Hayes and Garber - Cucurbit Breeding

108 BREEDING CROP PLANTS
same plant. According to Carleton, seeds of either form of
plant produce both kinds, and the ratio is not influenced by soil
quality. Dimorphism facilitates cross-pollination.
Breeding Buckwheat. Little attention has been given to the
improvement of buckwheat by breeding. It shows considerable
variation, and undoubtedly strains could be isolated that would
surpass present commercial varieties. Selections for yield
are being made in the United States. In Russia some work is
under way to produce strains or varieties with four-faced seeds.
These are supposed to be more resistant to early spring frosts.
RICE
Rice is thought by Carleton (1916) to have " originated somewhere
in the region from China to India inclusive." It has not
been recorded with other cereals that were grown in Egypt in
ancient times.
Little study has been made regarding classification
and genetic relationship of the wild and cultivated species.
Cultivated races are classified into glutinous and non-glutinous
groups. Other characters of importance in varietal classification
are size, shape, and color of seed; color of glumes and leaf
sheath; awned or awnless glumes; and length of glumes, whether
long or short. A short summary of inheritance of some individual
characters is of interest. (See Table XVIII.)
Inheritance of Characters. The endosperm of rice is glutinous
or starchy. The glutinous group is not grown in the United
States or generally in Europe as a commercial crop. On cooking,
it runs together into a pasty mass while the seeds of common rice
keep their shape when properly cooked.
rice is
The starch of ordinary
replaced by a sort of dextrine in the glutinous varieties.
Apparently one Mendelian factor difference separates these
groups. The color of the seed is also an endosperm character.
Blue is dominant over red and red over white.
The inheritance of plant characters may be explained by the
usual Mendelian method. The ratios given show that color
inheritance may be explained by one or more factors.
Ikeno
(1918) studied the inheritance of a number of size characters.
In some cases dominance was obtained in F\. In other characters
the FI was intermediate. Complex segregation occurred in
F 2 but with no definite ratios. Multiple factors were used to
explain the results.