不同施氮水平对烟富3／M26／平邑甜茶幼树当年及翌年氮素吸收、利用、分配的影响

Effects of different N rates on the absorption,allocation and utilization of urea-^(15)N in M.hupehensis Rehd.(Yan Fu3/M_(26)) in the current year and next year

以2年生烟富3/M26/平邑甜茶幼树为试材,研究了不同施氮水平对苹果矮化中间砧幼树当年及翌年15N吸收、利用和分配的影响。结果表明,适量施氮肥利于幼树生长和氮肥利用率的提高,更利于翌年树体生长及氮肥利用率的提高。以不施氮肥(N0)处理为对照,适量施氮肥(N100)或过量施氮肥(N200)条件下均通过促进根系生长进而促进地上部生长,且N100处理对地上部生长的促进作用较N200更为显著。氮肥施入至春梢旺长期和春梢停长期,N100处理对根系生长的促进作用显著,根冠比由高到低分别为N100>N200>N0,且春梢旺长期根系15N分配率为N100(42.93%)>N200(37.10%)>N0(26.39%),春梢停长期各处理根系15N分配率由高到低仍为:N100(28.61%)>N200(20.30%)>N0(14.27%)。至秋梢旺长期,N100处理生长势显著高于N0,但各器官15N分配率无显著差异;N100与N200处理树体生长势无显著差异,但N100处理地上部15N分配(85.93%)显著高于N200处理(77.28%),根系15N分配率(14.07%)显著低于N200处理(22.72%)。至翌年春梢旺长期,N100树体生物量迅速增高至N0的175.83%和N200的176.41%,根冠比和根系15N分配率显著低于N0和N200。N200处理始终保持较高的根冠比和根系15N分配率但不利于地上部生长。冬季叶片脱落是苹果矮化中间砧幼树最大的氮流失途径,流失量为当年氮吸收量的44.56%51.25%。

Experiments were designed to test the absorption, allocation, and utilization of urea25N by 2 years-old M. hupehensis Rehd （YanFu/M26）under different N rates in the current year and next year. The results show that both the rational application rate of nitrogen fertilizer （ N100） and overuse rate （ N200 ） could promote the growth of trees and theirlSN utilization rate in the current and following year significantly. Nitrogen application could promote the development of roots, benefiting the growth of shoots as a results.. The Nloo treatment has better promotion effect than the N200 treatment on the shoot growth. The most obvious promotion of N fertilizer to the root growth happens during the period from fertilization to the vigorous growth of autumn shoots and the end of spring shoots growth stage, the obtained ratio of root to shoot is in order of Nl0o 〉 N200 〉 No, and the allocation oflSN in roots is in the same order with the value 42. 93%, 37.10% and 26.39% at the vigorous growth stage of spring shoot, and 28.61% , 20. 30% and 14. 27% at the end stage of spring shoot growth stage, respectively. The growth vigor ofNl00 treatment is superior to the No treatment till the difference is found on15N distribution ratios of both. stage of vigorous growth of autumn shoots, with no significant The aboveground15N distribution ratio of the N100 treatment （85.93%） is significantly higher than N200 treatment （77.28%）, while the root ratio （ 14. 07% ） is significantly lower than N200 treatment （22. 72% ）. Compared with the No and N200 treatments, the biomass weight of the N10o treatment is increased by 75.83% and 76.41% respectively till the vigorous growth stage of spring shoots the next year, while the root to shoot ratio and rootlSN distribution ratio of N100 are significantly lower than the NO and N200 treatments. Even with a high root to shoot ratio and root15N distribution ratio, N200 treatment is not suitable for growth. The defoliation in winter is the main nitrogen loss of dwarfed interstock apple saplings, accounting for 44.56% N 51.25% of total nitrogen uptake in current year.