玉米、小麦和大麦与蚕豆间作体系不同根系分隔方式对蚕豆结瘤的影响

Effects of Root Barriers on Nodulation of Faba Bean in Maize/Faba Bean,Wheat/Faba Bean and Barley/Faba Bean Intercropping Systems

本实验选取3种对土壤氮素竞争能力不同的禾本科作物大麦(Hordeum vulgare)、小麦(Triticum aestivum)和玉米(Zea mays)分别与蚕豆(Vicia faba)间作,建立对土壤氮素竞争能力不同的作物组合;并采用3种分隔方式(塑料膜分隔、尼龙网分隔和无分隔)建立同一作物组合条件下作物种间根系相互作用的不同强度,来研究不同作物组合及种间根系相互作用强度对蚕豆结瘤的影响。结果如下:(1)蚕豆的结瘤并未随3种禾本科作物氮素竞争能力的增强而增加,但是3种间作体系蚕豆的结瘤却均表现出无分隔处理多于塑料膜分隔处理,即同一间作体系种间根系相互作用越强,越有利于蚕豆结瘤的产生,存在种间互利作用;(2)在玉米/蚕豆间作体系中,无分隔处理的蚕豆根瘤数目和根瘤重显著高于塑料膜分隔处理,分别高出67.5%和70.1%;在大麦/蚕豆间作体系中也表现出无分隔处理的根瘤重显著高于塑料膜分隔处理(高出46.3%);(3)玉米/蚕豆间作体系与小麦/蚕豆和大麦/蚕豆间作体系相比,无分隔处理时土壤氮素含量显著高于后2个间作体系,但是玉米/蚕豆间作体系对蚕豆结瘤的促进作用更强。上述结果表明,在蚕豆/玉米间作体系中,玉米促进蚕豆生物固氮除了氮素竞争机制外,还可能存在其它机制。

We aimed to examine the effect of interspecific root interactions on root nodulation of faba bean(Vicia faba 'Lincan 5') when intercropped with maize(Zea mays 'Nongda 108'),wheat(Triticum aestivum 'Long 17'),and barley(Hordeum vulgare 'Ganpi 3').We changed the intensity of root interactions artificially through different barrier treatments(plastic,nylon mesh,and no barrier).Then,we chose three cereals(barley,wheat and maize) with varying ability to compete for nitrogen in soil,intercropped with faba bean.Results showed that firstly nodulation of faba bean was increased when crop roots were able to interact completely without a barrier,suggesting positive effects on root nodulation between faba bean and cereals.Secondly,the intercropped maize/faba bean with complete root interactions showed a significant increase(about 67.5% and 70.1%) in nodule weight and number compared with plastic barrier treatment,respectively.Although the N-min of maize/faba bean was more than that of the wheat/faba bean and barley/faba bean,the nodulation was increased significantly in the maize/faba bean system.Therefore,this paper highlights that there is another mechanism behind increased nodulation in maize/faba bean intercropping.