Development of Yield and Quality Estimation Methods for Tea-plant by Image Processing.
ASA-CSSA-SSSA International Annual Meetings (November 12-16, 2006)
This study was conducted to evaluate growth condition of tea plants and to estimate quality of tea leaves at each growing stage by spectral image analysis. The experimental plots were designed for five levels of nitrogen application levels. The spectral characteristics of their canopies were measured by a handheld spectroradiometer from 400 nm to 1,000 nm ...
This study was conducted to evaluate growth condition of tea plants and to estimate quality of tea leaves at each growing stage by spectral image analysis. The experimental plots were designed for five levels of nitrogen application levels. The spectral characteristics of their canopies were measured by a handheld spectroradiometer from 400 nm to 1,000 nm with 3 nm intervals, in the growth season of new leaves. Those canopies were recorded by a video camera with several band pass filters. Surface temperature of tea leaves were measured with thermo-radiometer and thermo-couples. At the same time, chlorophyll contents in the leaves were measured with a chlorophyll meter. And the picked new leaves were analyzed with NIR analyzer for several chemical contents in the leaves. The spectral reflectance curves were differentiated with respect to wavelength on the first and second orders. As a result, several characteristic peaks were identified. These peaks ranges with +/-10 nm were named characterized waveband, CW. Several indices consisted of these CW’s were proposed and compared with ground truth data. It was demonstrated that the index, ND77,66 =(R770–R660)/(R770+R660), strongly coincided with the results of chlorophyll meter and nitrogen content of NIR analysis. It was shown that the ND77,66, ND77,52, and ND54,52 were in concord with the quality components of live new tea leaves observed by NIR products analyzer. These results suggest that the spectral reflectance measured out of contact with a plant non-destructively is effective in evaluating the leaf growing condition, estimating the leaf quality and determining the most suitable leaf picking day in terms of leaf quality. It can be an alternative to conventional methods using a chlorophyll meter. Moreover, the spectral images taken by a video camera with band pass filters will make it possible to analyze differences of growth stages of plants.
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Yield Estimation and Quality Evaluation of Sweet Potato Using Spectral Reflectance.
ASA-CSSA-SSSA International Annual Meetings (November 12-16, 2006)
Many studies suggest that measuring spectral reflectance is useful to evaluate above-ground biomasses and qualities of standing plants. Few, if any, attempts to use spectral reflectance to estimate the growth conditions of creeping plants, however, have been done. In this study, therefore, the practical use of spectral reflectance data was investigated in the fi...
Many studies suggest that measuring spectral reflectance is useful to evaluate above-ground biomasses and qualities of standing plants. Few, if any, attempts to use spectral reflectance to estimate the growth conditions of creeping plants, however, have been done. In this study, therefore, the practical use of spectral reflectance data was investigated in the field of agriculture especially for sweet potato (Ipomoea batatas Lam. cv. kogane-sengan), which is one of the economically important crops in Kagoshima, Japan. It is well known that the total leaf area of a plant reflects its growth condition since the area affects its photosynthetic rate. In this study, the total leaf areas of sweet potato plants and their root yields were observed periodically during the cultivation period. But before digging up and destroying the samples, the spectral properties of their canopies were measured with a handheld spectroradiometer (400nm to 1000nm at 3 nm interval, IFOV with 3 degrees), and their numbers of leaves were counted nondestructively. These spectral curves were differentiated with respect to wavelength on the first and the second orders so that inflection points representing peaks and bottoms were found on the curves. Then the relationships among the wavelength corresponding to each peak, total leaf area, and root yields were analyzed. Normalized differential index with the reflectances of 520 nm and 710 nm, ND520,710 = (R520|R710) /(R520+R710) showed the close relation with total leaf area, the amount of yield, and nitrogen content of leaves, too. This result demonstrates the potentiality of the use of spectral reflectance signatures for estimating the yield of sweet potato before harvest.
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