Graphic analysis of trait relations of rapeseed using the biplot method

Interest in growing winter rapeseed (Brassica napus L.) in Iran is increasing due to its potential returns relative to other oilseed crops. The objectives of this study were (i) to investigate the interrelationships among different traits of winter rapeseed and (ii) to determine the effects of sowing date and variety on the seed yield and other traits of winter rapeseed with application of the biplot methodology in visualizing agronomic research data. Four winter rapeseed varieties were grown on three sowing dates during 2 yr. The results showed that variety 1 (SLM046) produced maximum seed yield and oil content in the second (21 September) and the third sowing dates (1 October). Thousand seed weight was positively and significantly associated with seed yield and the number of pods per plant, but oil content was not correlated with yield or the other traits. The study revealed that treatment by trait (TT) biplot can graphically display the interrelationships among traits and facilitate visual comparison of treatments.