Effects of nitrogen fertilizer on fructan accumulation，translocation and their heterosis in hybrid wheat

صينى. 氮肥影响作物的碳氮代谢及生长发育。选用6个杂交小麦及其7个亲本材料在施氮（200 kg／ha）和不施氮（0 kg／ha）条件下，比较研究了不同生育期不同器官果聚糖的积累与转运及其杂种优势。无论施氮与否茎鞘和总麦草中果聚糖的积累模式基本相似。茎鞘是贮存果聚糖的主要营养器官，分配了总麦草果聚糖积累量的63％-87％，并在开花期其积累量达最大值。总麦草转运的85％以上的果聚糖来源于茎鞘，其对籽粒产量的贡献率最大（9.42％-19.36％）。氮缺乏减少叶片中果聚糖的积累量，但增加茎鞘和总麦草中果聚糖的积累量。穗轴及颖壳、茎鞘和总麦草的果聚糖积累在挑旗期、抽穗期和开花期存在一定的杂种优势（4.7％～51.7％），叶片、茎鞘和总麦草的果聚糖转运量、转运率也具有较强的杂种优势，施氮增强叶片中果聚糖的转运优势，但减弱茎鞘和总麦草中的转运优势。结果说明，杂交品种比其亲本具有更强的果聚糖转运能力，施氮对茎鞘果聚糖的积累与转运及其杂种优势均有抑制作用。

إنجليزي. Nitrogen fertilizer is one of the most important factor to influence the carbon and nitrogen metabolism as well as the growth and development of crops. The objective of this study was to compare the fructan accumulation and translocation as well as their heterosis in different organs at various growth stages using six hybrids of wheat and their seven parents grown by a split plot design with two replications under two levels of nitrogen applications 0 kg/ha and 200 kg/ha. Above-ground plant parts were harvested at 75, 90, 105, 120, 140, and 160 d after sowing, corresponding with stages of stem elongation, flag leave emergence, heading, flowering, milk-ripe and maturity, respectively. The samples were partitioned into leaf, stem and sheath, stalk and chaff of spike, and grain, then microwaved for 4 min, and dried in oven at 60℃. Fructan content of the hammermill-ground sample and grain nitrogen content were determined by Near Infrared Reflectance spectrometry. Significant differences between nitrogen application levels in fructan accumulation and content were observed in all vegetative organs at most sampling dates. Genotypic differences were found at heading stage, flowering stage and milk-ripe stage. The patterns of fructan accumulation in stem and sheath and total straw were similar under two nitrogen application levels. The most fructan, about 63%-87% of the fructan accumulation of total straw, was stored in stem and sheath, and the maximum fructan accumulation was at anthesis （Fig. 1 ）. Fructan translocation of stem and sheath, which accounted for more than 85% of that of total straw, showed the highest contribution to grain yield （9.42%-19.39% ） （Table 2）. Fructan accumulation in leaf was reduced, but that in stem and sheath and total straw were increased under nitrogen deficiency. The heterosis of fructan accumulation （4.7% 51.7% ） of stalk and chaff of spike, stem and sheath, and total straw, were appeared at flag leaf emergence, heading stage and flowering stage （Table 1 ）. Also, there were high heterosis for fructan translocation and fructan translocation efficiency of leaf, stem and sheath and total straw. The heterosis of fructan translocation was enhanced in leaf, while decreased in stem and sheath and total straw for nitrogen application （Table 3）. In conclusion, the fructan capacity translocation from vegetative organs to grain is stronger in hybrid wheat than in their parents, and the fructan accumtrlation and translocation as well as their heterosis in stem and sheath were restrained by nitrogen application.