BREEDING CHRYSANTHEMUM AND ROSES FOR LOW NIGHT TEMPERATURES IN SOUTHERN FRANCE
The method is cross-breeding of the best performes of different parentages in a convergent schema. The tests of growth and flowering at low temperature are carried out at the wanted night temperature in winter in conventional glasshouses and soil benches.
The results are of different orders:
- Genotypes deserving to be tested by the growers, which may be new cultivars, if well received then protected by UPOV.
Material for a continuation of the selection (progenitors) and a genetical pool of plants with low temperature requirements.
- Informations on the general behaviour and on the various consequences of the selection process, after comparisons of the new types in different conditions of heating and at different seasons of growth.
Some advantages and drawbacks of the selections adapted to low temperature can be presented on basis of our limited experience:
With CHRYSANTHEMUM, 3 to 4 cross cycles give rise to types well adapted to a winter crop at 11°C night in our area. These 9 to 11 weeks types grow very fast at higher temperatures (above 14°) and are specialized for winter and reduced heating. The cultural practice must be changed: cuttings in peat blocks, drip-irrigation, no after-lighting, etc…
With ROSES, after 2 cycles, it appears difficult to obtain a normal production (in number and size of the flowers) with an earliness similar to Sonia, at constant night temperature below 11°C. The yields are not easily determined in small plots.
Selection of Roses (schema)
Varietal basis . The usual varieties of years 1965 to 75 intercrossed in two or three cycles of a preceding programme for winter production at medium night temp. (14°) led to original clones. A few variety were also introgressed.