This study was undertaken to assess the combining ability of 6 rice varieties, for viscosity parameters and determining gene action controlling Rapid Visco Analyser (RVA) characters. F2 progenies derived from a 6×6 half diallel mating design with their parents were grown in a randomized complete block design with three replications at the research farm of Rice Research Institute of Iran (RRII) in 2015. The diallel analysis by Griffing`s method indicated the involvement of additive and non-additive gene actions controlling RVA traits. For traits PV and FV RI18447-2 and IR50 were the best combiners for increasing and decreasing, respectively. Deylamani and IR50 were the best combiners for increasing and decreasing BV, respectively. Beside, due to more portion of non-additive gene action in controlling trait SV, The Gilaneh × RI18430-46, and Deylamani × RI18430-46 crosses were the best for increasing and decreasing SV, respectively. The high estimates of broad sense heritability and narrow sense heritability for BV and FV, indicated the importance of additive effects in expression of these traits. Therefore, selection base breeding methods will be useful to improve these traits and selection in the early generations could be done to fix the favourable genes. Low estimate of narrow sense heritability for SV revealed that non-additive gene effects play important role in controlling setback viscosity. So, hybrid base breeding methods will be useful to improve this trait.

Wheat is an essential crop throughout the world and especially in Pakistan. It has a great yield potential which can cope with the raising food challenges of the world but there is a more need to increase its yield with its increasing demand. There is a need to increase the yield by improving the genetic characters. Breeder’s intention is to find out the variability in the genetic lines and by the use of these lines they can develop the high yielding breeding lines. Multi-ovary is a novel character to increase the number of grains per spikelet. What type of gene actions control that? From this review we get that some support the single dominant gene controlled trait, some support the two recessive non-complementary genes controlled trait and some favour the both as it is controlled by both dominant and recessive genes in different tri-grain lines. Secondly there is a need to study the genetic variation for the yield contributing traits. So that we can improve our genotypes to attain high yield. How we can evaluate yield and yield components. Combining ability is a considerable tool for this. Literature revealed that additive gene action contributes more towards yield than non-additive. In this many lines also came forward as good combiners which in future we can use them for a successful wheat hybridization program.

Combining ability analysis has an important position in rapeseed breeding. To evaluate genetic and combining ability effects, three Brassica napus L. testers “Punjab Sarson, Legend and Durre-NIFA” and five lines “Duncled, K-258, ZN-R-1, ZN-R-8, ZN-M-6” were crossed using line × tester design in Randomized Complete Block Design (RCBD) with three replications. Mean sum of squares of the analysis of variances (ANOVA) for genotypes was highly significant for all of the traits. Most of the lines and testers exhibited significant results of mean sum of squares for combining ability. Line ‘Duncled’ was proved good general combiner for oil (8.8), protein (3.7), erucic acid (33.0), oleic acid (13.0) and glucosinolate (-19.3) over other lines and tester ‘Durree-NIFA’ for protein (6.6), erucic acid (-23.4), and linolenic acid (-5.3) over other testers. Significant specific combining ability effects were also observed. The best hybrid combinations were Legend × ZN-R-1 for oil (9.6), Punjab Sarson × Duncled for minimum erucic acid (-14.0) and linolenic acid contents (-6.0), and Legend × ZN-M-6 for maximum protein (8.2) and minimum glucosinolate contents (-11.1). The maximum oil contents were observed in ‘Legend × ZN-R-1’ (52.4%). The cross ‘Punjab Sarson × Duncled’ expressed maximum values of protein (26.5%) and oleic acid (62.5%) while minimum for erucic acid (2.3%), linolenic acid (5.4%) and glucosinolate contents (19.3µmol/g). This research discloses the significance of non-additive genetic effects for most of the studied traits except oil contents. These studies will also help to improve nutritional values of rapeseed crop by selecting noble crosses.

Combining ability analysis has a key position in rapeseed breeding. To estimate the combining ability effects for yield controlling traits in rapeseed, three testers and five lines were crossed using line × tester design in randomized complete block design with three replications. Mean sum of squares of analysis of variances for genotypes were significant for all of the traits; indicating the presence of significant genetic variation. All the interactions between lines and testers exhibited significant results of mean sum of squares for combining ability. Line ‘Duncled’ was found good general combiner for decreased Plant height (PH:-2.0), Days taken to 50% flowering (DF: -15.8) and Days taken to maturity (DM:-3.4) while tester ‘Punjab Sarson” for increased Number of seed/siliqua (SS: 2.2), Number of siliquae/plant (SP: 2.2) and decreased DF (-3.0) traits. Significant general and specific combining ability effects were observed. The best hybrid combination on the basis of specific combining ability effects was “Durre-NIFA × ZN-M-6” for Seed yield/plant (SY: 2.7), DF (-6.1) and DM (-3.5). PH (-0.2), Siliqua length (SL: -0.1), SS (-0.03) and SY (0.2) showed non-additive genetic effects. The half of the characters revealed additive and remaining half showed non-additive genetic effects. The present study unveiled the importance of both type of genetic effects demanding the application of integrated breeding approaches for exploiting the variability. ‘Punjab Sarson × ZN-M-6’ exposed maximum SS (30) and SP (837). Maximum SY (75.9g) and minimum DF (64) were showed by ‘Legend × Duncled’. The present research delivers valuable information of genotypes for promoting yield by means of improving yield related characters.