Interactive effects of Meloidogyne incognita and Fusarium oxysporum f.sp. vasinfectum on okra cultivars

Abstract

In the present study, nine okra cultivars were assessed for their resistance levels against both predisposal and simultaneous infections of the root-knot nematode Meloidogyne incognita and the wilt-causing fungus Fusarium oxysporum f.sp. vasinfectum, with the objective to identify cultivars with collective resistance against these two significant pathogens. Okra cultivars displayed varying resistance to M. incognita and F. oxysporum f.sp. vasinfectum based on different inoculation sequences. When nematodes were introduced 15 days before fungus, no high or moderate resistance was observed. Instead, some cultivars showed moderate susceptibility (Pusa Swami, PB Selection, Green Star), susceptibility (Sabz Pari, Neelum, Tulsi), or high susceptibility (Ikra-1, Ikra-2, Arka Anamika) to nematodes. Conversely, nematodes introduced after fungus resulted in some resistance and moderate resistance among certain cultivars, and simultaneous inoculation led to varied responses. In terms of gall formation, eggmasses, and reproductive factors, different cultivars exhibited varying levels of susceptibility. Ikra-2 had the highest, followed by Arka Anamika and Ikra-1, while Pusa Swami had the least, followed by PB Selection and Green Star. Sequentially introducing nematodes before fungus led to the highest gall formation, whereas the reverse sequence resulted in the least on all cultivars. Simultaneous inoculation yielded lower gall formation than nematodes first followed by fungus. Introducing fungus prior to nematodes reduced gall numbers to the lowest level. In summary, resistance of okra cultivars to nematodes and fungus depended on inoculation order. Okra cultivars exhibited varying susceptibility levels, and the timing of inoculation influenced gall formation and reproductive factors.