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VIII. Identification of Sorghum Varieties for Maturity

VIII. Identification of Sorghum Varieties for Maturity

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283



MATURITY GENES OF SORGHUM



TABLE XI11

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

MalMamu8Man



44M X SOM, Fz

Malmmma3RMa4



Days to

flower



X



44M



M a l ~ M a 3 M a 4 80M



X



EH



Ma~Mazrnarmac



CH



44

46

48

50

52

54

56

58

60

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90



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



284



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

TESTER

LINESOF MILO

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



285



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

root-rot resistance.

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.

C. IDENTIFICATION

OF VAFXETIES

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

VIII, A.



286



J. R. QUINBY



TABLE XIV

Identification of Sorghum Varieties for Dominance or Recessiveness a t Four Gene

Loci and Their Times of Flowering at Plainview, Texas, in 1964

Variety



Genotype



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)

Hegari (H)

Early Hegari (EH)

Combine Hegari (CH)

Bonita

Combine Bonita

Texas Blackhull Kafir

Combine Kafir-60

Redlan

Pink Kafir (31432

Red Kafir PI19492

Pink Kafir PI19742

Kalo

Early Kalo

Combine 7078

TX414

Caprock

Durra PI54484

Fargo



Days to flower

90

82

68

64

56

56



60

58

48

44

70

60

72

64

62

68

59

70

70

72

72

62

59

58

60

70

62

70



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

other varieties.

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



287



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



288



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



289



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,



290



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.

IX.



Allelic Series at the Maturity Gene loci



A. INTRODUCXION

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.



TABLE XV

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

MalMazmaJbfas

Days to

flower

56

58

60

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94



Hegari (H)

MalMeMaamar

I



12

6

5

2

1

2



-



-



-



X



MalM@Mama,

3



3

4



4

6

-



2

1



3

6

15

20

20

18

2

-



Combine

Hegari (CH)

MalMazmaaMm

10

15

7



C H X lOOM

MalMa2maJta4



x



lOOM



MalMazMaaMaa



Ma,Ma-JMa&fad



-



-



-



1

-



-



-



-



2

5

10

23

17

30

15

6



-



-



-



-



-



-



f



2

0



m



3



cn



8

cn

$2



8K



-



-



8

27

6

-



M



2



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