不同氮效率夏玉米临界氮浓度稀释模型与氮营养诊断

【目的】建立豫中地区玉米临界氮稀释曲线,比较不同氮素利用率玉米品种模型差异,探讨基于此的氮营养指数用于诊断、评价玉米氮素营养的可靠性,为实现玉米合理施用氮肥提供理论依据。【方法】以伟科702和中单909两个不同氮利用效率的品种为试验材料进行连续三年的田间定位试验,共设5个氮肥水平(0、120、180、240和360 kg/hm^2),分析不同施氮量对两个玉米品种拔节期、大喇叭口期、吐丝期、收获期干物质的影响,基于不同时期干物质和植株氮浓度建立两个品种临界氮稀释曲线,分析不同氮利用率品种玉米临界氮稀释曲线模型的差异和氮营养指数及其与相对地上部生物量和相对产量的关系。【结果】中单909的氮利用率显著高于伟科702。在各生育时期,两个玉米品种地上部生物量随施氮量变化表现为N0 –0.341,中单909 Nc=30.801DM^–0.370)具有很好的稳定性。相比中单909的模型参数,伟科702的参数a提高了15.70%,参数b降低了7.84%,且参数a变化值大于参数b。同一时期两个品种基于此模型的氮营养指数均随施氮量的增加而上升;施氮量低于180 kg/hm^2时,随着玉米生育时期的推进,氮营养指数随施氮量的增加呈先升高再降低的趋势,当施氮量超过240 kg/hm^2时,氮营养指数一直升高。氮营养指数与相对地上部生物量、相对产量相关性均达到显著水平。【结论】本文建立的豫中地区的两个品种玉米临界氮稀释曲线模型及氮营养指数,可以很好地诊断和评价玉米植株氮素营养状况。不同氮利用率品种间临界氮浓度稀释曲线模型参数存在差异,氮高效的品种具有较低的单位生物量氮浓度和较高的曲线斜率,其各时期临界氮浓度低于氮利用率低的品种。

Critical nitrogen concentration dilution model and nitrogen nutrition diagnosis in summer maize with different nitrogen efficiencies

【Objectives】The objective of this study was to establish the critical nitrogen dilution curve of maize in central area of Henan Province, China, to compare differences of nitrogen use efficiency among different varieties of maize, and to study the reliability of nitrogen nutrition index for diagnosing and evaluating nitrogen nutrition in maize, which would provide theoretical basis for rational nitrogen fertilization of maize. 【Methods】In this paper, Weike702 and Zhongdan909, as the two different nitrogen use efficiency varieties, were studied for three consecutive years in a field trial with five nitrogen levels (0, 120, 180, 240 and 360 kg/hm2). Effects of different nitrogen application rates on dry matter of both varieties at jointing, spike formation, silking and harvest stages were analyzed, critical nitrogen dilution curves of two varieties were established based on the dry matter and plant nitrogen concentration in different periods, differences of critical nitrogen dilution curve models for maize with different nitrogen use efficiencies were analyzed, and the nitrogen nutrition index and its relationship with relative shoot biomass and relative yield of maize were analyzed. 【Results】The nitrogen use efficiency of Zhongdan909 was significantly higher than that of Weike702, and the shoot biomass of both varieties showed N0 < N120 < N180 = N240 = N360. With the increase of N application rate, the aboveground biomass of two varieties of maize could be divided into two parts: nitrogen limitation and non-limiting nitrogen, the critical nitrogen dilution curve models of the two cultivars (Weike702, Nc = 35.638DM –0.341, Zhongdan909, Nc = 30.801DM–0.370) had good stability. Compared with the model parameters of Zhongdan909, the parameter a of Weike 702 increased by 15.70%, its parameter b decreased by 7.84%, and the value of a changed more than that of the parameter b. The nitrogen nutrition indices of the two cultivars based on this model at the same period were raised with the increase of nitrogen application rate. The nitrogen nutrition index was first increased and then decreased with the increase of nitrogen application rate in maize growth period when the nitrogen application rate was less than 180 kg/hm2. When nitrogen application rate exceeded 240 kg/hm2, the nitrogen nutrition index was increased continuously. The correlations between nitrogen nutrition indices and relative shoot biomass, relative yield of maize also reached a significant level. 【Conclusions】In this paper, the nitrogen nutrition status of maize plants can be diagnosed and evaluated using the critical nitrogen dilution curve model and nitrogen nutrition index of two varieties of maize in central Henan Province. There were differences in the parameters of critical nitrogen concentration dilution curve between different nitrogen use efficiency varieties. Varieties with high nitrogen use rate had lower nitrogen concentration per unit biomass and higher curve slope, and the nitrogen concentrations were lower than those with the low nitrogen utilization rate.