INHERITANCE OF RESISTANCE TO FUSARIUM WILT IN YARDLONG BEAN VIGNA SESQUIPEDALIS (L.) FRUHW

The objective of this study was to determine the mode of inheritance of resistance to Fusarium wilt (Fusarium oxysporum f. sp. trancheiphlum) in yardlong bean (Vigna sesqupedalis (L) Fruhw. ) .Two Fusarium wilt resistant cultivars of yardlong bean, 'Zhuchang Dou' and 'Zhu Yan', were crossed in turn with two susceptible cultivars, 'Hong Zui Yan' and 'SI Gi Ching'. The F, generations of the crosses all showed resistance to the disease as identified by the inoculation with mixed spores of 5 isolates of F.oxysporum f .sp .tranchei-p'il'um that were collectel in the region of Guangzhou. Progeny of the F2 generations of all the corosses segregated in the ratio of 3 : 1 (resistant t suscepsible) , indicating that resistance is governed by a single dominant gene. The same ratio could be obtained whether a resistant cultivar or a susceptible cultivar was used as the maternal parent in the crosses, when theF, plants were backcrossed to the susceptible parents, the BC 1 population segregated in the ratio of 1 t 1 (resistant : susceptible) , but when they were backcrossed to the resistant parents, the BC 1 generations were entirely resistant. The results as shown by the F1 , F2 and the BC 1 generations demostrated that the resistance of 'Zhu Chang Dou' and 'Zhu Yan' to Fusarium wilt was governed respectively by one dominant gene.