VARIABILITY AND GENETIC PARAMETERS FOR GRAIN YIELD AND ITS COMPONENTS AND KERNEL QUALITY ATTRIBURTES IN CMS BASED RICE HYBRIDS (ORYZA SATIVA L.)
The present investigation was under taken to study the extent of variability and genetic parameters with 16 parents and 48 hybrids for nine yield and its components and twenty five quality characters. The magnitude of difference between PCV and GCV was relatively low for all the traits, indicating less environmental influence. High GCV and PCV were recorded for harvest index, total number of productive tillers per plant and gelatinization temperature in parents and for total number of productive tillers per plant, number of grains per panicle, gelatinization temperature and amylose content in hybrids. High heritability coupled with high genetic advance as per cent of mean were recorded for gelatinization temperature, harvest index, total number of productive tillers per plant, number of grains per panicle, kernel length, kernel L/B ratio and grain yield per plant in case of parents and for gelatinization temperature, amylose content, total number of productive tillers per plant, number of grains per panicle and harvest index in case of hybrids indicating the additive gene effects in the genetic control of these traits and can be improved by simple selection in the present breeding material.
Genetic variability, heritability and correlation coefficients of grain quality characters in rice (Oryza sativa L.).
Ninety-two rice (Oryza sativa L.) genotypes were evaluated during kharif 2013 to estimate the genetic variability, heritability and correlation coefficients for 14 physicochemical and cooking quality traits. The experiment was conducted in a complete randomized block design with 3 replications. Highly significant (P < 0.01) differences were observed for all 14 quality characters studied. Among the traits, head rice recovery (%), water uptake, gel consistency and alkali spreading value exhibited high estimates of genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV). Highest broad sense heritability and genetic advance was obtained for head rice recovery (89% and 29%), milling (84% and 21%), water uptake (90% and 24%), amylose content (93% and 29%) and gel consistency (90% and 31%) which suggested that these traits would respond to selection owing to their high genetic variability and transmissibility. High estimates of heritability in association with medium genetic advance observed for KLAC (89% and 13%), elongation ratio (86% and 11%) and alkali spreading value (80% and 19%) suggested the role of both additive and non-additive gene action in their inheritance. The significant positive correlation of KLAC with ER (r = 0.638) and L/B ratio (r = 0.556), ASV with water uptake (r = 0.426), hulling % with milling % (r = 0.60) and with HRR % (r = 0.150) indicated that these are the primary traits for improvement of rice grain quality.
Investigations on the rôle of organic matter in plant nutrition
1. As the result of decomposition of green manure in a swamp soil, the coarse fractions (including coarse and fine sand) of the surface layer (first 3 inches) decreased by 11·2 per cent. while the fine ones (silt+clay) increased by 9·8 per cent. in the course of 43 days. The effect was less pronounced in the manured soil maintained at 60 per cent. saturation, while no alteration was to be noticed in the case of the unmanured specimens. 2. Treatment with dilute hydrochloric acid prior to dispersion had no appreciable effect on the estimates of mechanical composition obtained in the different cases. Loss in solution was also comparatively small. 3. The silica-sesquioxide ratio increased slightly as the result of decomposition of green manure in swamp soil. The composition of the fine fractions was also altered, the total percentages of the oxides of iron, aluminium and silicon increasing from 90·5 to 99·3 in the course of 71 days. 4. The practical significance of the above and related observations has been discussed.