柑橘全爪螨虫害快速检测仪的研制与试验

Development and experiment of Panonychus citri infestation fast detector

为实现在果园现场快速、准确和无损地检测果树受柑橘全爪螨为害程度,该文研制了基于光学测量技术的柑橘全爪螨虫害快速检测仪,并通过试验检验了仪器的使用效果。检测仪采用光反射法,测量果树冠层叶片对红光和近红外光的反射率,根据反射率计算全爪螨为害程度指数作为仪器的输出结果,进而按照无、轻度和重度3个级别判定柑橘全爪螨虫害程度。硬件设计中选取中心波长为665和815 nm的发光二极管阵列作为红光和近红外光源,通过光调制/解调技术、专门设计的光路和光电探测适配电路,克服了自然光线对检测结果的影响。仪器使用效果为:通过标准白板试验确定检测系数k等于2.622;检测结果受树叶密度影响较小;检测结果受自然环境光线影响较小,但气温对检测结果有一定影响;检测仪可区分无、轻度和重度3个级别的全爪螨虫害程度,当虫害程度较低时,检测结果稳定;检测仪输出结果与叶片表面柑橘全爪螨卵数间具有较高的相关性。进一步研究的方向为引入温度补偿的方法以减小温度对检测结果的影响,同时分析当为害程度较严重时结果稳定性较低的原因。

In order to achieve a rapid, accurate, non-destructive, in-situ detection of Panonychus citri （McGregor） infestation levels to the fruit trees, a Panonychus citri （McGregor） fast detector based on optical measurement techniques was designed and developed in this study. The instrument’s working effect was tested through experiments. The optical reflection method was adopted by the detector as the detection principle, and the tree canopy’s light reflectance in the red and near-infrared light zone was measured. The Panonychus citri （McGregor） index （PCI） was introduced in this study as the equipment output and was calculated in accordance with the measured reflectance. Furthermore, the Panonychus citri （McGregor） infestation status at a tree’s selected canopy outer area was divided into three levels as None, Light, and Heavy based on the number of eggs on top of the leaves within a specific region at the tree canopy’s outer area. The relationship between the infestation levels of the regions and their corresponding PCI readings was analyzed. In the hardware design, light emitting diode （LED） arrays having center wavelengths of 665nm and 815nm were selected as the red and near-infrared light sources. Natural light interference at the detector was mostly reduced by using a 40 kHz light modulation/demodulation technology, a specially designed optical path, and a photoelectric detection adapting circuit. Results from the instrument’s working effect test indicated that： the detection coefficient k equals to 2.622;the detection was less slightly affected by the foliage density;the detection was less affected by the natural environmental light, but was affected by the temperature to some extent; the three Panonychus citri （McGregor） infestation levels as None, Light and Heavy could be distinguished by the detector, and when the infestation level was low, the result was stable. High correlation was achieved between the detector’s PCI reading and the number of eggs on top of a piece of leaf, which indicated that the relationship between Panonychus citri （McGregor） infestation level and the egg number achieved in this study was consistent with previous experiments. Further research will test a temperature-compensation method to reduce the influence of temperature on the detection results. Reasons for lower-stability detection in the Heavy level of infestation will also be analyzed.