摘要
用^(15)N同位素稀释法,在盆栽和草场小区条件下研究了新疆主要禾本科牧草和新疆大叶苜蓿在单播和混播系统中的氮行为。牛尾草、老芒麦、冰草和无芒雀麦植株在混播系统中,来自肥料和土壤氮的比例较单播时都有较大幅度的降低。在混播系统中发生了苜蓿固氮产物向禾本科牧草转移。新疆大叶苜蓿在混播中的固氮率比单播时显著提高。固氮产物转移可能是通过苜蓿植株根瘤和残根的脱落和腐解。
The N behavior in alfalfa and gramineous forage grasses,tall fescue,Siberian wildrye,wheatgrass and awnless brome were studied in potting and pasture experiments in 1986-1988 by using 15N isotope dilution technique.Comparison was made between the mixed culture and monoculture.The %Ndff and %Ndfs of grasses were decreased by 14.19% and 20.76% respectively,while %Ndfa of alfalfa was increased by 20.22% in mixed culture as compared with monoculture.The 15N and soil N uptake data revealed that this enhancement was largely due to a lower competitive ability for soil N by alfalfa than by grass in mixed stands,causing the alfalfa to depend more on atmospheric N2 fixation.20.62% of N of grasses in mixed culture was from the N2-fixation by alfalfa,causing N level in rootsphere of alfalfa decreasing,which was considered to be on.e of the reasons that %Ndfa increased in mixed culture.N transfer may be carried out by the decomposition of roots and nodules of alfalfa plants.
出处
《核农学报》
CAS
CSCD
1992年第2期99-104,共6页
Journal of Nuclear Agricultural Sciences
关键词
苜蓿
单播
牧草
固氮转移
混播
Mixed culture,N transfer,15N isotope dilution,Xinjiang alfalfa
