Screening of interspecific guava hybrids for resistance to root-knot nematodes and fusarium wilt disease complex

Guava ( Psidium guajava L.) is one of the fifth most significant fruit crops in India. Nowadays, several biotic stresses viz ., root-knot nematodes (RKNs) and Fusarium wilt, pose a significant threat to its cultivation. This study aimed to identify the source of resistance to biotic stresses in wild Psidium spp. and their F 1 interspecific hybrids, conducted during 2022–2024. The findings revealed that P. cattleianum var. cattleianum and P. cattleianum var. lucidum were found to be immune to Meloidogyne spp . ( M. incognita and M. enterolobii ) with an RGI score of zero, and Fusarium oxysporum f.sp. psidii (FOP) with zero per cent wilting. A total of 17 interspecific hybrid progenies (‘Arka Poorna’ × P. cattleianum var. cattleianum ) showed resistance against M. incognita, and 14 were found resistant to FOP on challenge inoculation . Three interspecific hybrids of different combinations were found to have combined resistance to M. enterolobii and FOP, and one with moderate resistance. Histopathological studies revealed the presence of large giant cells, numerous eggs, root cavities, and damage to cortical tissues in RKNs-infected roots of susceptible plants. Disintegration of cortex tissues, necrosis and blockage of vascular bundles were observed in the roots of wilted plants, while P. cattleianum var. cattleianum showed healthy vascular bundle morphology in plants inoculated with FOP. These combined resistant progenies have good potential for guava improvement, especially for resistance breeding, and could be used either as rootstocks or as scion varieties, based on further evaluation of various horticultural traits.