华南地区龙眼的温度适宜性及其变化趋势

运用温度适宜度模型对华南地区龙眼生产和生育期的适宜性及其时空差异进行了计算、评价和预测。首先分析龙眼各生育期适宜度,结果表明,休眠期、花芽生理分化期、花芽形态分化期适宜性较低,具有较高的变率,开花期、果实发育成熟期、抽梢期表现出较高的温度适宜性,变率也较小,并且通过进一步研究发现影响华南地区龙眼生产的关键问题不是冷害,而是冬春季节的热害;其次分析华南地区各县区的平均温度适宜度,结果表明,华南地区龙眼温度适宜性的地域分异呈纬度地带性规律,并根据龙眼减产率将华南地区划分为最适宜型、适宜型、次适宜型、低适宜型和不适宜型五大适宜度类型;最后分析龙眼各生育期温度适宜度的年际变化,发现未来各生育期中除果实发育成熟期和抽梢期无明显变动外,其他生育期的温度适宜度都有下降趋势,同时对华南地区各站点龙眼温度适宜度的变化趋势作分析,结果表明,除福建省部分地区有弱上升外,总体上华南地区温度适宜度有下降趋势,且存在着地区差异,并且未来龙眼的适宜种植区将有可能北移,根据各站点未来适宜度变化的方向和强度进行分类,将华南地区划分为强下降型、次强下降型、弱下降型和上升型四大变动类型。

Temperature suitability of longan and its changes in South China area

Being an important subtropical fruit tree, longan is sensitive to temperature change. Selecting 60 counties in South China area and using the temperature suitability model, the article calculates the temperature suitability of longan, evaluates the temporal and spatial differences and also predicts the temperature suitability of longan. Firstly, the article analyzes the temperature suitability of longan at different growth stages. The result shows that temperature change has a great impact on the temperature suitability of dormancy stage, physiologic differentiation of flower bud stage and morphologic differentiation of flower bud stage, all of which have low suitability and high variability. On the contrary, the other three stages have high suitability and low variability. This is caused by the temperature differences between the different growth stages. It is hot damage in winter and spring rather than cold damage that plays an important role in longan production in South China area by further study. Secondly, the article analyzes the suitability in terms of average temperature of the 60 counties, the result shows that the temperature suitability increases with increasing latitude in South China area, based on the relationship between yield reduction rate and the temperature suitability degree, the article divides South China area into five types: the high suitability type, whose value is higher than 0.80; the suitability type, whose value ranges from 0.75 to 0.80; the medium suitability type, whose value ranges from 0.65 to 0.75; the low suitability type, whose value ranges from 0.55 to 0.65; the no suitability type, whose value is lower than 0.55. Finally, the article analyzes the inter-annual change of temperature suitability at different growth stages, and the result shows all the growth stages except for fruit growth and maturity stage and treetop growth stage have a decreasing trend in the future. At the same time it analyzes the temperature suitability change trend of the 60 counties, and finds that these places also have a decreasing trend except for the part area of Fujian Province and there exists difference among them, also the suitability region will be possibility extending to the north zone in the future. Similarly based on the temperature suitability over 10 years change trend of the 60 counties, the article divides South China area into four suitability change trend types: the high-decrease type, whose value is lower than -0.01; the medium-decrease type, whose value ranges from -0.005 to -0.01; the low-decrease type, whose value ranges from -0.005 to 0; the increase type, whose value ranges from 0 to 0.01.