Using Hyperspectral Data for Detecting Late Frost Injury to Winter Wheat under Different Topsoil Moistures
MENG Lei1, WU Yong-feng1*, HU Xin2, LÜ Guo-hua1, REN De-chao2, SONG Ji-qing1*
1. Key Laboratory of Agricultural Environment, Ministry of Agriculture, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China
2. Wheat Research Laboratory, Shangqiu Academy of Agriculture and Forestry Sciences, Shangqiu 476000, China
Abstract：To explore the characteristics of hyperspectral reflectance responding to late frost damage in winter wheat canopy under different topsoil moisture levels and test abilities of sensitive wavelengths to predict extents of yield change, respectively, pot experiments with three levels of topsoil moisture of Dry (<10%), Moderate (10%～20%) and Wet (>20%) were conducted at the jointing stage of winter wheat in the year of 2013 and 2014. After topsoil moisture treatments, frosting experiments were carried out in a specified cold climate chamber. This study analyzed differences of the ear number per plant, kernel number per ear, 1000-kernel weight, yield per plant and canopy spectral reflectance and corresponding first derivative reflectance of the frosted winter wheat canopy under different topsoil moisture levels. Correlativity and linear fitting were made for hyperspectral parameters and yield change rate of the frosted winter wheat. The results indicate that (1) kernel number per ear and yield per plant generally have a reducing trend with the decrease of topsoil moistures. Late frost injuries showed the most significant (p<0.05) influences on winter wheat yield under conditions of the treatment Dry. (2) In green peak region (near 523 nm), yellow edge region (near 571 nm), red edge region (near 732 nm) and two water absorption bands (around 952 nm and 1 145 nm) of the near-infrared region, the first derivative reflectance of winter wheat canopy was more different under conditions of the treatment Dry + Frost than the treatment Moderate + Frost and Wet + Frost. (3) After removing the influences of different topsoil moistures on spectrum reflectance, difference curves of the first derivative reflectance responding to late frost damages under the treatments Dry, Moderate and Wet were quite different mainly in the yellow edge region (centered at 570 nm) and the red edge region (centered at 710 nm). (4) In the two years experiments, yellow edge area (SDy) and first derivative value at 570 nm (d570) were significantly (p<0.05) and positively correlated with yield change rate (YCR) of the frosted winter wheat, respectively, which shows that hyperspectral parameters in the yellow edge region can be used to detect the differences of late frost damage due to the different topsoil moistures impacts. This study will provide a basis for prediction of the variations in winter wheat yield under the stacking effects of different topsoil moistures and late frost damages using hyperspectral reflectance parameters .
孟 雷，武永峰，胡 新，吕国华，任德超，宋吉青. 土壤表层湿度影响下冬小麦晚霜冻害及冠层光谱检测[J]. 光谱学与光谱分析, 2017, 37(05): 1482-1488.
MENG Lei, WU Yong-feng, HU Xin, LÜ Guo-hua, REN De-chao, SONG Ji-qing. Using Hyperspectral Data for Detecting Late Frost Injury to Winter Wheat under Different Topsoil Moistures. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2017, 37(05): 1482-1488.
