Abstract:The feasibility of using SPAD value as a measure for chlorophyll content of poplar by potted poplar was tested, and methods of the poplar leaf chlorophyll content estimation by hyperspectral analysis technology were explored. Through analyzing the characteristics of poplar leaves’ hyperspectral curve, the characteristic bands combination of 350 nm, 715 nm and 1 150 nm were extracted by optimum index factor. The normalized difference vegetation index (NDVI) calculated by the maximum correlation bands (705 nm, 953 nm) between NDVI and the poplar chlorophyll content, the maximum correlation bands (647 nm， 691 nm， 721 nm) between the first derivative of hyperspectral data and the poplar chlorophyll content and leaf chlorophyll index (LCI) were made by regression analysis to establish the estimation models. In order to select the best model, these models were analyzed and compared. The results showed that exponential relationship between SPAD values and chlorophyll content measured by chemical method and its corresponding value was significant, determination coefficient R2 was up to 0.902 3. The fitting accuracy of the estimation model with the characteristic bands combination of 350 nm, 715 nm and 1 150 nm was extracted by optimum index factor and correlation coefficient was the highest. The determination coefficient R2 was 0.944 5, root mean square error was 2.553 8 mg/cm2. Therefore, the characteristic bands combination of 350 nm, 715 nm and 1 150 nm extracted by optimum index factor and correlation coefficient is able to build a more accurate model for estimation of poplar chlorophyll content.
