山毛豆/桉树间种系统中植物生长对施N与根系隔离的响应

Responses of Plant Growth to N Application and Root Separation in Intercropping System of Tephrosia candida and Eucalypt

为探索山毛豆(Tephrosia candida)和桉树(Eucalyptus spp.)间种系统内物种相互作用的途径和机制,量化种间竞争对植物生长的影响,采用盆栽试验,研究施氮(-N、+N 105 mg/kg)和根系隔离(完全分隔、尼龙网分隔和不分隔)处理对系统中植物生长的影响。结果表明,+N处理显著提高桉树的株高、地径、生物量、N浓度和吸N量,显著减少山毛豆根瘤数量和重量。根系不隔离处理显著提高桉树的株高、地径、生物量和吸N量,显著增加山毛豆根瘤数量和重量。施N或根系隔离处理对山毛豆的生物量和N浓度影响不明显,对吸N量影响较大。山毛豆/桉树间种系统中,桉树生长所需的N主要来源于土壤,山毛豆生长所需的N有部分来源于生物固氮;山毛豆对桉树生长的促进作用以根系相互交叉接触产生养分传递为途径,但随土壤N含量增加,作用呈减弱趋势。

In order to clarify pathways and mechanisms of species interaction and quantify effects of interspecific competition on plant growth in intercropping system of Tephrosia candida and eucalypt,pot experiment was conducted to investigate effects of N application(-N,+N 105 mg/kg)and root separation treatments(complete separation,mesh separation and no separation)on plant growth.Results showed that+N treatment significantly increased plant height,ground diameter,biomass,N concentration and N acquisition of eucalypt,but significantly reduced number and weight of root nodules of T.candida.By no separation treatment,plant height,ground diameter,biomass and N acquisition of eucalypt were significantly increased,and number and weight of root nodules of T.candida were significantly increased.Effects of N application or root separation treatments on biomass and N concentration of T.candida were not significant and effect on N acquisition was significant.N for eucalypt growth in intercropping system of T.candida and eucalypt mainly came from soil.N for T.candida growth partly came from biological N fixation.Promotion effect of T.candida on growth of eucalypt was through cross contact of roots to produce nutrient transfer,but effect was weakened with increase of N content in soil.