RESUMO
This paper studied the effects of nitrogen application rate on the soil enzyme activities in the rhizosphere of wheat cultivars Lankaoaizao 8, a large spike genotype, and Yumai 49-198, a small spike genotype, under high yield condition. The results showed that the enzyme activities in rhizosphere soil had similar changing trends with wheat growth. The protease, urease and dehydrogenase activities in rhizosphere soil increased with wheat growth, maximized at heading stage, jointing stage, and heading stage, respectively, and decreased thereafter. Catalase activity increased with wheat growth, and peaked at maturing stage. At the same growth stage, the protease, catalase and dehydrogenase activities in rhizosphere soil of the two cultivars increased with increasing nitrogen application rate and peaked at 180 kg N x hm(-2). Urease activity also increased with increasing nitrogen application rate, and the maximum activity was observed at 360 kg N x hm(-2).
