Analysis And Color Detection Of Volatiles Induced By Four Kinds Of Rice Diseases And Insect Pestes

Forecasting is an important part of the comprehensive management of crop diseases and insect pests.Early monitoring and early warning of diseases and insect pests of crops are important basis for effectively preventing and controlling the occurrence and development of diseases and insect pests in crops.In the long-term coevolution,plants have gradually formed complex defense mechanism in response to external biotic or abiotic aggression and stress,in which volatile compounds induced by harmful organisms play an important role in the communication between plants and surrounding organisms.At present,studies have shown that volatile compounds induced by harmful organisms can be used as reliable signals for monitoring diseases and insect pests of crops.Rice is one of the important food crops.The occurrence of diseases and insect pests affect the yield and quality of rice.Accurately identifying and monitoring the occurrence of diseases and insect pests is of great significance to prevent and control of diseases and insect pests in rice.With the continuous progress of modern agricultural technology and information technology,the collection and monitoring technology of diseases and insect pests information in rice has made great progress,but how to better monitor the occurrence information of diseases and insect pests in rice and apply it to the early monitoring and early warning of diseases and insect pests in rice are still being explored.To this end,this study uses rice and 4 kinds of important diseases and insect pests of rice(Rhizoctonia solani Kühn,Xanthomonas oryzaepv.Oryzae,Nilaparvata lugens(St(?)l),Chilo suppressalis(Walker)),the volatile compounds induced by 4 kinds of diseases and insect pests were isolated and identified,and the realization method of using induced volatile compounds to monitor harmful organisms in rice was explored,in order to lay the foundation for the monitoring of diseases and insect pests in rice through the volatile compounds induced by harmful organisms.The main results are as follows:(1)Isolation and identification of rice volatile compounds induced by important diseases and insect pests.The volatile compounds from rice were isolated and identified by dynamic headspace adsorption and GC-MS.Under the experimental conditions,a total of 43 kinds of volatile compounds were isolated and identified from rice,including 23 kinds of alkane volatile compounds,13 kinds of olefin volatile compounds,3 kinds of ketone volatile compounds and 3 kinds of alcohol volatile compounds respectively,and 1 type of aldehyde volatile compounds.After being damaged by diseases and insect pests,the types of volatile compounds in rice were not different from those in healthy rice,but the relative contents of some volatile compounds changed significantly.Compared with healthy rice,the relative contents of alcohol volatile compounds and aldehyde volatile compounds increased after rice were inoculated with sheath blight;the relative contents of alkane volatile compounds increased after rice were inoculated with bacterial blight;When rice were fed by brown rice planthopper,the relative content of alkane volatile compounds decreased and the relative content of ketone volatile compounds increased;When rice were fed by rice stem borer,the relative content of olefin volatile compounds increased.(2)The duration of disease infection has a significant effect on volatile compounds in rice.The dynamic headspace adsorption and GC-MS were used to separate and identify the volatile compounds in rice after the disease infects rice for different times(1d,2d,3d,4d,5d).Results show that the relative contents of 10 kinds of volatile compounds were significantly different among rice infected with sheath blight at different times.Among them,the relative contents of 5 kinds of volatile compounds including α-Pinene,Decane,2-ethyl-1-Hexanol,Cedrene and 2-methyl-Pentadecane gradually decreased after 1 day of sheath blight infection,significantly increased after 3d infection.The relative contents of 6 kinds of volatile compounds were significantly different among rice infected with bacterial blight at different times.Among them,the relative contents of 2 kinds of volatile compounds,2-Heptanone and Nonane,decreased with the increase of bacterial blight infection time.(3)The duration of feeding insect pests has a significant effect on volatile compounds in rice.The dynamic headspace adsorption and GC-MS were used to separate and identify the volatile compounds in rice after the insect pests infects rice for different times(12h,24 h,36h,48h).Results show that the relative contents of 3 kinds of volatile compounds were significantly different among rice fed by brown rice planthopper at different times.Among them,the relative contents of Decanal and(E)-5-Tetradecene were increased in the rice fed by brown rice planthopper for 24 h,but decreased in the rice fed by brown rice planthopper for 36 h.The relative contents of 6 kinds of volatile compounds were significantly different among rice fed by rice stem borer at different times.Among them,the relative contents of 1-Decanol increased with the increase of feeding time.(4)Chromogenic detection of rice volatile compounds induced by diseases and insect pests.Visualized detection of 8 kinds of different volatile compounds in rice induced by4 kinds of diseases and insect pests were performed using 2,4-Dinitrophenylhydrazine and Schiff.Results show that the 2 kinds of chemical chromogenic agents could distinguish Decanal,2-Nonanone and 2-Heptanone,but could not distinguish various alkanes.In this study,4 kinds of volatile compounds induced by rice diseases and insect pests were isolated and identified,and the changes of rice volatile compounds at different times when a single diseases and insect pests infested rice was clarified.It was found that 2 kinds of chemical chromogenic agents had certain effect on the color development of aldehydes and ketones.