Canopy hyperspectral characteristics and its predication model for the amount of grain aphid Sitobion avenae under different wheat cultivars.

[Objectives]It is becoming more and more important to use mixed wheat cultivars to control wheat pests.The paper studied the key spectral parameters and models of different wheat cultivars under being damaged by different amount of grain aphid Sitobion avenae.These results contribute to estimating the amount of aphids per one hundred plants under mixed wheat cultivars.[Methods]Three cultivars wheat(‘1376'‘Amigo'and‘Xiaoyan-22') and four damage levels of slight(20-30 aphids per hundred plant),moderate(450-550 aphids per hundred plant),moderate and serious side(1200-1300 aphids per hundred plant),and serious(2200-2300 aphids per hundred plant) were used in this study.Hyperspectral reflectance within 400-900nm of these cultivars wheat canopies were measured by the ASD portable spectrometer under different damage levels.The correlations and regressions were analyzed between single wavebands,vegetation indices of Ratio Vegetation Index(RVI) and Normalized Difference Vegetation Index(NDVI) and the amount of aphids per one hundred plants.[Results]The percent reflectance on three cultivars wheat canopy decreased with the increase of infestation by wheat aphid at visible light wave bands(400-700nm) and near-infrared wave bands(701-900nm).Furthermore,the percent reflectance significant difference occurred in some wave bands(P0.01).The sensitive wave bands included visible wave band of 405nm and near-infrared band of 835nm on all three cultivars wheat.These sensitive bands were selected out to calculate the vegetation indices of RVI and NDVI.Unvaried linear function models for determining the amount of aphids per one hundred plants were established based on above sensitive wave bands,RVI,and NDVI.Meanwhile,the model equation based on the two sensitive wave bands had very significant correlation with the amount of aphids per one hundred plants for all three cultivars wheat,and the model according to the spectral reflectivity at 405 nm were optimum for all cultivars wheat,i.e.for ‘1376',y =-100 327.99 x + 2 189.09(P =0.002),for‘Amigo',y =-18 185.44 x + 2 196.83(P = 0.004),and for‘Xiaoyan-22',y =-46 758.63 x + 3 047.74(P =0.008).However,the model equation based on the RVI and NDVI had non-significant correlation for all cultivars wheat except RVI for ‘1376'(P =0.005).[Conclusion]The amount of grain aphid S.avenae per one hundred plants for wheat of different cultivars couldbe predicted simultaneously using sensitive wave bands of hyperspectral remote sensing technique.