Comparison of yield, yield components and seed quality (oil and protein content) of two rapeseed cultivars as affected by different levels of soil-applied nitrogen and zinc

A greenhouse experiment was conducted in order to evaluate the influence of different nitrogen (N) and zinc (Zn) levels on yield، yield components، seed quality and N and Zn contents of two cultivars of rapeseed (Brassica napus L.). In this study، two cultivars of rapeseed (Talayeh and Opera)، three N levels (100، 200 and 300 mg/kg) and three Zn levels (0، 5 and 10 mg/kg) with three replications were used. The results showed that significant differences were observed between the cultivars in the studied traits. Increasing N and Zn significantly increased plant height، number of siliques per plant، number of seeds per silique، 1000-seed weights، seed yield، oil، straw and root yields and protein content. Oil seed content was the highest in application of 100 mg/kg N rate and then decreased or increased at higher N and Zn rates، respectively. The highest grain yield، oil yield and protein percentage were obtained with 300 mg/kg N and 10 mg/kg Zn. Increase in seed yield was related to increase in the number of siliques per plant and number of seeds per silique. Application of treatments increased concentration of N and Zn in the seeds، straw، and roots of both rapeseed cultivars. The interaction of N and Zn showed significant effects on most studied traits of rapeseed.