华南地区气候温暖,雨水充沛,植物茂盛,农作物四季生长不绝,农业复种指数及单位面积产量均很高,但美中不足的是每年冬季常出现短期(数日至十数日)的急骤降温,以致各种农作物,尤其是热带性作物遭受不同程度的寒害。例如1955年1月出现40年来未有的低温(大部分地点气温在0℃以下,个别地点在3℃以下),橡胶等热带作物以及甘薯等作物均遭受到严重伤害,造成巨大损失。

The winter climate of South China is usually mild, but occasionally when the cold waves break out from Siberia or elsewhere and push southward, the temperature may drop 10, 15, or even 20℃ within a few days, therefore damages caused by the sudden drop ef tempe-rature on tropical plants were incurred frequently. Comparisons of changes of temperature of Northwest, North and Central China, indicate that the drop of temperature in South China is the most striking one during the invasion of cold waves. Here the author proposes the use of complex index number for the temperature variations, so the special characteristics of the temperature range and the interdiurnal tempera-ture variation may be revealed. A discussion is also given for the low temperature damages to agricultural plants. In this paper much attention was placed on the distribution of such to:v temperatures as influeaced by different topographical features during the cold spells, and suggestion was made as to how to select shelters for tropfeal agricultural plants. Four kinds of temperature dropping types effecting agricultural plants were mentioned. And measures to be taken for protection of pleats against low temperature damages were suggested.