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VIII. Identification of Sorghum Varieties for Maturity
MATURITY GENES OF SORGHUM
Frequency Distributions of Flowering of F2 and Parental Populations Grown a t
Plainview, Texas, in 1964 and 1965 Showing the Effect of Heterozygosity
at Loci 3 and 4
CH X EH, Fn
44M X SOM, Fz
M a l ~ M a 3 M a 4 80M
superficially resemble normal curves, and this resemblance could lead
to the erroneous assumption that numerous gene loci are involved in
maturity. Because there may be interest in the methods used in genetic
studies of maturity in sorghum, a brief account of the methods used is
presented here even though the methods have been presented previously
(Quinby and Karper, 1945, 1961; Quinby, 1966).
Parental and segregating populations are grown and the plants tagged
for time of flowering. A plant is considered to have flowered as soon
as one spikelet blooms and anthers are visible. A small tag on which the
days from planting to flowering is written is tied on each head on the
day it flowers. Flowering data are recorded by tallying the number of
plants that flower on each day. If F, rows are to be grown, F, plants
are always selfed by bagging. Days to flowering are calculated from
J. R. QUINBY
the day of planting. The days to flower assigned to a genotype is the
day on which a substantial part of the population has started to flower.
This day is usually the second or third day after the first plant in the
genotype has flowered.
In the early stages of identification, F, generations were grown
into the F, to verify the F, identifications. The growing of F, rows,
tagging all the plants for time of flowering, and recording the data
from the tags was so time consuming that the verification hampered the
identification of other varieties. More recently, an easy but effective
way to identify and to verify the identification of varieties for maturity
has been used, A variety of unknown maturity genotype is crossed to
the 100M, 90M, 80M, and H genotypes, and F, populations are grown.
One of the F, populations will segregate only at one locus and the 3 :1
segregation will reveal the identity of the unknown variety. The identification can be verified by looking for the expected 2 and 3 gene segregations in the other segregating populations. The problem in using this
method is the identification of the dominant or recessive condition at locus
3. lOOM and 90M genotypes are difficult to distinguish in segregating
populations and single gene 3 :1 segregations are difficult to distinguish
from 2-gene, 12:4 segregations.
Little use has been made of F, plants in identifying varieties for
maturity constitution. The time of flowering of F, plants would be useful, but usually not many seeds were produced and frequently those
were planted in the greenhouse, in Jamaica, or in some planting other
than one close to June 1.
At Chillicothe and Plainview, Texas, segregations that separate
the different genotypes are always obtained from early June plantings.
For a time at Chillicothe, because of the migration of chinch bugs to
sorghum in early June, it was necessary to delay planting until June 20.
Maturity of early genotypes was hastened by such late planting, but
clear-cut segregations were always obtained. Plantings on May 15 at
either Plainview or Chillicothe are not fruitful of results because the
longest days of summer are needed during the period prior to floral
initiation to separate certain genotypes, particularly 60M from SM60.
B. THEORIGINOF MATURITY
The three maturity gene loci reported in 1945 were found in Milo
(Quinby and Karper, 1945). This variety reached Colombia, South
America, from Africa during the days of the slave trade and subsequently
reached the United States in 1879 (Karper and Quinby, 1946, 1947).
When Milo reached the United States, it was one variety, apparently, of
the genotype Ma, Ma, Ma, Ma, Dw, Dw, Dw, d w Y . In the years be-
MATURITY GENES OF SORGHUM
tween 1879 and 1950, farmers selected at least seven varieties of shorter
stature and earlier maturity. In addition, a number of strains resistant
to Periconia root rot were selected by farmers or plant breeders working
for public institutions at the time the disease became prevalent in the
Great Plains and in California during the 1930’s (Quinby and Karper,
1949). These selected strains are all Milos and differ from one another
only in a few genes for height, maturity, pericarp color, or Periconia
Two Milo strains were used as parents to obtain 8 tester lines for
maturity that have been used in genetic studies and are the first 8 listed
in Table I. The parent lines were Early White Milo, SA1170, that
originated from one resistant plant growing in a Periconia root-rot infested field southeast of Quanah, Texas. SA1170 must have originated
from the original introduction by mutating to recessive mal, to recessive
y, and to resistance to Periconia root rot. The second variety, Double
Dwarf Yellow Milo, SA292, came from a resistant plant from a diseased
field in California, and seed was obtained from Dr. Dale Smeltzer of
the California Station at Davis. SA292 originated by mutating to recessive dw, and dwz, to recessive ma, and ma3, and to resistance to Periconia root rot.
