Report on the Agricultural Experiment Stations, 1939 Page: 26

                                
26          REPORT ON EXPERIMENT STATIONS, 19 3 9
SORGHUM
Improvement.-Early-maturing sorghum varieties developed by
the Texas station cooperating with the Department (B.P.I.) have
made possible the production of two crops in a single year in south
Texas and an almost unlimited quantity of forage. By combining
the grain and drying it in commercial dehydration plants, the early
spring crop can be placed on the market when supplies of carry-over
grain are low and prices are relatively high. These agencies continue
to serve growers by developing improved strains and varieties
that are more desirable than older sorghums because of greater
yields, increased resistance to diseases and insects, or greater nutritive
value.
A_ strain of Double Dwarf milo resistant to Pythium root rot (P.
arrhenomnes) developed by the California station has saved an
important industry in the delta section of California and probably
also in other sections of the State. Resistant strains developed in
the Great Plains had been found poorly adapted to California conditions.
Sorghum strains low in hydrocyanic acid, released by the
South Dakota station-for example, low-acid Dakota Amber (No.
39-30-3)-ripen uniformly, and when harvested in the matured stage
and well cured in shocks promise to eliminate considerable forage
poisoning.
Hydrocyanic acid (HCN) content.-Extended study by the South
Dakota station has shown that environmental conditions promoting
normal and regular growth in sorghum evidently lead to minimum
HCN content, while conditions retarding normal development result
in corresponding increase in HCN in subsequent growth. The HCN
content varied with variety; was controlled by heritable factors,
low HCN being partly dominant over high HCN; averaged eight
times as high in leaves as in stems; varied with time of day and
locality; was lower in response to fertilizers except nitrogen; rose
after green manure; was lower in irrigated than on dry land, dropping
with increased soil moisture; was gradually lost in curing,
particularly in the sun and with exposure to air; was liberated faster
and more completely than normal by freezing; and was not related
to total sugar content in the strains studied.
Growth curves.--Hegari and milo, field-grown at the Arizona station
cooperating with the Department (B.P.I.), produced about 10
to 15 percent of the final dry weight of stalks and heads in the first
half of the growing period. A much slower increase in growth in
early developmental stages and a faster increase at later stages were
noted than expected from the symmetrical sigmoid growth curve
typical -of many plants. Size of seed planted was related closely to
the dry weight per stalk in early development stages of varieties of
sorghum, corn, and proso, representing a wide range of seed sizes.
Seedling size was a logarithmic function of the "active mass" in the
seed.
SOYBEANS
Soybean growing for seed, hay, pasture, and soil improvement,
and lately as a vegetable, continued to expand rapidly in the Corn
Belt and other northern States, in the South, and in other regions
of the United States, attaining a total of 10,006,000 acres in 1939.