[Effects of water managements on soil nematode communities in a paddy field]

This paper studied the effect of water managements on the abundance, trophic groups and community composition of soil nematodes in a paddy field in the Lower Reaches of Liaohe Plain at the depths of 0-10 cm, 10-20 cm and 20-30 cm during rice (Oryza sativa L.) growth season. The total number of nematodes at 0-10 cm soil depth was lower in percolation-controlling treatments than in control during pre-tillage and yellow ripeness stage. No significant difference was found in the total number of nematodes at 10-20 cm soil depth during the study period, but significant difference was observed in 20-30 cm soil depth during pre-tillage and yellow ripeness stage. Sixteen families and 22 genera were observed, and Plectus, Tylenchus and Monhystera were the dominant genera. Plectus and Tylenchus were sensitive to different water managements. Significant difference was found in the number of bacterivores at 0-10 cm soil depth during pre-tillage and yellow ripeness stage in percolation-controlling treatments, which exhibited a similar trend with the total number of nematodes. Bacterivores and plant-parasites were the most abundant trophic groups in all plots and at all soil depths during the study period, averaging 60.8% and 33.8% of the nematode communities, respectively, and omnivores-predators were the least abundant groups.