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Cucurbit Genetics Cooperative Report 16:18-21 (article 7) 1993

Independence of fruit length and 10 other characters in cucumber.

Nick E., Fanourakis

Technical Educational Institute, Heraklion Crete 71500, Greece

Fruit length of cucumber exhibits great variability. Although the inheritance of fruit length has been investigated, data are not comparable because of the varying germplasm sources used and the collection and analysis measure applied (2, 3, 4, 5). Limited agreement exists regarding the inheritance of fruit length, however most researchers agree that it is a quantitative character. The quantitative nature of the inheritance of fruit length and its association with the fruit neck has been studied. (!). We report here the linkage relations of fruit length with 10 other qualitative characters of cucumber.

The long fruited line 791 from our cucumber breeding program was crossed with the non-necked American variety SMR-18 and F2 and BC progeny were produced. Parents, F1, F2, BCP1 and BCP2 progeny were evaluated for fruit length and the following characters: bitterness (bi), powdery mildew resistance (pm), female sex expression (F), spine size (ss), warted fruit (Tu), uniform color of immature fruit (u), mature fruit color (R), glossy fruit (D), structure of epidermis (pe), and spine color (B). Evaluation and classification was made as previously described (1).

The sumbols "+" and "-" were uised to denote contrasting phenotypic classes for the segregating characters. Thus "+" stands for bitterness, femaleness, rough spines, warted fruit, nonuniform color of immature fruit, red color of mature fruit, dull fruit epidermis, palisade epidermal structure, and black spines. The "-" stands for nonbitterness, monoecious flowers, fine spines, nonwarted fruit, uniform color of immature fruit, cream color of mature fruit, glossy epidermis, flat epidermal structure, and white spines respectively. For powdery mildew "R" designates resistance, "I" intermediate resistance and "S" susceptibility.

The continuous variation of fruit length allowed for separation of F 2 and BC generations in classes differing by 8 cm. Plants were classified for other characteristics within each class of fruit length. Observed ratios within each class were compared with the total ratio of the characteristic over the classes by X2 analysis. Thus the deviation of the partial ratios from the total ratio of the characteristic indicates linkage associations of any characteristic with the fruit length.

Partial phenotypic segregations and X2 analysis for each particular character are generally indicated in Tables 1 and 2. Observed ratios within each class of fruit length do not indicate significant deviations from the total phenotypic character ratios. Significant deviations were, however, found in one F2 class for female sex expression, and in some classes of the BC1P2 generation for spine size, warted fruit, uniform color of immature fruit, dull fruit epidermis, and structure of epidermis. The rest of the partial BC ratios for these characters follow the expected segregation. Moreover, the respective partial ratios in the F2 generation segregate according to the expectation. Thus, it is hard to accept the observed deviation as indicative of any linkage relationships. Therefore, we propose that the segregation of the fruit length and the characteristics evaluated is independent.

Table 1. Phenotypic F2 segregation and X2 values of the 10 characters within each class of fruit length of cucumber.

Trait
Total ratio
Fruit length (cm)
12-19, 99
20-27, 99
>28.00
  Ratio X2 Ratio X2 Ratio X2
bi +: 151 12 0.10 94 1.64 47 3.34
  -: 49 3   37   7  
  R: 14 0 1.54 11 0.49 3 1.85
pm I: 22 1   13   9  
  S: 164 14   108   42  
F +: 81 9 2.36 43 3.20 29 3.91
  -: 119 6   88   25  
SS +: 157 12 0.02 95 2.33 40 1.09
  -: 43 3   35   15  
Tu +: 157 12 0.02 106 0.43 39 1.88
  -: 43 3   24   16  
u +: 157 12 0.02 106 0.43 39 1.88
  -: 43 3   24   16  
R +: 156 13 0.59 102 0.01 41 0.51
  - 44 2   28   14  
D +: 157 11 0.24 106 0.43 40 1.09
  -: 43 4   24   15  
pe +: 156 12 0.02 106 0.43 38 2.89
  -: 44 3   24   17  
B +: 155 13 0.59 101 0.06 41 0.51
  - 45 2   29   14  

* Significant difference at 0.05 level.

Table 2. Ssegregation and X2 values of the BCX1P2 generation for the 10 characters of cucumber within each class of fruit length.

Trait
Total ratio
Fruit length (cm)
0-27.99
28-35.99
>36.00
Ratio
X2
Ratio
X2
Ratio
X2
bi
+:
81
4
0.25
60
0.02
17
0.35
 
-:
88
6
67
15
pm
R:
33
2
0.28
27
0.80
4
2.40
I:
46
4
30
12
S:
97
7
74
16
F
+:
125
7
1.86
94
0.03
24
0.24
-:
51
6
37
8
ss
+:
55
9
8.74**
43
0.15
3
7.13**
-:
121
4
88
29
Tu
+:
72
9
4.31*
59
0.92
4
10.68**
-:
104
4
72
28
u
+
73
8
2.16
61
1.40
4
11.06**
-
103
5
70
28
R
+:
92
7
0.01
69
0.01
16
0.03
-:
81
6
60
15
D
+:
74
9
3.93*
61
1.14
4
11.45**
-:
102
4
70
28
pe
+:
72
9
4.15*
59
1.01
4
11.00**
-:
102
4
70
28
B
+:
92
7
0.01
69
0.01
16
0.07
-:
84
6
62
16

*, **: significant differences at 0.05 and 0.01 levels, respectively.

Literature Cited

  1. Fanourakis N.E. and E.E. Tzifaki. 19193. Correlated inheritance of fruit neck with fruit length and linkage relations with 10 other characteristics of cucumber. Euphytica (in press).
  2. Imam, M.K., M.A. Abobakr and H.M. Yacoub. 1977. Inheritance of some characters in cucumber, Cucumis sativus L. II. Some quantitative characters. The Libyan J. Agric.
  3. Kingston, B.D. 1973. A genetic study of some fruit characteristics of the cucumber, Cucumis sativus L. Ph.D. Thesis, Texas A and M Univ., College Station.
  4. Owens, K.O. 1982. Analysis of generation means and components of variance for fruit size in two cucumber populations, and genetic and breeding studies on cucumber fruit size utilizing inbred backcross lines. Ph.D. Thesis, Univ. of Wisconsin-Madison.
  5. Pike, L.M. and B.D. Kingston. 1975. Inheritance of fruit length and shape in cucumber, Cucumis sativus L. HortSci. 10:318.
  6. Smith, O.S., R.L. Lower, and R.H. Moll. 1978. Estimates of heritability and variance components in pickling cucumber, J, Amer. Soc. Hort. Sci. 103: 222-225.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 15 December, 2009