Physiological And Biochemical Reaction Of Susceptible Grape Cultivars Infected By Root-knot Nematode

In order to investigate the effects of grape growth and storage nutrition caused byroot-knot nematode (RKN） infection, three RKN-susceptible grape cultivars CabernetSauvignon, Chardonnay and Fujimineri were involved in this study. Changes in RKN-infectedgrape plant such as enzyme activities, alible nutrition in roots and leaves, absorption anddistribution law of plant nitrogen, as well as assignment changes of mineral elements indifferent organs were explored. The purpose of this research was to find out physiological andbiochemical changes of susceptible grape plant after inoculating RKN. Furthermore weintended to screen out some physiological indexes which can be used in identification forfurther study. Central results were as follows:1. Plant growth of Cabernet Sauvignon was restrained remarkably with a reduction in thegrowth rate by17.4%compared with control. Grape root and shoot represented differentresponses after inoculating RKN, the fresh weight of shoot and leaf decreased8.9%whileroot increased33.3%, as a result the root shoot rate raised44.9%significantly.2. Photosynthetic pigment content of Chardonnay decreased markedly after RKNinoculation, total pigment content in different part of grape plant-top, middle and bottomdecreased24.7%、14.1%,14.6%respectively; chlorophyll a, chlorophyll b and carotenoiddecreased respectively than that of control. Cha/Chb rate in bottom leaves decreased by19.6%compared with control while the rate increased significantly in top and middle leaves.In addition, Net photosynthesis rate in top, middle and bottom leaves also declined6.0%、9.2%,26.6%, and stomatal conductance of bottom leaves deceased40%, indicating thatbottom leaves were affected most.3. RKN damage led to a decline of starch content in Fujimineri leaf. In the five observationperiods average starch conten in infected leaves decreased25.6%than that in control. Solublesugar content was lower than control on the9th day after inoculation while other four periods increased; the free proline appeared a trend—the content in earlier stage increased afterinoculation then declined in later stage, Enzyme activity like PAL and PPO demonstrated asimilar trend while SOD activity showed an opposite trend4. Root activity of Fujimineri roots with knots increased markedly after inoculating RKN,and non-infected root of the same plant had an improvement simultaneously. The solublesugar content had an increase soon after inoculation then declined while free proline contentappeared a remarkable increase in later stage. The last sample results indicated that freeproline content in knot was2.6times of non-infected root and3.3times of control. The PALof root knot remained a higher activity than non-damaged root and control, on105th day afterinoculation it was6.2and3.9times higher than the other two type roots. On the contrary, theSOD activity of root kont declined, but the differences were not marked.5. Inoculating RKN weakened Cabernet Sauvignon plants’ absorption ability of mineralelements, and interfered their distribution in different plant organs. Nitrogen-15derived fromfertilizer(Ndff） increased significantly in fine roots, Ndff of infected fine roots increased9.6%and38.9%compared with that of non-infeced fine root and control. RKN damageimproved nitrogen-15content of fine roots especially the fine roots with knots, and reducedthe content contained in coarse roots. Phosphor in infected fine roots had an improvement by10.0%and36.2%repectively compared with that of the other two type fine roots, and thecoarse roots also had a rise by13.3%. When it came to other mineral elements, potassium indamaged fine roots rose by42.2%and50.2%remarkably, as well as Mg, Cu, Zn and Fe, theabove four elements’ total content in roots had an obvious improvement while Ca had no clearchange.Nutrient elements in leaves and shoots were lesser influenced by RKN damage, averageNdff of leaves and shoots declined while nitrogen-15distribution and accumulation didn’tchanged, the total content of N, P, K decreased a little with no clear difference. Ca, Mg, Cu,Zn in leaves and shoots increased slightly and Fe declined obviously.6. Cabernet Sauvignon plant appeared a reduction in storage nutrition in shoot and root afterdefoliztion. Starch content, soluble sugar content, free amino acid, soluble protein in shoot declined by6.0%,20.0%,27.4%,20.0%respectively, as well as in root with a decline of thelatter three materials by34.4%,10.3%,23.5%.