Pathogen Identification And Mechanism Study Of Ginger Laipi Disease

Ginger Laipi disease was a new disease occurred on ginger in resent years. The diseaseseverely reduced ginger yield and quality, and then limited the development and property ofginger. In this experiment, the disease occurrence law was surveyed, disease pathogen wasidentified as south root-knot nematode, nematode yearly generation changes and relationshipbetween nematode population density and ginger yield was studied, the resistance reactionand physiological changes in ginger infected with root-knot nematode were also studied,which established the foundation for disease prevention and ginger breeding. 1. Through field investigation on greenhouse inoculation, microscope and electronicscanning, and esterase isozyne electrophoresis, the result turned out that south root-knotnematode (Meloidogyne incognita) was the pathogen, which caused ginger Laipi disease. Andthere was no compound infection. The nematode completed four entire generations in onegrowing season and the duration each generation is about 35 d. Juvenile peak appeared at thefirst ten days of Jul., the middle ten days of Aug., the middle ten days of Sept. and the last tendays of Oct respectively. The greatest population densities of the nematodes mainly occurredin 0-40 cm layer of the soil below the surface. Once ginger Laipi disease occurred, the plant height, stem diameter and shoots per plantwere decreased dramatically. It also showed the symptoms like light leaf color, rotten roots,verruca rhizome and bad quality. The yield would reduce by 20%-50%. Investigation showedthat ginger Laipi disease was closely related with soil texture, planting rotation andfertilization, sandiness soil, consecutive planting and excessive potassium might aggravatethis disease. 2. Stepwise analysis indicated that the soil total porosity, organic matter, effectivephosphorus, potassium, iron and manganese of ginger-producing field had remarkable effectson the density of M.incognita; while organic matter, effective nitrogen, potassium, calcium,iron, zinc and boron were close related to yield of ginger. 7生姜癞皮病病原鉴定及发病机理研究 Curve model showed that density of M.incognita was the lowest while soil total porositywas 37.91%, organic matter was 3.16%, effective phosphorus was 130.69 mg·Kg-1,effectiveiron was 145.93 mg·Kg-1 and effective manganese was 48.60 mg·Kg-1 respectively. Thedensity of M.incognita was the highest while effective potassium was 243.62 mg·Kg-1. Theyield reached the highest while contents of organic matter, effective nitrogen, potassium,calcium, iron, zinc and boron reached 2.64%, 224.33 mg·Kg-1, 237.78 mg·Kg-1, 2270mg·Kg-1, 73.46 mg·Kg-1, 7.71 mg·Kg-1 and 0.33 mg·Kg-1 respectively. Combined with thesoil basic characteristic of Shandong ginger-producing field, the following plans to control theginger Laipi disease were proposed: reduce the soil total porosity and potassium properly;improve the content of organic matter, effective nitrogen, effective calcium, iron, manganese,zinc and boron to the greatest extent, especially the organic matter, effective nitrogen and zinc,which could not only control ginger Laipi disease, but also improve ginger yield to someextent. 3. Results indicated that M.incognita severe effected ginger height, stem diameter, shootper plant and leaf area, M.incoginta also decreased roots activity, chlorophyll content and Pn,and altered daily variety of Pn, finally reduced ginger yield by 47.96%. There had lowercontent of Vc and Volatized oil, and higher content of fiber in Infected rhizome, whichdecreased ginger qualities. But the increase of sugar, starch and amino acid content and NRactivity were favorable to the growth and development of M.incognita. Results showed that the ginger growth damage increased with the enhancement ofM.incognita initial population density. And ginger yield decreased by 27.91%, 37.73% and42.14% under the inoculation of 50, 100 and 200...