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【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。
【Objective】 There is controversy about the suitable nitrogen application period for cotton. Some scholars recommended the best nitrogen application period as post-emergence and budding period. Some studies suggest that the pre-sowing and early flowering are better than others. Nitrogen isotope tracing technology can distinguish fertilizer and soil nitrogen absorbed by crops, and can further study the fate and application of nitrogen fertilizer in crops. In this paper, nitrogen isotope tracing technique was used to study the relationship between nitrogen and bottom tracing ratio and nitrogen application period on nitrogen absorption and yield of cotton, in order to provide a theoretical basis for nitrogen fertilizer management in cotton fields of North China Plain. 【Method】 Pot experiment was conducted in this study. CCR 79 and CCRI 60 transgenic Bt + Cp TI cotton varieties were used as material, 1 nitrogen (N1), nitrogen (N2), 0: 1 (N3), nitrogen application rate at the bud stage and topdressing rate 0: 1 (N4) , 15N recovery, biomass accumulation and seed cotton yield. 【Result】 The results showed that the ratio of nitrogen uptake from different organs in different organs of early flowering cotton plants increased significantly from 25.88% to 42.45% with the increase of basal application of nitrogen fertilizer. The Ndff% of cotton with different treatments at harvest increased significantly with the increase of nitrogen application rate, with an increase of 26.92% and 54.14%, respectively. The Ndff% of cotton treated with N3 and N4 was significantly higher than that of N1 and N2. The yield of seed cotton of N2 treatment was higher than that of other treatment, but the difference was not significant with N1 treatment. There was no significant difference between N2 treatment and N1 and N3. The accumulation of 15N per plant in two cultivars N3 and N4 was significantly higher than that of N1 and N2, and the recovery of 15N at the harvest stage was significantly higher than that of N1. The recovery rate of 15N in N2-treated cotton was higher than that in N1, but the difference did not reach significant level. The recovery rate of 15N under N2 treatment was lower than N1 after cotton harvest, but the difference was not significant. 【Conclusion】 Under the experimental conditions, the seed cotton yield and 15N recovery of two cotton cultivars with 1: 2 nitrogen ratio were better than those with the ratio of bottom-top dressing ratio of 1: 1 and the top-bottom dressing ratio of 0:1 The recovery was highest among the four treatments, but did not show any yield advantage, and these results have yet to be further validated in field trials.