Horticultural Characters for the Dihaploid Plants Derived from Anther Culture in Cucurbita pepo L.

E.I. Metwally, S.A. Moustafa, B.I. El-Sawy, and T.A. Shalaby

Horticulture Department, Faculty of Agriculture, Tanta University, Kafr El-Sheikh, 33516 Egypt

Additional index words. evolution

Abstract. Sixteen dihaploid lines obtained from 'Eskandarani' through anther were evaluated for horticultural characters. Differences among genotypes (dihaploid lines and 'Eskandarani') were highly significant for all horticultural characters evaluated; 'Eskandarani' produced the largest values for all the vegetative traits evaluated. Number of nodes to first female flower was 11.8 and 17.1 for dihaploid lines 8 and 3, respectively. The number of days from planting to the first male flower ranged from 39.8 days for dihaploid line 3 to 50.6 days for dihaploid line 6. The number of days from planting to the first female flower ranged from 43.3 to 53.3 days for 'Eskandarani' and dihaploid line 14, respectively. Sex ratio (male:female) ranged from 1.3 to 31.0 for 'Eskandarani' and dihaploid line 14, respectively. The differences were highly significant for all fruit characteristics, and early and total yield. The original parent produced the highest early and total yield.

 

 

In Egypt summer squash (Cucurbita pepo L. ) is a popular crop. The area cultivated in 1994 was 65, 507 feddans which produced 471300 tons. 'Eskandarani' is widespread in Egypt, and has high genetic variability (Abdel-Al et al., 1973). The production of pure lines requires several to many years through inbreeding and selection (Metwally, 1985, 1989). Homozygous dihaploid plants can be of great value in plant breeding and crop improvement programs. Such plants can be produced by anther and ovule culture (Metwally et al., 1998). The aim of this work was to know the behavior (horticultural characters) of the dihaploid plants derived from anther culture.

Materials and methods

Sixteen dihaploid lines were obtained from 'Eskandarani' through anther culture (Metwally et al., 1998). The sixteen dihaploid lines and 'Eskandarani' were evaluated at the Experimental Farm of the Faculty of Agriculture Kafr El-Sheikh. Seeds were sown on 1 Apr. 1995. The experimental design was a randomized complete block design with four replications. Plot size was 6 m2 and contained 20 plants. All agricultural practices were done as commonly practiced in the district. For studying the differences between dihaploid lines in the plant per formance, three plants were uprooted from each plot after 45 days from sowing and the following data were recorded: stem length, number of leaves per plant, fresh and dry weight per plant, and leaf area per plant. Five plants in each plot were labeled and the total number of staminate and pistillate flowers during the season were counted and the following data were recorded: number of days from sowing till the opening of the first pistillate flower, number of days from sowing till the opening of the first staminate flower, number of staminate flowers before the first pistillate one, number of pistillate and staminate flowers, and sex ratio (male:female).

In each plot, 10 pistillate flowers were labeled before anthesis and subsequently picked three days after anthesis. The following individual fruit data were recorded: weight (g), length (cm), and diameter (cm). The plots were harvested at two-day intervals and the following fruit data were recorded at each picking: early yield (fruit which were picked in the first five pickings) and total yield (fruit from all of the pickings) as number and weight of fruit. Means were calculated and subjected to analysis of variance; Duncan's multiple range test was used for means comparisons among the genotypes (Duncan, 1955).

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Results and discussion

Vegetative traits. Data presented in Table 1 show that the differences among genotypes were highly significant for stem length, number of leaves, leaf area per plant, fresh weight, and dry weight per plant. 'Eskandarani' plants produced the largest values for the three vegetative characters as

well as for fresh and dry weights per plant compared with its 16 dihaploid lines. All the lines differed from 'Eskandarani' for at least one of the five characters measured. One line (6) differed for all five characters, and seven lines (2, 4, 7, 9, 10, 12, 14) differed from 'Eskandarani' for four of the five characters.

 

Table 1. Vegetative traits of 16 dihaploid squash lines and their parent ('Eskandarani') 60 days after sowing, means on a per plant basis.

