为了探究干旱胁迫对茶树幼苗叶绿素荧光参数的影响, 选取龙井茶树幼苗进行干旱胁迫实验。利用叶绿素荧光成像技术提出斜率荧光指数SFI评估茶树幼苗干旱胁迫状况, 计算1~8天内同一时刻灰度均值的极差R, 以R的相对误差δ＜5%确定极差稳定的时间范围, 建立该区间内曲线上各点斜率变化与胁迫天数的相关模型。分析比较了斜率荧光指数SFI、动态荧光指数DFI、光合功能指数PFI、荧光衰减比率Rfd与胁迫天数之间的相关性。结果表明: Rfd和PFI与胁迫天数之间没有明显的相关性, SFI和DFI与胁迫天数之间有相关性。感兴趣区域ROI为50×50pixel时, SFI与干旱胁迫的天数之间的相关性(决定系数R2=0.94)明显高于DFI与胁迫天数之间的相关性(R2=0.60)。利用SFI评估茶树幼苗受干旱胁迫状况具有更高的准确率, 为现代农业中监测植物生长状况提供了参考。

To investigate the effect of water stress on chlorophyll fluorescence parameters of tea seedlings, Longjing tea seedlings were selected for water stress experiments. The slope fluorescence index SFI was proposed to assess the drought stress condition of tea seedlings by using chlorophyll fluorescence imaging technique, and the polar difference R of the mean gray value at the same time within 1~8 days was calculated, and the relative error of R was used to determine the stable time range of the polar difference, and the correlation model between the change of slope of each point on the curve and the number of days of stress was established in this interval. The correlations between the slope fluorescence index SFI, dynamic fluorescence index DFI, photosynthetic function index PFI, and fluorescence decay ratio Rfd and the number of days of stress were analyzed and compared. The results showed that there were no significant correlation between Rfd, PFI and days of stress; and there were correlation between SFI, DFI and days of stress. The correlation between SFI and days of drought stress (coefficient of determination R2=0.94) was significantly higher than that between DFI and days of stress(R2=0.60) when the ROI of the region of interest was 50×50pixel. The use of SFI to assess the drought stress status of tea tree seedlings has higher accuracy and provides a reference for monitoring plant growth in modern agriculture.