Effects Of Seeding Ways To Dry Direct Seeding With Soil Moisture Conservation On Rice Blast And Prediction Of Rice Blast In Ningxia

Rice is one of the main food crops in the world and also in China.Rice blast is one of the main diseases that affect the yield of rice.Diseases of varying degrees may occur wherever rice is grown.In recent years,dry direct seeding with soil moisture conservation has become a cultivation model strongly promoted by rice growing areas in Ningxia,but there is no systematic research report on the impact of this seeding mode on rice blast.In this study,the occurrence and damage of rice blast under different seeding measures of dry direct seeding with soil moisture conservation were investigated in three rice growing areas of Yongning,Lingwu and Litong District in Ningxia.A portable spore collector was developed,and a spore image recognition program based on the morphological features of Magnaporthe grisea,the correlation between rice blast’s occurrence and meteorological factors was fitted according to thirty years of survey and meteorological data of rice blast in order to predict the trend of the occurrence of rice blast in Ningxia.The main results are listed as follows:1.Effects of different seeding methods to dry direct seeding with soil moisture conservation on rice blast(1)There was an obvious binomial correlation between the disease index of rice blast and the sowing rate according to the amount of dibbling,and the optimal sowing rate was 11-13 grains per hole.In terms of seeding methods,the peak value of rice blast’s disease index of both dibbling and drill sowing was higher,but the peak value of rice blast’s disease index in diibbling will be earlier than that in the drill sowing.For different sowing dates,it has little effect on the disease index of rice blast and there is no significant difference.The optimal sowing date was about April 1.The planting mode with spacing of 20×12.5 cm for soil moisture conservation was the best in terms of planting density.(2)Among the three seeding methods of dry direct seeding with soil moisture conservation,water after sowing and aerial seeding used for UAV,the incidence of rice blast was the least in dry direct seeding with soil moisture conservation.(3)According to the ten kinds of rice varieties were investigated,the leaf blast disease index epidemic dynamics change were basically the same,which showed mild onset in the early stage,sporadic occurrence in the field,and insignificant difference.In comparison,the rice’s cultivars of Changliyou and Daohuaxiang have relatively stronger disease resistance.2.A portable spore collector with the characteristics of light control and time control was developed,and the spore identification procedure of rice blast’s pathogen was obtained based on Yolov3 model.Multi-scale features are used to detect objects and a more accurate and efficient recognition model is obtained.The average identification accuracy of the test is 88.85%.The verified recognition accuracy is 66.85%on average,and the recall rate is 74.68%.3.Based on the historical data of rice blast in Pingluo,Zhongning,Yongning and Litong districts of Ningxia and the survey data in Yongning,Lingwu and Litong districts of Ningxia,the correlation analysis was conducted according to the meteorological data of all regions over the years,and the results were as follows:(1)GLM prediction model was obtained by correlation analysis of rice blast disease index with years and meteorological factors in five rice planting regions in Pingluo,Zhongning,Yongning,Litong districts and Lingwu in Ningxia:y1=1032-0.521Y-0.01672X13+0.8249X21+0.3655X32-1.746X35+3.43X36-1.704X37-1.105X38(P<0.05),which could be used to predict the rice disease condition in Ningxia.(2)GLM equation between rice blast disease index(Y1)and meteorological factors in Pingluo County:Y1=28.68377-3.4232X2-3.36894X10-0.99561X11+0.10813X13-3.30516X14+10.02765X15-3.71712X 16+0.79119X18+4.51833X22-2.88821X24(P<0.05),which could predict the occurrence degree of rice blast in Pingluo County in order to provide theoretical basis for rice production control.GLM equation between rice blast leaf rate(Y2)and meteorological factors in Pingluo County:Y2=110.0017+5.2595X7-3.6751X24-0.2315X26-3.2238X28(P<0.016),which could predict the leaf blast incidence.GLM equation between rice blast occurrence area(Y3)and meteorological factors in Pingluo County:Y3=-25.33321-0.35124X4-0.11185X5+4.30122X15-2.6296X17+0.42125X18(P<0.056),which could be used to predict the occurrence area of rice blast in Pingluo County.GLM equation between rice loss(Y4)and meteorological factors in Pingluo County:Y4=-946.4084-134.9633X10-60.1231X11+3.0375X13+317.3502X1 5-115.4826X16+44.9526X18-8.1098X20+148.4633X22-41.5823X23-79.2274X24(P<0.05),the rice loss will be predicted in Pingluo County.(3)Prediction of rice blast disease index in 2035 of Ningxia based on thirty years of Pingluo data,the spatial variation of rice blast disease index was not obvious in Yongning,Litong District and Lingwu’s rice planting areas,and the disease index was about 0.50.The rice blast disease index of Pingluo and Zhongning growing areas will be obvious change,and the disease index of leaf blast disease was about 1.50.The results provided a theoretical basis for the prevention and control of rice blast in Ningxia.