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Cucurbit Genetics Cooperative Report 17:122-124 (article 36) 1994

INheritance of Hard Rind in C. maxima x C. moschata Crosses

Koch, P.S. and P.T. Della Vecchia

Agroflora S/A, Caixa Postal 427, 12900-000, Braganca Paulista, SP, Brazil

Along with the development of cv. Alice (1), a bush type of C. maxima, we have selected a sister line with fruit carrying the hard rind trait. Because hard rind lines show good field resistance to fruit rotting, there is some interest in using it as the female parent in F1 seed production. Hard rind in C. pepo and C. andeana x C. maxima is determined by a single dominant gene (3). Herrington et al. (2) presented data from a cross between C. maxima x C. eucadorensis suggesting that hard rind was recessive to soft rind in this cross and that the C. maxima cv. Queensland Blue has a dominant gene (Hi) which inhibits the expression of hard rind. It was of interest to know whether this inheritance pattern would hold true for other C. maxima accessions and the inheritance of this trait in crosses between C. maxima x C. moschata.

Materials and Methods. This pedigree and main characteristics of the breeding lines and cultivars used in the present study are presented in Table 1. Inbred lines were selfed for at least three generations and cultivars were observed for at least two generations before use, and were uniform for the trait under investigation. F1 seeds were produced by crossing the C. maxima hard rind inbred line AF839L as the female parent with all other lines and cultivars. A segregating F2 population was obtained for the cross (AF839L x AF724). Two hard rind and four soft rind F3 lines during the summer season of 1991, and the F3 lines during the Autumn season of 1992. Rind classification was made after steaming pieces of the mature fruits for 10 minutes. Soft rinds disintegrate after this treatment, whereas hard rinds remain hard.

Results and Discussion. Hard rind in F1 plants of crosses between C. maxima x C. moschata was dominant to soft rind (Table 2). In all crosses between C. maxima x C. maxima lines or cultivars, hard rind in F1 plants was recessive to soft rind (Table 2). Segregation for the trait in the F2 and in the F3 (selected lines) generations did not differ significantly from the expected 3:1 and 1:0 ratios, based on chi-square values, for a single gene model of inheritance (Table 2). These data support that of Herrington et al. (2) and suggest that the Hi gene (Hard rind inhibitor) may be a common feature among the C. maxima cultivars. If this holds true for other C. maxima cultivars, it may be feasible to use hard rind lines as the female parents in F1 seed production in C. maxima x C. maxima crosses for a better control of fruit rot under tropical conditions.

Table 1. Pedigree and main characteristics of the breeding lines and cultivars used in the study of the inheritance of hard rind in C. maxima x C. maxima and C. maxima C. moschata crosses.

Line or Cultivar Number
Pedigree
Origin
Type
Rind Plant Type
C. maxima
AF89
cv. Exposicao
Brazil
soft
large indeterminate
AF139
cv. Sumare
Brazil
soft
large indeterminate
AF600L
(T4 x Delicious) S6
Brazil
soft
medium indeterminate
AF721
cv. Golden Nugget
Australia
soft
bush
AF723
cv. Jarrahdale
Australia
soft
large indeterminate
AF724
cv. Baby Blue
Australia
soft
short indeterminate
AF839L
(Coroa x Zapallo de Tronco)S6
Brazil
hard
bush
C. moschata
AF543L
Kurokawa S6
Japan
soft
medium indeterminate
AF822L
Aizuwase S3
Japan
soft
medium indeterminate

Table 2. Segregation patternfor rind texture in C. maxima C. maxima and C. maxima x C. moschata.

Number of Plants
Lines or Crosses
Total
Soft Rind
Hard Rind
Expected Ratio of Soft:Hard
X2
P
AF89 (C. maxima)
12
12
0
--
--
--
Af139 (C. maxima)
11
11
0
--
--
--
AF6001 (C. maxima)
12
12
0
--
--
--
AF721 (C. maxima)
12
12
0
--
--
--
AF723 (C. maxima)
10
10
0
--
--
--
AF724 (C. maxima)
9
9
0
--
--
--
AF89 (C. maxima)
12
0
12
--
--
--
AF543L (C. moschata)
12
12
0
--
--
--
AF822L (C. moschata)
11
11
0
--
--
--
C. maxima x C. moschata
AF839L x AF543L F1
25
0
25
--
--
--
AF839L x AF822L F1
22
0
22
--
--
--
C. maxima x C. maxima
AF839L x AF89 F1
21
21
0
--
--
--
AF839L x AF139 F1
18
18
0
--
--
--
AF839L x AF600L F1
23
23
0
--
--
--
AFf839L x AF721 F1
25
25
0
--
--
--
AF839L x AF723 F1
19
10
0
--
--
--
AF839L x AF724 F1
23
23
0
--
--
--
Af839L x AF822L F2
253
260
83
3.1
0.12
0.50-0.75
HR-11 AF839L x AF724 F3
51
0
51
0:1
--
--
HR-2 AF839 x AF724 F3
45
0
45
0:1
--
--
SH-12 AF839L x AF724 F3
60
60
0
1:0
--
--
SH-2 AF839L x AF724 F3
67
54
13
3:1
1.12
0.25-0.50
SH-3 AF839L x AF724 F3
62
51
11
3:1
1.74
0.10-0.25
SH-4 AF839L x AF724 F3
64
44
20
3:1
1.33
0.10-0.25

1  HR = Hard rind
2  SH = Soft rind

Literature Cited

  1. Della Vecchia, P.T., P.E. Takazaki and A. Terenciano. 1991. "Alice": nova cultivar de morganga, Cucurbita maxima Duch, com habito de crescimento moita. Horticultura Brasiliera 9(1):27.
  2. Robinson, R.W., Munger, H.M., Whitaker, T.W. and Bohn, G.W. 1976. Genes of the Cucurbitaceae. HortScience 11:554-568 .
  3. Herrington, M.E. and Brown, P.S. 1988. Inheritance of leaf and fruit characteristics in Cucurbita maxima Duch. cv. Queensland Blue x C. ecuadorensis Cutler and Whitaker. Queensland J. Agr. & An. Sci. 45(1):45-48.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
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