Screening Selected Solanum Plants as Potential Rootstocks for the Management of Root-Knot Nematodes (Meloidogyne incognita)

Root-knot nematodes (RKNs) (Meloidogyne spp.) represent agricultural pest of many economic crops, including tomatoes and potatoes. They advance a complex parasitic relationship with roots of tomato plants leading to modification of host structural and physiological functions in addition to significant yield loss. Resistance in solanaceous plants to RKNs has been identified and associated with the possession of Mi gene. The reaction of four Solanum rootstocks (S. aethiopicum L., S. macrocarpon L., S. lycopersicum L."Mongal F1," and S. lycopersicum L. "Samrudhi F1") was evaluated in pots and in a natural Meloidogyne spp.-infested field in a two-year trial (2015-2016), to identify RKN-resistant rootstock(s), which can be utilized in tomato grafting as a management measure against these nematodes. A rootstock's reaction to RKNs was assessed using root gall scores (GSs), egg count/g of root, and reproductive factors (Rfs) at the end of 6 and 12 weeks after transplanting (wat) in infested fields, respectively. Solanum macrocarpon, S. aethiopicum, and Mongal F1 showed tolerant responses with reduced root galling and low to high reproductive factors in pot and field experimentation. Although Samrudhi F1 was resistant in both pot and field trials and consistently decreased nematode root galling (<1.00) and reproduction (Rf < 1.00), it failed to significantly increase yield, as compared with the highest yield obtained by the tolerant rootstock, Mongal F1 (870.3 and 1236.6 g/plant, respectively). Evaluation of the four rootstocks against four (0, 500, 1,000, and 5000) RKN inocula levels (Juveniles) showed no significant differences among the growth parameters (fresh and dry shoot and root weights). Root-knot nematode-susceptible tomato varieties, for example, Pectomech F1, a popular tomato variety in Ghana, can be grafted onto the RKN-resistant and RKN-tolerant rootstocks for increased yields.