15N示踪法研究弱光对不同穗型冬小麦氮素积累和转运的影响

摘要

在大田试验条件下,采用15N示踪法,设置不遮光(T0)、开花后1～10d遮光(T1)、开花后11～20 d遮光(T2)和开花后21～30 d遮光(T3)4个处理,每个处理设置15N尿素作底肥+普通尿素作追肥和普通尿素作底肥+ 15N尿素作追肥两个15N示踪的微区,研究灌浆期弱光条件下不同穗型小麦品种对不同来源氮素的吸收、分配、转运和氮素利用效率的影响.结果表明,灌浆期不同阶段遮光均不利于植株对氮素的吸收、积累和转运,品种间表现一致,呈T0 ＞T3 ＞T2 ＞T1规律；小麦植株吸收的氮素68.0 ％～71.39％来自土壤氮,对追施氮的吸收量大于底施氮,灌浆期遮光增加了土壤氮素在营养器官的分配比例,不利于营养器官中土壤氮素向籽粒中的转运；各处理籽粒产量、肥料氮吸收量、氮肥利用率和肥料偏生产力均表现为T0 ＞T3＞ T2 ＞T1.相同处理条件下,济麦22籽粒产量和对肥料的利用大于山农8355.小麦灌浆期阶段性遮光降低了植株对氮素的吸收、转运和籽粒产量,以灌浆前期遮光影响最大,中期次之,后期最小；相同遮光条件下济麦22的籽粒产量和氮素利用率较高.%Shading post flowering caused by cloudy weather and the surrounding protective trees often occurs in the Huang-Huai-Hai Plain of China. In the present study, two winter wheat cultivars with different spike types, a large-spike cultivar of Shannong8355 and a multiple-spike cultivar of Jimai22, were used to evaluate the effects of shading at different grain-filling stages on nitrogen accumulation and translocation by using I5N tracer technique. There were four shading treatments, shading from day 1 to day 10 after the anthesis ( Tl) , shading from day 11 to day 20 after the anthesis (T2), shading from day 21 to day 30 after the anthesis (T3) and no shading (TO). The results indicate that the shading at different grain-filling stages decreases the uptake and translocation of N of the two cultivars which are in the order; TO ＞ T3 ＞ T2 ＞ Tl. The amounts of nitrogen derived from soil range from 68. 0% -71. 39% and the percentages of nitrogen derived from the basal fertilizer in the vegetative organs are lower than those derived from the topdressing fertilizer. The shading at different grain-filling stages increases the absorption amount and proportion of soil N in the vegetative organs, and inhibits translocation of those to the grain. The grain yield, N uptake from fertilizer, fertilizer N use efficiency and partial factor productivity from fertilizer N at different grain-filling stages are also in order: TO ＞ T3 ＞ T2 ＞ Tl. In conclusion, the shading at different filling stages decreases the uptake and translocation of N and grain yield, and the uptake and translocation are highest under the shading at the early filling stage and the lowest at the later filling stage. Under the same shading condition, the grain yield and N use efficiency of Jimai22 are higher than those of Shannong 8355.