Influence of warming climate and the green revolution on the optimum range of weather parameters of longan yield in Taiwan since 1909

Abstract

Abstract Longans are the fruits of a subtropical evergreen tree (Dimocarpus longan Lour.) and are widely distributed in Southern China and Southeast Asia. However, there is a lack of historical records of these fruits. In addition to air temperature, other factors, such as the green revolution effect (GRE), sunshine duration, flower bud differentiation, flowering, and production period, may also be important for longan yield. This study incorporated Duncan’s multiple range tests, linear regression models, and multi-regression models, using the forward stepwise method. The results showed that a warming climate was unfavourable to the longan fruits yield (LFY), as the mean negative impact of climate change on LFY was 2489.6 ± 1072.2 kg/ha (mean difference ± 95% CI) under GRE. When considering warming climate and GRE, the results showed that, at the time of flower bud differentiation, the optimum ranges of mean air temperature and relative humidity (RH) were 18.0–19.4 °C and 73.9–75.7%, respectively; during flowering, the optimum ranges of cloud cover, sunshine-hour, and rainy days were 6.8–7.3 oktas, 381.3–476.6 h, and 28.9–41.9 days, respectively; during the production period, the optimum ranges of mean diurnal temperature and RH were 6.8–7.4 °C and 75.1–79.4% respectively. A smaller optimum range of weather parameters aids in a greater slope of the accumulated frequency of the LFY. The GRE and small optimum ranges of weather (stable weather conditions) were found to assist in ensuring stable LFY.