|Authors: ||B. Atanassova, H. Georgiev|
|Keywords: ||hybrid seed yield, positional sterility 2 (ps 2)|
Male sterility in tomato is recognized as a useful trait in breeding programs that address facilitation and improvement of the process of hybrid seed production.
In Bulgaria, during the last 10 years the use of positional sterile 2 (ps 2)-sterile seed parents in tomato hybrid seed production is not any more merely a theory, but a theory that is applied in practice.
Up to now no problems concerning their seed production and hybridity have been reported.
Comparative study on the time necessary for the emasculation of floral buds, (as practiced when using fertile seed parent) and flowers at anthesis, (as practiced when using a ps 2-line as seed parent), made it clear that emasculation during anthesis was easier and almost two times more rapid than emasculation applied on the floral buds.
However, the easier and more rapid anther emasculation is not the only criterion for an efficient hybrid seed production.
Hybrid seed yield and the percentage of hybridity of the seed obtained are also of great importance.
The study was therefore designed to compare the hybrid seed yield and hybridity of the seed obtained from four ps 2-sterile lines as depending on the developmental stage in which stamen emasculation and pollination took place and on the environmental conditions.
The results obtained provided evidence that the introduction of ps 2-sterile seed parents in breeding tomato hybrids was not only a way for facilitating hybrid seed production but also a way to ensure 1.5-2.0 times higher hybrid seed yield, and this regardless of the genotype and alterations in the climatic conditions.
These data were confirmed by production figures.
The percentage of hybridity of the seed obtained in all variants was 100%. During the last 10 years based on the lines included in the study, as well as based on other ps 2-lines, a number of tomato hybrids were developed and released: Balkan, Kom, Geo 12, Rila, Dorina, Precoce, Kamena, Elina, Odysseus.
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