Comparison of soil nematodes community structure and diversity in cucumber greenhouses in different cultivation years

ObjectivesAiming at the problem of soil continuous cropping obstacle, this study investigated the soil health status in greenhouses with different cultivation years, based on the community structure and diversity of soil nematode and the difference of soil ecosystems in different cultivation years.

MethodsSoil samples were collected in greenhouses which were continuous used for cultivation of cucumber for 8, 10, 13 and 16 years, and a control soil sample was collected in an open field nearby, in which only one season of cucumber was produced. The community structure and diversity of soil nematode were analyzed using the morphological identification method.

ResultsThere were 21 nematode genera detected in all the samples. Both the total nematode and plant-parasite nematode numbers per 100 g of dry soil were in order of 10 a > 16 a > 13 a > 8 a and 1 a, and the total nematode number were significantly different among cultivation years, ranging from 61 to 437 per 100 g dry soil. The nematode ecological indices responded differently to cultivation years. The Shannon index (H′) was in order of 16 a > 13 a > 1 a > 8 a > 10 a, while the evenness index (J) was in order of 13 a > 16 a > 1 a > 8 a > 10 a. The dominance index (λ) was in the order of 10 a > 16 a > 13 a > 8 a > 1 a. However, the Wasilewska index (WI) was in a reverse trend. For all soils the nematode channel ratio (NCR) was higher than 0.5, ranging from 0.6 to 9.8. The lowest nematode maturity index was found in the 16 year-soil, resulting in the highest PPI/MI ratio. The richness index (SR) increased firstly, then decreased gradually and finally bottomed at the lowest value in the 10-year soil. The nematode in the 10-year soil distributed in the IV quadrant, while the others distributed in the I quadrant.

ConclusionsThe soil in the 1-year open field is low in nematode number, showing a stable soil ecosystem. Continuous cropping leads to accumulation of nematode in number but decrease in nematode genera, the soil micro community becomes poor in health and unstable. The worst nematode diversity and stability are appeared in the 10-year soil in the tested condition.