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 F, hybrid showed high resistance to the disease. The ratios
of resistant to susceptible plants in the F2 and B c, populations ( backcross tot he
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 yieldrplant was
highly significant.