供氮水平对枫香种源幼苗生长及氮、磷吸收利用的影响

在砂培条件下研究枫香6个种源幼苗对不同氮素水平的响应差异,结果表明:苗木生物量、根冠比和氮磷吸收量及利用率在不同氮水平间、同一氨水平内不同种源间及氮水平与种源间的交互作用,均存在极显著差异,随着供氮水平的降低,枫香各种源大体呈生物量减小、根冠比增大、氮磷吸收量减少,氮利用率上升和磷利用率下降的变化趋势,尤其在缺氮时,变化幅度剧增.当由标准氮水平增加到丰氮水平时,不同种源的反应不一,无一定变化规律.在6个种源中,南昌和南丹种源在各氮素水平上均保持较大的生物量,但对缺氮的反应较为强烈,更适宜较高的氮素供应条件.延平种源在低氮、缺氮水平上具有较大的生物量,较高的氮磷吸收量和利用率,是对低氮耐受力较强的种源.

Effects of N Rate on Seedling Growth and Uptake and Utilization of Nitrogen and Phosphorus in Different Provenances of Liquidambar formosana Hance

The seedlings of six typical Liquidambar formosana Hance provenances(Yixing of Jiangsu,Yongkang of Zhejiang,Nanchang of Jiangxi,Shaowu of Fujian,Yanping of Fujian and Nandan of Guangxi)were selected and did a sand-breeding experiment in which we set up four levels of N(N_0,N_(1/2),N_1,N_2)to study different response to N rate. The results obtained were described as follows:Biomass,R/S ratio and uptake content and utilization efficiency in between provenances,between the phosphate rate and their interaction had significant differences,respectively,With nitrogen supply decreasing,six provenances were generally the same trend that biomass decreased,R/S ratio increased,the nitrogen and phosphorus uptake content reduced and nitrogen and phosphorus utilization efficiency increased,especially in no nitrogen(N_0),dramatic increase in the magnitude of changes.From standard nitrogen(N_1)to abundant nitrogen(N_2),different provenance responded differently and there was no consistent variation law.In six provenances,both Nanchang and Nandan provenance kept at a greater biomass in all N rates,but more intense response to no nitrogen,more suitable for a higher N supply.Because Yanping provenance had greater biomass,the higher N and P uptake content and utilization efficiency in no and low nitrogen,it can be considered to be an excellent low-N-stress-tolerance-type provenance.