Study On Diagnosis Of N Status Of Cucumber And Tomato Using Digital Image Processing

In this study, the cucumber and tomato were conducted at a few of levels of nitrogen, andthe canopy image of cucumber and tomato were shot by digital camera. Digital imageanalysis method, which combined with soil and plant N rapid test, was studied for N statusdiagnosis and N fertilization recommendation. The possibility of using digital image analysismethod for cucumber and tomato N status diagnosis was studied, and the digital indexeswhich can represent the N supplying level of vegetable were established. In addition, thestandard method of digital image acquisition and saving was established. What digital imageanalysis method was applying for vegetable N diagnosis has become a new kind of methodfor vegetable N fast-testing technique. The main results were as follows:The biomass and leaf area index etc of cucumber and tomato were improved when Nfertilizer concentration was high, and this kind of respond is very sensitive at low level of Napplying; The photosynthesis and dry weight accumulation were strengthen when N fertilizercontent was improved, and this is why vegetable can catch a high yield by a lot of N wasapplied; The N supplying level of cucumber and tomato can be reflected by nitrateconcentration in petiole, canopy total N, total N in leaf and SPAD readings. Thus, plant Nrapid test can become a kind method of N diagnosis in cucumber and tomato.The digital image processing technique could be used of N status detection of cucumberand tomato. The results show significant inverse relationships between greenness intensityand canopy total N, SPAD readings, plant nitrate concentration and total N concentration inleaf. So the absolute greenness intensity value of vegetable can become an indicator whichforecasted N supplying level.The canopy digital image was conducted by soft device, and the elementary imageparameters were distracted. The image parameters were analyzed, and the result were asfollows; the relationship between the normalized greenness intensity G/(R+G+B) andsoil-plant testing indexes in cucumber; and G/B were best in tomato.In this study, the difference of image index among vegetable verieties is existing, thecucumber of southern type and northern type is distinguished apparently by canopyimage, but the distinguish is no so obvious at the same type; It is not apparent between twoverieties in tomato.It is the optimum at 12:00～13:00 when we shot canopy image, and angle betweenvegetable canopy and digital camera is 30°～60°. JPEG format with a pixel resolution of1024×768 could be used for digital images saving. The brightness of the field background andthe light condition did not affect the image acquisition and the results of color analysis. Irrigation could enhance soil color, and due to the decrease of light reflection. The ripe fruitcolor will affect vegetable canopy color seriously.Field digital image analysis method combined with soil and plant rapid test could be usedfor N fertilization recommendation. In this study, N fertilization recommendation wascombined with vegetable growing, and the main recommendation standards as follows:N fertilization recommendation. System in cucumber: In the first harvest stage, whenG/(R+G+B) was less than 0.391, cucumber was in N surplus state, did not need N topdressing,when G/(R+G+B) was 0.391～0.413, cucumber was in optimum N supply state, and whenG/(R+G+B) exceeded 0.413, cucumber was in N stress state, In the early days of harvest,when G/(R+G+B) was less than 0.415, cucumber was in N surplus state, did not need Ntopdressing, when G/(R+G+B) was 0.415～0.427, cucumber was in optimum N supply state,and when G/(R+G+B) exceeded 0.429, cucumber was in N stress state; In the medium termharvest stage, when G/(R+G+B) was less than 0.426, cucumber was in N surplus state, did notneed N topdressing, when G/(R+G+B) was 0.426～0.440, cucumber was in optimum N supplystate, and when G/(R+G+B) exceeded 0.442, cucumber was in N stress state, the last stage ofharvest, when G/(R+G+B) was less than 0.448, cucumber was in N surplus state, did not needN topdressing, when G/(R+G+B) was 0.447～0.461, cucumber was in optimum N supply state,and when G/(R+G+B) exceeded 0.461, cucumber was in N stress state.In the first fruit expending stage, when G/B was less than1.461, tomato was in N surplusstate, did not need N topdressing, when G/B was 1.461～1.522, tomato was in optimum Nsupply state, and when G/B exceeded 1.522, tomato was in N stress state. In the second fruitexpending stage, when G/B was less than 1.625, tomato was in N surplus state, did not needN topdressing, when G/B was 1.626～1.713, tomato was in optimum N supply state, and whenG/B exceeded 1.714, tomato was in N stress state. In the harvest stage, when G/B was lessthan 1.855, tomato was in N surplus state, did not need N topdressing, when G/B was1.855～1.914, tomato was in optimum N supply state, and when G/B exceeded 1.916, tomatowas in N stress state. In the mid-harvest stage, when G/B was less than 1.901, tomato was inN surplus state, did not need N topdressing, when G/B was 1.901～1.957, tomato was inoptimum N supply state, and when G/B exceeded 1.959, tomato was in N stress state.