Cucurbit Genetics Cooperative Report 1:34 (article 31) 1978
W. N. Whitwood and J. L. Weigle
Robson Seed Farms, Hall, NY 14463
Seeds of Cucurbita pepo cv. Early prolific Straight Neck, were treated with a .035M solution of ethyl- methanesulfonate (EMS) for twenty-four hours at room temperature. The M1 plants were selfed in the field to form the M2 generation. Twenty M2 seeds were planted in flats and grown until the 2 true-leaf stage in the greenhouse. Two M2 lines, entries 185 and 623, segregated for a mutant plant habit phenotypically resembling that of the extreme dwarf gourd previously reported by Scarchuk (1). Plants with the compact habit were slower to germinate, had small hypocotyls, and compact nodes compared to the normal. In the greenhouse, the pistillate flower development was greatly reduced and 2-3 weeks later the staminate flower formation was also slower with only 3-4 flowers per plant. Several attempts to self or sib the extreme dwarf plants in the greenhouse failed to produce any fruit. Normal plants from entry 185, entry 623 and extreme dwarf gourd were selfed and the progenies examined for the occurrence of extreme dwarf seedlings (Table 1-34). Segregation for the two mutant entries and for the extreme dwarf gourd indicated simple monogenic inheritance.
An allelism test was conducted between the two compact mutants isolated from ‘Early Prolific Straight Neck’ and an F1 gourd heterozygote (normal gourd x extreme dwarf gourd). The data from these backcrosses (Table 1) indicates that the two compact mutants isolated from ‘Early Prolific Straight Neck’ were the same allele as the naturally occurring mutation in gourd.
Table 1. Plant habit segregation in an F2 and backcross generation for two induced compact mutations and extreme dwarf mutation in gourds, (C. pepo).
Generation |
Entry |
Trait |
Observed |
Ratio |
X2 |
Probability |
| F2 | Entry 185 | compact | 26 | l | ||
| normal | 101 | 3 | 1.61 | .10-.25 | ||
| F2 | Entry 623 | compact | 28 | 1 | ||
| normal | 101 | 3 | 0.731 | .25-.50 | ||
| F2 | Gourd selfed Ex | compact | 30 | 1 | ||
| normal | 96 | 3 | 0.099 | .75-.90 | ||
| BC | (Normal gourd x extreme | compact | 290 | 1 | ||
| dwarf gourd) x 185 compact | normal | 328 | 1 | 2.35 | .10-.25 | |
| BC | (Normal gourd x extreme | compact | 166 | 1 | ||
| dwarf gourd) x 623 compact | normal | 179 | 1 | 0.491 | .10-.25 | |
| BC | (Normal gourd x extreme | compact | 98 | 1 | ||
| dwarf gourd) x extreme | normal | 96 | 1 | 0.02 | .75-.90 | |
| dwarf gourd |
Literature Cited
- Scarchuk, John. 1974. Extreme dwarf gourd Cucurbita pepo var. ovifera Alef. HortScience 9:135.