基于种植密度的烤烟氮素吸收累积特征分析

Analysis of nitrogen uptake and accumulation characteristics offlue-cured tobacco based on planting density

通过大田试验,探究不同种植密度:13 890(D1)、15 150(D2)、16 660(D3)、18 510株·hm^-2 (D4)对云烟97、NC71和K326烤烟氮素吸收分配的影响,以期为优化当地烤烟群体结构,发挥最大密植效应提供理论依据。结果表明,随着生育进程的推进,烤烟氮含量呈下降趋势,降幅为91.10%~180.10%,动态曲线可用指数函数拟合;密植后,云烟97、NC71初始氮含量呈下降趋势,分别降低了0.07%、0.14%,K326则从4.26%降低到 4.24%,再升高到 4.30%;密植对K326氮含量下降速率无显著影响,而云烟97、NC71高密度处理氮含量降幅显著,下降速率相较对照(D1)分别增加9.09%、8.26%。烤烟氮累积动态可用Logistic模型拟合,氮累积峰值参数出现时间相较D1均有不同程度的提前,其中云烟97高密度处理(D4)的氮素快速累积起始时间、终止时间和最大氮累积速率出现时间分别提前7.18、17.26 d和12.22 d,且最大氮累积速率呈增加趋势,增幅为12.46%~34.69%。从不同生育期来看,旺长期以前氮素累积随种植密度的增加明显上升,密植效应显著,其中D4处理上升幅度达30.65%~ 314.58%;旺长期以后氮素累积趋于稳定。密植后,中心花开放期烤烟根茎和下部烟叶氮累积增幅显著,相较D1分别增加32.67%~ 49.01%和42.97%~ 58.98%,而中上部烟叶氮累积受限。综上得出:K326高密植(D4)、NC71中密植(D3)、云烟97中低密植(D1、D2之间)有利于烟叶氮素吸收利用和光合作用,以发挥烤烟最大密植效应。

In order to provide a theoretical basis for optimizing the population structure of local flue-cured tobacco and giving the maximum dense planting effect, a field experiment was adopted to study the effects of different planting densities: 13 890(D1),15 150(D2),16 660 plants·hm^-2 (D3) and 18 510 plants·hm^-2 (D4) on the nitrogen (N) uptake and distribution in Yunyan 97, NC71 and K326 flue-cured tobacco.The results showed that the N content in flue-cured tobacco decreased by 91.10%~180.10% with the growth process and a dynamic exponential function could be used to describe N content variation in the plant.With dense planting, the initial N content of Yunyan 97 and NC71 decreased by 0.07% and 0.14% respectively, while K326 decreased from 4.26% to 4.24% and then increased to 4.30%.Planting density did not significantly impact decreasing rate of N content in K326, however, the N content of Yunyan 97 and NC71 decreased significantly in high dense planting (D4),compared to the control (D1),the decreasing rate raised by 9.09%(Yunyan97) and 8.26%(NC71).The Dynamic Logistic model showed the time of N rapid accumulation and peak value of N accumulation in dense planting flue-cured tobacco were earlier but at different degrees than that of D1.The start time, termination time of rapid accumulation of nitrogen and maximum N accumulation rate in high dense planted Yunyan 97 (D4)were 7.18 d, 17.26 d and 12.22 d earlier than D1, respectively, and the maximum N accumulation rate increased by 12.46%~ 34.69%.In different growth stages, the N accumulation significantly increased with increasing planting density before the fast-growing stage, and the dense planting effect was significant, esp.the D4 treatment increasing by 30.65%~314.58%;the N accumulation tended to be stable after the fast-growing stage.With the dense planting, the N accumulation in roots and stems, and lower leaves of flue-cured tobacco significantly increased by 32.67%~49.01% and 42.97%~58.98% than that of D1, respectively, while the N accumulation of middle and upper leaves was limited during the flowering stage.In summary, high-dense of K326 (D4), mid-dense of NC71 (D3), and mid-low density planting of Yunyan 97 (D1 and D2) were optimum planting to the N uptake and photosynthesis to achieve the maximum dense planting effect of flue-cured tobacco.