On-Farm Conditions Limiting Yield Elaboration Process of Transplanted Rice in Southern Thailand.

Abstract

An on-farm experiment was conducted during the 1988-1989 rainy season, to grade the conditions limiting the grain yield elaboration process of transplanted rice after different managements of nurseries. 48 kg nitrogen/ha application was compared with no application in mainplots transplanted with seedlings coming from three treatments : 45 days, 30 days, 30 days fertilized with 20 kg nitrogen/ha. The other techniques were decided by the farmer. Nitrogen application on mainplot affected the elaboration of the spikelets of the transplanted 45 days old seedlings only, yet below the level expected (1,200 against 9,000 spikelets/m²). Grain filling appeared to be affected by several insect damages. Otherwise, the rice crop hardly responded to the treatments. Some trouble was provoked by stem borer damages in the elaboration of the spikelets. Though the plant density was low in every treatment, ranging from 40 to 100 plant/m², it was not limiting. The importance of the insect damages and existence of a limiting element in the soil other than nitrogen are assumed.