| Wheat（Triticum aestivum）is an important food crop in the world,and the wheat aphid is the main pest of wheat,which seriously reduces the yield and quality of wheat,and causes huge losses to wheat production.Improving cultivation management has been an important technical measure for integrated pest management.It has been reported that reasonable application of silicon can enhance the insect resistance of plants.However,it is not clear whether silicon application affect the occurrence of wheat aphid and natural enemy,further affecting wheat production in the wheat field ecosystem.Based on this,different silicon application methods and silicon concentrations were set with the winter wheat AK58 in this study.The effect of silicon applicaiton on the development and reproduction and the selection behaviors of Sitobion miscanthi were tested in the laboratory,and the effect of different ways and concentrations of silicon application on the interaction relationship between"Wheat-Wheat Aphid-Natural Enemy"was studied in the filed.In order to investigate the best way and concentration of silicon application to achieve the ecological control of wheat aphid,so as to esablish alternative measures to reduce the application of pesticides and fertilizers.The main results are as follows:1.The effect of spraying silicon fertilizer in the laboratory on the development and reproduction of S.miscanthi.Three fertilization levels were set for the potted wheat seedling:0 g/L（control,no silicon）,1 g/L and 2 g/L（SiO2）.At the age of 35 days of the wheat,the effect of different silicon application levels on the development and reproduction of S.miscanthi were measured by the method of population biology.Compared with the control,the application of silicon prolonged the whole aphid nymphs stage,shortened the adult stage and reduced the longevity and offsrpings.Two silicon concentration treatments significantly reduced net reproduction,intrinsic growth rate and finite growth rate of aphid population,and 2 g/L silicon treatment significantly increased average generation period and prolonged population doubling duration and increased the rate of winged aphid.Silicon application can inhibit the population growth of S.miscanthi.All of results showed that spraying silicon concentration inhibited the population dynamics of S.miscanthi.2.The effect of spraying silicon fertilizer in the laboratory on the selection behaviors of S.miscanthi.This experimental setup was the same as for the effects of silicon application on the development and reproduction of S.miscanthi.The selective test of the wing S.miscanthi to wheat of silicon application was conducted in the insect cage,and the non-selective test of the wingless S.miscanthi to the wheat of silicon application was carried out in vitro.The results showed that the selection rate of wing wheat aphid treated with 2 g/L silicon decreased by 17.88%respectively compared with the control;The mean number of aphid treated with 1 g/L and 2 g/L silicon decreased significantly which were reduced by 9.97%and15.84%compared with the control after 24h,48h and 72h.The results showed that silicon spraying application to wheat had a certain repellent effect on the S.miscanthi.which was not beneficial to the preference of S.miscanthi.3.The effect of spraying silicon fertilizer on the interaction relationship between"Wheat-Wheat Aphid-Natural Enemy".The experiment was carried out in the comprehensive experimental base of Chinese Academy of Agricultural Sciences,Qiliying Town,Xinxiang County,Henan Province.Four levels of silicon fertilizer（calculated according to the effective component SiO2）:0 g/L（control,no silicon）,0.5 g/L、1 g/L、2 g/L silicon solution were sprayed one time respectively at the early stage of wheat stem elongation、heading and grain filling period.The parameters of growth period,leaf area,biomass and production,the average number of Sitobion miscanthi and Rhopalosiphum padi and predatory natural enemies and parasitism rate were investigated in the field.The results showed that 0.5g/L silicon had slight effect on leaf area,biomass and housand grain weight during the two years.The maturity period of wheat was advanced in 2-3 days by applying 1 g/L and 2 g/L silicon,and the leaf area increased significantly by applying 1 g/L silicon concentration for two years.The effect of 1 g/L silicon treatment on wheat biomass and housand grain weight is inconsistent in 2018 and 2019.The effect of 1g/L silicon treatment on wheat biomass was significantly higher than the control in 2018,but significant difference was not shown in 2019.On the contrary,the effect on thousand grain weight had no significant effect on the comparison with the control in 2018,and it was significantly higher in 2019.The leaf area,biomass,thousand grain weight were significantly higher than the control by applying 2 g/L silicon concentration in two years.Spraying 1 g/L、2 g/L silicon fertilizer can reduce the amount of S.miscanthi and R.padi in the field.Meanwhile,silicon application can increase the parasitism rate of parasitoids in2018 and increase the occurrence of lady beetles and hoverfly significantly in 2019.The results showed that the application of 1 g/L、2 g/L silicon fertilizer on wheat plants could improve the ecological regulation ability of wheat field system,the specific performance is to reduce the occurrence of aphids,increase the occurrence of natural enemies,and promote the improvement of wheat yield.4.The effect of soil-application of silicon on Wheat-Wheat Aphid-Natural Enemy and different silicon application ways on economic benefits.Before growing,four levels of silicon fertilizer（SiO2）were respectively applied in the field soil:0 kg/hm2,40 kg/hm2,80 kg/hm2 and 120 kg/hm2.The growth period,leaf area,biomass,ear number,grain number per ear,thousand grain weight,yield and the occurrence of S.miscanthi,R.padi and natural enemies were investigated.The results showed that the agronomic trait of wheat could be improved by soil-application of 80 kg/hm2 and 120 kg/hm2 treatment in the field.The maturity of wheat was advanced about 2-4 days after silicon treatment,Meanwhile,the leaf area and biomass of wheat increased significantly.The leaf area and biomass of wheat treated with 80 kg/hm2 and120 kg/hm2 treatments increased by 21.3%,38.16%and 7.01%,7.67%respectively.Application of silicon in soil can reduce the occurrence of S.miscanthi and R.padi.The treatments of 40 kg/hm2,80 kg/hm2and 120 kg/hm2 silicon fertilizer reduced the amount of S.miscanthi by 29.99%,35.82%,42.38%;80kg/hm2 and 120 kg/hm2 silicon fertilize reduced the the amount of R.padi by 32.53%,35.94%.When silicon fertilizer with 80 kg/hm2 and 120 kg/hm2 treatments were applied,grains per ear and thousand grain weight and the yield of wheat were significantly increased compared with the control in the field.The number of grains per ear and thousand grain weight were increased respectively by 0.73 grain,1.04grain,1.08g and 1.33g.The yield of wheat increased by 4.69%and 6.32%compared with the control.The number of lady beetles increased by 11.67 and 12.33 respectively in the wheat area treated with 80kg/hm2 and 120 kg/hm2 treatments,but there was no significant effect on the number of laceing,hoverfly and the parasitism rate of parasitoids.The net income per mu increased by 15.48 yuan and 43.09 yuan respectively by foliar spraying 1 g/L and 2 g/L silicon,the net income per mu will increase by 29.71 yuan and 34.81 yuan respectively by soil-application of 80 kg/hm2 and 120 kg/hm2 treatments.So spraying 2g/L silicon fertilizer can control wheat aphids,protect natural enemies,and greatly increase wheat yield and benefit at the early stage of wheat stem elongation,heading and grain filling time. |
