Biological nitrogen fixation of Chinese Milk Vetch (Astragalus sinicus L.) as affected by exogenous carbon and nitrogen input

文献类型： 外文期刊

第一作者： Yang, Lu

作者： Yang, Lu;Yang, Lu;Cao, Weidong;Nie, Jun;Xu, Changxu;Cao, Weidong

作者机构：

关键词： Biological nitrogen fixation; Straw return; Carbon availability; Nitrogen availability; Leguminous green manure

期刊名称：SYMBIOSIS （ 影响因子：2.268； 五年影响因子：2.471 ）

ISSN： 0334-5114

年卷期： 2021 年 85 卷 1 期

页码：

收录情况： SCI

摘要： Crop residue management and fertilizer application are common practices altering soil carbon (C) and nitrogen (N) status. However, a full understanding of how the biological N fixation (BNF) of Chinese Milk Vetch (CMV), (Astragalus sinicus L.), is regulated by exogenous C and N addition remains elusive in the CMV-based rice rotation system. Here, in a 7-year field experiment of double rice and CMV rotation, mineral fertilizer was applied in the rice seasons and straw was returned to the soil after harvesting. Their effects on the growth, N uptake, and BNF of succeeding CMV plants were examined at the flowering stage of CMV in 2015-2017. Meanwhile, these effects were further explored using two substrates with distinctive C availability (rice straw and glucose) plus low to high N inputs on two paddy soils under pot conditions. The results showed that 58%-85% of N uptake in CMV plants at the flowering stage was derived from BNF, corresponding to 24 to 55 kg N ha(-1). Compared with the non-addition control or straw return alone, the percentage of BNF in CMV decreased significantly in treatments with fertilization and straw return (mulching or high stubble retention). The BNF amount increased by 34.7% due to better CMV growth when rice straw was retained as high stubble. These results indicated that BNF could be improved by enhancing CMV growth and that the responses in terms of %BNF to N addition varied with C availability, i.e. rice straw vs. glucose. In both paddy soils, the %BNF decreased with increasing rates of N application as expected. The reduction in BNF was less in the glucose-included treatments than in the straw added treatments. This was possibly associated with an inhibition of BNF by the slightly increased mineral N concentrations and significantly less availability of P in the glucose-added soils. Overall, significant interactions between soil variables and plant growth and N uptake were observed for the N-2 fixation of CMV, which explained 62.0%-79.7% of total variation of BNF in CMV plants. The study highlighted the fact that the patterns of CMV's N-2 fixation in relation to N inputs, varies with C availability of added substrates and residue management in Chinese Milk Vetch based double-rice systems.

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