Dr. B. KRISHNA VENIPAVAN SHANKAR, H.P.2017-10-112017-10-112015http://krishikosh.egranth.ac.in/handle/1/5810032882D5187The present investigation was carried out during kharif, 2014 at Agricultural College Farm, Bapatla with 22 genotypes of rice to obtain information on the nature and extent of variability, heritability, genetic advance as per cent of mean, correlation and the magnitude of direct and indirect effects of early vigour, yield and quality characters on grain yield in dry direct sown rice (Oryza sativa L.). The analysis of variance revealed significant differences among the genotypes for all 27 characters studied viz., plant height (cm), ear bearing tillers per plant, days to 50% flowering, panicle length (cm), filled grains/ panicle, test weight (g), grain yield per plot (kg), kernel length (mm), kernel breadth (mm), L/B ratio, amylose content, alkali spreading value, root length at 10 DAS in field (cm), shoot length at 10 DAS in field (cm), root dry weight at 10 DAS in field (mg), shoot dry weight at 10 DAS in field (mg), seedling dry weight at 10 DAS in field (mg), vigour index, root length at 20 DAS in field (cm), shoot length at 20 DAS in field (cm), root dry weight at 20 DAS in field (mg), shoot dry weight at 20 DAS in field (mg), root length at 10 DAS in lab (cm), shoot length at 10 DAS in lab (cm), root dry weight at 10 DAS in lab (mg), shoot dry weight at 10 DAS in lab (mg) and seedling dry weight at 10 DAS in lab (mg) indicating that the data generated from the above diverse material shall represent wide variability. Among the genotypes studied, BPT 2741 recorded maximum grain yield followed by JGL 11727, BPT 2570, BPT 2755, BPT 2751 and BPT 2605. All these genotypes manifested high values for all yield components studied and possessed semi dwarf plant stature. When we consider the yield potential, grain Name of the Author : PAVAN SHANKAR H.P Title of the thesis : GENETIC VARIABILITY STUDIES ON EARLY VIGOUR, YIELD AND QUALITY TRAITS IN DRY DIRECT SOWN RICE GENOTYPES (Oryza sativa L.) Degree to which it is submitted : Master of Science in Agriculture Faculty : Agriculture Major field of study : GENETICS AND PLANT BREEDING Major Advisor : Dr. B. KRISHNA VENI University : Acharya N G Ranga Agricultural University Year of Submission : 2015 quality and vigour related traits together BPT 2741, JGL 11727, BPT 2570, BPT 2605, JGL 384 and MTU 1010 may be identified as superior and suitable for dry direct sown rice. The results of genetic parameters revealed that high GCV and PCV coupled with high heritability and high genetic advance as percent of mean were recorded for filled grains per panicle among yield components, for alkali spreading value among quality traits and for root and shoot dry weight in lab conditions suggesting an additive type of gene action. Thus apparently substantial contribution of additive genetic variance is involved in the expression of these traits. Hence, good response to selection can be attained for improvement of these traits. All other remaining traits studied manifested low to moderate estimates for genotypic and phenotypic coefficient of variation, moderate to high heritability estimates and low to high genetic advance as percent of mean indicating the role of both additive and non-additive gene effects in the expression of these traits. Hence, heterosis breeding or recurrent selection could be better alternative methods for improvement of these traits. The correlation studies revealed that all the yield components studied along with kernel length, kernel breadth and L/B ratio among quality traits exhibited positive correlation with grain yield. Among vigour related traits, root length at 10 DAS under field and lab, shoot length and shoot dry weight at 10 and 20 DAS under field and lab conditions, seedling dry weight at 10 DAS both under field and lab conditions and root dry weight at 20 DAS under field conditions manifested positive correlations with grain yield suggesting simultaneous improvement of these traits with grain yield. Studies of path coefficient analysis revealed positive direct effects coupled with positive correlation coefficients of grain yield with plant height, ear bearing tillers, days to 50% flowering, panicle length, test weight, kernel breadth, L/B ratio, alkali spreading value exhibited both direct effect and correlation coefficient in positive direction. Among vigour related traits, shoot length at 10 DAS at field and lab, shoot dry weight at 10 and 20 DAS under field conditions, seedling dry weight at 10 DAS in field, root length at 10 DAS under lab manifested positive direct effect along with positive correlation. Hence, under dry direct sowing conditions, simple selection of all the above traits would bring improvement to grain yield in rice.en-USnullThesis