Vertical distribution of Heterodera oryzicola in rice fields and influence of some edaphic factors and fertilizer application on the nematode

Abstract

The distribution of cysts in the soil was related to the root distribution. In the tests on influence of soil porosity, the root growth had increased with the increase in soil porosity and this in turn had increased nematode activity as has been reported earlier with the cereal cyst nematode (Southy, 1956). The tests with soil moisture regimes showed 60 to 90% soil moisture were ideal and perhaps for the same reason, serious infestations of the nematode occur in upland fields and light and low infestations are reported from low and wet lands in Kerala state (Rao and Jayaprakash, 1978). High levels of fertilizers increased the root weight which was conducive to an increase in H. oryzicola populations.