Early White Milo, SA1170, is genetically ma1M a , M a , M a , for maturity and Dw, DwpDw, dw, for height. Double Dwarf Yellow Milo,
SA292, is M a , maz ma3M a , for maturity and dw, dw, Dw, dw, for height.
SA1170 and SA292 were crossed, and eight maturity genotypes were
obtained. The linkage between genes M a , and dw, was broken, and the
8 genotypes are all 3-dwarfs of the dw, dw, Dw, dw, height constitution.
Only one source of each recessive and each dominant at the first three
maturity loci was involved in obtaining the 8 genotypes.
Four gene loci that control time of floral initiation have been recognized, and 28 varieties have now been identified for dominance or
recessiveness at the four loci. Interest in the genetic identity of varieties
lies in the interaction of their alleles in different combinations. The
maturity genotypes of 28 varieties are shown in Table XIV. The first
11 varieties were identified earlier (Quinby and Karper, 1945, 1961;
Quinby, 1966). The other 17 varieties are identified only as being dominant or recessive at the four maturity gene loci. Allelic series exist at
each locus, as will be explained in Section IX. Proof of the genetic
identity of the additional 17 varieties will not be presented here. The
identifications were made by using the methods described in Section
J. R. QUINBY
Identification of Sorghum Varieties for Dominance or Recessiveness a t Four Gene
Loci and Their Times of Flowering at Plainview, Texas, in 1964
100-day Milo (100M)
90-day Milo (90M)
80-day Milo @OM)
60-day Milo (60M)
Sooner Milo (SM100)
Sooner Milo (SM90)
Sooner Milo (SM80)
Sooner Milo (SM60)
Ryer Milo (44M)
38-day Milo (38M)
Early Hegari (EH)
Combine Hegari (CH)
Texas Blackhull Kafir
Pink Kafir (31432
Red Kafir PI19492
Pink Kafir PI19742
Days to flower
1. Maturity Genotypes o f the Hegaris
The varieties of the Hegari group are Hegari, Early Hegari, Combine
Hegari, Bonita, and Combine Bonita. Hegari was an introduction from
the Egyptian Sudan in 1908 (Vinall et al., 1936).
Hegari has been identified earlier as being Ma, Ma, M a , ma4 for
maturity (Quinby, 1966) and has been used in the identification of
Early Hegari was found on a farm at Otis, Colorado, in 1936 (Karper,
1949), and it must have resulted from a mutation to early maturity in
the Hegari variety that was found and increased by a farmer. Early
Hegari has been found to be Ma, Ma, ma3ma,, and the mutation must
have occurred at the third locus.
MATURITY GENES OF SORGHUM
Combine Hegari has Dwarf Yellow Milo, 60-day Milo, Hegari, and
Early Hegari in its parentage; Hegari appears in its pedigree 3 times
and Early Hegari once. Combine Hegari is genetically M a , M a , ma3 M n ,
for maturity, and could have received dominant Ma, from either Milo
or Hegari, must have received dominant Ma, from Hegari, could have
received recessive ma3 from either Milo or Early Hegari, and must have
received dominant Ma, from Milo.
Bonita originated as a selection from a cross between Chiltex, a
Feterita-Kafir derivative, and Hegari (Karper, 1949) and has been
identified as ma, M a 2 ma, Ma,. Because of its origin, Bonita must have
received recessives m a , and ma3, and dominant Ma, from either Feterita
or Kafir and could have received dominant Ma, from any of its three
parents. Even though 3 chromosomes or parts of 3 chromosomes in
Bonita came from either Feterita or Kafir, the F, of Bonita X Hegari
looks exactly like Hegari except for being later in maturity.
Combine Bonita originated as a selection from a cross of Hegari X
Bonita and has been identified as ma, Ma, M a , Ma,. Combine Bonita
must have received recessive ma, from Bonita, could have received
dominant M a , from either Bonita or Hegari, and must have received
dominant Ma, from Hegari and dominant Ma, from Bonita.
It is obvious that the breeding work that was done by several digerent
plant breeders and covered a period of about 25 years and resulted in
Bonita, Combine Bonita, and Combine Hegari consisted of reshuffling
of maturity genes and little else.
