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V. Rice Breeding and Improvement in the United States
RICE IMPROVEMENT AND CULTURE IN UNITED STATES
in 1926. Rice experiments were conducted also at Elsbeny from 1928
to 1941 and later at Palmira in Missouri. Rice investigations were started
at the Delta Branch Experiment Station, Stoneville, Mississippi, in a
small way about 1950, and a fairly comprehensive breeding program now
is being conducted. Breeding investigations are conducted cooperatively
by the U.S. Department of Agriculture with State Agricultural Experiment Stations at each of these locations. Most of the earlier work
consisted of testing selections from foreign introductions. Some of the
varieties developed by selection from 1909 to about 1930 were CALORO,
NIRA, and REXORO. CALORO
and COLUSA are the leading
varieties at this time in California, and REXORO is grown on a significant
acreage in Louisiana and Texas. Salmon L. Wright, a rice farmer in
Louisiana, obtained material from varietal experiments on demonstration farms before the establishment of the Rice Experiment Station
at Crowley. From this material he selected the medium-grain varieties
BLUE ROSE and EARLY PROLIFIC and the long-grain varieties EDITH and
LADY WRIGHT. None of these varieties is now in production, but for many
years, about 1915 to 1944, they were the leading varieties in the South.
The varieties developed during these earlier years were described
by Chamliss and Jenkins (1923), Jones ( 1936), and Jones et al. ( 1941).
Rice improvement investigations were summarized by Jones ( 1936).
He stated that at that time the objectives were “to develop varieties
that are resistant to diseases, that do not lodge or shatter, that mature
at the desired time and that produce high field and mill yields of good
table quality.’’ It is seen that the present-day objectives, as given in
Section V, B, are simply a refinement and more detailed statement of
the earlier objective.
IN THE UNITED
Rice-breeding research at all experiment stations in the United States
is closely coordinated. This coordination is achieved because most of
this work is conducted cooperatively by the U. S . Department of Agriculture and the State Experiment Stations. The Rice Technical Working
Group meets biennially, so all rice breeders and geneticists can discuss
their common problems with other rice research workers. Uniform
yield and disease experiments conducted in the South further unify
Objectives of the rice-breeding program are to develop short-,
medium-, and long-grain varieties that germinate quickly and have
seedling vigor; tolerate low temperatures in the germinating and seedling
stages; are resistant to alkaline soils and salt in the irrigation water; are
C . ROY ADAIR, M. D. MILLER, AND H. M. BEACHELL
resistant to diseases and insects; respond to maximum rates of fertilizers;
have short, stifE straw and resist lodging; mature uniformly; produce
high field and mill yields over a wide range of environmental conditions;
and have the desired cooking and processing characteristics.
Breeding methods used for rice have followed the usual pattern for
all small grains. Up until about 1920, rice varieties were introduced from
most rice-producing countries and tested for adaptation in the United
States. Selections were made from the better varieties and several fairly
well-adapted varieties were obtained. These are mentioned in Section V, A.
It was not possible to attain all breeding objectives by these methods;
so, about 1920, some of the rice breeders started to make crosses in an
attempt to combine desired characteristics. All varieties that have been
released since 1942 are progeny of hybrids. The backcross or a modified
backcross method now is commonly used.
One example of a method now commonly used to achieve a breeding
objective is described: In 1956, the potential threat of hoja blanca, a
virus disease, to rice production in the United States was recognized.
In 1957, experiments were started in Cuba and Venezuela to test all
available material to determine the reaction to the hoja blanca disease.
It was learned that many varieties and breeding lines were resistant. All
the leading commercial varieties grown in the United States were
susceptible to hoja blanca, but short- and medium-grain types were
resistant and could be grown if the disease became established in this
country. There were no hoja blanca-resistant long-grain varieties adapted
to the environmental and cultural practices in the United States. Crosses
between resistant types and leading United States long-grain varieties
were made in the field in 1957. The F1 plants were grown in the
greenhouse and some were backcrossed to the long-grain parent during
the winter of 1957-1958.
When this program started, the backcrossed plants were saved
until their progeny had been tested to see which carried genes for
resistance to hoja blanca. The plants carrying resistance were then
backcrossed to the long-grain parent. It now i s possible to plant the
backcross seeds; and as soon as the plants tiller, they can be divided
and a part of each plant tested for reaction to hoja blanca in the greenhouse. Results of these tests are available by the time the plants flower so
that resistant plants can be backcrossed to the recurring parent. Plants
have been selected from each round of crossing and the progeny
continued in the selecting and testing program.
Concurrently with testing this material for reaction to hoja blanca,
the lines were tested for cooking and processing characteristics as
described in Section V, C.
RICE IMPROVEMENT AND CULTURE IN UNITED STATES
C. RESULTS OF THE RICE-BREEDING
All the rice varieties now grown in the United States were developed
by the U. S. Department of Agriculture in cooperation with the State
Agricultural Experiment Stations and other agencies. All varieties being
grown on farms and a few varieties that had been used as parents but
were not in production were described by Johnston (1958). Of the
22 varieties described by this author, 16 were developed and released
after about 1930, and 6 had been developed and released earlier. One
of these older varieties is BLUE ROSE, one of the Salmon L. Wright
varieties mentioned in Section V, A. Most of these varieties were described by Jones et aE. (1953). Two additional varieties, GULFROSE and
BELLE PATNA, have been released since 1958.
