Response of Nitrogen, Phosphorus and Potassium Fertilization on Productivity and Quality of Winter Rapeseed in Central China

Winter rapeseed (Brassica napus L.) is a dominant oilseed crop and has become an alternate crop both for edible oil production and energy agriculture. This study was conducted to find out the response of nitrogen (N), phosphorus (P) and potassium (K) fertilizer combinations on yield, oil and protein contents in oilseed rape crop. Four fertilizer treatments of N, P and K fertilizers (NPK, NP, NK, and PK) were applied according to the local recommendations at three different sites in Hubei province, during the year 2012-2013. Rapeseed yield was significantly increased by 61-72% under NPK fertilization as compared to PK across study sites. Yield responses to fertilization were ranked as NPK>NP>NK>PK, illustrating that N was the most limiting nutrient in rapeseed productivity following P and K. Oil and protein yields were significantly affected to applied N, P, and K fertilizers. Among all combinations, NPK combination performed best. Oil and protein contents along with other fatty acids (palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid) were not influenced significantly by the application of P and K fertilizer. By increasing the amounts of N fertilizer application, oil contents of rapeseed reduced and protein contents increased consistently. These results suggest that NPK combination is more productive as compared to the other combinations. (C) 2016 Friends Science Publishers