Cucurbit Genetics Cooperative Report 4:11 (article 5) 1981

A Second Source of Non-bitterness in Cucumber

H. Inggamer and O. M. B. de Ponti

Institute for Horticultural Plant Breeding, Wageningen, The Netherlands

The non-bitter character is commercially of vital importance in The Netherlands, bitter cucumbers being unwanted and thus unsalable.

In the 1950s, a continuous search went on at the IVT for non-bitter plants. In the gene bank then available, among 15,000 individuals one plant of the United States variety Improved Long Green (ILG) was found which was completely non-bitter in all vegetative and generative parts. Probably it was a spontaneous mutant. According to Andeweg and De Bruyn, the non-bitter character depends on one recessive gene (1). In the 1960s, this character was incorporated into the Dutch varieties with the result that at present almost all varieties are completely plant non-bitter.

In 1969, the IVT received from a missionary the pickling cucumber variety Jiwika, originating from the village of Jiwika in the Balliem valley in the central highlands of New Guinea. It was said to be plant-bitterfree.

Crosses were made both with the non-bitter ILG mutant and a bitter line. All 48 F₁ plants from the cross between Jiwika and the non-bitter ILG mutant were found to be completely free from bitter principles. Of the F₂ progeny from the cross of Jiwika and the bitter line, 192 plants were tested for the presence of bitter principles. Of those, 47 plants were found to be completely non-bitter. From this it may be concluded that in Jiwika too, the non-bitterness is governed by one recessive gene and that this gene is identical with the ILG gene, designated bi.

Recently, it was found that the gene Bi is not inherited in dominant fashion but intermediary (2). This could be demonstrated via the development of a method for the quantitative determination of cucurbitacin.

Literature Cited

1. Andeweg, J. M. and J. W. de Bruyn. 1959. Breeding of non-bitter cucumbers. Euphytica 8:13-20.
2. Ponti, O. M. B. de and F. Garretson. 1980. Resistance in Cucumis sativus L. to Tetranychus urticae Koch. 7. The inheritance of resistance and bitterness and the relation between these character. Euphytica 29: 513-523.