Different Irrigation and Nitrogen Fertilizer Treatments on Some Agro-Physiologic Traits in Rapeseed (Brassica napus L.)

Abstract

In order to investigate the effect of irrigation and nitrogen fertilizer on agronomical and physiological traits of two winter rapeseed varieties, an experiment was established in a randomized complete block design as split-plot factorial arrangement with four replications in 2005-2006 at Agricultural Research Station of Khorramabad, Iran. Irrigation as main-plot factor consisted of four levels (I60, I90, I120 and I150). Sub-plot factors included nitrogen in four levels (N0, N70, N140, and N210 kg N ha(-1)) and two varieties (Zarfam and SLM046). Thousand-seed weight (TSW) in all irrigation and nitrogen levels was lower in the 2006 than that of the 2005. Seed oil percentage (SOP) was decreased with increasing water use only in second year. As nitrogen rate increased, SOP decreased and seed oil yield (SOY) increased in the 2006 significantly (p < 0.05). With increasing water supply, SOY increased in first year. Zarfam variety had a higher TSW and SOP in both years. According to combined analysis results, seed and oil yield were not significantly affected by irrigation treatments and rapeseed varieties. Seed yield had not significant difference between 70 to 210 kg N ha(-1) treatments. Both Water Use Efficiency (WUE) and dry matter remobilization efficiency (DMRE) were increased by decreasing water supply in I90 to I150 treatments. But N0 and N210 resulted in the lowest WUE and DMRE, respectively. Considering all traits, the first year of experiment was better than second year. The irrigation x variety interaction had a significant (p < 0.01) effect on seed yield and WUE. Generally, I150N70V1 combination is recommended in the region of the study due to high performance in production of seed and oil yield.