Monitoring The Damage Of Rice Leaf Folder Using Rice Canopy Spectral Reflectance Temperature And Leaf SPAD Reading

The rice leaf folder,Cnaphalocrocis medinalis,is an important pest on rice and has caused significant losses to rice production in china.Effective monitoring of the damage of the rice leaf folder will help us take prevention and control measurements timely and accurately to reduce the losses caused by the pest.This study analyzed the correlation of rice canopy spectral reflectance,canopy temperature and leaf SPAD value with the leaf-roll rate and yield loss caused by the rice leaf folder,and established regression models to monitor rice leaf-roll rate and rice yield.The results will provide a guide for monitoring the damage of the rice leaf folder.The research obtained the following results:By planting rice in the plot and artificially inserting different numbers of rice leaf folder larvae for damage,the results showed that the leaf-roll rate increased with the number of inoculations and the damage time,and the higher the leaf-roll rate the lower the yield of the plot.When the rice was in the booting stage,the leaf-roll rate and reflectance of the plot all showed a very significant positive correlation in the(400-1000nm)waveband.When the rice was in the heading stage,which was reflected in the red light zone(710-1000nm).There was a very significant negative correlation between the spectral reflectance and the leaf-roll rate.In the jointing stage,the canopy reflectance of rice had a very significant correlation with the leaf-roll rate in the green and red wavelength bands.From the jointing stage to the blooming stage,the green light zone(450-560nm)and the red light zone(750-950nm)reflectance was significantly or extremely significantly related to leaf-roll rate.Leaf-roll rate and canopy temperature reached a very significant negative correlation at 6 and 19 days after inoculation.The leaf-roll rate and SPAD showed a very significant negative correlation at different times after inoculation.The plot leaf-roll rate(Y)regression monitoring model established at the booting stage was: Y=-12.84SIPI+0.036Tc(average temperature)+18.32,the accuracy of the back-check was 75%,and the prediction accuracy was 71.4%.The grain weight and 1000-grain weight of the plot rice after the rice leaf folder damage was measured,and the relationship between the spectral index,canopy temperature and SPAD value of different growth stages was analyzed.The results showed that the spectral index of rice canopy m NDVI,RVSI,PRI.all showed a high correlation with rice yield indicators.The rice canopy temperature in the tillering stage and jointing stage was extremely significantly correlated with 1000-grain weight and grain weight,and the SPAD value also exhibited a extremely significant negative correlation with yield.The 1000-grain weight(Y)regression monitoring model was established for the spectral index,temperature and SPAD value at the heading date: Y=0.063 Carter3+0.001 m NDVI+0.512 NWI+0.105.The accuracy of back-check was 71.4%,but the prediction accuracy was 57.1%.and needed to be improved.In short,the damage of the rice leaf folder will cause changes in the rice canopy spectral reflectance,temperature and SPAD value,and use these three types of indicators combine to establish a simple linear regression model can be used to monitor the leaf-roll rate and yield loss the damage caused.by the rice leaf folder.