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IV. Origin, Botany, and Genetics of Rice

IV. Origin, Botany, and Genetics of Rice

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TABLE IV

Chromosome Number and Distribution of O q z a Species

Species

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.

0.



sativa L.

sativa L. forma spontanea Roschev.

perennis Moench

grandiglumis ( Doell. ) Prod.

punctata Kotschy ex Steud.

stapfii Roschev.

breviligukta A. Cheval. & Roehr.

australiensis Domin

gkberrima Steud.

alta Swallen

latifolia Dew.

oficinalis Wall. ex Watt

eichingeri Peter

minuta Presl

granulata Nees & Am. ex Hook. f.

meyerianu (Zoll. & Mor.) Baill.

schlechteri Pilger

ridleyi Hook. f.

COaTCtata Roxb.

brachyantha A. Cheval. & Roehr.

tisseranti A. Cheval.

perrieri A. Camus

subulata Nees



Chromosome

no. (2n)

24 and 48

24

24

24 and 48



-



24

24

24

24

24 and 48

48

24

48

48

24 and 48

24



48

48

24



-



24



Distribution

India and Indochina

Asia

Tropical America, West Indies, Tropical Africa, Ceylon, and India

South America

North East Tropical Africa

West Tropical Africa

West Tropical Africa

Australia

West Tropical Africa

South America and Central America

Central America, South America, and West Indies

India and Burma

East Africa

Malay Peninsula, Philippines, Sumatra, Java, and Bomeo

India, Burma, Java, and Siam

Java, Bomeo, Philippines, and Siam

New Guinea

Malay Peninsula, Siam, Borneo, and New Guinea

India and Burma

West Tropical and Central Africa

Central Africa

Madagascar

South America



2



j

5



2



2

a

5E

2

d



i

?



i!



94



C. ROY ADAJR, M. D.



MILLER, AND H. M. BEACHELL



larities in the hybrid. A subsequent doubling of the chromosomes

attained the secondary balance of n = 12, the present existing number

in 0. satiua. More recently, Shastry et al. (1960) reported that on the

basis of their length and arm ratios, 12 pachytene bivalents in a s t r a i n

of 0. satioa could be identified. This report cast some doubt on the

validity that 0. sativa is a secondary balanced allotetraploid.

It was suggested by G. Watt, according to Chattejee (1948), that

OT~JZU

safiuu might have been derived from wild rices in India. Ramiah

sativa

and Chose (1951) stated that “there is clear evidence that OTYZU

var. futzta which occurs mainly in South and East Asia in a large number

of forms and crossed freely with 0. sativa has contributed to the

enormous varietal diversity existing in India.” Sampath and Govindaswami (1958) presented evidence in support of their theory that

0. satiua var. fatua Prain is a progeny of the cross 0. sativa x 0. perennis Moench., and that 0. perennis was the progenitor of 0. satiua. Results

reported by Yeh and Henderson (1961) support this theory. However,

0. sutiua var. fatw occurs as a weed in rice fields in South and East

Asia and crosses readiIy with cultivated varieties (0.sativu); so its does

contribute to the “varietal diversity.”

Much is known regarding interrelationships between species of 0y z a

as a result of investigations presented by Roschevicz (1931), Kihara

( 1959), Chattejee (1951), Sampath and Rao (1951), Ramiah and Chose

( 1951), and Yeh and Henderson ( 19sl). However, as Kihara ( 1959)

pointed out, much study is needed to elucidate fully the origin and

evolution of the genus Oyza.

The 23 species of Oyzn and the chromosome number and distribution as enumerated by Chatterjee (1948) and Kihara (1959) are shown

in Table IV. Since the synonomy used by Chatterjee was followed, some

of the species shown by Kihara ( 1959) and Roschevicz (1931) are not

listed. “Oryzu perennis var. b a h g a ” is not listed although Yeh and

Henderson (1961) presented evidence that this form should have specific

status as 0. balunga.”



B. DESCRIPTION

OF THE RICE PLANT

Rice ( O y z a sutiua) in the Gramineae tribe Oryzeae usually is

described as an annual although it is a perennial when soil moisture

and temperature are optimum for continued growth. Rice plants have

been maintained in the greenhouse for over twenty years. The roots

which arise from the lower nodes spread laterally and do not usually

penetrate more than 6 inches in depth. The primary culm has 12 to 18

nodes, depending upon the variety, but only 4 to 7 elongate. There is a

bud or potential bud in the axil of the leaf at each node that can give



RICE IMPROVEMENT AND CULTURE IN UNITED STATES



95



rise to a tiller. When space and soil fertility are optimal, some varieties

may produce as many as 100 tillers although when sown at the rate

usually followed in the United States, the number of tillers is 2 or 3.

