Two crosses were made between different watermelon cultivars, i.e. Charleston Gray X Baby Sugar and Crimson Sweet X Baby Sugar as well as there reciprocal crosses, in order to study the inheritance and nature of resistance to fusarium wilt disease. The F1 hybrid showed high resistance to the disease. The ratios of resistant to susceptible plants in the F2 and Bc1 populations ( backcross to the susceptible parent) were 3 : 1 and 1: 1, respectively . The earliness and total yield/plant were inherited quantitatively. The nature of dominance for earliness and total yield/plant ranged from partial to over dominance in both crosses. The estimates of broad sense heritability for earliness and total yield/ plant ranged from intermediate to above intermediate, while those of the narrow sense heritability ranged from low to intermediate. With regard to number of gene pairs differentiating the two parental cultivars for earliness ranged from 1 to 3 and for total yield/plant from 1 to 5 pairs. Plant reaction to fusarium wilt disease were negatively correlated with each of earliness, fruit length, diameter and weight and total yield/plant, Moreover, there were highly significant positive correlations between plant reaction to fusarium wilt disease and each of reducing, non-reducing and total sugars. Also, negative correlation with each of total, free and congested phenols in the cross Crimson Sweet X Sugar Baby was found. The combined effect of plant disease reaction, number of branches/plant, fruit set percentage and fruit length, diameter and weight on total yield/plant was highly significant |
