The impact of climate changes on yield of longan production in Northern Thailand

Abstract

Secondary information on environmental factors of 26 years (1983-2009) was analyzed for effects on longan production in Chiang Mai and Lampang Provinces. Climatic data were selected and focused on flower induction period of longan (November-December). The results showed that there were no correlations between yield and weather changes. However, the air temperature in Chiang Mai Province had an effect on longan yield with decreasing temperatures during flower induction period causing increased longan productivity. Furthermore, the minimum temperature in the range of 16.00 to 17.04°C correlated well with higher yield. In Lampang Province, the minimum, mean and maximum temperature correlated well with high productivity. Minimum temperatures in the range of 16.27 to 17.47°C correlated well with higher yield. High rainfall and low relative humidity in Chiang Mai Province resulted in increased productivity, whereas in Lampang Province, rainfall and relative humidity had the opposite effect. The amount of rainfall between 32 and 63 mm (for 2 months) increased productivity, whereas higher rainfall did reduce yields. Light duration (sunshine hours) of about 5.83 to 6.88 h per day during flower induction period, increased longan yield in Chiang Mai Province and 6.11 to 6.93 h per day caused the same effect in Lampang Province.