Weedy rice possesses a high diversity in yield attributing characteristics and is an important resource for rice improvement programmes. The present investigation was carried out to estimate the genetic parameters and the correlations of yield attributing characteristics of weedy rice using 370 weedy rice accessions in Sri Lanka. Analysis of variance revealed significant differences (p < 0.05) among the weedy rice accessions for all the characteristics studied, implying the presence of a substantial amount of genetic variability and scope for selection. Shattering percentage, total number of spikelets per plant and the number of filled seeds per panicle exhibited high genotypic and phenotypic coefficients of variation. The degree of difference between phenotypic and genotypic coefficients of variation was relatively low for all the characteristics, except for the total number of spikelets per panicle, indicating comparatively less environmental influence. Very high heritability values coupled with very high genetic advance were observed for the shattering percentage, total number of spikelets per plant and the number of filled seeds per panicle. High heritability values coupled with high genetic advance were recorded for height at the booting stage, number of panicles per plant and tiller number at the seedling and booting stages suggesting the prevalence of additive gene action in the expression of these characteristics and the possible selection for effective improvement based on their phenotypic performance. Correlation studies showed that simply selecting comparatively taller plants with long seeds would identify high yielding weedy rice plants, which may be used in rice improvement programmes.

Forty genotypes of mungbean were evaluated to compare the genetic divergence and association among agronomic and yield characteristics. Analysis of variance indicated highly significant (p < 0.01) differences for all the traits except for 1000 seed weight. The phenotypic and genotypic coefficient of variation was the highest for grain yield per plant, followed by pod length. High broad sense heritability (> 60 %) along with high genetic advance was observed for total yield per plant, pod length, number of seeds per pod and plant height, indicating that these characteristics would be best for phenotypic selection. A significant negative correlation was observed between days to flowering and total yield per plant. Positive correlations were observed between plant height, pod length and 1000 seed weight with total yield per plant. Multivariate analysis showed that the first three principal components cumulatively accounted for 69.77 % of the total variation. The present findings could be useful in selecting superior genotypes in mungbean breeding programmes.

Rice (Oryza sativa L.) is the main food crop for more than half of the world population. Use of heterosis is one of the greatest practical achievements of plant breeding. Two single crosses, Bg 379-2 x Mu 8-7 (Cross 1) and Bg 379-2 x Bw 400 (Cross 2) were chosen to study the heterosis and genetic effects in yield related agronomic characters of rice. F 1 hybrids along with their parents were evaluated in a Randomized Complete Block Design with four replicates. Cross 1 showed significant heterobeltiosis for leaf width (LW), panicle length (PL) and plant height (PH) while Cross 2 showed significant heterobeltiosis for LW, culm length (CL), and PH. Additive genetic effect is higher than the dominance effect in days to 50% flowering (DF), CL and panicles per plant (PP) in Cross 1, while dominance effect is higher than the additive genetic effect in seedling height, LW, CL and PH in Cross 2. Bg 379-2 x Mu 8-7 is a more potential cross that agreed with breeding objectives, especially to extract short age high yielding breeding lines.