Ecological Control Of Kiwifruit Root-knot Nematodes Based On Biodiversity

Root-knot Nematodes as an important pathogen in the roots of kiwifruit,its damage has become one of the constraints of the development of the kiwifruit industry.At present,the prevention and treatment of kiwifruit root-knot nematode disease is mainly based on chemical control,but long-term use of chemical pesticides often causes many problems such as disease resistance,environmental pollution and pesticide residues.In this study,by identifying the disease characteristics of kiwifruit root knot nematodes infecting the roots,at the same time,observe the morphology of the pathogen nematode and supplement it with molecular biology to clarify its type;using crude plant ethanol extracts to determine the virulence of root-knot nematodes,Screening out crude extracts with good nematode activity for field verification;Root-knot nematodes are regulated by different plants associated with kiwi orchards,Investigate its improvement effect on the orchard ecology,The plants with better regulation effects were further interplanted.Initially clarify the impact of biodiversity on kiwifruit ecological environment,fruit quality,soil microorganisms,enzyme activity and other factors on kiwifruit root-knot nematodes,explore new effective ways to prevent and control root-knot nematode disease.The main research results are as follows:1.The nematode morphology and molecular biology methods were used to study the occurrence of root-knot nematodes in kiwifruit orchards.The results showed that the morphology and molecular biology r DNA-ITS sequence analysis confirmed that the pathogenic nematode and Meloidogyne incognita had 99%homology.Therefore,it can be determined that the kiwifruit root-knot nematode species obtained is Meloidogyne incognita.2.The activity and toxicity of 22 kinds of plant ethanol extracts against the 2^ndstage of root knot nematodes were determined.Extraction of plant extracts to root knot nematodes are active,have some of which houttrynia cordata,Tagetes erecta,Ricinus communis plant extract of nematodes poison activity is stronger;After treatment for 24 hours,the adjusted mortality rate was 90.89%,88.26%and 89.32%,respectively.LC₅₀ was 2.31 mg/m L,2.66 mg/m L and 3.38 mg/m L,respectively.Field control experiments showed that Tagetes erecta had the best control effect among the three plant extracts,and the control effect reached 55.90%.3.6 kinds of accompanying plants?Triticum aestivum,Hordeum vulgare,Houttuynia cordata,Vulpia myuros,Vicia faba and Lolium multiflorum?were interplanted in kiwifruit orchard to investigate the occurrence of treated kiwifruit root-knot nematode disease of separately,to research and test the effects of accompanying plants on weeds species,ecology,fruit quality and yield.The results showed:accompanying plants had certain regulation effect on root knot nematode.among which orchard with H.cordata has the lowest incidence rate,it is13.74%.and the relative control effect reached 57.14%.In the mean time,accompanying plants can reduce weed population,improve soil water content and porosity,decrease soil bulk density,also H.cordata can reduce soil temperature.In addition,H.cordata could also improve kiwifruit yield and fruit quality.After treatment,the average fruit transverse diameter was 52.44 mm and longitudinal diameter 79.33 mm.The volume,weight of single fruit and yield raised by 24.75%,12.04%and 12.05%respectively compared with the control?conventional cultivation?,the differences were significant;In special,after accompanying H.cordata treatment,the contents of vitamin C,dry matter,Soluble solids,soluble protein,soluble sugar,etc greatly enhanced,compared with control group?conventional cultivation?,they were 24.60%,28.29%,43.46%,26.03%and 45.86%respectly.4.After interplanting with H.cordata,the physical and chemical properties,microbial species and quantity,and enzyme activity of kiwifruit rhizosphere soil have changed significantly compared with the control group,Among these,the content of Alkali-N,Olsen-P and Avail K in the rhizosphere increased by 13.95%,7.92%and3.94%,respectively;While bacteria dominate in the soil microbial species,followed by actinomycetes,the number of bacteria,fungi and actinomycetes increased by19.01%,28.89%and 16.32%compared with the control group;And the activities of soil catalase,urease,sucrose,and phosphatase activities in soil were increased by17.02%,12.63%,17.57%,and 7.98%,accordingly.Related analysis showed:after interplanting with H.cordata,the Avail K content was in very positive correlation with number of bacteria,fungi and actinomycetes,urease activity,sucrase activity and phosphatase activity in kiwifruit rhizosphere soil.The number of soil bacteria was positively correlated with sucrase activity and particeularly positively correlated with phosphatase activity;On the other side,the number of soil fungi was in high positive correlation with invertase activity.But the number of soil actinomycetes was positively correlated with sucrase activity and phosphatase activity greatly.