Abstract:
A parthenocarpic breeding line, Oregon T5, from
Oregon State University, was crossed with several commercial
cultivars. Progenies were studied for 2 years
as both direct-seeded plants and transplants in the
field at Corvallis, Oregon to determine the inheritance
of parthenocarpy in Oregon T5. Both quantitative
and qualitative measurements of parthenocarpy
were used.
F₁, F₂ and backcross data indicated that the
inheritance of parthenocarpy in T5 is recessive.
F₂ data fit a 9 seedy:7 seedless ratio, suggesting
duplicate recessive genes.
F₂ data from a cross with 'Severianin', an unrelated
parthenocarpic cultivar, indicated the inheritance
of parthenocarpy in T5 is due to different
genes than in 'Severianin'. These data also support
the hypothesis of 2 genes for parthenocarpy in
T5, with a possible interaction of modifiers for
parthenocarpy from both parents.
Chi square tests showed an association between
parthenocarpy and earliness as measured by number
of days to first ripe fruit. This earlier ripening
in T5 crosses resulted from a shorter interval between
flowering and ripening, and not from earlier flowering,
in most cases. In general, no association was indicated
between parthenocarpy and fruit size.
