Reaction of Commercial Cultivars of Kiwifruit to Infection by Root-knot Nematode and Its Biocontrol Using Endophytic Bacteria

Root-knot nematodes (RKN) cause considerable economic losses to kiwifruit production annually. Screening of resistant cultivars has been one of the long-standing methods to manage root-knot nematodes. Here, the reaction of the four most common commercial cultivars of kiwifruit, namely, Actinidia chinensis var. deliciosa cv. Hayward, A. chinensis var. deliciosa cv. Abbott, A. chinensis var. deliciosa cv. Bruno, and A. chinensis var. chinensis cv. Haegeum (commonly known as 'Golden' kiwifruit) to infection by the RKN, Meloidogyne incognita, was evaluated. Among examined cultivars 'Golden' was the most susceptible, having on average 52.8 galls, 56.1 egg masses per gram of root, and 642 J2 population per 200 gram of soil. 'Bruno' showed the highest resistance, with 3.3 galls, 4.1 egg masses per gram of root, and 79 J2 in 200 g of soil. Then, two potential biological control agents, namely Priestia megaterium 31.en and Agrobacterium tumefaciens 19.en were used on 'Hayward' seedlings against M. incognita and showed a significant reduction in the number of galls and egg masses on roots, juvenile population in the soil, and increased the growth parameters of the plants compared to non-treated seedlings. We demonstrated that integrated management using resistant cultivars and biological control can provide a safe and economic method to control RKN, and these resistant cultivars can be used in breeding programs.