Phenotypic and genotypic characterization of tomato genotypes for resistance to root-knot nematode, Meloidogyne incognita

Root-knot nematode is a major constraint to tomato cultivation in open and protected structures. Resistance sources need to be continuously identified for combating pathogens affecting the yield. In the present studies, forty-seven genotypes of tomato were evaluated phenotypically along with their genotypic characterization. On the basis of their phenotypic reaction, the genotypes were grouped into four categories viz.: resistant, moderately resistant, susceptible and highly susceptible. Of these genotypes, only five were found to be resistant while forty-two were rated from moderately resistant to highly susceptible. Multiplication of Meloidogyne incognita was greatly reduced (Rf < 1) in resistant genotypes as compared to susceptible genotypes. Root galling index was also very low in resistant genotypes. Using molecular markers, the presence of the Mi-1.2 resistance gene was also confirmed in five resistant genotypes (L-0272, NR-14, L-097, L-0275 and PNR-7). These resistant sources could become a source of germplasm in breeding programs for the development of resistant cultivars.Le nématode à galles est une contrainte majeure à la culture de la tomate dans des structures ouvertes et protégées. Les sources de résistance doivent être identifiées en permanence pour lutter contre les agents pathogènes affectant le rendement. Jusqu’à présent, quarante-sept génotypes de tomate ont été évalués phénotypiquement, de même que leur caractérisation génotypique. Selon leur réaction phénotypique, les génotypes ont été regroupés en quatre catégories : résistant, modérément résistant, sensible et très sensible. Parmi ces génotypes, seuls cinq se sont révélés résistants tandis que quarante-deux ont été classés de modérément résistants à très sensibles. La multiplication de Meloidogyne incognita était fortement réduite (Rf < 1) dans les génotypes résistants par rapport aux génotypes sensibles. L'indice de galles racinaires était également très faible dans les génotypes résistants. À l'aide de marqueurs moléculaires, la présence du gène de résistance Mi-1.2 a également été confirmée dans cinq génotypes résistants (L-0272, NR-14, L-097, L-0275 et PNR-7). Ces sources résistantes pourraient devenir une source de matériel génétique dans les programmes de sélection pour le dévelop-pement de cultivars résistants

Management of Root-Knot Nematode with Non-Chemical Methods for Sustainable Production of Cucumber under Protected Cultivation

The multi-faceted benefits of growing crops under protected cultivation are gradually establishing it as a promising technology for vegetable cultivation in India. However, the adoption of successive cropping patterns in soil-based closed structures is leading to the buildup of soil-borne pathogens and pests, which are becoming a major hindrance to the sustainable production of these crops, particularly in the northern plains. Root-knot nematodes (RKNs) are a critical threat to protected cultivation and farmers are required to contribute a significant amount of time and money for their management. To reduce the overdependence of chemicals, the present study explored the potential of plant-based by-products as amendments for the management of RKN in cucumbers grown under a plastic greenhouse. A pot trial was conducted to assess the efficacy of different plant-based amendments against nematodes in cucumber plants. The pot trial results revealed that the application of mustard cake (MC) and neem cake (NC) at 1 t ha−1 either alone or as a combined application with farmyard manure (FYM) of 2.5 t ha−1 was effective against RKN infestation, reflecting the improved plant growth parameters of cucumber. Based on the results of the pot trials, treatments with plant-based amendments and FYM i.e., T1: MC 1 t ha−1; T2: NC 1 t ha−1; T3: FYM 2.5 t ha−1; T4: MC 1 t ha−1 + NC 1 t ha−1 + FYM 2.5 t ha−1, along with the treated check carbofuran 3 G 2 kg (a.i.) ha−1 (T5) and untreated check (T6), were evaluated in multi-locational field trials. The results revealed that the combined application of MC 1 t ha−1 + NC 1 tha−1 + FYM 2.5 t ha−1 exhibited promising results in decreasing RKN infestation (56–58%) in all of the three RKN-infested polyhouses, with significantly enhanced yields at all of the three locations. Soil organic carbon also increased significantly in the amended plots, indicating improved soil health. The results of the present work hold good promise for the management of RKN in the protected cultivation of cucumber with an environment friendly approach, along with the additional incentives of improved soil health