Heterosis and combining ability for seed yield and its components traits in rapeseed Brassica napus L.

Pakistan is basically an agricultural country and its economy depends upon the agricultural outputs. But in case of oilseed crops Pakistan is spending huge foreign exchange for importing edible oil. So there is dire need to focus on the research to improve production of oilseed crops. Brassica napus L. is one of the most important oilseed crops. Keeping in view the importance of Brassica napus L. as oilseed crop the present· study was conducted to estimate heterosis and combining ability in F1 populations of diallel crosses of Brassica napus L. in the research area of the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, during 2014-2015. Five parental lines of Brassica napus L. were crossed using Diallel Mating System. Twenty five crosses along with their parents were grown in the field in three replications. Data were recorded on various yield and yield related traits i.e. plant height, number of primary branches per plant, number of secondary branches per plant, number of siliques per plant, number of seeds per siliqua, siliqua length, seed yield per plant, 1000-seeds weight, harvest index, mature leaf shape, mature leaf dissection and beak shape. Genotypic correlations of various yield related traits studied were in general higher than their respective phenotypic ones. Siliqua length and 1000 seed weight had highest significant and positive correlations with seed yield per plant at both genotypic and phenotypic levels. The cross combination, KN-258, KN-258 showed highest better parent heterosis for No. of primary branches per plant, KN-258 x Zn-R-3 for harvest index and KN-258 x Excel for seed yield per plant. The analysis of variance for combining ability showed significant results for all the traits. KN-258 was good general combiner for seed yield per plant. The best crosses on the basis of SCA effects were Zn-r-3 x Excel for seed yield per plant, G-46 x Zn-R-5 for No. of seeds per siliqua, KN-258 x Excel for 1000 seed weight, G-46 x Zn-R-5 were best specific combiner for number of siliquae per plant and harvest index and siliqua length. The observation of path coefficient analysis revealed that 1000-seed weight and harvest index are main traits regarding the seed yield per plant. Therefore, the indications from above discussion based on heterosis, combining ability, estimates of correlation, direct and indirect effects revealed that 1000 seed weight and harvest index may be used as selection criteria in breeding programmes for high yielding varieties. KN-258 and Excel can be efficiently used for the improvement of seed yield per plant in Brassica napus L.