Abstract:

Objective: This paper aims to determine the high temperature and drought index and its influence relationship in the key growth period of Camellia oleifera by investigating the influence of meteorological factors on the yield of C. oleifera, so as to early warn the high temperature and drought disaster of C. oleifera. Method: In this study, the standardized yield data of C. oleifera in different regions of Hunan Province and the meteorological data from 2007 to 2015 were collected. The data included the average temperature, precipitation, sunshine hours, days of precipitation and days of heat accumulation temperature ≥ 30℃ and high temperature ≥ 30℃ in the fruit expansion period and oil conversion period of C.oleifera. A regression analysis was carried out with the standardized yield of C. oleifera and the meteorological data to determine the factors and thresholds that could indicate the occurrence of drought, and to establish a yield prediction model. Result: At the fruit expansion stage, there was a significantly negative correlation in between the precipitation days and the standardized yield of C. oleifera. In the fruit expansion stage and the oil conversion stage, the heat accumulation temperature ≥ 30℃ and the days of high temperature ≥ 30℃ were significantly negatively correlated with the standardized yield of C. oleifera. The threshold values of high temperature and drought were when the accumulated temperature of ≥ 30℃ reached 36.7℃ or the high temperature ≥ 30℃ lasted for 26 days in the fruit expansion stage, and the accumulated temperature of ≥ 30℃ reached 13.6℃ or the high temperature ≥ 30℃lasted for 10 days in the oil conversion stage. The results showed that the model with daily accumulated temperature ≥ 30℃ in fruit expansion stage was the best for predicting standardized yield of C. oleifera. Conclusion: The threshold values of accumulated temperature or high temperature days in fruit expansion period and oil conversion period, which would lead to high temperature and drought disaster, can be used as early warning signal for yield reduction of C. oleifera. In this study we also put forward the measures for disaster prevention and mitigation. The heat accumulation temperature ≥ 30℃ and the days of high temperature ≥ 30℃ are the key factors from fruit expansion stage to oil conversion stage of C. oleifera, based on which a model for predicting the yield of C. oleifera is established, and it can better predict the yield of C. oleifera in medium and short term. This study provides reference for management decision-making of C. oleifera.

Key words: Camellia oleifera, heat accumulation temperature, high temperature hours, high temperature days, drought monitoring, production forecast