水稻冠层反射光谱监测褐飞虱种群密度及水稻穗粒质量的可能性

[目的]本文旨在阐明褐飞虱迁入后不同时期种群的密度、水稻冠层光谱反射率和穗粒质量三者间的相互关系，以期为建立监测褐飞虱发展动态及危害损失的高光谱遥感方法提供指导。[方法]对笼罩内处于孕穗期的水稻，每桶水稻接入0、2、4、6、8、10和12对的褐飞虱雌、雄成虫，形成不同的危害程度。在接虫后5、11、20、26、36、41和48 d测定水稻冠层光谱反射率和调查褐飞虱种群密度。水稻黄熟后，测定水稻的穗数、穗质量和千粒质量。采用Pearson相关分析方法获得不同时期褐飞虱虫量、水稻光谱反射率和水稻穗质量、千粒质量间的关系。[结果]接虫后26 d，笼罩内褐飞虱种群数量达到高峰；接虫后36 d内的种群数量均与起始接虫量显著相关，但41 d后的虫量与起始接虫量相关不显著。接虫后5~20 d的水稻冠层光谱反射率与褐飞虱种群数量均无显著的相关性，但26 d及以后的反射率在近红外光（700~925 nm）和绿光（550 nm左右）处与虫量呈显著的负相关。接虫后41 d内的褐飞虱种群数量与穗质量、千粒质量呈显著的负相关，且相关系数在接虫后26 d时最大。接虫后20~48 d内的水稻反射率在近红外波段均与水稻穗质量和千粒质量显著正相关。[结论]连续测定水稻冠层反射光谱不仅可表征褐飞虱种群的密度大小，而且具有提前预测水稻产量的能力。水稻在绿光区和近红外光区的光谱反射率有望用于反演褐飞虱种群的密度和受害后水稻的穗粒质量。
[Objectives] In order to set up a new method to monitor brown planthopper(BPH) population dynamics and rice yield loss based on spectral reflectance from rice canopy,relationships between population densities at different days after immigration,reflectance from rice canopy,and grain weight of rice were studied. [Methods] Different numbers of 2-day-old adult BPH(0,2,4,6,8,10 and 12 pairs of female and male per pot rice) were released into potted rice at booting stage,and then the rice was covered with net cages. Reflectance from rice canopy and population densities of BPH were measured at 5,11,20,26,36,41 and 48 d after BPH release. When rice matured,the panicle and 1 000-grain weights were examined,and the Pearson correlation analysis was used for these data. [Results] A peak of population density occurred at the 26th day after adult BPH release. The relationship between population density and the number of adult BPH released was significant from 5 to 36 days after BPH release,but it did not become significant after 41 days. Reflectance from rice canopy at the 5-20 d after BPH release was not related to population density of BPH,but after 26 days,the correlation of reflectance at the green(550 nm) and near-infrared(700-925 nm) wavelengths with BPH density was significant. The population densities of BPH at the 5-41 d after adult release were significantly correlated with the panicle and 1 000-grain weights,and the maximum correlation coefficient occurred at the 26th day. The reflectance at the near-infrared wavelengths from rice damaged for 20-48 d by BPH was significantly related to panicle and 1 000-grain weights. [Conclusions] Reflectance continuously measured from rice canopy has the potential not only to monitor the population density of BPH,but also to predict the rice yield. Reflectance at green and near-infrared wavelengths from rice canopy can be used to set up models to predicate the population density of BPH and grain weight of rice