高密度直播油菜高产优质和氮肥高效的适宜氮肥施用模式

【目的】探讨高密度直播油菜(36×104plant/hm2)的合理氮肥管理措施。【方法】2011-2012年油菜季选用甘蓝型油菜品种德油6号,在成都平原稻-油轮作区开展了氮肥施用量、施氮方式对油菜产量、品质和氮肥利用率影响的大田试验。氮肥施用量试验在相同施氮方式(底肥+1次苗期追肥)下设置5个施氮水平(N 0、90、180、270和360 kg/hm2);施氮方式试验在同等施氮量(N 225 kg/hm2)条件下,设置3种施氮方式(一次性底施、底肥+1次苗期追肥、底肥+2次苗期追肥)。【结果】直播油菜农艺性状都随施氮量增多而呈增加趋势,而施氮方式对株高、一次分枝数和单株角果数无显著影响。增施氮肥可显著提高油菜籽粒产量和菜油产量,含油率则有所下降。随施氮量增加,油菜籽芥酸含量呈上升趋势,而硫甙含量略呈降低趋势。施氮方式对油菜籽含油率、芥酸和硫甙含量均无显著影响。油菜产量和氮肥贡献率(NCR)都随施氮量(90 270 kg/hm2)加大而提高,当施氮量继续增加(360kg/hm2)时却出现明显下降。但180与270 kg/hm2两施氮量处理间的油菜产量、氮肥贡献率(NCR)和氮肥表观利用率(REN)均无显著差异。随施氮量增加,氮肥农学利用率(AEN)、氮肥偏生产力(PFPN)和氮肥表观利用率(REN)表现出明显降低趋势。当施氮量≥270 kg/hm2时,氮肥农学利用率(AEN)、氮肥偏生产力(PFPN)和氮肥表观利用率(REN)均显著低于90 kg/hm2处理。同等施氮量下,氮肥分期施用可以提高直播油菜籽粒产量和菜油产量,并以底追两次施氮相对较高。底追两次施氮方式的氮肥利用率(AEN、PFPN、NCR、REN)均相对高于其他施氮方式。【结论】在本试验中等肥力条件下,高密度直播油菜(36×104plant/hm2)的合理氮肥施用模式为施氮量180kg/hm2和底追两次施氮方式。

Suitable nitrogen fertilization mode for high yield and quality and high N use efficiency in high density direct-sown rapeseed(Brassica napus L.)

【Objectives】 The reasonable nitrogen fertilizer management strategies in rapeseed(Brassica napus L.) with high planting density(36×104 plant/hm2)and direct-sown conditions were studied. 【Methods】 Two field experiments were conducted in Chengdu Plain under a rice-rapeseed rotation system. The effects of different N rates(0, 90, 180, 270, 360 kg/hm2) in the same N application mode(a basal fertilizer and a top dressing) and different N application modes(single application of basal fertilizer, twice application of a basal fertilizer and a top dressing, three times of application as a basal fertilizer and two top dressings) in the same N rate(225 kg/hm2) on yield, quality and nitrogen fertilizer use efficiency in rapeseed were studied.【Results】 The results indicated that the increase of N application rates demonstrated an enhancement trend in agronomic traits in direct-sown rapeseed. However, the effects of N application modes on plant height, branch number and pods per plant were not significant. With the increase in N application rates,the seed yield and oil yield of rapeseed were increased significantly and the oil content percent was decreased to some extent, and the increase of N application rates led to an enhancementtrend in erucic acid content, and resulted in a slight decrease in glucosinolate content. But no significant differences in the contents of oil, erucic acid and glucosinolate were observed between the different application modes of N.Yield and N fertilizer contribution rate(NCR) increased with the increase of N application rates(90-270 kg/hm2), but apparently decreased when the N application rate reached to 360 kg/hm2. Agronomic efficiency of applied N(AEN),partial factor productivity of applied N(PFPN) and apparent recovery efficiency of applied N(REN) obviously decreased with the increase of N application rates. No significant differences were observed in yield,N fertilizer contribution rate(NCR) and apparent recovery efficiency of applied N(REN) between the rates of N 180 kg /hm2 and N 270 kg /hm2. Agronomic efficiency of applied N(AEN),partial factor productivity of applied N(PFPN) and apparent recovery efficiency of applied N(REN) significantly decreased when the N application rate was more than 270 kg/hm2 compared with the 90 kg/hm2 rate. The split nitrogen fertilizer application modes enhanced seed yield or oil yield and the twice of application mode as a basal fertilizer with a top dressing have a higher value under the same N application rate(225 kg/hm2). The values of nitrogen fertilizer use efficiency(AEN,PFPN,NCR,REN) in the treatment with the twice of application mode as a basal fertilizer and a top dressing were relatively higher than those in other N application modes. 【Conclusion】 The rate of N 180 kg/hm2 and the twice of application mode as a basal with a top dressing are suitable nitrogen fertilization mode under high planting density(36×104 plant/hm2)and direct-sown rapeseed in moderate soil fertility.