Stem length Leaf area Wt (g)

Line (cm) Leaves (dm2) Fresh Dry

1 19.87 b­e 22.33 b­e 87.85 bc 996.00 a­e 68.00 bcd

2 20.20 b­e 21.13 cde 56.39 cd 615.00 cde 44.00 cd

3 17.33 de 22.07 b­e 94.32 bc 1068.00 abc 83.00 ab

4 19.80 b­e 25.07 b 69.20 cd 768.33 b­e 52.00 bcd

5 18.13 cde 19.20 efg 69.92 cd 1002.67 a­e 72.33 abc

6 15.40 e 17.33 fg 45.57 d 476.33 e 36.33 d

7 21.00 a­d 19.33 efg 61.57 cd 784.67 b­e 59.33 bcd

8 22.80 abc 23.00 bcd 81.83 bcd 1100.67 abc 61.00 bcd

9 17.73 cde 23.00 bcd 74.20 cd 638.67 cde 52.00 bcd

10 17.80 cde 19.40 efg 66.30 cd 650.67 cde 46.67 cd

11 15.93 de 16.87 g 81.52 bcd 922.33 a­e 64.33 bcd

12 17.87 cde 22.60 b­e 66.66 cd 676.00 cde 44.00 cd

13 17.73 cde 24.27 bc 116.90 ab 1209.67 ab 63.67 ab

14 16.33 de 19.40 efg 69.53 cd 537.00 de 42.67 cd

15 25.60 a 29.27 a 79.08 bcd 955.33 a­e 65.33 bcd

16 23.47 ab 20.60 def 94.69 bcf 1046.67 a­d 68.33 bcd

Eskandarani 20.87 a­d 31.67 a 133.55 a 1362.00 a 103.33 a

F test ** ** ** ** **

**Significant differences at P < 0.01 according to F test. Means followed by a common letter are not significantly different at the 5% level according to Duncan's test.

Table 2. Flowering traits of 16 dihaploid squash lines and their parent ('Eskandarani').

Nodes to Days to Days to Males Females

Line first female first male first female per plant per plant Male:female

1 14.4 bc 48.1 abc 47.7 cde 72.5 cd 4.7 ef 15.3 b

2 13.9 bcd 42.9 cd 46.3 ef 42.0 ij 11.0 abc 3.8 fg

3 17.1 a 38.8 d 47.1 def 45.2 hi 7.7 cde 5.8 efg

4 13.1 b­e 46.5 abc 48.6 bcd 64.8 ef 6.2 def 10.4 c

5 15.0 b 45.1 abc 47.1 def 72.5 cd 9.5 bcd 8.1 def

6 13.1 b­e 50.6 a 49.0 be 51.5 h 8.2 cd 6.2 def

7 14.6 bc 44.2 bc 47.6 cde 39.5 ij 11.7 ab 3.4 fg

8 11.8 e 44.2 bc 45.5 f 34.5 g 10.0 bc 3.5 fg

9 13.1 b­e 48.3 abc 49.1 bc 47.5 hi 6.2 def 7.6 def

10 12.7 cde 48.2 abc 47.1 def 43.5 i 6.2 def 7.0 def

11 13.2 b­e 46.1 abc 49.1 bc 52.8 gh 9.2 bcd 5.7 fg

12 14.6 bc 47.0 abc 48.1 cde 60.0 fg 6.2 def 9.6 cde

13 13.3 b­e 47.7 abc 50.3 b 67.8 de 4.7 ef 14.3 cd

14 12.9 cde 49.3 ab 53.3 a 124.0 a 4.0 f 31.0 a

15 13.8 bcd 46.3 abc 49.3 bc 89.8 b 9.5 bcd 9.4 cde

16 14.1 bc 45.5 abc 47.8 cde 77.3 c 8.0 cd 9.7 cde

Eskandarani 12.0 de 45.1 abc 43.3 g 17.8 k 13.3 a 1.3 g

F test ** ** ** ** ** **

**Significant differences at P < 0.01 according to F test. Means followed by a common letter are not significantly different at the 5% level according to Duncan's test.

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The highly significant differences among the dihaploid lines and between the dihaploid lines and their parent (Eskandarani) in the vegetative traits and the drastic reduction in most dihaploid lines indicates that these dihaploid lines were produced from sexual parts (anthers) and not from somatic parts (filaments in anther).

Flowering. Differences among genotypes (dihaploid lines and original cultivar) were highly significant for all flowering traits (Table 2). Dihaploid line 8 had the fewest number of nodes to the first female flower, but it did not significantly differ from the original cultivar. Dihaploid line 3 had the most number of nodes to the first female flower, and significantly differed from the original cultivar. Plants bearing the first female flower on a lower node will be more earlier than that plants bearing the first female flower on higher node.

