| In this study,the incidence of paddy weeds and pests was investigated in Guangdong province using different strategies of conservation tillage,aiming to establish the appropriate technique methods,agricultural machines and related skills in different sites.The test has been conducted in two trail sites,Huizhou and Taishan in the years of 2016 and 2017.Eight cultivation methods,including no tillage-transplanting seeding(NTTS)(rice-rice),minimum tillage-transplanting seeding(MTTS)(rice-rice),no tillage-direct seeding(NTDS)(rice-rice),minimum tillage-direct seeding(MTDS)(rice-rice),no tillage-direct seeding&drought(NTDSD)(rice-rice),minimum tillage-direct seeding &drought(MTDSD)(rice-rice),no tillage-direct seeding&drought(NTDSD)(cabbage-ricecabbage),minimum tillage-direct seeding &drought(MTDSD)(cabbage-rice-cabbage)and conventional tillage(CT)as control,were applied to deeply explore and analyze the potential relationship among conservation tillage and the incidence levels of paddy weeds,pests as well as the economic benefit,which were expected to provide theoretical foundation for the promotion of efficient tillage with low consumption.1 The influence of conservation tillage on paddy weedsUnder the different tillage methods,the weed species were found basically the same in Taishan and Boluo,but the incidence levels in conversation tillage were lower than control treatment.Meanwhile,fields treated with no tillage and minimum til lage showed great reduction of weed emergence.In Taishan,the occurrence of the weedy rice and rice growing of itself were decreased by MTTS methods.In Boluo,direct seedling without irrigation effectively control the weeds germination.The results indicated that MTTS could efficiently control the paddy weeds in Taishan while control effect of weeds was significant in Boluo under NTDS without irrigation.2 The influence of conservation tillage on insect pests(1)Effects on rice planthopperUsing MTTS could efficiently control the rice planthopper in Taishan,showing significant difference compared to conventional tillage.In Boluo,the amount of rice planthopper was lower in every conservation tillage field.Specifically,MTDS without irrigation demonstrated the best control efficiency on rice planthopper.These results indicated that MTTS methods could be used to greatly reduce the incidence of rice planthopper i n Taishan while MTDS without irrigation was the most efficient way to prevent this paddy pest in Boluo.(2)Effects on rice leaf roller(Cnaphalocrocis medinalis Guenee)In Taishan,the population number of rice leaf roller in MTDS field was the highest with significant differences compared to other tillage methods.In Boluo,the rice leaf roller was effectively controlled under NTDS and MTDS.Moreover,the number of rice leaf roller was obviously lower under the tillage strategies including NTDS and MTDS compared to conventional tillage methods.The control effect of rice leaf roller was weak using MTDS in Taishan.In Boluo,on the contrast,the pests were efficiently managed by all conservation tillage methods,in which NTDS and MTDS demonstrated the best control efficacy.(3)The impact on Golden Apple Snails(Pomacea canaliculata)In Taishan,using NTDS and MTDS could realize the lowest population number of apple snails,displaying significant difference compared to conventional tillage field.The control effect under MTTS and NTTS were similarly effective.In Boluo,no control of apple snails were found under conservation tillage.More importantly,the amount of apple snails were increasing in NTTS and NTDS without irrigation.In late rice cultivation,using NTDS without irrigation could reduce the incidence of apple snails with significant difference compared to conventional tillage.The results indicated that conservation tillage was useful in apple snail controlling in Taishan and the effect of direct seeding was better than transplanting seeding.Meanwhile,NTDS without irrigation demonstrated the best control in Boluo.(4)The effects on the incidence of rice stem borersIn Taishan,the incidence of rice stem borers was the highest in the field under MTTS with significant difference compared to conventional tillage.In Boluo,no significant difference was observed among all tillage methods in early-and late-rice.Therefore,further study was needed to investigate the effect of conservation tillage on rice stem borers.(5)The influence on overwintering wormsIn Taishan,the best control in overwintering C hilo suppressalis was found under NTDS method with 28.57% of reduction in pest population.For Sesamia inferens,using MTDS showed the best management with 79.17% of population reduction.In Boluo,100% of overwintering C.suppressalis was decreased in N TDS and MTDS fields while 92.46% of overwintering S.inferens was declined in NMDS methods,determining that NMDS was the best method in S.inferens management.These results demonstrated that MTDS was the best strategy for controlling overwintering worms in Taishan while N TDS showed highest control efficiency in Boluo.3 The effect of conservation tillage methods on natural enemiesIn Taishan early rice,using conservation tillage patterns in early rice were conducive to an increase in the number of natural enemies,in which MTDS was the mos t efficient strategy,followed by MTTS method.In late rice cultivation,the population of natural enemies in all conservation tillage fields indicated steady increasing compared to control field,in which using MTTS was the most efficient approach.Taking together the results from early-and late-rice cultivation,the population number of natural enemies was increasing using MTTD method in Taishan.However,the effects in Boluo needed to be further studied.4The effects of conservation tillage on rice yield and economic benefitIn Taishan early-rice field,the crop yield increased by 9.3% using MTTS compared to conventional tillage.In late-rice cultivation,the NTTS crop demonstrated the highest yield,which increased 13.66% of rice per unit.In Boluo early-rice field,the yield increased by 40.5% in NTTS crop as the best improvement in crop production.In late-rice cultivation,adopting MTDS had the highest crop yield with 35.8% of production increase per unit.In Taishan early-rice field,the highest economic income was in MTDS crop with an increase of 159.6 yuan per unit.In late-rice cultivation,using NTTS was the best method to increase benefit since the income was 298.54 yuan higher than conventional tillage crop.In Boluo early-rice field,the highest income was in NTTS crop with an increase of 644 yuan per unit while NTDS could mostly promote and increase the economic income in late-rice cultivation with 74 yuan per unit more than conventional tillage crop.Taking together the results from the incidence of paddy weeds,pests and natural enemies as well as the economic benefit and geographic characters,it can conclude that transplanting seeding tillage showed better performance in paddy fields along the coast such as Taishan area.Meanwhile,the paddy fields in southeast Guangdong such as Boluo could adopt no/minimum tillage method without irrigation to promote conservation tillage. |
