■生物固氮(BNF)在农业生态系统中的氮素利用中起着至关重要的作用。植物的功能特征(草与豆类)影响BNF。然而,关于生态区和种植模式如何影响豆科植物固氮还知之甚少。本研究的目的是评估不同种植系统对地上干物质的影响。种间关系,结瘤特性,根构象,土壤物理化学,BNF,和三个生态区中的氮转移,并确定影响大气中氮(Ndfa)和氮转移(Ntransfer)的主要因素。
■应用15N标记方法。燕麦(AvenasativaL.),饲用豌豆(PisumsativumL.),普通豌豆(豌豆),和蚕豆(ViciafabaL.)在三个生态区(HZ:黄水谷;GN:三江源区;MY:祁连山盆地)中,以单种和混合物(YS:燕麦和牧草豌豆;YJ:燕麦和普通vetch;YC:燕麦和蚕豆)的方式种植。
■结果表明,混合显着促进豆类结瘤,优化了根系的配置,地上干物质增加,不同生态区域固氮能力增强。不同豆科植物类型和不同生态区的豆科植物从大气中获得的氮百分比(%Ndfa)和氮转移百分比(%Ntransfer)差异显著,但是混合种植显着增加了豆类的Ndfa%。影响Ndfa的因素包括种植模式,生态区(R),根瘤号,pH值,铵态氮,硝酸盐氮,微生物氮团(MBN),植物氮含量(N%),和地上干生物质。影响Ntransition的因素包括R,温度,高度,根表面积,固氮酶活性,有机物,土壤总氮,MBN,和N%。
■我们得出结论,混合种植对BNF有利,豆类混合种植是青藏高原可持续和有效的牧草管理实践。
UNASSIGNED: Biological nitrogen fixation (BNF) plays a crucial role in nitrogen utilization in agroecosystems. Functional characteristics of plants (grasses vs. legumes) affect BNF. However, little is still known about how ecological zones and cropping patterns affect legume nitrogen fixation. This study\'s objective was to assess the effects of different cropping systems on aboveground dry matter, interspecific relationships, nodulation characteristics, root conformation, soil physicochemistry, BNF, and nitrogen transfer in three ecological zones and determine the main factors affecting nitrogen derived from the atmosphere (Ndfa) and nitrogen transferred (Ntransfer).
UNASSIGNED: The 15N labeling method was applied. Oats (Avena sativa L.), forage peas (Pisum sativum L.), common vetch (Vicia sativa L.), and fava beans (Vicia faba L.) were grown in monocultures and mixtures (YS: oats and forage peas; YJ: oats and common vetch; YC: oats and fava beans) in three ecological regions (HZ: Huangshui Valley; GN: Sanjiangyuan District; MY: Qilian Mountains Basin) in a split-plot design.
UNASSIGNED: The results showed that mixing significantly promoted legume nodulation, optimized the configuration of the root system, increased aboveground dry matter, and enhanced nitrogen fixation in different ecological regions. The percentage of nitrogen derived from the atmosphere (%Ndfa) and percentage of nitrogen transferred (%Ntransfer) of legumes grown with different legume types and in different ecological zones were significantly different, but mixed cropping significantly increased the %Ndfa of the legumes. Factors affecting Ndfa included the cropping pattern, the ecological zone (R), the root nodule number, pH, ammonium-nitrogen, nitrate-nitrogen, microbial nitrogen mass (MBN), plant nitrogen content (N%), and aboveground dry biomass. Factors affecting Ntransfer included R, temperature, altitude, root surface area, nitrogen-fixing enzyme activity, organic matter, total soil nitrogen, MBN, and N%.
UNASSIGNED: We concluded that mixed cropping is beneficial for BNF and that mixed cropping of legumes is a sustainable and effective forage management practice on the Tibetan Plateau.