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以东农47为试材,采用15N标记的(NH4)2SO4为氮源,利用砂培方式研究了氮素营养水平对大豆籽粒氮素构成和产量的影响。结果表明:随外源氮水平增加,大豆产量呈先增加后降低的变化趋势,营养液中氮为50 mg.L-1时产量最高;前期高氮后期低氮处理时,随高氮处理的时间延长产量降低;于R4或R5期提高外源氮水平可以增加大豆产量。对大豆产量与籽粒中肥料氮所占比例、大豆产量与根瘤固氮所占比例分别作回归分析,经求导分析得出大豆籽粒中外源氮所占比例为39.1%、根瘤固氮所占比例为61.5%时大豆产量最高。由此推断,当外源氮对籽粒的贡献率为40%左右、根瘤固氮贡献率为60%左右时,能够同时满足大豆对根瘤固氮和外源氮的需求,有利于大豆产量的提高。
Using Dongnong 47 as test material, 15N labeled (NH4) 2SO4 was used as nitrogen source. The effects of nitrogen nutrition on nitrogen composition and yield of soybean were studied by means of sand culture. The results showed that with the increase of exogenous nitrogen level, soybean yield increased first and then decreased, and the highest yield was obtained when the nitrogen level was 50 mg.L-1 in the nutrient solution. In the low nitrogen stage, Prolongation of production decreases; increasing levels of exogenous nitrogen in stages R4 or R5 can increase soybean production. The results showed that the proportion of exogenous nitrogen in soybean grain was 39.1% and the proportion of nitrogen fixation in root nodule was 61.5 % Of the highest soybean production. The results showed that when the contribution of exogenous nitrogen to grain was about 40% and the contribution of nodulation to nitrogen fixation was about 60%, the demand for nitrogen fixation and exogenous nitrogen could be satisfied simultaneously, which was benefit to the increase of soybean yield.