Studies On The Spectrum Diagnosis Of Plant Nutrient Based On GIS

By the method of potted plant experiment and the RBG through CCD, this paper determines the reflectance of the maize canopy which were treated at various nutrition levels and determines the average RBG reflectance of the plant canopy by the grid GIS. The relation of the reflectance and the nutrient and the content of chlorophyll shows: (1) The content of nitrogen in maize plant is rising with the increasing of fertilization and it has negative correlation with the reflectance. The correlation in the green band is more dependable to the reflectance than the blue and red band. The reflectance has different sensitivity to different elements at various growing stages of maize. It has the best sensitivity to the content of N, K, Mg and Cu at elongating stage and the sensitivity is improved at the bugle stage. The plant has the strongest sensitivity to the green band at the bugle stage. (2)The content of phosphorus has the strongest sensitivity to the red band. At the bugle stage, the reflectance in the red band has highest correlation with the content of the phosphorus. (3) The content of potassium has a complex relation with the reflectance. It has the highest correlation in the blue and green band. At mature period, it has the highest correlation in the red band. (4) The content of chlorophyll and carotene has a high correlation, especially at the bugle stage when treated with nitrogen. However, when the plant is treated with phosphorus and potassium, the correlations show low. (5) By analyzing the sensitive stage and the sensitive band of the nitrogen, phosphorus and potassium, it shows that the bugle stage is the sensitive stage of most nutrition element. The reflectance of the maize canopy has low correlation with the content of the nutrient during early growth. The sensitive band of the nitrogen is green band, the phosphorus is red band and the potassium is blue and green band. (6) Most of the linear relationshiopof the content of the nutrient and the reflectance 'can be described by linear equation.