铜对大叶相思-根瘤菌共生固氮体系的影响

报道了两种根瘤菌 (大叶相思、美丽胡枝子 )对Cu2 + 的耐受性以及植物 根瘤菌共生固氮体系在Cu2 + 胁迫下结瘤、固氮和生长的变化 ,讨论了大叶相思在矿山尾矿废弃地作为先锋植物结瘤固氮的可能性 .结果表明 ,大叶相思根瘤菌对Cu2 + 离子的耐受性较强 ,可以耐受Cu2 + <0 80mmol的离子浓度 ,Cu2 +对它的半致死浓度为 0 12 9mmol.在无菌砂培无重金属影响条件下 ,其固氮酶活性为 2 7C2 H4 ·μg·g-1·h-1,当Cu2 + >0 12 5mmol会导致大叶相思固氮酶活性急剧下降 ,其有效半抑制浓度 (EC50 )为0 15 1mmol,Cu2 + 为 0 5 0mmol完色抑制大叶相思固氮酶活性 ,不阻碍结瘤 ,但严重抑制植物生长发育 ,引起植物叶片白化、植株矮化 .在外加N源不接菌和不加N源接菌两种处理组间 ,Cu2 + <0 12 5mmol时 ,以不加N接菌处理对大叶相思生长有利 .大叶相思对Cu2 + 吸收积累根部高于地上组织 .

Effects of copper on rhizobia-Acacia auriculaeformis symbiotic association

The effects of different levels of Cu\+\{2+\} were studied individually on the growth of two Rhizobium strains and host plant growth,nodulation(%) and nitrogen fixation activity in A.auriculaeformis under solution culture conditions so as to explore a probability of utilization of the genus Acacia in revegetation of Cu\+\{2+\}-contaminated land.The results shows that Rhizobium sp.(Acacia auriculaeformis)had more stronger tolerance to Cu\+\{2+\} iron than Rhizobium sp(Lespedeza formosa).The values of EC\-\{50\} respectively achieved 0\^129mmol for Rhizobium sp.and 0\^151mmol for the N\-2-fixation activity.When the concentration of Cu\+\{2+\} was over 0\^50 mmol,N\-2-fixation activity had been inhabited thoroughly.Although the formation of nodules of Acacia auriculaeformis could continued,the growth of host plant had been inhibited with the appearance such as stunting,chlorosis. Between the noinodulating but adding nitrogen treat group and the inodulating without any nitrogen resource treat group, when Cu\+\{2+\}<0.125mmol, the latter group showed better growth for A. auriculaeformis. There were higher contents of Cu in the underground tissues than in aboveground tissues.