Rapid Diagnosis Of Nitrogen And Moistrue For Pakchoi

Rapid diagnosis of nitrogen and water is an important means to improve the efficiency of the factorization production of pakchoi based on it's high demand of nitrogen and water.The development of spectral technology realizes remote sensing d biological physical and chemical parameters of crops.The application of thermal imaging technology can measure the crops internal moisture condition by surface temperature.Using the spectral reflection data of crops can predict the component content of crop nutrient elements.Using thermal imaging technology to extract the crops'leaves temperature,using the empirical formula to calculate the value of CWSI,and setting up crop water stress model to realize accurate,timely,non-destructive diagnosis of the crop's nitrogen and moisture.The purpose of the nitrogen nutrition diagnosis part is to study an accurate and efficient diagnosis method.;The purpose of the part of water experiment in this study is to gain the characteristic parameters of soil-crop–air as an organic whole and to establish a suitable water stress index model for pakchoi.The experimental material of the part of nitrogen is a kind of pakchoi named Huangwang,setting up 7 gradient of nitrogen(0 to 30 g/m~2);determined and analyzed total nitrogen content,the chlorophyll content and spectral reflectance of the first true leaves from the stage of the pakchoi with one to five leaves..The experimental material of the part of water is also the kind of pakchoi named Huangwang,setting up 3 gradient of water,using thermal imaging technology to extract the pakchoi's leaves temperature of different Irrigation quantity and setting up crop water stress model to realize quantitative analysis of water.The results of this study were shown below:1.Fresh weight showed a trend that it was first increased and then decreased.The research studied the relationship between nitrogen and fresh weight of pakchoi based on the regressional analysis,and got the best nitrogen level is 10g/m~2.2.The difference of the total nitrogen content of pakchoi existed in the whole growth period,but the most significant difference was in the period with four leaves and five leaves.3.As growth of pakchoi,the difference of the first true leaf chlorophyll content was gradually increasing under different nitrogen level,and the most significant difference was in the period with four leaves and five leaves.The first true leaf chlorophyll content and total nitrogen content has a positive correlation.4.As growth of pakchoi,the difference of the first true leaf spectral reflectance is gradually obvious under the different nitrogen levels,and the most significant difference was in the period with four leaves and five leaves The correlation analysis of spectral reflectance with the total nitrogen content of all wavelengths found that sensitive single band with nitrogen nutrition was in visible part,and the most relevant single waveband is 557.43nm.5.The change rule of canopy temperature was highly synchronous with air temperature and VPD.The analysis of the relationship of canopy temperature-the temperature and the canopy temperature–VPD obtained regression equation by linear fitting,R~2=0.67,R~2=0.95.Visibly canopy temperature is in significant correlation of air temperature and VPD,and provided theoretical basis to establish the pakchoi's CWSI model.6.First have to determine the linear regression equation of the temperature difference and VPD,Tca and VPD was in the significant negative correlation.VPD changes from 0~4.74 kPa,when VPD value equaled to 4.74 kPa,the gap between leaf temperature and air temperature reached the minimum-13.38.When pakchoi was seriously in water stress,VPD was 0 kpa,the gap between leaf temperature and air temperature reached the maximum value 1.065,figure out the result of CWSI for pakchoi.7.There was a significant linear negative correlation between CWSI and water ofpakchoi.The greater CWSI was the higher degree of water stress was;the lower CWSI was the more enough water was.