玉米苗期干旱胁迫对关键生育期的光谱特征影响分析

doi:10.3964/j.issn.1000-0593(2020)07-2222-07

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Abstract The spectral characteristics of vegetation can be used to monitor their growth and development. Additionally, exploring the changes in spectral characteristics of maize throughout its developmental period following water stress during the seedling stage provides theoretical data for building vegetation spectral databases, as well as a basis for the hyperspectral identification of vegetation water stress. Using the large-scale farmland soil moisture control field of Jinzhou Ecological and Agricultural Meteorological Station in western Liaoning as the research area, an ASD FieldSpec Pro spectrometer was used to spectrally observe maize at the seedling, jointing, tasseling and milk stages in the seedling water stress and water-suitability control areas. The differences in the spectral characteristics of the water stressed seedlings and those of the controls were identified based on the original spectrum, the first derivative spectrum and multiple spectral parameters. The results were as follows: (1) The characteristics of the original spectrum of maize subjected to drought stress in the seedling stage are significantly different from those of maize that receives suitable water in the same stage. Specifically, the reflectance in the visible or short-wave infrared band was higher than that of control maize at the same stage, while that of the near-infrared band was significantly lower than that of control maize, especially at the jointing stage, the difference was about 5%; however, these differences gradually decreased with crop growth. (2) The first derivative spectra of maize at the seedling, jointing, tasseling and milk stages revealed double peaks in the visible bands, and the peak of the red light position reached the highest level at the tasseling stage. The peaks of the red light position for the first derivative spectrum of maize from seedlings subjected to water stress were lower than those of control maize, and the differences were significant, especially in the jointing stage, when the difference was about 0.003. In the milk stage, the peaks of red were significantly reduced relative to the concurrent control maize and the distinguishability was weakened. (3) Comparison of the spectral parameters of maize under seedling water stress with those of control maize revealed that the red edge position undergoes a blue shift-red shift-blue shift from the seedling stage to the milk stage, while the green peak position undergoes a shift in the long-wave direction. However, the difference between the blue edge position and blue edge amplitude and the yellow edge position and yellow edge amplitude was not significant at the tasseling and milk stages, the red edge area is lower than that of the control, and the yellow edge area is higher than that of the control. (4) Among the eight water-sensitive vegetation indices, the difference index of NDWI and NDW-2 reached more than 50% in the four Critical developmental stages of maize, and the distinguishability was enhanced. Overall, this study provides basic data that can be useful for plant water stress spectral libraries and a basis for selecting spectral bands and setting hyperspectral bands for identification of crop drought.

Key words：The seedling stage of maize; Drought; Spectral difference

Received: 2019-03-18 Accepted: 2019-07-24

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S513

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)07-2222-07 OR https://www.gpxygpfx.com/EN/Y2020/V40/I07/2222