Preliminary Study of the Influence of Temperature, Relative Humidity and Amount of Rainfall on Longan Yield in Chiang Mai Province

Abstract

The influence of the meteorological factors temperature, relative humidity and amount of rainfall, on longan yield in Chiang Mai province, during 1958 - 1981 , was studied. the previous 24-year yield record was divided into 2 groups, the high yield producing year (>10 milkion kilograms) and the low yield producing year (< 5 million kilograms.) The monthly averages of daily maximum or minimum temperature, relative humidity , as well as the amount of rainfall between the two producing year groups were comparatively considered. The results of the study indicated that the monthly averages of daily minimum temperature between the two producing year groups, were not distinctly differetn. The amount of rainfall in March and also the monthly averages of daily maximum relative humnidity, during March and April, of the high yield producing years, are remarkably higher than those of the low yield producing years.