| Summary: | 碩士 === 國立臺灣大學 === 農藝學研究所 === 106 === Consider that heavy metals can accumulate in plants and soil, and can be intake by people through feeding. To establish a proper monitoring system is necessary. Therefore, we would like to create indices using reflectance spectra to perform nod-destructive estimation the concentration of bioavailable heavy metal in soil and accumulation amount in shoot. In this research, hydroponic rice (Oryza sativa L. cv. Taichung Sen 10 and Taiken 9, TCS10 and TK9) seedlings were treated with treatment combinations of three nitrogen concentrations (50, 100, and 200 ppm) and three heavy metal concentrations (Cd: 0, 50, 100, and 200 µM; Cr: 0, 100, 200 and 500 µM; Pb: 0, 100, 200 and 500 µM) to simulate the effects of heavy metals in soil solution on rice seedlings under different nitrogen management in the field. The reflectance spectra of leaves were recorded and used to calculate vegetation indices to observe the relation between vegataiton indices and the heavy metal concentration in shoots. The result indicated that heavy metals stress inhibited shoot length of rice seedlings. At high metal concentration, the reflectivity in 500-675 nm of yellow and green light would increase and blue shift of red edge would happen at the same time. Additionally, for the treatment effect of high nitrogen concentration, the reflectivity in green light and red light would decreas, and red shift of red edge would happen at the same time. The linear and quadratic models were constructed from the relation between heavy metal concentration of shoot and vegetation indices. The results showed that quadratic models had better correlation. And the quadratic models are more suitable for TK9 than TCS10. Therefore, it appears to be possible to calculate indices using reflectance spectra for non-destructive estimation the concentration of bioavailable heavy metal in soil and accumulation amount in shoot.
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