VARIATION PATTERN IN ULLUCO (ULLUCUS TUBEROSUS-BASELLACEAE), A SUPPOSEDLY ASEXUAL ANDEAN TUBER CROP

Variation of the endemic Andean tuber crop ulluco (Ullucus tuberosus) was studied on the basis of material of clones collected on expeditions to Peru in 1982 and 1983 and grown in the Botanical Garden of the University of Turku. The material consisted of 11 accessions bought from the markets of Cuzco, Juliaca and Puno, each accession containing many clones. There were 238 numbered clones, some of them probably duplicates of the same clone. Cultivation experiments were made in a plastic greenhouse under a shortened day and outdoors under the normal day-length regime. Of 29 characters studied, the majority showed statistically significant differences between accessions. The principal component analyses and stepwise discriminant analyses tended to group the clones within an accession, some accessions being more variable than the others. There was also variation in the ability of the different accessions to form tubers in the ca. 12 hours' day outdoors. In the outdoor experiment in 1984, 76.2 % of the plants flowered, in the greenhouse only 22.3 %. Certain clones flowered very profusely outdoors (even over 3000 flowers per individual) and these clones flowered more than the others also in the greenhouse. The stainability of pollen varied widely between accessions. One morphologically distinct accession from Cuzco, called "ullucito" at the market, had particularly good pollen and formed a few well-developed fruits in our outdoor experiment late in September. This is the first documented case of fruiting in cultivated ulluco, which has been considered a purely asexual crop. It is concluded that the existing local variation as well as the potential variation of ulluco by sexual reproduction could be exploited for selection and breeding work.

This report is a part of a larger research project on three Andean tuber crops, ulluco (Ullucus tuberosus), oca (Oxalis tuberosa) and anu (Tropaeolum tuberosum). These three crops never gained any real importance outside their original area although from time to time small-scale experiments have been done to introduce them to Europe. Particularly during and after the potato blight epidemy in the last century some hope was placed in the prospect of replacing potato with some of these crops originating from the same area. In the European literature of the last century we find some promising and even overoptimistic reports especially on ulluco (e. g. Sodoffsky 1851) but mostly rather disappointing results. The main obstacle to the successful cultivation of these Andean crops in Europe has been the different day-length requirement of the tuber production. The plant material used in these experiments