ASPECTS OF BREEDING FOR KEEPING QUALITY IN TULIPA

Research is reported on the possibilities of selecting for keeping quality in tulip breeding.
In glasshouse trials it was found that the keeping quality of flowers, left intact on the plant, was strongly correlated with that of cut flowers at 17°C. The period from flowering onset to start of discoloration and to perianth drop appeared to be effective selection criteria.
Flower longevity on the plant in the field and that of the cut flower after forcing in the glasshouse were significantly correlated.
This means that already in flowering progenies in the field a first screening for keeping quality is possible.
The interval between the different stages of senescence is not the same for all genotypes.
None of them can therefore be used exclusively as a criterion.
A more comprehensive criterion, i.e. the number of days the flower keeps its ornamental value, is effective when commercial varieties are compared, but for breeding on keeping quality all aspects of senescence must be considered.

With respect to selection for suitability for early forcing, different genotypes are being compared at various temperatures prior to forcing and during forcing.
It appeared that the relative differences in keeping quality between the cultivars and between the species were not changed by the temperature treatments prior to forcing or during forcing.
Therefore, screening on keeping quality may be done at any treatment.

Flower longevity showed a linear decrease with temperature during anthesis but not all cultivars showed the same reaction to temperature.
Though from selection at 17°C an average impression of the keeping quality may be obtained, a final selection both at lower and higher temperatures is advisable.

With a view to a more efficient choice of parents, breeding values of a range of cultivars were determined.
It appeared that most senescence phenomena are mainly based on additive gene action.
The choice of breeding partners can therefore be based on their phenotypic behaviour.

Populations from crosses on a diploid level show such a wide variation that even in a combination of two cultivars of which only one showed a reasonable keeping quality, a number of seedlings with good keeping quality can be found.

By an application of laughing gas (N₂O) on crosses between diploid cultivars and between species, tetraploids may be obtained with a better keeping quality than either parent.
A first release was made of such an artificially produced tetraploid.

III International Symposium on Postharvest Physiology of Ornamentals

J.P. van Eijk, W. Eikelboom

https://doi.org/10.17660/ActaHortic.1986.181.29