TOMATO FRUIT SET UNDER LOW TEMPERATURES

It has been established that parthenocarpy in the line 75/59 is regulated by two genes, pat-3 and pat-4. The relationship between 75/59, Severianin and Subartic plenty has been established. The pat-3, pat-4 and pat-2 systems have been studied against different genetic backgrounds. At present, new research methods are available to determine other parthenocarpic sources and their relationship with the above mentioned methods.

Similarly, studies which clarify the genotype X environment interactions related with parthenocarpic expression are underway.

The cultivation programme has been carried out using classical improvement methods. At present a collection of parthenocarpic lines (currently in F8) has been obtained. Five of these were registered as new tomato cultivars in 1988. New parthenocarpic hybrids derived from crossing several parthenocarpic lines which have been developed in this programme are also available; one of them "FREDA" was registered in 1988.

In competitive behaviour trials, it has been established that the new hybrids are competitive compared to other commercial hybrids currenlty available on the market.

Other improvement techniques such as cellular cultivars and genetic transformation of plant material, have recently been started. The quasi-isogenic lines have been used to determine the molecular identification of pat-2 gene by means of differential protein detection.

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