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Sclerotinia sclerotiorum is a necrotrophic fungus causing devastating stem rot and associated yield losses of canola/rapeseed (Brassica napus) worldwide, including in Australia. Developing host resistance against Sclerotinia stem rot is critical if this disease in canola/rapeseed is to be successfully managed, as cultural or chemical control options provide only partial or sporadic control. Three B. napus breeding populations, C2, C5 and C6, including the parents, F1, F2, BC1P1 and BC2P2, were utilised in a field study with an objective of exploring the inheritance pattern of disease resistance (based on stem lesion length, SLL), the genetic relationships of disease with stem diameter (SD) or days to flowering (DTF), and to compare these new adult plant stem resistances against S. sclerotiorum with those of seedling (cotyledon and leaf) resistances in earlier studies. Heritability (broad-sense) of SLL, was 0.57 and 0.73 for populations C2 at 3 and 5 weeks post-inoculation, and was 0.21 for C5 at 5 weeks post-inoculation. Additive genetic variance was evident within all three populations for DTF but not for SD. Narrow sense heritability for DTF was 0.48 (C2), 0.42 (C5) and 0.32 (C6). SD, DTF and SLL were all inherited independently with no significant genetic covariance between traits in bivariate analysis. Genetic variance for SLL in populations C2 and C5 was entirely non-additive, and there was significant non-additive genetic covariance of SLL at 3 and 5 weeks post-inoculation. Generation means analysis in population C2 supported the conclusion that complex epistatic interactions controlled SLL. Several C2 and C5 progeny showed high adult plant stem resistance which may be critical in developing enhanced stem resistance in canola/rapeseed. While population C6 showed no genetic variation for SLL resistance in this study, it showed significant non-additive genetic variance at the cotyledon and leaf stages in earlier studies. We conclude that host resistance varies across different plant growth stages and breeding must be targeted for resistance at each growth stage. In populations C2, C5 and C6, resistance to S. sclerotiorum in stem, leaf and cotyledon is always controlled by non-additive effects such as complex epistasis or dominance. Overall, our findings in relation to the quantitative inheritance of Sclerotinia stem rot resistance, together with the new, high-level resistances identified, will enable breeders to select/develop genotypes with enhanced resistances to S. sclerotiorum.

A diallel method was employed in which eight genotypically diverse lines of mungbean were crossed among themselves in all possible combinations excluding reciprocals. The mean square due to general combining ability (GCA) and specific combining ability (SCA) were significant for all the characters except mean square due to (SCA) for clusters per plant and seed yield per plant indicating importance of both additive as well as non-additive gene action. The estimates of variances due to specific combining ability were higher than general combining ability for all the traits except days to 50 % flowering, primary branches per plant, clusters per plant and seed yield per plant pointed out to be the preponderance of non-additive gene effects in the expression of these characters. Whereas predictability ratios were greater than the value of 0.5 for days to 50 % flowering, primary branches per plant, clusters per plant and seed yield per plant indicating the predominance of additive gene action for these characters. However, predictability ratio exhibited less than 0.5 values for rest of the characters indicating the predominance of non-additive gene action. The good general combiners for seed yield per plant were BM-4, PDM-139, ML-131, and IPM 99-125. The best specific cross combinations wereRMG-344 x RMG-1045, RMG-1035 x RMG-1045 and BM-4 x PDM-139. showed the highest positive significant SCA effect for seed yield per plant. These cross combinations could be utilized for further use in breeding programme for improvement in yield of mungbean.

Genetic parameters, variability, heritability and genetic advance were studied among 20 genotypes of chickpea during during rabi 2012-13. The characters, seed yield per plant and 100-seed weight had high values of GCV, heritability and GAM and were found to be under greater control of additive gene action. While the traits, primary branches per plant, number of seeds per pod and protein content with moderate to low heritability coupled with low genetic advance appear to be more affected by on non-additive gene action. Correlation and path coefficient analysis for seed yield per plant and its components indicated that out of 11 characters, seed yield per plant showed significant and positive correlation with harvest index, number of seeds per pod, primary branches per plant, number of pods per plant, biomass per plant, and 100-seed weight indicating that an intense selection for these characters will improve seed yield in chickpea. Path coefficient analysis revealed that days to maturity, primary branches per plant, biomass per plant, harvest index, protein content and number of seeds per pod were major characters influencing seed yield directly and indirectly. The results indicated that number of seeds per pod should be given greater emphasis for manipulation of seed yield in chickpea.

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