应用~(15)N研究氮肥运筹对棉花氮素吸收利用及产量的影响

【目的】有关棉花适宜的施氮时期存在争议,国外有学者推荐最佳施氮时期为出苗后和现蕾期,也有研究认为播前和初花期各施一半较好。氮同位素示踪技术能区分作物吸收利用的肥料氮及土壤氮,并能深入细致研究施入氮肥的去向及在作物体内的分配。本文采用氮同位素示踪技术研究氮肥底追比例,施氮时期对棉花氮素吸收和产量的影响,以期为华北平原棉区氮肥管理提供理论依据。【方法】采用盆栽试验,以转Bt+Cp TI基因抗虫棉品种中棉所79(CCRI 79)、中棉所60(CCRI 60)为材料,设氮肥底施与初花期追施比例1∶1(N1)、1∶2(N2)、0∶1(N3)、氮肥底施与蕾期追施比例0∶1(N4)4个处理,研究氮肥运筹对棉花初花期、收获期15N吸收、15N回收率、生物量积累和籽棉产量的影响。【结果】初花期棉株不同器官的氮素吸收来自氮肥(Ndff)的比例随底肥氮施用量的增加而显著增加,增幅为25.88%42.45%。收获期不同处理棉花单株Ndff%随追施氮量的增加而显著增加,增幅为26.92%54.14%,N3、N4处理的棉花单株Ndff%显著高于N1和N2。N2处理的棉花单株籽棉产量高于其他处理,但与N1处理的差异不显著,N2处理单株生物量与N1、N3差异不显著。2个品种N3、N4处理的棉花收获期单株15N积累量均显著高于N1和N2处理,棉株收获期15N回收率均显著高于N1。N2处理的棉花收获期15N回收率高于N1处理,但差异未达到显著水平。棉花收获后N2处理土壤15N回收率低于N1,但差异不显著。【结论】本试验条件下,2个棉花品种氮素底追比为1∶2时的籽棉产量与15N回收率优于底追比为1∶1处理,底追比为0∶1的处理15N回收率在4个处理中最高,但未显示出产量优势,这些结果有待在大田试验中进一步验证。

Effects of nitrogen fertilizer application strategy on N uptake,utilization and yield of cotton using 15N trace technique

【Objective】 There is controversy about suitable nitrogen(N) application period in cotton cultivation. Some scholars abroad recommended that the best periods of N application for cotton were the emergence and budding stage, while other researchers concluded that N application before the sowing andinitial flowering stage each half was better for cotton. N isotope tracer technique can distinguish N of crop absorption and utilization deprived from fertilizer N or soil N, and can thoroughly investigate direction of N fertilizer and distribution in cotton plant. This work was to study effects of N application ratios of the base fertilizer and topdressing and topdressing period on N absorption and yield of cotton based on N isotope tracer technique in order to provide theoretical basis for N management of cotton in North China Plain. 【Methods】 A pot trial using 15N trace technique was conducted with transgenic Bt+CpTI cotton(Gossypium hirsutum L.) cultivars, China Cotton Research Institute(CCRI 79 and CCRI 60) at the farm of Institute of Cotton Research of Chinese Academy of Agricultural Sciences in Anyang Henan in 2013.There were 4 treatments in the trial with total N application rate of 3.5 g each pot, and N application ratios of base fertilizer and topdressing at the initial flowering stage were 1:1(N1),1:2(N2) and 0:1(N3) respectively and as well as N application ratio of base fertilizer and topdressing at the budding stage 0:1(N4). Effects of different N application strategy on 15N absorption, 15N recovery efficiency, biomass accumulation of cotton at the initial flowering stage as well as the harvest stage and seed cotton yield at the harvest stage were examined. 【Results】 Percentages of N derived from fertilizer(Ndff) of different organs of cotton plants at the initial flowering stage are significantly increased with the increase of fertilizer rate of the basal N, and amplitude of the percentages of Ndff is 25.88-42.45. Percentages of Ndff of cotton plants at the harvest stage are significantly increased with the increase of fertilizer rate of the topdressing N, and amplitude of the percentages of Ndff of cotton plants is 26.92-54.14. Percentages of Ndff of cotton plants at the harvest stage under N3 and N4 are significantly higher than those under N1 and N2. Seed cotton yields of cotton plants of the 2 cultivars with N2 are higher than those of the other 3 treatments, and there is not significant difference between those of N2 and N1. Biomass accumulation amounts of cotton plants of the 2 cultivars with N2 are not significantly different from those of N1 and N3 respectively. 15N uptake amounts of cotton plants of the 2 cotton cultivars with N3 and N4 at the harvest stage are significantly higher than those with N1 and N2 respectively. 15N recovery rates of cotton plants of the 2 cotton cultivars with N3 and N4 at the harvest stage are significantly higher than those with N1, while 15N recovery rates of cotton plants of the 2 cotton cultivars with N2 at the harvest stage are higher than those with N1, and there is not significant difference between N2 and N1. 15N recovery rate of soil after the harvest with N2 is less than that with N1, and there is not significant difference between N2 and N1. 【Conclusions】 When N application ratio of the basal fertilizer and topdressing at the initial flowering stage is 1:2 in the pot trial, the seed cotton yield and 15N recovery rate of cotton are higher than those of the conventional N application ratio 1:1. When N application ratio of the basal fertilizer and topdressing at the initial flowering stage is 0:1, the 15N recovery of cotton is the highest among the 4 treatments, but the seed cotton yield is not improved. The results above in the pot trial should be further tested in field trial