不同施氮量及种植密度对小麦开花期氮素积累转运的影响

Effects of different nitrogen application amounts and seedling densities on nitrogen accumulation and transport in winter wheat at anthesis stage

本文以小麦品种‘周麦22’为材料,研究了不同施氮量[0 kg(N)?hm^(-2)、120 kg(N)?hm^(-2)、240 kg(N)?hm^(-2)和360 kg(N)·hm^(-2),以N0、N1、N2和N3表示]和种植密度(225×104基本苗?hm^(-2)、375×10~4基本苗?hm^(-2)和525×104基本苗?hm^(-2),以M_1、M_2和M_3表示)处理下小麦植株地上部不同空间分布各器官的氮素含量及其转运特性。结果表明:施氮量、种植密度及二者互作对开花期、成熟期植株地上部各器官氮素含量的影响均达显著水平。不同施氮量及种植密度处理小麦开花期至成熟期各营养器官氮含量和积累量下降。开花期和成熟期,植株单茎氮积累量为7.27~59.65 mg?茎-1和8.48~60.83 mg?茎-1,以N_0M_3处理最低,以N_3M_2最高。从空间位置看,植株地上部各营养器官开花期氮含量、氮积累量及花后氮转运量和对籽粒氮的贡献率均随空间位置下移而降低。营养器官氮含量、积累量及转运量随施氮量增加而呈递增趋势,上部和中部营养器官氮转运率高于50%。营养器官对籽粒氮的总贡献率高于67%。增施氮肥配套合理的种植密度,可以促进植株地上各营养器官氮的积累和转运,对植株下部器官氮积累转运的作用尤为明显,高肥及中密度处理(N3M2)下倒四叶、倒四节及余叶和余节氮含量和积累量增加,缩小了与上部各器官的差异。植株地上部群体氮素转运量为28.56~549.49 kg·hm^(-2),亦随施氮量增加而增加,以穗部和茎节氮转运量较高。施氮量对籽粒产量、蛋白质含量及蛋白质产量影响显著。施氮量与种植密度互作对籽粒蛋白质含量及产量影响显著,种植密度对籽粒蛋白质产量的影响亦达显著水平。从氮素转运和产量性状来看,施用氮肥240 kg·hm^(-2)配套225×10~4基本苗?hm-2的种植密度是黄淮小麦玉米两熟区小麦生产较为适宜的栽培模式。

To determine reasonable nitrogen（N） application amount and seedling density of wheat for improving N utilization efficiency and yield, N contents in organs in different parts of wheat plant were measured, and wheat response to N application（in terms of N accumulation and translocation） and planting density was studied. In the field experiment, ‘Zhoumai 22’ wheat cultivar was used in a split-plot design with N fertilization amount as the main plot and seedling density as the secondary plot. Nitrogen fertilization amounts during the whole growth period were 0 kg·hm-2（N0）, 120 kg·hm-2（N1）, 240 kg·hm-2（N2） and 360 kg·hm-2（N3）, respectively, while seedling densities were 225×104 seedlings·hm-2（M1）, 375×104 seedlings·hm-2（M2） and 525×104 seedlings·hm-2（M3）, respectively. The results showed that N application amounts, seedling densities and the interac-tions of the two factors had significant effects on N contents in organs in different positions of aboveground wheat at anthesis and maturity stages. N content and accumulation in the vegetative organs of wheat at maturity declined compared with those at anthesis. Total N accumulation in individual plant was changed within range of 7.27-59.65 mg·stem-1 at anthesis and 8.48-60.83 mg·stem-1 at maturity, and the maximum data was observed in N3M2 treatment, while the minimum level was observed in N0M3 treatment. N content and accumulation in vegetative organs of wheat apparently decreased with decreasing of spatial position at anthesis stage. Also N transport and contribution rate of vegetative parts to grain had the same spatial distribution trend. It suggested that flag-leaf and the first upper internode were higher while the fourth upper leaf and the fourth upper internode as well as the other bottom parts near the ground were apparently lower. N content, accumulation and transport capacity of vegetative organs increased with increasing N application rate. N transport rate in the organs of upper and middle spatial position exceeded 50%, and total N contribution rate of vegetative organs to grain exceeded 67%. Increased N fertilizer amount combined with suitable planting density improved the capacity of N accumulation and translocation in aboveground system. Among all the vegetative organs, the ones nearest the ground（such as the fourth upper leaf and internode） were more obviously affected by N application and seedling density while N content and accumulation in those parts were significantly higher under higher N application and medium-level density, narrowing the differences with upper parts of the plant. Also N transport of plant population（28.56-549.49 kg·hm-2） increased with increasing N application amount, especially for plant spike and internode. Grain yield, grain protein content and protein yield were significantly influenced by N application rate. While grain protein content and protein yield were significantly driven by applied N amount and N amount/seedling density interactions, protein yield was driven by seedling density. Considering N transport and grain yield, N application at 240 kg·hm-2 and seedling density at 225 × 104 plant·hm-2 were suitable for ‘Zhoumai 22’ in wheat/corn double cropping in Huanghuai region.