In agricultural production, one of the limiting factors on plant growth and yield is soil salinity. The plant growth regulators are of considerable importance in alleviating the negative effect of salt stress. The study was carried out to determine the effects of salicylic (SA) and gibberellic acid (GA3) on the growth and some physiological characters in canola (Brassica napus L.) under salinity conditions in greenhouse. For this purpose, a factorial experiment set up as completely randomized design was conducted with three levels of SA (0, 0.5 and 1 mM) and GA3 (0, 50 and 100 mg l-1) and four levels of NaCl (0, 50, 100 and 150 mM) with three replications. In the study, leaf area, plant height, electrolyte leakage, chlorophyll content and the loss of leaf turgor were investigated. Salt treatments reduced significantly all of the considered parameters, compared with the control. Salinity caused a significant reduction of 63 and 67%in plant height and leaf area, respectively, as compared to the control plants. On the contrary, electrolyte leakage was markedly increased (six-fold) with increasing NaCl levels. Gibberellic acid increased significantly plant height and reduced the loss of leaf turgor, without a significant improve in other parameters. The results indicated that application of SA and GA3 to salinity stressed plants did not significantly affect canola vegetative growth. However, GA3 caused a partial decrease in the adverse effect of salinity.

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.

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.