Abstract:Nematode community analyses are useful in assessing soil ecosystem status and function. The effects of two forms of mineral nitrogenous fertilizers (NO-3-N and NH+4-N) on nematode community composition and diversity in rhizosphere of cucumber were investigated during different growing seasons of cucumber in the greenhouses. The results showed that the total numbers of nematode were dramatically inhibited by fertilizers of NO-3-N and NH+4-N during the whole growing seasons, however there were no significant differences between the two treatments. Except that Tylenchus and Nothotylenchus were still dominated genus after the treatment with two forms of nitrogenous fertilizers, whereas Rhabditidae was changed from common family to dominant family and the mean relative abundance of Rhabditidae in the NO-3-N treatment was higher than that of Rhabditidae in the NH+4-N treatment. All the tropic groups in the soil nematode communities were stable. There was similar trend of the frequency of plant parasitic nematodes between NO-3-N treatment and NH+4-N treatment, the similar trend of the frequency of non-plant parasitic nematodes was also found. But the frequency of plant parasitic nematodes exhibited a contrary trend to that of plant parasitic nematodes after different nitrogenous fertilizer treatments. The changes in nematode diversity between the control plots and treated plots were compared by the biodiversity index (H′, J, SR, λ). Among these tested index, H′ and SR were effective in reflecting the effects of different nitrogenous fertilizers on the diversity of soil nematodes. In comparison with the NH+4-N treatment, the NO-3-N treatment promoted the stabilization of soil nematode diversity.