The number of days from planting to the first male flowering ranged from 38. 8 days for dihaploid line 3 to 50.6 days for dihaploid line 6. The number of days to the first female flower ranged from 43.3 to 53.3 days for 'Eskandarani' and dihaploid line 14, respectively. Metwally (1985) reported that female flowering in 'Eskandarani' occurs one or two days before male flowering. In contrast, in this study all the dihaploid lines except three (1, 6 and 10) produced male flowers before female flowering.

'Eskandarani' produced the lowest number of male flowers per plant (17.8), while dihaploid line 14 produced the largest number of male flowers (124.0, Table 2). 'Eskandarani' produced the largest number of female flowers per plant (13.3), but did not significantly differ from dihaploid

 

Table 3. Fruit characteristics of 16 dihaploid squash lines and their parent ('Eskandarani').

Fruit wt Fruit length Fruit diam

Line (g) (cm) (cm)

1 146.67 b­e 17.17 a­d 4.20 a

2 136.33 b­e 14.77 def 4.00 abc

3 103.00 e 17.67 abc 4.10 ab

4 123.00 cde 15.67 b­e 3.83 a­d

5 116.00 de 17.13 a­d 3.37 de

6 132.33 b­e 16.67 a­d 3.13 ef

7 161.00 abc 18.00 ab 3.77 a­d

8 145.33 b­e 13.10 f 3.33 de

9 158.33 a­d 16.30 b­e 3.63 b­e

10 145.33 b­e 15.67 b­e 3.80 a­d

11 148.00 bcd 19.00 a 3.53 cde

12 62.67 f 14.00 e­f 2.70 f

13 170.33 ab 17.60 abc 3.67 a­e

14 134.00 b­e 16.33 b­e 4.00 abc

15 118.00 cde 16.33 b­e 3.13 ef

16 142.33 b­e 15.27 c­f 3.37 de

Eskandarani 192.90 a 17.53 abc 4.13 ab

F test ** ** **

**Significant differences at P < 0.01 according to F test. Means followed by a common letter are not significantly different at the 5% level according to Duncan's test.

 

 

Table 4. Fruit yield of 16 dihaploid squash lines and their parent ('Eskandarani').

Early yield Total yield

No. of fruit Fruit wt (kg) No. of fruit Fruit wt (kg)

