Cucurbit Genetics Cooperative Report 16:58-59 (article 21) 1993
Warid A. Warid, Jaime J. Martinex, and Juan M. Loaiza
Department of Agriculture – DAG, University of Sonora, Hermosillo, Sonora, Mexico
The naked-seed squash has been reported by Curtis (2, 3). The seed lacks the lignified seed coat. Whitaker (5) referred to studies on this mutatin by several austrian and German investigators. Abak et al. (1) started a breeding project in 1985 for seed production in Turkey. Percent oil in naked seed strains of the present study is 35.4$ as reported by Farag (4).
Seeds of naked seed Kurbis squash were kindly provided by Dr. L. Tanasch of University of Austria in 1988. S0 plants were grown in Hermosillo at the University of Sonoro Experiment Station from seeds planted in April 1991 at a 0.5 X 3.0 m spacing. Fourteen plants were self pollinated in June 1991 and the fruits were harvested in August. S1 seeds were extracted and segregation for seed type, normal or naked, was observed. All but two of the selfed plants produced fruits having naked seeds. S1 naked seeds were planted in September 1991 under isolation, and harvested in December for observation. The plants exhibited normal growth, and produced open-pollinated fruits having naked seeds, confirming homozygosity of the naked trait.
Another planting of S1 seed was made in March 1991 under isolationl. The growth of S1 plants was normal and they partially recovered from viral infection by spraying with Dithane M-45. Vigorous, spiny vines with profuse male and female flowering, and normal set of fruits by open pollinationw ere observed. Mature fruits were harvested in July 1992. Data were recorded on 74 fruit from 31 plants. These were cut cross-wise and seeds were extracted and dried at ambient temperature. Fruits were morphologically described, and data were recorded on number and weight of fruits per plant. Fruit and seed traits were correlated on a single fruit basis. Simple and partial correlations were computed for fruit weight, number and weight of seeds, and seed size (mg/seed).
Results. There was no segregation for seed type. Fruits of all S1 plants contained naked seeds. However, the green color of the exposed cotyledons (inner seed coat) varied in intensity from medium green to dark green. The mature fruit was round, oblate in shape. The pedicel end was spiny, solid, rather soft and ridged with 8 angles and inconspicuous flaring. The color of fruit skin (rind) was orange and splashed green. The rind was smooth and not hard. The flesh had a creamy color and fibrous texture. The placenta was gelatinous and orange.
The number of fruits per plants varied from 1 to 9 and averaged 3.3. Total fruit weight per plant ranged from 0.47 to 12.67 kg with a mean weight of 4.64 kg. Among the 74 individual fruits, the range of fruit weight was 0.47 to 3.17 kg, and the average was 1.55 kg. Number of seeds per fruit ranged from 16 to 393 and averaged 136. The average seed weight per fruit was 18.2 g and ranged from 1.4 to 64.1 g. Seed size averaged 134 mg and varied from 46 to 223 mg.
A strong association existed between number and weight of seeds per fruit, as evidenced from simple and partial correlation values (0.921 – 0.925) that were positive and highly significant (Tables 1 and 2). The values of the coefficient of determination indicated that 85 to 86 percent of the variation in seed weight can be ascribed to number of seeds. Seed size showed a strong, positive association with fruit weight (r = 0.488). Twenty-four percent of the variation in seed size can be attributed to fruit size.
Table 1. Simple correlation between fruit characters of naked seed squash (n = 74 fruits).
Coefficient of |
||
Characters correlated |
Correlation r |
Determination r² |
| Fruit wt. vs Number of seeds | 0.207 ns | 0.043 |
| Fruit wt. vs Weight of seeds | 0.346 ** | 0.120 |
| Number of seeds vs Weight of seeds | 0.921 ** | 0.848 |
| Fruit wt. vs Seed size | 0.488 ** | 0.238 |
Table 2. Partial correlation betwen fruit characters of naked seed squash (n = 74 fruits).
Coefficient of |
||
Characters correlated |
Correlation r |
Determination r² |
| Fruit wt. vs Number of seeds (fixing Wt. of seeds) | -0.306 * | 0.094 |
| Fruit wt. vs Wt. of seeds (fixing Number of seeds) | 0.408 ** | 0.166 |
| Number of seeds vs Wt. of seeds (fixing Fruit wt.) | 0.925 ** | 0.856 |
Literature Cited
- ABak, K. M. Sakin and S. Sakin-karakullukcu. 1990. Improvement of pumpkin for naked seeds. XXIII Intern. Hort. Congr. Abstr. 3074.
- Curtis, L.C. 1946. The possibilities of using species of perennial cucurbits as source of vegetable fats and proteins. Chemurgic Digest 5:221-224
- Curtis, L.C. 1948. The use of naked seed in Cucurbita pepo as a source of high quality liquid vegetable fat, as a high analysis protein, as a new confection, and as a sandwich spread. Proc. Amer. Soc. Hort. Sci. 52:403-406.
- Farag, R.S. 1992. Personal communication. Lab. Chemical Analyses, College of Agriculture, University of Cairo, Egype.
- Whitaker, T.W. 1960. Breeding squash and pumpkins. Handbuch der Pflanzenzuchtung 6:331-350.