夏花生施用氮肥对根瘤中固氮酶和叶片硝酸还原酶活性的影响

INFLUENCE OF N FERTILIZER ON THE NITROGENASE ACTIVITY (NA) IN NODULES AND THE NITRATE REDUCTASE ACTIVITY (NRA) IN LEAVES OF SUMMER SOWING PEANUT(ARACHIS HYPOGAEA)

氮肥对夏花生根瘤中固氮酶的活性有抑制作用，主要是降低了根瘤菌的侵染和根瘤的形成。但这种抑制作用主要表现在结荚以前．随生育期推进，抑制作用逐渐减弱。不同生育期追施氮肥对固氮酶活性的抑制作用，前期较重且时间长，后期较轻且时间短。施氮增进叶片硝酸还原酶（ＮＲ）活性．但不全是正相关，生育前期和后期都有所变化。ＮＲ与固氮酶之间在固氮酶活性受抑制的硝态氮浓度下呈负相关，而其未受抑制或抑制较轻时，二者呈正相关。

Applying N fertilizer to summer sowing peanut inhibited nitrogenase activity innodules. reduced mainly the Rhizobium infection and noduleformation. These inhibitoryeffects occured chiefly before pod setting phase. but the effects on NA weakened graduallywith the growth of Peanut.Top-dressing of N fertilizer at different phases all inhibited NA.but the inhibitory effects got more severe and longer with the earlier application. The nitrate reductase activity in leaves was promoted by applying N fertilizer. but the NRA didnot consistently positively correlate to the amount of N fertilizer during the whole growingseason.Within the range of N-NO3 concentration exhibiting inhibitory effect on NA.there was negative correlation between NR and N-ase. When the concentration ofN-NO3 did not exhibit inhibitory effect on NA or inhibited NA slightly. there was a positive correlation between NR and N-ase.