Seed regeneration of melon germplasm

Between 2002 and 2008 the UPCT (Universidad Politécnica de Cartagena) has regenerated and characterized 125 melon accessions from the germplasm bank of the UPV (Universidad Politécnica de Valencia). Thirty of them were contaminated, since their seeds generated plants of different types. The other 95 accessions were uniform regarding type. Sixty-six of the 95 uniform accessions were regenerated using only hand pollination, which yielded an average of 1322 seeds per accession. The remaining 29 accessions were multiplied using pollination mesh cages, combined with a few hand crosses in case the plants of the cage had been morphologically different. We obtained an average of 3895 seeds for each of these 29 accessions. It seems reasonable to attribute these differences in seed yield to the fact that pollination in cages takes place in more natural conditions than when it is manual. In the cases where accessions were contaminated, the exclusive use of hand pollination produced an average of 572 valid seeds per accession. The use of cages reduced the amount of valid seeds to 334 seeds per accession, after rejecting the seeds obtained in cages (since several types of melon plants appeared), and only keeping those obtained from the additional hand crosses. The use of cages is not more expensive than the exclusive use of hand pollination, if the accessions are not contaminated, and it seems to favour controlled multiplication. For contaminated accessions, the use of cages does not seem so advantageous. In any case, seeds harvested in cages can be used in the culling of contaminated accessions by means of hand pollination in later seasons, since it is likely that a fraction of seeds comes from self-pollinations or crosses among plants of the authentic variety.