HYPERSPECTRAL SPECTROSCOPY TO DETECT DIFFERENT RESPONSES OF TWO SOYBEAN (GLYCINE MAX) CULTIVARS TO CHARCOAL ROT (MACROPHOMINA PHASEOLINA) TOXIN

ABSTRACT Previous studies have confirmed the potential of hyperspectral spectroscopy (HS) to detect charcoal rot toxin effect on soybean (Glycine max). However, there is no evidence that it can differentiate among difference responses to that effect. This research tested the potential of HS (900–2400 nm) to differentiate different responses to charcoal rot effect caused by the fungal pathogen Macrophomina phaseolina. Known susceptible ‘Pharaoh’ and resistant ‘Spencer’ cultivars of soybean seedlings at the V1 stage were tested, and HS reflectance was measured in each treatment at 0 h (just before toxin treatment), 24 h, and 36 h after toxin treatment. For both cultivars, reflectance generally decreased up to 10% over time for controls and increased for treated seedlings up to 22%. Pharaoh had significant increases in reflectance 24 and 36 h after treatment, while Spencer did not exhibit significant changes in reflectance over the 24 and 36-h periods. The ratio of Al-Ahmadi et al. (2018) was also evaluated. Spencer showed a higher ratio than Pharaoh. Based on our results, HS can be used to compare the relative resistance of soybean cultivars to charcoal rot and is a potential screening technique to classify soybean cultivars based on their resistance to charcoal rot toxin.

摘要：先前研究已证实高光谱光谱学（hyperspectral spectroscopy, HS）可用于检测炭腐病毒素对大豆（Glycine max）的影响，但尚无证据表明其能够区分不同的响应类型。本研究探究了高光谱（900~2400 nm）区分由病原菌菜豆壳球孢（Macrophomina phaseolina）引发的炭腐病不同响应的潜力。试验采用V1期的大豆幼苗，分别为已知感病品种‘Pharaoh’与抗病品种‘Spencer’，并在毒素处理前0 h（毒素处理即刻）、处理后24 h及36 h对各处理组的高光谱反射率进行测定。结果显示，对于两个供试品种，对照组的反射率随时间普遍下降最高达10%，而处理组幼苗的反射率则最高上升22%。感病品种‘Pharaoh’在处理后24 h和36 h的反射率出现显著升高，而抗病品种‘Spencer’在24~36 h时段内反射率未出现显著变化。本研究同时评估了Al-Ahmadi等（2018）提出的反射率比值，结果表明‘Spencer’的该比值高于‘Pharaoh’。基于本研究结果，高光谱技术可用于比较不同大豆品种对炭腐病的相对抗性，是一种可基于大豆品种对炭腐病毒素的抗性进行分类的潜在筛选技术。