Influence of the upland rice cyst nematode, Heterodera elachista, on the yield of the upland-cultured paddy rice

Abstract

When paddy rice was grown under upland condition in pots which had been inoculated with 0, 400, or 4, 000 larvae of the upland rice cyst nematode, distinct differences in grain weight were observed; the grain weights per pot were 71.2gm, 67.2gm, and 59.5gm, respectively. It was also found that the reduction in rice yield was related to the time of invasion of the roots by the nematode; higher rates of the yield reduction were observed when the roots were invaded by the nematodes before tillering stage. In a field experiment, negative correlation between the yield and the final population of cysts in soil were found more clearly in early seeding culture than in later ones. Actual influences of the nematodes on the plant growth were considered more severe at later stages of the plant growth.