Abstract
AbstrAct. The cultivation of zucchini under greenhouse winter conditions in Almería (Spain) reduces the number of
male flowers and pollen, as well as the activity of natural pollinators. The removal of the synthetic auxin treatments
currently used to set fruit in zucchini therefore requires the development of parthenocarpic varieties. We have explored
45 landraces of C. pepo with elongated fruits, morphotypes zucchini, vegetable marrow and cocozelle, to identify
new sources of parthenocarpy for zucchini breeding programs. After two consecutive screening assays for both the
percentage of parthenocarpic marketable fruits and parthenocarpic fruit growth rates, 5 accessions were selected.
The parthenocarpy of some of these accessions differs from that of commercial hybrids in that it was not found to
be associated with the syndrome of fruits with attached flowers, an undesirable trait in the current parthenocarpic
hybrids. Moreover, we have observed that parthenocarpy is inversely correlated with ethylene production in the fruit.
Whereas in non-parthenocarpic accessions unpollinated fruits produced a boost of ethylene at 3 days post-anthesis
(DPA), concomitantly with fruit abortion and senescence, in parthenocarpic cultivars the fruits barely produced ethylene
at 3DPA. Therefore, ethylene production in ovary/fruits at 3 DPA could be used as a marker to identify and select
parthenocarpy in squash. Nevertheless, earlier evaluations of ethylene production and sensitivity in vegetative organs
and in male flowers are not so well correlated with parthenocarpy in the analyzed cultivars.
