Hayes and Garber - Cucurbit Breeding

176 BREEDING CROP PLANTS
hybrid segregation. In some crosses, studied independently by
McLendon (1912) and Balls, between the dominant fuzzy-seeded
and the recessive smooth-seeded forms, evidence was found of a
single-factor difference as well as a two-factor difference. Balls
also discovered that long fiber was dominant to short and that
but one main factor difference existed. Likewise a dominant
long petal crossed with a recessive short petal gave in the F 2
generation a 3:1 segregation. In a cross between Egyptian
(Abassi) and Texas Upland, Balls obtained transgressive segregation
in height of plants. Similar results were secured in
studying the inheritance of date of flowering and weight of seed.
The results of the study of weight of seed are of general interest.
0.050 0.100 0.150 Gram
FIG. 42. Seed weights of parent varieties, King and Charara, and Fi and Fz
generation crosses. (After Balls.}
In a cross of Afifi and Truitt, where the mean seed weights of the
parents were 0.105 g. and 0.135 g. respectively, the weight of the
Fi was 0.165 g. Weights in F 2 varied from 0.08 g. to 0.175 g. The
light-seeded forms bred comparatively true in F 3 although differing
somewhat in means. The larger-seeded types bred true in
F 3 or segregated, giving both large-and small-seeded forms. An
illustration of this sort of behavior for the parents, FI and Fz
generations, is given in figure 42 diagrammatically. As has been
pointed out, length of lint is also inherited and in some cases
segregation approaches a simple 3:1 ratio with long lint as the
dominant character. Later generations in some crosses gave
pure parental types as well as other lint lengths which appeared