The culms have hollow stems and solid nodes and vary in length from

2 to 6 or more feet, depending upon variety, soil fertility, and other

factors. Most varieties in the United States have culms 3 to 5 feet long.

The leaf consists of a sheath, auricle, ligule, junctura, and blade. There

is a leaf at each node, but the number of functional leaves at any one

time is usually 4 or 5 because the older, lower leaves die as new leaves

are produced. The leaf blades vary in width from about a fourth to more

than a half inch, and the color ranges from light yellowish green to

dark green.

The inflorescence is a panicle with the branches arranged singly or

in pairs. It varies from compact and erect to open and drooping.

The spikelet has one flower; it is strongly compressed laterally and

articulates below the two small outer glumes. Two bract-like organs

occur at the enlarged end of the pedicel. Weatherwax (1929) stated

that these bractlets are sometimes sufficiently elongated to be mistaken

for glumes. The true glumes are above the articulation. The “flowering

glumes” are the lemma, which has five nerves and may terminate in an

awn, and the palea, which has three nerves, two of which may terminate

in short conical teeth. There are two lodicules at the base of the palea,

which become turgid and open the flowering glumes at anthesis. The

flower consists of six stamens and a two-branched plumose stigma.

Anthesis usually occurs between 9:00 A.M. and 2:OO P.M. (Adair, 1934).

The time the flowers open is influenced by temperature and sunlight.

They open earlier on warm and sunny days than on cool or cloudy days.

Rice is normally self-pollinated although as much as 0.5 per cent natural

crossing may occur in the United States (Beachell et al., 1938). The

amount of natural crossing is higher when the relative humidity of the

air is high.

C. GENETICS, CYTOLOGY,

AND LINKAGE

GROUPSIN RICE

Most genetic studies on rice have been conducted in Japan, India,

China, or the United States. Most cytological studies that have been

reported were done in Japan, India, or the United States. Several papers

summarized rice genetic studies and two or three attempts were made

during the last twenty years to standardize the system of gene nomenclature in rice.

Jones (1936) summarized information on the mode of inheritance

of characters in rice. Kadam and Ramiah (1943) pointed out the need

of a standard system of gene nomenclature and suggested a system that



96



C . ROY A D A I R , hl. D. MILLER, A N D H. M. BEACHELL



might be used. They also summarized results of all available genetic

studies on rice. Nagao (1951) summarized the rice genetic data and

proposed a modification of the system outlined by Kadam and Ramiah.

Nagao also defined 4 linkage groups. Jodon (1955) summarized the

information on rice genetics and defined 8 linkage groups, and Nagao

and Takahashi (1960) gave a preliminary report on 12 linkage groups

in rice.

The International Rice Commission (FAO) Working Party on Rice

Breeding in the 1955 meeting recognized the need for a standardized

system of genic nomenclature and for a comprehensive survey of the

information available on linkage relationships in rice. A committee then

was appointed to undertake the work of proposing a system of nomenclature and summarizing the data on linkage groups. A preliminary

summary of the committee report (Anonymous, 1959) outlines the system

suggested for nomenclature of rice genes and gives the recommended

symbols for each gene that has been studied. The system proposed by

this committee follows the rules of the International Genetic Congress.

The report of this committee also summarized the information on linkage

groups in rice which followed closely the summary by Nagao and

Takahashi (1960). A more extensive review of the subject has been

prepared by this committee (Anonymous, 1962).

V. Rice Breeding and Improvement in the United States



A. HISTORYOF RICEBREEDING

IN THE UNITED

STATES

Although rice varieties were introduced subsequent to the establishment of rice culture in South Carolina, no effort was made by Federal

or State agencies to improve rice varieties for the United States until

rather recently. An abortive attempt was made in 1866, but the seed of

the four varieties introduced failed to germinate. However, work was

started by the U. S. Department of Agriculture in 1899 when Seaman A.

Knapp, then an explorer in the Division of Botany, introduced from

Japan 10 tons of Kyushu rice which was distributed in southwestern

Louisiana and probably eastern Texas, where he arranged farm demonstrations of rice varieties and cultural methods. Many varieties were

introduced and tested by Department workers on demonstration farms

in Louisiana and Texas and later in Arkansas and California before the

establishment of Rice Experiment Stations in these states.

The Rice Experiment Station at Crowley, Louisiana, was established

in 1909. The Biggs Rice Field Station, Biggs, California, and the Rice

Experiment Station, Beaumont, Texas, were established in 1912. The

Rice Branch Experiment Station, Stuttgart, Arkansas, was established



RICE IMPROVEMENT AND CULTURE IN UNITED STATES



97



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,

COLUSA, FORTUNA,

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.



B. CURRENT

OBJECTIVES

AND METHODS

FOR



THE RICE-BREEDING

PROGRAM

IN THE UNITED

STATES



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

the work.

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



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