Phenotypic diversity analysis and performance of elite lines of Brassica napus L.

Thirteen elite lines of Brassica napus L. were tested. Nine phenotypic traits viz., days to 50% flowering, days to maturity, plant height, branches, pods, pod length, pod width, pod weight and seed yield were studied. ANOVA revealed significant results for all the traits while summary statistics exhibited high level of genetic variability in days to 50% flowering, days to maturity, plant height and number of pods. On the other hand, number of branches, pod length, pod width, pod weight and seed yield need more attention for improvement. Coefficient of correlation revealed significant combinations among various traits which could be utilized directly. Cluster analysis based on linkage distances described grouping pattern into three clusters for dissimilarities. Elite line 24866 of Pakistani origin placed in separate cluster prominently that is due to best performance for maximum traits, hence recommended for farmers’ field large scale cultivation. Introduction Oilseed rape (Brassica napus L.) is being cultivated throughout the world as major oilseed crops. Four continents including America, Europe, Australia and Asia are important for food cultivation as oil and meal while non-food uses are as biofuel or lubricants. It stands second world crop after soybean (Jan et al. 2017, Tomkowiak et al. 2020). The close relationship between six particularly important species (Brassica carinata, B. juncea, B. oleracea, B. napus, B. nigra and B. rapa) was described by the triangle of U theory (UN 1935). It is a major contributor of carbohydrates, proteins and vegetable oil that is essential for human nutrition and absorption of fat-soluble vitamins. In an ideal healthy environment saturated as well as unsaturated fatty acids are very important. Therefore, oils with low saturated fatty acids < 6%, high oleic acid > 50%, moderate linoleic acid < 40% and low linolenic < 14% are considered ideal for edible purposes (Hu et al. 2007). Moreover, for combating biofuel consumption and climatic change challenges oilseed rape is getting popularity as a biodiesel crop. It is estimated that substantial demand in oilseed crops would be increased many-folds in near future (FAO 2002, Nikzad et al. 2020). Canola is a term which arose from “Canadian Oil” and is used to represent any variety of rapeseed that contains low levels of erucic acid (EA) and glucosinolates (Canola Council of Canada 2003). B. napus is self-fertile; however, outcrossing rates as high as 47% have been reported (Williams et al. 1986). Genetic diversity of oilseed rape is considered to be low because of the short cropping history and the strong breeding focus on seed quality characters, i.e. low erucic acid and glycosinolate contents which narrowed down the genetic base (Friedt and Snowdon 2009). Breeding for agronomic and economic values tends to bias the exploitation of genetic variation (Ali et al. 2018). Therefore, it is necessary to continuously integrate diverse germplasm into the breeding process in order to maintain a high level of genetic diversity. Hybrids produced from crosses between genetically diverse resynthesized rapeseed and adopted oilseed types showed a high yield potential (Seyis et al. 2005). The latter study demonstrated that crosses *Author for correspondence: <drsajjad.iqbal@uog.edu. pk>.