氮肥和密度对高粱产量及氮肥利用率的影响

为了研究氮肥施用量和密度对高粱产量的影响,在大田试验条件下,采用裂区设计,以密度为主区,以氮肥施用量为副区,分别设置3个密度水平（7.5万、10.5万和13.5万株/hm ²）和5个氮肥水平（0、75、150、225和300kg/hm ²）,对不同密度和氮肥处理的产量构成因素和农艺性状进行分析,结果表明：高粱的产量先随密度的增加和氮肥施用量的增加呈增加趋势,在密度为10.5万株/hm ²,施氮量为225kg/hm ²时,高粱的产量达到最高。在不同密度和氮肥处理,高粱的单位面积穗数和穗粒数变异较大,千粒重变异较小。密度主要是通过单位面积穗数,氮肥主要是通过穗粒数来影响产量的构成。施氮量与高粱产量是非线性关系,氮肥在高密度条件下对产量的调控更加明显。氮肥的农学利用率在高密度处理比低密度处理要高,并随着氮肥施用量的增加呈先增加后减少的变化趋势,在密度为13.5万株/hm ²,施氮量为150kg/hm ²时,氮肥的农学利用率达到最大。本研究表明,增加密度、控制氮肥用量是增加高粱产量和提高氮肥利用率的有效措施,建议晋杂23号在汾阳种植时宜采用密度为10.5万株/hm ²,施氮量为225kg/hm ²的种植模式。

Effects of Nitrogen and Density Interaction on Grain Yield and Nitrogen Use Efficiency of Sorghum

The purpose of this study was to explore the effects of nitrogen amount and density on the sorghum yield. The experiment was carried out under field condition and the split plot design was used with the plant density as main plots and the nitrogen amount as the sub plots. The sorghum density were set as three levels with 7.5×10 ⁴ plants/hm ², 10.5×10 ⁴ plants/hm ² and 13.5×10 ⁴ plants/hm ² and the amount of N were set at five levels with 0kg/hm ², 75kg/hm ², 150kg/hm ², 225kg/hm ² and 300kg/hm ², respectively. The results showed that the sorghum yield improved with the increased density and nitrogen application, and the yield was reached to the highest when the density was 10.5×10 ⁴ plants/hm ² and the nitrogen was applied with 225kg/hm ². Under the different levels of nitrogen applications and plant densities, there was an obvious variation for ear number and grain number, however, small variations were obtained for the thousands seeds weight. It indicated that the grain yield was influenced by the plant density mainly affected by the ear number per area, and by the nitrogen fertilizer mainly affected by the grain number per panicle. A non-linear relationship was achieved between the nitrogen application and the sorghum yield which meants that the sorghum yield could be adjusted by the nitrogen application under the high plant density. For the agricultural utilization ratio of nitrogen fertilizer, it was higher under high density level than that under low density level, and it firstly increased and then decreased with the increase of nitrogen application. In addition, it was proved that the agricultural utilization ratio of nitrogen fertilizer reached to the highest with the plant density of 13.5×10 ⁴ plants/hm ² and nitrogen application of 150kg/hm ². The study concluded that increasing the density and controlling the amount of nitrogen fertilizer were effective tools to increase the sorghum production and the utilization rate of nitrogen fertilizer. The plant mode of nitrogen application of 225kg/hm ² under the plant density of 10.5×10 ⁴ plants/hm ² for the variety of Jinza 23 was recommended in Fenyang region.