Line Plant Plot Plant Plot Plant Plot Plant Plot

1 1.3 fg 25.0 fg 0.20 c­e 4.0 c­e 3.5 i 70.0 i 0.55 i 10.9 i

2 3.8 b 75.3 b 0.63 b 12.5 b 10.3 a 206.3 a 1.67 b 33.3 b

3 3.0 c 60.0 c 0.49 b 9.8 b 8.4 b 167.0 b 1.40 c 27.9 c

4 1.1 fg 22.7 fg 0.16 d­f 3.2 d­f 4.6 g­i 91.0 g­i 0.72 g­i 14.4 g­i

5 1.4 ef 28.7 ef 0.14 d­f 2.8 d­f 5.8 d­f 116.7 d­f 1.07 de 21.4 de

6 0.5 gh 9.0 gh 0.05 ef 1.0 ef 4.7 f­i 93.0 f­i 0.64 hi 12.8 hi

7 2.0 de 39.7 de 0.23 cd 4.6 cd 7.1 c 141.7 c 1.31 cd 26.1 cd

8 2.7 cd 53.3 cd 0.50 b 10.0 b 6.8 cd 136.3 cd 1.26 cd 25.2 cd

9 0.8 fh 15.7 f­h 0.11 d­f 2.2 d­f 5.2 e­h 103.0 e­h 0.93 e­g 18.6 e­g

10 2.0 de 40.7 de 0.34 c 6.7 c 5.3 e­g 106.3 e­g 1.00 ef 19.9 ef

11 1.0 fg 20.7 fg 0.12 d­f 2.3 d­f 6.1 c­e 121.3 c­e 0.89 e­h 17.7 e­h

12 1.0 fg 19.0 fg 0.22 c­e 4.4 c­e 3.8 i 75.0 i 0.99 ef 19.7 ef

13 1.2 fg 23.7 fg 0.18 c­f 3.6 c­f 4.5 g­i 89.7 g­i 0.90 e­g 17.9 e­g

14 0.1 h 2.0 h 0.01 f 0.2 f 1.7 j 33.0 j 0.27 j 5.3 j

15 0.9 fg 18.0 fg 0.18 c­f 3.5 cf 4.5 g­i 89.7 g­i 0.88 e­h 17.6 e­h

16 1.1 fg 22.3 fg 0.18 c­f 3.5 cf 4.0 hi 79.0 hi 0.81 f­h 16.1 f­h

Eskandarani 4.5 a 89.7 a 0.94 a 18.7 a 10.1 a 201.0 a 2.19 a 43.7 a

F test ** ** ** ** ** ** ** **

**Significant differences at P < 0.01 according to F test. Means followed by a common letter are not significantly different at the 5% level according to Duncan's test.

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significant. The superiority of 'Eskandarani' for early yield may be due to its early production of female flowers compared to the dihaploid lines. In other studies, Abdel-Al et al. (1973) reported that the first inbreeding generation of Cucurbita pepo L. showed some superiority in early yield over the original population.

Total fruit yield. 'Eskandarani' and dihaploid line 2 produced the most fruit per plot (Table 4). The differences among genotypes were highly significant. 'Eskandarani' surpassed all the dihaploid lines for total fruit weight. The superiority of the 'Eskandarani' may have been due to its better vegetative growth, the higher number of fruit per plant and the large average fruit weight compared with its dihaploid lines. In earlier studies, some investigators isolated inbred lines superior than their original parent of Cucurbita pepo L. (Abdel-Al et al., 1973; Metwally, 1989).

Literature cited

Abdel-Al, Z.E., A.M. Khalf-Allah, and G.S. Shenouda. 1973. Effect of visual selection and inbreeding on some quantitative characters of summer squash. Alex. J. Agr. Res. 21:277­282.

Duncan, D.B. 1955. Multiple range and multiple F-test. Biometrics 11:1­42.

Metwally, E.I. 1985. Inheritance studies on squash crop. PhD thesis, Fac. Agr., Tanta Univ.

Metwally, E.I. 1989. Inbred strains of summer squash 'Eskandarani' after ten generations of inbreeding and selection. J. Agr. Res. Tanta Univ. 15:20­27.

Metwally, E.I., S.A. Moustafa, B.I. El-Sawy, and T.A. Shalaby. 1998. Haploid plantlets derived by anther culture of Cucurbita pepo L. Plant Cell Tissue Organ Cult. 52:171­176.

Metwally, E.I., SA. Moustafa, B.I. El-Sawy, S.A. Haroun, and T.A. Shalaby. 1998. Production of haploid plants from in vitro culture of unpollinated ovules of Cucurbita pepo L. Plant Cell Tissue Organ Cult. 52:117­121.

lines 2 and 7. Dihaploid line 14 had the fewest female flowers per plant (4.0).

The male:female flower ratio ranged from 1.3 ('Eskandarani') to 31.0 (dihaploid line 14). Differences among genotypes were highly significant (Table 2).

It is clear from the flowering traits that the original plant had drastic values compared to the other dihaploid lines also, the differences among the different dihaploid lines were statistically highly significant. These data confirm that these dihaploid lines were not produced from somatic parts of their original plants.

Fruit characteristics. Differences among genotypes were highly significant for fruit weight, fruit length, and fruit diameter (Table 3). Dihaploid lines 7, 9, and 13, and 'Eskandarani' had the highest fruit weights; dihaploid line 12 had the lowest fruit weight.

Dihaploid lines 1, 3, 5, 7, 11, and 13, and 'Eskandarani' produced the longest fruit, while dihaploid line 8 had the shortest fruit. 'Eskandarani' and dihaploid lines 1 and 3 had the largest fruit diameter, while dihaploid line 12 were the smallest in diameter. It is clear from the fruit traits (i.e., fruit weight, fruit length and fruit diameter) that the differences within dihaploid lines and between dihaploid lines and 'Eskandarani' were highly significant. These fruit data confirm that these dihaploid lines were derived from the sexual part of the anthers and not from somatic parts.

Early fruit yield. Differences were highly significant for early yield as a number and weight of fruit (Table 4). All dihaploid lines produced less early yield than 'Eskandarani', and such reduction in early yield was highly significant. Differences among the dihaploid lines were also highly

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