A pot experiment was conducted to evaluate the influence of pre-inoculation of cucumber plants with each of the three arbuscular mycorrhizal (AM) fungi Glomus intraradices, Glomus mosseae, and Glomus versiforme on reproduction of the root knot nematode Meloidogyne incognita. All three AM fungi tested significantly reduced the root galling index, which is the percentage of total roots forming galls. Numbers of galls per root system were significantly reduced only in the G. intraradices + M. incognita treatment. The number of eggs per root system was significantly decreased by AM fungus inoculation, no significant difference among the three AM fungal isolates. AM inoculation substantially decreased the number of females, the number of eggs g−1 root and of the number of eggs per egg mass. The number of egg masses g−1 root was greatly reduced by inoculation with G. mosseae or G. versiforme. By considering plant growth, nutrient uptake, and the suppression of M. incognita together, G. mosseae and G. versiforme were more effective than G. intraradices.

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Pre-inoculation with arbuscular mycorrhizal fungi suppresses root knot nematode (Meloidogyne incognita) on cucumber (Cucumis sativus)

Screening plants resistant against Meloidogyne incognita and integrated management of plant resources for nematode control

Root-knot nematodes (Meloidogyne spp) are destructive agricultural pests that reduce the productivity of cultivated vegetables worldwide, especially when vegetables are cropped continuously in greenhouses. Cucumbers (Cucumis sativus L.), in particular, suffer extensive damage due to root-knot nematodes, and only a few wild species are known to be resistant. Grafting of cultivated plants to rootstocks of known resistant germplasms could be an effective method to resolve this problem. In this study, 21 cucumber germplasms and seven rootstocks were evaluated for resistance based on the growth of cucumber seedlings and resistance indexes to Meloidogyne incognita, which were surveyed 25 days after inoculation with M. incognita. Cluster analysis and principal component analysis (PCA) were used to investigate the resistance of 21 cucumber germplasms and seven rootstocks based on their growth and resistance indexes after inoculation with M. incognita. These analyses showed that the 21 germplasms and seven rootstocks could be divided into three groups based upon their resistance levels: moderately resistant, susceptible, and highly susceptible to M. incognita. All 21 cucumber germplasms exhibited susceptibility or high susceptibility to M. incognita and most rootstocks exhibited moderate resistance. The PCA results were consistent with those of the clustering analysis. The Jinyou No.1 cultivar had the highest resistance to M. incognita among the 21 cucumber germplasms, and Huangzhen No.1 cultivar had the highest resistance among the seven rootstock cultivars.

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Screening and identification of cucumber germplasm and rootstock resistance against the root-knot nematode (Meloidogyne incognita).

Reduced Meloidogyne incognita infection of tomato in the presence of castor and the involvement of fatty acids.

The plants of cucumber, Cucumis sativus cv. Green Long grown in earthen pots filled with nematode infected soil (1500 juveniles of Meloidogyne incognita/kg soil) without any treatment under polyhouse conditions showed stunted growth with mild chlorosis of the leaves and excessive galling on the roots. Seed treatment with Pseudomonas fluorescens ITCC-B0034, Bacillus subtilis RP24, Trichoderma harzianum ITCC-6796, T. longibrachiatum ITCC-7437, T. viride ITCC-6889, and nematicide (carbofuran) decreased the galling (16–68%), egg mass production (12–62%), and the nematode soil population (29–87%) over untreated control. Maximum decline in the galls/root system was recorded with carbofuran (68%), T. viride (66%) and T. harzianum (61%). The above treatments caused around 55–62% suppression in the egg mass count. The root zone population of M. incognita was decreased by 87% (carbofuran) and 79–84% (T. viride and T harzianum) over control. Treatments with carbofuran, T. viride and T. harzianum significantly enhanced the plant growth of nematode infected cucumber plants (15–28%), followed by P. fluorescens (13–20%) over inoculated control. Treatment with P. fluorescens also significantly enhanced the growth of uninoculated plants. Nematode inoculation decreased the plant biomass (28%), leaf chlorophyll a (24%), chlorophyll b (20%), total chlorophyll (25%), carotenoids (27%), and photosynthesis rate (23%), and increased the transpiration rate (18%) over control. The above biochemical and physiological parameters increased by 5–17% in nematode infected plants receiving T. viride, T. harzianum or carbofuran treatments.

Management of root-knot nematode in cucumber through seed treatment with multifarious beneficial microbes in polyhouse under protected cultivation

During 2001～2003, systemic investigation on occurrence and damage of vegetable root-knot nematode diseases under protected cultivation was conducted in Shandong province. The results showed that vegetable root-knot nematode diseases in protected field existed universally. Nematode-infected plants were found in 67.6% greenhouses and the rate of totally diseased plants was 50%. In four or more years old of cucumber or tomato greenhouses, the rates of greenhouse and plant were even up to 95% and 66%, respectively. Identification host and perineal pattern techniques were used to identify the root-knot nematode species in the samples which were collected from infected fields. Meloidogyne incognita was the dominant species occurring under protected cultivation vegetable field in Shandong province. M. incognita populations were found in 97.94% samples, while M. arenaria race 1 populations were found in 7.73% samples. Moreover, most of the M. arenaria infected samples were co-infected with M. incognita, with only one exception.

Zhiqiang Zhao

Papers

Species Identification and Occurrence Investigation of Vegetable Root-Knot Nematodes under Protected Cultivation in Shandong Province