中文摘要：

在发生晚霜的茶园中，试验研究了防霜机不同时间尺度启闭的防霜效果。在茶树萌芽前不同天数、降霜前和日出后不同时间，分别设定开始启用和启闭防霜机的处理，测定其对茶树生长、冠层温度和防霜范围的影响。结果表明：在茶树萌芽前20、15、7d开始启用防霜机，使新梢长度、芽密度和百芽质量均比对照增加20％以上；防霜机在降霜前2．0、1．5、1．0h启动，对茶树防霜效果更显著，作用半径比对照增大60％以上；防霜机在日出后2．0、1．5、1．0h延停，在开始的1h内可平均减缓冠层温升45．76％，并减小茶树叶片光合强度的降幅。所以，晚霜时为保持茶树较好的长势和产量，应在茶树萌芽前不少于7d开始启用防霜机，且合适的启动和延停时机分别为降霜前1．0h和日出后1．0h。

英文摘要：

Frost protection effect experiments in tea fields were conducted according to wind machine operation timing on different time scales. The treatments of starting to use wind machines before tea sprouting, starting before frost occurrence and stopping after sunrise were set up respectively. And the impact of wind machine operation on the growth of tea trees, temperature rise in the canopy and protection coverage was measured. The results indicated that starting to use wind machines 20 d, 15 d and 7 d before tea sprouting increased the length of young shoot, bud density and 100-bud weight by over 20% compared with the control test; Starting wind machines 2.0 h, 1.5 h and 1.0 h before frost occurrenceled to better protection and enlarged the coverage radius by,more than 60% compared with the control test. Delayed stopping of wind machines by 2.0 h, 1.5 h and 1.0 h after sunrise reduced the temperature rise of the canopy by 45.76% in the first hour, and narrowed the reduction of the photosynthetic intensity of tea leaves. Therefore, to protect tea trees from late frost cold for better growth and yield, the appropriate application of wind machines should be more than 7 d prior to the tea budding, and the operation timing of starting and stopping for a certain frost event should be 1.0 h before frost occurrence and 1.0 h after sunrise, respectively.