2. Maturity Genotypes of Several Kajirs
Texas Blackhull Kafir, FC8962, originated as a pure-line selection
from the Dwarf Blackhull Kafir that was commonly grown in Texas
prior to 1920 (Vinall et al., 1936) and is quite similar to Western Blackhull Kafir and Sharon Kafir formerly grown in Kansas and Oklahoma.
How Blackhull Kafir reached the United States is unknown. Blackhull
Kafir is unlike the Pink and Red Kafirs from South Africa. A latematuring, white-seeded sorghum variety reached South Carolina about
1880 (Karper and Quinby, 1947); a head of this variety shown in the
Annual Report of the Kansas Experiment Station of 1889 shows it to
resemble Kafir. This variety was later grown as Guinea Kafir. Blackhull
Kafir was first grown at the Kansas Experiment Station in 1895. It is likely
that Guinea Kafi mutated to short stature and early maturity and that
Blackhull Kafir was selected and increased by some farmer.
Texas Blackhull Kafir is the variety that contributed the sterile genes
that, in company with sterile cytoplasm from Milo, produced cytoplasmic
J. R. QUINBY
male-sterility ( Stephens and Holland, 1954). The maturity genotype of
Texas Blackhull Kafir has been found to be ma, M a , Mu, Ma,.
Combine Kafir, TX319'7, is of unknown parentage but is a typical,
white-seeded, black-glumed Kafir (Karper, l 9 , S ) . 3-Dwarf plants unaccountably appeared in a field of Waxy Kafir, TS25289, and some of these
plants were selected. After two backcrosses of one of the dwarf plants
to Texas Blackhull Kafir, Combine Kafir TX3197 was selected. Combine
Kafir-60 has a similar origin, The two Kafirs differ slightly in appearance
but both have the same genetic constitution, ma1M a , mu3 Ma,. The F,
populations of 90M x TX3197 and lOOM X TX3197 are quite similar,
and it is possible, although unlikely, that TX3197 is dominant at the
third locus. TX3197 and Combine Kafir-60 are the female parents of
several vigorous hybrids.
Redlan originated as a selection from a cross between CI1090, a
Milo x Kafir derivative, and Blackhull Kafir, C171 (Karper, 1954).
Redlan has been identified as m a , Ma, M a , Ma,. Redlan must have
received recessive mu, and dominants M a , and M a , from Kafir and
could have received dominant M a , from either Kafir or Milo. Sieglinger
told me recently that, intending to select a 3-dwarf, white-seeded Kafir
from the cross, he selected numerous white-seeded plants but only one
or two red-seeded plants from the F, generation. As the years went by,
the white-seeded strains disappeared from the breeding blocks and only
Redlan remained. It is apparent, because of the linkage of recessive
ma3 and the dominant pericarp color Y in Dwarf Yellow Milo, that
Sieglinger selected a cross-over when he selected the progenitor of
Redlan that was dominant Mu,Y.
Redlan must have received recessive m a , and dominants M a , and
M a , from Blackhull Kafir and could have received dominant M a , from
either Kafir or Milo. Redlan is the female parent of several vigorous,
rather late-maturing hybrids.
Pink Kafir, CI432, was selected from a Pink Kafir introduced by the
U. S. Department of Agriculture from South Africa prior to 1905. The
selection was distributed from the Fort Hays Branch Experiment
Station in 1909 and was widely grown in Kansas for many years (Vinall
et al., 1936). The variety has been identified as ma, M a , M a , Ma,.
Pink Kafir, PI19742, was a direct introduction from South Africa by
the United States Department of Agriculture. The variety is later to
flower than CI432 and was never grown commercially in the United
States. PI19742 has been identified as ma, M a , M a , Ma,.
Red Kafir, PI19492, was another introduction from South Africa by
the United States Department of Agriculture and was never grown commercially in the United States. Two earlier-maturing varieties of Red
MATURITY GENES OF SORGHUM
Kafir were at one time extensively grown in Kansas (Vinall et al., 1936).
PI19492 has been identified as ma, M a , M a , Ma,.
3. Maturity Genotypes of Kalo and Early Kalo
Kalo originated as a selection from the progeny of a cross between
Pink Kafir, CI432, and Dwarf Yellow Milo in the hands of A. F. Swanson
at the Fort Hays Branch Experiment Station at Hays, Kansas. The
variety has been identified as ma, m a , M a , Ma,. Because of its origin,
Kalo received recessive ma, from Pink Kafir, recessive ma2 from Milo,
dominant M a , from Pink Kafir, and dominant M u , from either Pink
Kafir or Milo.
