Effects Of Nitrogen,Phosphorus,Potassium,Boron And Magnesium On Yield,Quality And Nutrient Efficiency Of Different Varieties Of Rapeseed Under Late Sowing Conditions

Oilseed rape is one of important edible oil crops in China.It is of great significance to ensure the high-efficient production of rapeseed for the safety of oil supply.In the current rice-oil rotation system,the planting area of double-cropping rice accounts for a certain proportion.With the delay in the maturity of late rice,the contradiction of rice-oil crop for rotation are aggravated.Variety transformation and fertilizer input are important factors for achieving high yield,high quality and high efficiency of rapeseed.Nitrogen（N）,phosphorus（P）,potassium（K）,boron（B）and magnesium（Mg）are the most important nutrient limiting factors in the production of winter oilseed rape in China.However,the responses of different varieties to fertilization are always different under late sowing conditions,therefore,making a reasonable fertilization recommendation according to the characteristics of varieties under late sowing conditions is helpful to tap the potential of yield and quality of varieties and promote the efficient use of nutrients.The effects of N,P,K,B and Mg on yield,quality and nutrient use efficiency of 24 main winter rapeseed varieties in the Yangtze River Basin（YRB）under late sowing conditions were studied by field experiment,the nutrient efficiency of different varieties was evaluated,in order to provide theoretical support for“Fertilization according to variety”under the condition of late sowing.The main findings are as follows:（1）Under late sowing conditions,fertilization significantly improved the crop growth and increased the yield of rapeseed.Under the condition of this experiment,compared with N,P,K,B and Mg balanced fertilization（OPT）treatments,the aboveground biomass of the OPT-N,OPT-P and OPT-K treatment were decreased by97.1%,97.5%and 36.3%,respectively.While there were no significant differences among the OPT,OPT-B and OPT-Mg treatment.In terms of yield components,nutrient deficiency limited yield potential mainly by affecting pod number per plant and seed number per pod.Compared with the OPT treatment,the seed yield of the OPT-N,OPT-P,OPT-K and OPT-Mg treatment were declined by 96.7%,96.8%,30.7%and 3.6%,respectively.Minor differences on seed yield between the OPT and OPT-B treatment were observed.Under the condition of late sowing,the contribution of each nutrient to rapeseed yield was N≈P>K>B≈Mg.There were slight differences in the varieties in different regions.For the varieties in the upper YRB,the contributions of nutrient to seed yield were N≈P>K>Mg>B,While in the middle YRB it was N≈P>K≈B≈Mg,and the down YRB it was N≈P>K>B≈Mg.（2）Under late sowing conditions,fertilization affected the quality of rapeseed,which was helpful to increase the yield of oil and protein.Different fertilization treatments had different effects on the fatty acid composition of rapeseed.Compared with the OPT treatment,the linolenic acid content of the OPT-N treatment was decreased by 7.9%,the stearic acid content of the OPT-B treatment was reduced by16.7%,and the stearic acid content of the OPT-Mg treatment increased by 19.6%.The palmitic acid content of the OPT-N,OPT-B and OPT-Mg treatments were increased by 9.4%,8.1%and 13.6%,respectively.Under the condition of late sowing,the effect of fertilization on oil yield and protein yield was similar to yield.The contribution of each nutrient to oil yield and protein yield was N≈P>K>B≈Mg and N≈P>K>Mg>B,respectively.（3）Under late sowing conditions,fertilization significantly increased aboveground nutrient accumulation and seed nutrient requirement of different varieties.Compared with the OPT treatment,shoot N,P,K,B and Mg accumulation of the OPT-N,OPT-P,OPT-K,OPT-B and OPT-Mg treatment were declined by 41.6kg N/hm²、8.5 kg P₂O₅/hm²、54.2 kg K₂O/hm²、17.5 g B/hm²、2.4 kg Mg O/hm² on average,respectively.And the nutrient requirement per 100 kg rapeseed was decreased by 0.88 kg N,0.15 kg P₂O₅,4.24 kg K₂O,2.20 g B,and 0.12 kg Mg O,respectively.Under the condition of late sowing,the nutrient efficiency of different varieties was quite different,the fertilizer recovery efficiency of varieties in the upper YRB was relatively high.（4）Based on the shoot nutrient accumulation of the nutrient omission treatment and the nutrient recovery efficiency under late sowing conditions,the nutrient efficiencies of different varieties were preliminarily evaluated in terms of nutrient absorption efficiency and nutrient responsiveness.The results showed that under the condition of late sowing there were 5 varieties with high N efficiency and high response,3 varieties with high P efficiency and high response,3 varieties with high K efficiency and high response,5 varieties with high B efficiency and high response,and 4 varieties with high Mg efficiency and high response.Among them,Fu You2,Qin You10,Qian You Zao2,De Xin You88,He Sheng You555,Zhong You Za19 and Zhe You28 were the varieties with high efficiency and high response to multiple nutrients.