Effects Of Nitrogen Fertilizer Application On The Interactions Between Rice And Nilaparvata Lugens(St(?)l)

Nitrogen is one of the most important influencing factors in rice field ecosystem.It not only plays a decisive role in the formation of rice yield,but also has a great influence on the herbivores population and paddy community.The abuse of nitrogen fertilizer in the process of rice planting in our country not only leads to a series of environmental problems,but also causes the pest population to be rampant.It is important to study the effects of different nitrogen treatments on the interaction between rice and pests,which is of great significance for the rational use of nitrogen fertilizer and pest management.For this purpose,we use rice and brown planthopper(BPH),Nilaparvata lugens(St?l)which is one of the most harmful pests as the research object,through behavioral and electrophysiological methods to investigate the effects of different nitrogen treatments on the feeding,oviposition,growth and host positioning of BPH.Than using a variety of physical and chemical methods,research for the volatile matter,nutrient status and surface physical structure of rice.Field experiments were conducted in two years to verify the actual performance of different nitrogen treatments in the field.The main results are as follows: 1.Feeding behavior of BPH on different nitrogen rates in RiceThe effect of different nitrogen treatments on feeding behavior of BPH was studied by EPG.The results showed that the total duration of np and ph on Luoyou10 decreased significantly with the increase of nitrogen,and the total duration of N4-b increase with the nitrogen increased significantly,no significant difference between the total duration of N4-a under different nitrogen treatments.There were no effects of different nitrogen treatments on the feeding of BPH in Yangliangyou6.We found that nitrogen treatment reduced rice sheath surface hook density by SEM,and negatively correlated with the level of nitrogen,and the hair hook density of resistant varieties of Luoyou 10 was significantly higher than susceptible varieties yangliangyou6.But with the increase of nitrogen rate,there was no significant difference between the two varieties.2.Oviposition and developmental duration of BPH on different nitrogen fertilizer levels in RiceThe results indicated that the oviposition amount and hatchability of BPH in Luoyou10 with non-nitrogen treatment was significantly less than middle and high nitrogen treatments.The oviposition amount of BPH in Yangliangyou6 with non-nitrogen treatment was significantly less than middle and high nitrogen treatments.There was no significant difference between Yangliangyou6 with different nitrogen treatments.The results of GC-MS determination of free amino acids in rice phloem showed that there were 15 kinds of amino acids on two kinds of rice with different nitrogen rates.The effects of nitrogen rate on the free amino acids in phloem were related to rice varieties;Asparagine in Luoyou10 with high nitrogen treatment was significantly higher than non-nitrogen and middle nitrogen treatments.The free amino acids in phloem of Yangliangyou6 were not significantly different under different nitrogen treatments.3.Effects of different nitrogen treatments on host location behavior of BPHThrough the H-tube we can see that BPH significantly trend to rice with middle and high nitrogen treatments.Among the two species,BPH significantly trend to Yangliangyou6 under the condition of non-nitrogen treatment.The results of field simulated selection showed that BPH significantly tended to the rice with middle nitrogen and high nitrogen treatments;Among the two species,BPH significantly trend to Yangliangyou6 under the condition of high nitrogen treatment.The volatile of rice was determined by GC-MS,we identified 14 major volatiles,and the different nitrogen treatments have a significant effects on rice volatiles and related to rice varieties.With the amount of nitrogen increased,limonene and ?-Cedrene in Luoyou10 was increased.Limonene and ?-Cedrene in Yangliangyou6 was also increased.4.Effects of different nitrogen treatments on field population of BPHField trials on the number of BPH in 2015 and 2016 show that The population of BPH in non-nitrogen treatment area was significantly lower than that in middle nitrogen and high nitrogen treatment area,which also shows that the BPH tend to choose more high nitrogen area.But in the comparison of two varieties,the population of BPH were no significant differences.The records of microclimate in the field showed that the amount of nitrogen had a significant influence on the microclimate of rice field.The main results showed that with the increase of nitrogen application rate,the microclimate in the field tended to be stable,and the field temperature decreased with the increase of nitrogen application rate,while the humidity decreased with the increase of nitrogen application rate.There was a significant linear relationship between the humiture factor and the number of BPH in Yangliangyou6 treated with non-nitrogen treatment.