施肥对台湾桤木根系生长及结瘤的影响

摘要

为阐明施肥对台湾桤木根系生长及结瘤的影响,对广西引种的台湾桤木进行1年生苗施肥试验,研究了4种土壤类型(T1:酸性黑壤土、T2:酸性黄心土、T3:酸性红壤土、T4:碱性红壤土)下的3种施氮水平(N1:0 g,N2∶ 3 g,N3∶6 g)对台湾桤木根系生长及根系结瘤的影响.结果表明:相同土壤类型下,N1(0 g)处理的台湾桤木苗木总根长、根系表面积、总体积、根系干重、根瘤鲜重、根瘤干重、根瘤数量、根瘤最大直径、根瘤平均直径以及根瘤固氮酶活等指标均明显高于N2(3 g)和N3(6 g)的相应值.4种土壤类型中以土壤pH值为4.77～5.00的酸性红壤或者黄壤更为适合台湾桤木生长.综合来看,1年生台湾桤木在不添加氮肥的情况下,可通过自身生物固氮满足其生长需求,有利于根系生长和根系结瘤;在施加氮肥3～6 g时,反而抑制其根系生长及根系结瘤,并且使其根瘤固氮酶活性下降.%In order to illuminate the fertilization influence on the growth and the nodule formation of of the root system of Alnus formosana,we did a fertilization experiment on the 1-year old seedlings of A.formosana introduced by Guangxi and made a research on how 3 different-level nitrogen applications in 3 types of soil influenced the growth and the nodule formation of the root system of A lnus formosana.The result indicated that in the same type of soil the seedlings applied with N1(0 g) showed higher indices than those treated with N2(3 g) and N3(6 g),including total root length,superficial area of the root system,and total volume of the root system,the dry weight of the root system,the fresh weight of root nodules,the dry weight of root nodules,the number of root nodules,the maximum diameter of root nodules,the average diameter of root nodules,the nitrogenase activity of root nodules.Among the four types of soil,T2 and T3,acid red soil and yellow soil with pH ranged from 4.77 to 5.00,were more suitable for the growth of A.formosana.It revealed that one-year-old A.formosana without the application of nitrogenous fertilizers could meet its own demand for the growth by biological nitrogen fixation,which is beneficial to its growth and nodule formation.When nitrogenous fertilizers of 3-6 g were applied,the growth and the nodule formation would be restrained,and the nitrogenase activity of root nodules would reduce.