On farm experiments have been conducted during four seasons in Southern Thailand,spedially in one homogeneous irrigated agrocceological unit of Ta Chiat irrigation area, Phatthalung Provinces, in order to generate reference curves for the grain yield claboration precess in the variety of rice RD7. Data are available for plant stands raging from 25 to 350 plants/m2,allowing up to 40 panicles/m2. The level of spikelets per paniele can reach 90 and no perecntage of grain filling exceeds 85 % . A close relationship is found between the bionass at panicle initiation and the final number of panicles/m2 colleced at harvest. Nitrogen requirement,under no other limiting conditions, appeared to be of 1 kg nitrogen/ha for a gain of 6 panicles/m2 or 300 spikelets/m2 grain yield claboration precess in diverse farmmer's plots conditions could then be analysed in a comprehensive way by taking into account the varicial potentiality on one hand,andthe environment and the farmers' practices on the other. Cases of error were found in the dates of spling the fertilizer dressigs. Limiting factors other than nitrogen cound be assumed in some famers' plots.