| Research was conducted in order to study the environmental effects on characteristic variation in the photoperiod sensitive rice varieties at Nakhon Si Thammarat Rice Research Center during 2011-2013. Rice varieties in the study were included Pathum Thani 1, Phitsanulok 2, RD31 and RD41. Results showed that rice grown in April having plant height, number of tillers per hill, number of panicles per hill and panicle length more than rice grown in January and July. The number of filled grains and yields were highest when grew in January. Rice grown in April had high percentage of unfilled grains. The influence of other climatic conditions did not show obviously effect on the growth of rice varieties in the study. |
