Irrigation Method Perfermence On The Accumulation And Disappearance Dynamic Of Rice Yield And Main Natural Enemies Insect Pests

Effects of different irrigation methods on the population dynamic of the main natural enemies and pests to guide the development of green and organic rice is of great significance. In this study, Xiang wan-12 (indica rice) was used as the experimental materials, and the experiment was set up four irrigation methods:deficit irrigation, wet irrigation, intermittent irrigation and long-term irrigation. There were two isolation modes to treat each of the irrigations that semi-isolated and fully isolated isolation. This paper systematically studied the effects of irrigation methods on the agronomic characters, yield, main natural enemies and pests of rice under the condition of the biological and chemical control of pests. Acquired results were as follows:1.Under the conditions of biological control, the irrigation methods affected rice in growth period significantly and the height of rice in deficit irrigation was significantly lower than other irrigation methods. In full-heading stage was significantly different between deficit irrigation and other treatments.. Dry matter of rice in deficit irrigation treatment was significantly lower than in the other three irrigation methods in the conditions of biological control, but no significant difference in chemical control, and in the whole, the dry matter of rice in biological control was lower than that in chemical control. Under the conditions of biological control, both isolation methods showed that the yield of the long-term irrigation was the highest, and the deficit irrigation was the lowest, but under the conditions of chemical control, the deficit irrigation showed the highest, the most important reason is that the grain number per panicle and seed setting rate were high.2.Rice planthoppers occurred the lightest by the long-term irrigation and the highest by the deficit irrigation in both semi-isolated and fully isolated isolation mode, the effect of irrigation on rice leaf roll rate is not significant. However, the rate of roll leaf in the condition of biological control is higher than the chemical control significantly, but less than 2.5%, within the scope of the rice economy loss threshold, rice planthopper occurred mainly in the 1-3 instar nymphs,it occurred in the long-term irrigation least, and the deficit irrigation most, but all accounted for more than 50% of the total. The adult and 1?3 instar nymphys by the deficit irrigation occurred earlier than the other three irrigation methods.,which was conflict with the concept of water-saving irrigation.3.The amount of pardosa pseudoannulata population was significantly different by any irrigation methods in the conditions of biological control, which was the lowest by the deficit irrigation. The amount of cyrtorhinus lividipennisnot population by the deficit irrigation method was large at the early growing stage, but at the later growing stage it changed inversely. However, the amount of cyrtorhinus lividipennisnot population by the long-term irrigation method showed contrary trend. Young pardosa pseudoannulata (1?2 age) and middle-aged spiderling were susceptible to the effects of chemical pesticides, while senile spiderling (5?6 age) and adult spider were affected by chemical pesticides little. Moreover, the long-term irrigation method can effectively reduce that chemical pesticide poisons Pardosa pseudoannulata.4.The correlation of between pardosa pseudoannulata, cyrtorrhinus livdipennis reute and rice planthopper were significant,but there was no significant correlation between pardosa pseudoannulata, cyrtorrhinus livdipennis Reute and leaf roller, when the number of rice planthopper population below 1891.1/hundred plexus, pardosa pseudoannulata can fully control the occurrence of rice planthopper. Otherwise only pardosa pseudoannulata population was difficult to control the occurrence of rice planthopper. After analyzing data with the quadratic polynomial regression analysis between pardosa pseudoannulata, cyrtorrhinus livdipennis Reute and Rice planthopper and there was the result. Combine with P]pardosa pseudoannulata and cyrtorrhinus livdipennis reute can significantly affect the population dynamics of rice planthopper.In summary,the effects of natural enemies control insect pest under long-term irrigation conditions was the best in the condition of biological control,and the yield was the highest, however, the yield and control effect of deficit irrigation was the lowest,and the water waste of long-term irrigation was serious,Therefore,whether to explore a method of break long-term irrigation to reach the goal of saving water and playing an important role between natural enemies and insect pest,to provide some scientific basis for the development of green and organic rice.