【摘要】 应用同位素¹⁵N 示踪技术,盆栽结瘤(R_j1)与不结瘤(r_j1)等位基因系大豆,研究豆株对土壤氮（N_S）,肥料氮（N_F）和空气氮（N_G）的吸收利用特点,试验结果表明:r_j1豆株只利用 N_S 和 N_F,对氮肥反应敏感;R_j1豆株的氮素来源,开花前N_S>N_F>N_G,开花后 N_G>N_S>N_F,对磷钾肥反应敏感;氮肥对结瘤固氮有明显抑制作用,程度轻重及时间长短与施氮量有关,抑制作用在固氮高峰期前基本消失的施氮水平有利结瘤固氮;适量施用氮肥可促进豆株对 N_S 的吸收,¹⁵N₁P₂K_4/3 R_j1和¹⁵N₂P₂K_4/3R_j1两处理的激发率分别为1.535和1.778;豆株吸收N_S 与结瘤固氮间呈显著负相关,施氮肥不合理不仅直接抑制结瘤固氮,还能通过增加吸收 N_S 而间接影响结瘤固氮,三种来源氮素在豆株各器官的分配有明显差异,豆根吸收的 N_F 和 N_S 较多的组成营养器官;结瘤固定的 N_G 较多的进入结实器官;根瘤菌与豆株共生能显著扩大氮源、增加产量,¹⁵N₁P₂K_4/3R_j1处理提供的 N_G 可达总吸氮量的67.8%,¹⁵N₁P₂K_4/3R_j1处理比¹⁵N₁P₂K_4/3r_j1处理的籽实产量提高3.1倍。更多还原

【Abstract】 The absorption,utilization and fixation of nitrogen from soil （Ns）,fertil- izers （N_F） and air （N_G） innodulating (R_j1) and non-nodulating (r_j1) allelotye soybean respectvely,were examined by using ¹⁵N-isotopic technique.The results of experiments showed that the plant type r_j1 was sensitive to nitrogen fertilizers and utilized only N_S and N_F,while the plant type R_j1 was sensi- tive to phosphate fertilizers and it’s demands for nitrogen were in the order of N_S>N_F>N_G before flowering,and N_G>N_S>N_F after flowering.Nitrogen fertil- izers could inhibit symbiotic nitrogen fixation.The degree and duration of the in- hibition were related to the amount of the nitrogen supply.The appropriate level of nitrogen supply at which the inhibition disappeared before the peak period of nitrogen fixation was in favour of symbiotic nitrogen fixation.Besi- des,the appropriate supply of nitrogen fertilizers could increase the absorp- tion of NS.The stimulating rates were 1.535 and 1.778 in ¹⁵N₁P₂K_4/3 R_j1 and ¹⁵N₂P₂K_4/3 R_j1 two treatments respectively.There was a significant negative correlation between the absorption of NS and symbiotic nitrogen fixation.If the fertilizs were not supplied rationally,the symbiotic nitrogen fixation would beinhibited not only directly but also indirectly via increasing the ab- sorption of Ns,there was obvious difference in the distribution of three sourc- es of nitrogen among soybeen organs.N_S and N_F contributed mainly to the growth of vegetative organs,while N_G from symbiotic nitrogen fixation was transfered much into reproductive organ,The symbiosis between nidule bacteria and soybean plant could broaden the sources of nitrogen and increase yeild. For instance,¹⁵N₁P₂K_4/3 R_j1 treatment provided NG up to 6.78% in total ab- sorption of nitrogen and increased yeild as 3.lfold of ¹⁵N₁P₂K_4/3 r_j1 treatm- ent.更多还原