were found to be promising for seed cotton yield and acceptable fiber quality, as they recorded good sca, per se performance and significant standard heterosis. Genotypic correlations in general are higher than phenotypic correlations indicating that the apparent associations are largely due to genetic reasons. The traits plant height, number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight and lint yield per plant were found to possess significant association in desirable direction with seed cotton yield per plant at both genotypic and phenotypic levels. In path analysis studies revealed that lint yield per plant was found to have high positive direct effect on seed cotton yield per plant.en-USnullThesis