Diagnosis Of Nitrogen Nutrition Based On Scanning Leaf Image Characteristics Of Sugar Beet

Tn order to reduce the waste and environmental pollution caused by excessive application of nitrogen fertilizer in sugar beet production,it is an ideal way to supply nitrogen fertilizer constantly and quantitatively according to the characteristics of fertilizer requirement of sugar beet in different growth stages,and actual-time and rapid diagnosis of nitrogen content in sugar beet plant is the premise of realizing this aim.Based on observations and recording by traditional nitrogen nutrition diagnosis and scanner,the dynamic indices growth and development of sugar beet are recorded,and the status of nitrogen nutrition in sugar beet in different N fertilization treatments were analyzed,meanwhiler the plant shape change were analyzed.The color parameters of sugar beet have been obtained by digital image processing technology used the scanner,the correlation between color parameters and nitrogen content by traditional nitrogen diagnostic methods of sugar beet in different N fertilization treatments under field experiment conditions was studied,we established the optimum leaf position and color parameters for the diagnosis of nitrogen nutrition in sugar beet,and the optimum growth period and equation model for rapid diagnosis of nitrogen nutrition in sugar beet,for providing a theoretical basis for the application of digital image processing technology in the diagnosis of nitrogen nutrition in sugar beet.The following are the results and conclusions of this research:1?It were significantly or extremely significantly correlated(0.489<R<0.702)between the SPAD values and chlorophyll contents of No.L5,L6,L7 and L8 leaf position in the canopy at different growth stages,which show less affected by the growth period,so the two indices could accurately and steadily reflect the nitrogen nutritional status of the whole plant,Therefore,the four leaves(e.g.L5,L6,L7 and L8)were selected as the diagnostic leaf for nitrogen nutrition status in sugar beet growth stages.2?There were 37 color parameters in 4 leaves at the later stage of leaf cluster growth,all of which had significant or extremely significant correlation with leaf nitrogen content,in which,32 color parameters had significant or extremely significant correlation with total plant nitrogen content,and 40 color parameters had significant or extremely significant correlation with chlorophyll content.However,in the other three growth periods of sugar beet,this was no significant correlation relationships among above mentioned indices;the late stage of leaf cluster growth was used as a critical period for the diagnosis of nitrogen nutrition in sugar beet by using computer digital image processing technology in this study.3?Curve fitting of color parameter index and SPAD values in late growth period of leaf cluster showed that L7 and L8 leaves had the best correlation with R/B,with correlation coefficients of 0.809 and 0.736,followed by G/B and NBI indices,similarity,L5,L6 leaves Followed.Hence,in the diagnosis of nitrogen nutrition in sugar beet,the R/B parameter is recommended,for its better correlation and stability than other color indices.4?The curve fitting of nitrogen fertilizer application rate and yield showed that the determinant coefficient of cubic equation was 0.901,and the equation model was y=42015.025+152.515x+0.508x2-0.003x3,which show the shape of "parabola",The highest theoretical yield of 67955.09kg/hm2 was obtained under Niso treatment(the peak of parabola),and then began to decline,the results revealed that 180 kg/hm2 of nitrogen application was suitable for nitrogen application rates.According to the distribution of R/B in different levels of nitrogen application rates,when R/B value is greater than 1.54,the yield is lower,corresponding to the state of insufficient nitrogen supply,when R/B is less than 1.36,the theoretical yield reaches its peak in turn,which is the ideal state of nitrogen supply.