The annual acreage and production of rice varieties in the United
States for 1956 to 1960, inclusive, are given (Table V ) . The total
acreage was about the same in 1960 as in 1956 but it was lower in 1957
and 1958. The acreage of the R E x o R o - t y p e varieties declined sharply
during this period, but there was an increase in acreage in 1960 as
compared with that in 1959. The acreage of CENTURY PATNA 231 declined
sharply. The acreage of BLUEBONNET 50 increased slightly as did that
of ARKROSE. The CALROSE acreage increased in 1960 in California with
a corresponding decrease in the acreage of the short-gain varieties
CALORO and COLUSA. The acreage of TORO increased sharply in 1957
and 1958 and then declined in 1959 and leveled off in 1960. The greatest
change in varieties was the rapid increase in the acreage of NATO and
the corresponding decline in the acreage of ZENITH and MAGNOLIA.
The days from seeding to maturity, plant height, and grain yields
for 13 of the leading varieties are given (Table VI). The long-grain,
late-maturing varieties TEXAS PATNA, TP 49, and REXORO are grown only
in Louisiana and Texas. These varieties normally will not mature before
killing frosts in the other areas. The midseason long-grain varieties
BLUEBONNET 50, TORO, and SUNBONNET are grown throughout the Southern
area as is the early long-grain variety CENTURY PATNA 231. The midseason medium-grain variety ARKROSE is grown only in Arkansas. The
early-maturing medium-grain varieties NATO, ZENITH, and MAGNOLIA are
grown in all the southern rice-producing states. The medium-grain variety
CALROSE and the short-grain varieties CALORO and COLUSA are grown in
California. These three varieties sometimes are fairly productive in
the South but seldom are grown there because their yields are erratic
in the area and because of limited market demands for the rices. The
short-grain varieties sometimes are grown in Arkansas when seeding
is delayed because of inclement weather.
Annual United States Rice Acreage and Production by Varieties, 1956-19W
Includes TEXAS PATNA and TP 49.
Includes BLUEBONNET and SUNBONNET.
0 Includes a small acreage of KAMROSE and BLUE ROSE.
d Not the same each year, but includes REXARK, NIRA, R-N,
R-D, LACROSSE, and others.
e 1000 bags of 100 pounds each.
I Statistics compiled by the Rice Millers Association, New
g Included with
50 in report.
RICE IMPROVEMENT AND CWLTVRE IN UNITED STATES
The cooking and processing characteristics of rice varieties and
breeding lines have been tested in the cooperative quality laboratory at
Beaumont, Texas. Typical United States long-grain varieties cook dry
and flaky and are suitable for use in quick-cooking and canned soup
products. Typical United States medium- and short-grain varieties cook
moist and somewhat cohesive and are more suitable for making “dry”
cereals and for use in baby foods and in brewing. Eating habits of different ethnic groups vary; so there is a demand for all types for use as
Length of Growing Period, Plant Height, and Grain Yield of 13 Rice Varieties
Yield per acre
height 1953-58 1953-59 1955-58 1951-60
Arkansas, Louisiana, and Texas.
home-cooked table rice. The dry-flaky cooking characteristic is associated
with a high percentage of amylose, a medium-high gelatinization temperature, and a maximum viscosity of the cooked paste when cooled to
55°C. The amylose content is estimated by the starch-iodine method
( Halick and Keneaster, 195s), which requires only a small sample, and
quantitatively by the method described by Williams et al. (1958).The
gelatinization temperature is estimated by the digestion in dilute alkali
(Little et al., 1958) and determined fairly accurately by using the birefringence-end point-temperature or granule-swelling methods ( Halick
et al., 1960).For final testing of a new variety, the gelatinization temperature and pasting characteristics are determined with an amylograph
( Halick and Kelly, 1959).
Dimmsions, Physical, and Chemical Characteristics of Milled Kernels of 14 Rice Varietie9
ratio (cohesive(1:) ness No.)b
a Data from a study conducted by the Crops, Human Nutrition, Western Utilization, and Southern Utilization Research Divisions, Agricultural Research Service and Foreign Agricultural Service, U. S. Department of Agriculture.
b Batcher et al. (1956).
RICE IMPROVEMENT AND CULTURE IN UNJTED STATES
Data for some of the physical and chemical characteristics of 14
rice varieties are given (Table VII) . MOCHIGOMI is a “glutinous” variety;
that is, it has a very low percentage of amylose. The other 13 are
“common” varieties and have a comparatively high amylose content
although the range in the amylose:amylopectin ratio among the varieties
in this group is fairly wide.
The kernels of long-grain varieties (Table VII) are 6.5 mm. or more
in length and the 1ength:width ratio is 3.27 to 3.47:l. The kernels of the
medium-grain varieties range from 5.37 to 6.06mm. in length and have
FIG.1. Spikelets and milled kernels of: ( a ) long-grain variety BLUEBONNET 50;
( b ) medium-grain variety NATO;and ( c ) short-grain variety CALORO.
a 1ength:width ratio of from 2.09 to 2.46:l. KerneIs of the short-grain
varieties range from 4.56 to 5.01mm. in length, and the 1ength:width
ratio varies from 1.66 to 1.77:l. Kernels of all long-grain varieties were
lighter in weight than kernels of most medium- and short-grain varieties.
Spikelets and milled kernels of typical long-, medium-, and short-grain
varieties are shown in Fig. 1.
The gelatinization temperature of the starch was low for all shortand medium-grain varieties and intermediate for most long-grain
varieties. The two exceptions were CENTURY PATNA 231, which had a high,
and TORO, which had a low, gelatinization temperature.
The long-grain varieties TP 49 and REXORO had the highest amylose
50 and SUNBONNET had somewhat lower amylose
M. D. MMILLER,AND H. M. BEACHELL
content. The amylose content of CENTURY PATNA and
range as most medium- and short-grain varieties.
is in the same
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