Hayes and Garber - Cucurbit Breeding

BREEDING OF VEGETABLES 245
reactions are known indicate (McRostie, 1919; Burkholder,
1918) that resistance to either the alpha or beta strain is inherited
as a simple dominant, involving but a single factor difference.
It seems, therefore, very easy to produce resistant varieties to
both strains by crossing and selection and thus to combine desirable
economic characters and anthracnose resistance.
McRostie (1921) has recently published an interesting paper
on further studies of disease resistance in common beans. The
more extensive results obtained bear out the earlier views on
the mode of inheritance of resistance to bean anthraxnose. The
studies carried out show that bean mosaic susceptibility is inherited.
In FI there was a partial dominance of susceptibility
over resistance and in F z a segregation which indicated a two
factor hypothesis.
In crosses between susceptible and resistant
varieties in relation to the dry root rot, caused by the fungus,
Fusarium martii phaseoli Burk., there was a dominance in F\
of susceptibility and a segregation in F% that appeared to be on
a 9 :7 basis. In nearly all cases resistant F 2 plants bred true to
this character in Fz. Results of this nature show the great
practical importance of the application of Mendelian principles
to breeding for disease resistance. It seems very likely that a
large
part of our serious plant diseases will be controlled eventually
by the production of
disease resistant varieties.
TOMATO
Classification Characters and Inheritance. The tomato belongs
to the genus Lycopersicum of which there are several
cultivated species. Tomatoes are classified on the basis of vine
habit, either standard or dwarf, leaf type, period of maturity,
size and color of fruits, and other characters. As a result of
breeding experiments, many different combinations of characters
have been made. Price and Drinkard (1908) were among the
first investigators to report on the simple Mendelian behavior of
certain tomato characters. Table LXIII, taken from similar
ones compiled by Tschermak (1916) and Jones (1917), presents
a brief summary of inheritance in the tomato.
Fruit shape is dependent on several factors according to
Crane (1915) and Groth (1912, 1915). Some of the foliage
characters are also somewhat complicated in their inheritance
(Groth, 1911). The inheritance of each of the other characters
listed in the table is dependent on single factor differences.