Early Kalo also originated at Hays, Kansas. After Kalo was distributed by the Kansas Station, Swanson continued to grow progeny
rows of Kalo and a few years later found one of the progeny rows
segregating for an earlier maturity, The early genotype was increased
and distributed as Early Kalo. Early Kalo has been identified as
m a , M a , M a , Ma,.
It is apparent that the earliness of Early Kalo results from the interaction of recessive m a , and dominants M a , and Ma,. This is the same
interaction that causes SMlOO ( m a , Ma, M a , Ma,) to be earlier than
SM80 (ma,m a z Ma, Ma,), as reported in Section VI.
It could be that Early Kalo originated as a mutation from the recessive rnaz of Kalo to dominant Ma,. However, there could be another
explanation. Pink Kafir, CI432, is dominant at both loci 2 and 3, and it
is probable that dominant M a , in Early Kalo came from CI432. Kalo
and Early Kalo are similar in maturity in many plantings. Swanson probably carried along heterozygosity at locus 2 in at least one progeny
row of Kalo. If this is true, both Kalo and Early Kalo are expected
segregation products of a cross between Pink Kafir, CI432, and Dwarf
Yellow Milo. However, Kalo was homozygous for maturity when distributed, and it is possible that the dominant M a , in Early Kalo came
from a dominant mutation.
4. Maturity Genotypes of Miscellaneous Varieties
Combine 7078 is a variety of uncertain parentage that is the male
parent of RS610, a vigorous hybrid. Combine 7078 has been identified
as ma, M a , ma3 Ma,.
TX414 is a selection from the progeny of a cross between Combine
7078 and TXO9, a derivative of Feterita. TX414 is the male parent of
RS626, a head smut-resistant version of RS610. TX414 is genetically,
m a , M a , ma3Ma,.
Caprock is a variety of Dawn Kafir and Milo parentage (Karper,
J. R. QUINBY
1949) that is the male parent of several vigorous hybrids. Genotypically,
Caprock is mu1 M a , M a , Ma,. Caprock must have received recessive
mu, and dominants Ma, and M a , from Dawn Kafir and could have
received dominant Ma, from either parent.
Durra, PI54484, is a tall variety that was never grown on farms in
the United States but was identified for height (Quinby and Karper,
1954). It has been identified for maturity as mu1M a , mu, Ma,.
Fargo was selected by H. W. Smith, a Kansas farmer and plant
breeder, from the progeny of a cross between Blackhull Kafir and Dwarf
Yellow Milo (Vinall et al., 1936). The variety is genetically Alu, ma2M a , Ma,. Fargo must have received dominant M a , and recessive ma2
from Milo, and dominant M a , from Kafir, and could have received
dominant M a , from either Milo or Kafir.
Allelic Series at the Maturity Gene loci
Sorghum is a tropical species that could not be grown in the temperate zones if mutations to early maturity had not occurred. Mutations
that allow early floral initiation have been preserved in temperate zones
in Africa and Asia. Several mutations to earliness have occurred and been
preserved in the United States since sorghum was introduced here about
a century ago.
The gene is now considered to be a complex structure with innumerable sites at which a mutation can take place. This being true, a mutation
would not duplicate any previous mutation at the same locus, and this
circumstance would result in multiple allelic series at any locus where
mutations would be preserved by selection. For this reason, multiple
allelic series would be expected at the maturity gene loci in sorghum,
and it would be unwise to assume that any dominant or recessive allele
duplicates any other dominant or recessive allele unless both are known
to have come from the same inbred line.
Because of the different origins of recessive maturity alleles in
temperate zones, differences among recessive alleles are expected. Differences among dominant alleles also exist, and allelic series consist of
both dominants and recessives. Data are shown in Table XV to indicate
that the dominants in Hegari and in 100-day Milo are different. Flowering distributions of Hegari, Combine Hegari, and 100-day Milo are
shown with flowering distributions of F, populations of crosses between
Combine Hegari and Hegari and between Combine Hegari and 100day Milo.
Frequency Distribution of Flowering of Parental and FZPopulations of Combine Hegari X 1 W a y Milo and
Combine Hegari X Hegari Grown at Plainview, Texas, in 1965
CH X H
C H X lOOM