施氮水平对7S亚基缺失大豆根系形态和结瘤固氮的影响

为有效推广功能型大豆7S亚基缺失品种,以7S亚基缺失大豆品系东富2号为研究对象,设置4种施氮水平(纯N),N0(0 mg·kg~(-1))、N1(25 mg·kg~(-1))、N2(50 mg·kg~(-1))、N3(75 mg·kg~(-1)),采用桶栽法研究大豆根系形态和结瘤固氮对不同施氮水平的响应。结果表明:N1(25 mg·kg~(-1))水平下根系干重加大,根冠比增大,根瘤固氮潜力高,单株产量较高。N2(50 mg·kg~(-1))水平下根长、根表面积、根体积在生育后期增长较快,根系干重较大,根冠比低,固氮酶活性最高,单株籽粒产量最高。N3(75 mg·kg~(-1))水平下植株干重较大,无效生长较多,根瘤数少,固氮潜力和根冠比低,单株产量不高。综合籽粒产量和根系特性指标,功能型大豆7S亚基缺失品系东富2号的适宜施肥量为25~50 mg·kg~(-1)。

Effect of Different Nitrogen Application Levels on the Root Morphology,Nodulation and Nitrogen Fixation in 7S Subunit Lacked Soybean

In order to popularize 7S subunit lacked soybean effectively,the experiment was conducted with 4 nitrogen levels (pure N-)inculding N0 (0 mg·kg-1),N1 (25 mg·kg-1),N2 (50 mg·kg-1) and N3 (75 mg·kg-1) with Dongfu 2(7S subunit lacked soybean line).The response of soybean root morphology,nodulation and nitrogen fixation to different nitrogen application levels were studied with pot cultivation.The results showed that under N1 (25 mg·kg-1) level root dry weight and root to shoot ratio increased,root nodule nitrogen fixation potential and yield per plant were higher than others.Under N2 (50 mg· kg-1) level root length,root surface area,root volume were larger than the other treatments in the late growth stage,root dry weight was biggest,root to shoot ratio was lower,nitrogenase activity and seed yield per plant were highest.Under N3 (75 mg· kg-1) level plant dry weight was higher,but plant invalid growth was occurred.Nodule number,nitrogen fixation potential,root to shoot ratio and yield were lower.Taking into account of seed yield and root characteristics,appropriate N fertilizer amount of 7S subunit lacked soybean was 25-50 mg·kg-1.