Estimation Of Some Physiological Indices Of Cotton Based On Leaf Color Characteristic

The study was carried out at the Dongchang base of Cotton Research Institute, CAAS in 2006. It wasrandomized blocks designed with three replicates, cotton varieties was CRI 29, CRI 45, CRI 46, DP99B andBiaoza A1, applying the digital image-processing technology and the statistical analysis methods to analyzethe images of cotton leaves which were obtained by scanner, combing with normally calculations of laboratory,the experiment studied the color parameters, the content of chlorophyâ…¡, nitrogen, phosphorus, andpotassium(K) of cotton leaves, and estimated parameters of model based on leaf color. The results were asfollows:1. The color parameters of digital image in the different stage growth of each variety were analyzed. Theresults indicated that the average of R, G and B were 93.54, 116.72, 64.84, the average of R/(G+B), G/(R+B)and B/(R+G) were 0.52, 0.75, 0.30, and the average of G/B, R/B and G/R were 1.85, 1.47, 1.26 respectively,which made it clear that the leaf reflected more green lights than red and blue lights, while absorbed less thanred and blue lights.2. The correlation between the content of chlorophyâ…¡and the color parameters: The correlation betweenthe content of chlorophyâ…¡and color parameter R/B and H was the biggest in the seedling stage and squarestage, it was -0.596, 0.726 and -0.806, 0.588 respectively. The correlation of the color parameter G and I wasthe biggest in the boll stage, it was -0.580 and -0.723. R/B, H and G, I were the better color parameters toestimate the content of chlorophyll in the seedling stage, square stage and boll stage. The correlation betweenthe content of chlorophyll and color parameter R within five varieties was different, but it was not verysignificant, it was not different with other color parameters.3. The correlation between the content of nitrogen and the color parameters: The correlation between thecontent of nitrogen and color parameter R/B and H was the biggest in the seedling stage, it was 0.531 and-0.422. The correlation of the color parameter G, I and R, I was the biggest in the square stage and boll stage,it was 0.739, 0.760 and -0.896, -0.905 respectively. Those were the better color parameters to estimate thecontent of nitrogen in the seedling stage, square stage and boll stage. The correlation between the content ofnitrogen and color parameter R within five varieties was different, but it was not very significant, it was notdifferent with other color parameters.4. The correlation between the content of phosphorus and the color parameters: The correlation betweenthe content of phosphorus and color parameter G/(R+B) and 1 was the biggest in the seedling stage, it was0.670 and -0.646. The correlation of the color parameter G and H was the biggest in the square stage, it was0.705 and 0.437. The correlation of the color parameter B and I was the biggest in the boll stage, it was 0.766and -0.734. those were the better color parameters to estimate the content of phosphorus in the seedling stage,square stage and boll stage. The correlation between the content of phosphorus and color parameter R withinfive varieties was different, but it was not very significant, it was not different with other color parameters.5. The correlation between the content of potassium(K) and the color parameters: The correlationbetween the content of potassium(K) and color parameter G/R and H was the biggest in the seedling stage, itwas -0.661 and -0.424. The correlation of the color parameter R/(G+B) and S was the biggest in the squarestage, it was -0.848 and 0.688. The correlation of the color parameter G/R and I was the biggest in the bollstage, it was -0.690 and -0.852. Those were the better color parameters to estimate the content of potassium(K)in the seedling stage, square stage and boll stage. The correlation between the content of potassium(K) andcolor parameter B/(R+G), R/B within five varieties was different, but it was not very significant, it was notdifferent with other color parameters. 6. The correlation between the yield of seed and the color parameters: The p of quadratic polynomialstepwise regression equation was the lowest, it was 0.0039 and the residual was the lowest too. The equationwas determinated the best, it can be used to estimate the seed cotton yield. The product of the color parameterG/R In May 29 and S in July 20 make the greatest contribution to the equation, The product of the colorparameter R In June 8 and G in July 20, B in June 8 and S in July 20, B/(R+G) in July 20 and G in August 10also make a greater contribution to the equation.7. The study indicated that the color parameters of cotton leaves obtaining by digital image-processingcould be used to evaluate the content of chlorophyll, nitrogen, phosphor, potassium(K) and the yield of seedcotton. The evaluating model had been estimated fitting for the different stage of growth.