How to use Field spectrometer to detect rice reflectance performance under drought stress?

Posted By : JOJO

Nov 19, 2020

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Water shortage is a global problem restricting agricultural production. In recent years, the contradiction between global water supply and demand has become more prominent. For China, 43% of the area is arid or semi-arid, and the water distribution in China is also very large imbalance in time and space, which makes the contradiction between water supply and demand in China more acute, which is one of the biggest crises facing China's agricultural production.

Since the 21st century, China has experienced severe drought every year, which often affects several provinces. For example, the great drought in the southwest of China in 2010 affected nearly 5000000hm2 of crops and caused over 19 billion yuan of economic losses. As the largest grain crop in China, it is particularly important to study the effects of different drought stress on rice and develop drought-resistant varieties for agricultural development.

This experiment aims to understand the performance of rice basic types under different drought stresses, and measured the spectral data of 10 rice varieties with different relative water content (RWC) under different drought threat levels.

The experiment showed the reflectivity patterns of rice under different drought stress.

1) when rice water content (RWC) decreases, the reflectance in the near-infrared region increases due to the weakening of water absorption characteristic peaks at 1400nm and 1900nm.

2) There is a similar change in the wavelength region of 350-700nm. In the absorption range of chlorophyll a and chlorophyll B, the reflectivity increases with the decrease of RWC.

3) Secondly, with the decrease of RWC, the wavelength of 1400-1925nm moves to the shorter wavelength, and the reflectivity increases.

4) The scattering of spongy mesophyll at 810-1350nm also reflects the same trend of increased reflectivity with decreased RWC.

5) Finally, the absorption at the 1100-2500nm band is also a strong absorption area. With the decrease of RWC, the leaf wilt is mainly through the water in the fresh leaves, and then becomes more obvious through the dry matter such as protein, lignin and cellulose.

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