Screening of cucumber (Cucumis sativus L.) cultivars against southern root knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood

Fourteen cultivars of cucumber were screened for their resistance to the Southern root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood in an in planta experiment. The pots were maintained in greenhouse with CRD for 50 days after inoculation. The cultivar DS92-05 induced significant mortality and was rated “moderately resistant (MR)”. This cultivar showed increase in plant growth parameters including vine length. The cultivars DS92-06, Laghman, Sultan and Desitype were moderately susceptible (MS). The cultivar Rehan and DS96-299 were rated susceptible (S) whereas DS97-299, Chaiya, Beitalpha, Alto, DS92-04 and Local were rated as highly susceptible (HS). DS92-05 is thus promising for sustainable agriculture, specially in those areas with high population density of Southern Root knot nematode. Introduction Cucumber (Cucumis sativus) is one of the most important vegetable crops in open-field and plastic-tunnel farm lands in Pakistan (Kaur et al. 2010). In world’s vegetable market, cucumber is fourth important vegetable crop after cabbage, tomato, and onion (Efediyi and Remison 2010). It is a good source of roughages, vitamins, fiber and minerals (Hussain et al. 2011). In Pakistan, the cultivation area under cucumber and gherkins is 3,528 ha. Total production of cucumber and gherkins is 50,164 tonnes (FAO 2016). Cucumber plant is susceptible to different plant parasitic nematodes among which the root-knot nematode Meloidogyne incognita is known to occur throughout the world. They are considered among the top five major plant pathogens and the first among the ten most important genera of plant parasitic nematodes in the World (Mukhtar et al. 2013). Meloidogyne spp. are widely distributed and are among important damaging plant parasitic nematodes of cucumber in Pakistan (Anwar and McKenry 2010). Disease incidence in different localities has been reported to be 46% in open-field cucumbers (Nagesh et al. 2005). Meloidogyne species live in soil as eggs and second stage juveniles (J2S). The J2S puncture the root walls of cucumber, and attain feeding site into the vascular tube that makes the giant cells. Above-ground symptoms on cucumber include drooping, dwarfing and general off-colored look of the infected plants (Youssef 2001). The main control measures for nematodes have been the use of chemical nematicides. But due to the spreading hazards of chemicals now non-chemical methods are encouraged. The most effective strategy to control root knot nematodes in cucumber is the use of resistant germplasm. The use of resistant varieties is not only economical for the farmers but it also greatly reduces nematode populations in infested fields (Clark and Mayer 1988). Development of resistance in *Author for correspondence: <asadraja@aup.edu. pk>. Chinese Academy of Agricultural Science, Institute of Vegetable and Flower, Beijing, P.R. China. Department of Livestock, Management, Animal Breeding and Genetics, Faculty of Animal Husbandry and Veterinary Sciences, The University of Agriculture, Peshawar, Pakistan.