INTRODUCTION

Until very recently the contribution of the diploid edible potatoes of South America to breeding in the Northern Hemisphere has been limited to a few, unimproved genotypes. To examine the potential of this material, a substantial and widely based sample should be acclimatized to higher latitudes, extensively screened for fungal and viral disease resistances, and suitable breeding strategies devised (bearing in mind its diploid nature) for combining it with a range of modern Solanum tuberosum ssp. tuberosum (Tuberosum) parents. Any general advantages which could reasonably be expected from the new material, such as more rapid attainment of particular breeding goals at the diploid level, the presence of unexploited additive variation for yield components, and of heterotic effects in hybrids should be utilized as fully as possible. This paper describes briefly a programme for the use of S. phureja (Phureja) germplasm at Pentlandfield, based upon these requirements.

METHODS

Work on the improvement and subsequent utilization of diploid potatoes began in 1967 with a mass-selection scheme, which was continued until 1979 (Carroll 1982). In 1968 crossing was started to produce first generation hybrids with dihaploids of Tuberosum. Further crossing and selection took place amongst the hybrid material, and a pedigree scheme for Phureja was initiated, using individual selections from the mass population. Direct crosses between Phureja and Tuberosum cultivars began on a small scale in 1973 using the “diplandroid” system to produce tetraploid offspring. Several hundred pollinations of 2x males with 4x females produced hardly any progeny based on “diplogynoids” (Sudheer (Carroll) 1977).