Study On The Physical And Chemical Properties Of Soil,Insects' Occurrence,and Assessment Of Grain Yields Of Transgenic Bt Rice By Spraying Pesticide

The planting of genetically modified(GMO)crops has become to bring huge economic and social benefits.It can efficiently control lepidoptera insect pests,which is,in turn to reduce the use of pesticides,and simultaneously increase the yields and protect the ecological environment.However,GMO crops can also bring environmental risk due to the exogenous transgenes,such as resistance decline or lose,weediness,ecological invasion,genetic drift and pollution,food safety and affecting biodiversity,etc.Over the years,there are many researches to study the effects of GMO crops on the ground parts,but fewer experiments were carried out to study the effects of GMO crops on the soil fertilizers.In this study,the transgenic Bt rice(cv.HuaHui 1)and its parent line(cv.Minghui 63)were selected as experimental materials,and one systematic experiment was carried out from May of 2013 to 2016 to study the effects of transgenic Bt rice planting on soil nutrients' content and fertility indexes(including of organic matter,available N,P and K,and total N,P and K),and rice grain yields(i.e.,grains weight per 100 rice plants),and the population dynamics of insect pests(including of brown planthopper Nilaparvata lugens and white-backed planthopperm Sogatella furcifera,and rice stemborer Chilo suppressalis)and natural enemy insect(Cyrtorhinus lividipenni)combined with the use of pesticides,finally to provide reference frame for the safety evaluation on soil fertilizer and yields indexes during the sustainable usage and popularization of transgenic Bt rice,and simultaneously to make clear the outbreak patterns of insect pests and population dynamics of natural enemy insects.The main results of this study were as follows:1.Effects of transgenic Bt rice planting and pesticides spraying on soil available nutrientsFrom May of 2013 to 2015,we annually took survey with five sampling times(i.e.,May,July,August,September and October)through two-way(transgenic treatment and pesticide spraying)repeated measurements of analysis of variance(ANOVA),the results showed that only the pesticide spraying significantly affected soil available N(P<0.05),P(P<0.05)and K(P<0.05)in 2015.Frome May of 2013 to 2016 with 16 times of sampling investigation(2013-2015:May,July,August,September and October;2016:May),two-way repeated measurements of ANOVAs indicated that there were no significant effects of transgenic treatment,pesticides spraying or their interaction on soil nutrient contents of available N,P and K(P>0.05).While there were significant effects of transgenic treatment and pesticides spraying on soil available nutrient contents of monthly sampling by using two-way ANOVAs(P<0.05,0.01 or 0.001).2.Influence of transgenic Bt rice planting and pesticides spraying on soil total nutrientsFrom May of 2013 to 2015,we annually took survey with same sampling protocol as before and analyzed with two-way repeated measurements of ANOVAs.The results showed that transgenic treatment only significantly affected soil total K,and pesticides spraying only significantly affected soil total N in 2015(P<0.05),while transgenic treatment or pesticide spraying didn't significantly affect soil total P and organic matter(P>0.05),and there was no significant interaction effects between transgenic treatment and pesticide spraying on soil nutrients' content of total N,P and K,and organic matter(P>0.05)in 2013,2014 and 2015.From May of 2013 to 2016 with 16 times of sampling investigation,two-way repeated measurements of ANOVAs indicated that there were no significant effects of transgenic treatment,pesticides spraying or their interaction on soil nutrient contents of total N,P and K,and organic matter(P>0.05).While there were some significant effects of transgenic treatment,pesticides spraying and their interaction on soil total nutrient contents of monthly sampling by using two-way ANOVAs(P<0.05 or 0.01).3.Population dynamics of insect pests of rice planthoppers and stemborers,and natural enemy of Cyrtorhinus lividipenni in the pesticiede spraying field and non-pesticide spraying field of transgneic Bt rice and its control parental lineThrough two years(2014-2015)survey of population dynamics of insect pests,N.lugens,S.furcifera and C.suppressali,s,and natural enemy C.lividipenni,the results indicated that pesticide spraying significantlyinfluence the population dynamics of S.furcifera nymphs and adults,and N.lugens nymphs in 2014 and 2015(P<0.001),and C.suppressalis larvae in 2014(P<0.05),and C.lividipenni in 2014(P<0.001)and 2015(P<0.01),except for the sampling investigation of population dynamics of C.suppressalis larvae and N.lugens adults in 2015(P>0.05).While transgenic treatment only significantly affected population dynamics of C.suppressalis and there are significant interaction effect between transgenic treatment and pesticide spraying in 2014(P<0.05),and also significantly affected population dynamics of C.lividipenn.in 2015(P<0.05).The abundances of insect pest N.lugens,S.furcifera and C.suppressalis,and natural enemy C.lividipenni in pesticide spraying field were all higher than those in non-pesticide spraying field for transgenic Bt rice and its control parental line,respectively;and the abundance of C.suppressalis fed on transgenic Bt rice was lower than those fed on its control parental line in pesticide spraying field and non-pesticide spraying field,respectively.Furthermore,there were positive relationships between the population abundances of C.suppressalis and N.lugens(S.furcifera.4.Effects of transgenic Bt-rice planting and pesticide spraying on rice yieldThe rice yield(grains weight per 100 rice plants)was measured in 2013,2014 and 2015.The results indicated that the yield rank of the four transgenicxpesticide treatments was transgenic Bt rice with pesticide spraying>the control parental line with pesticide spraying>transgenic Bt rice with non-pesticide spraying>the control parental line with non-pesticide spraying.The grain yield per mu of transgenic Bt rice was significantly heavier than that of the control parental line in pesticide spraying field(+4.50%)and non-pesticide spraying field(+8.92%),respectively.Moreover,the grain yields of transgenic Bt rice(+21.58%)and its parental line(+25.37%)in pesticide spraying field were significantly heavier than those in non-pesticide spraying field,respectively(P<0.05).Based on the above results,transgenic Bt rice planting with insecticide spraying didn't significantly affect soil available nutrient contents and soil total nutrient contents,while markedly influenced inect pests of rice planthoppers and rice stemborers,simultaneously adversely impacts population occurrence and abundance dynamics of natural enemy such as C.lividipenni.