Resumen: [EN] Fresh market demands high quality fruit and, therefore, citrus growers and researchers are constantly looking for
solutions to avoid seed presence. Current horticultural techniques have low effectiveness or high cost. The
objective of this study is to evaluate the inhibition effect of seven products on the in vivo pollen tube growth in
Nadorcott mandarin, which is a high-value seedy variety. To achieve this main objective, three inorganic fer
tilizers (ammonium nitrate, potassium nitrate, sulfur), and four saccharides (saccharose, methyl cellulose, cal
lose, chitosan) were applied to Nadorcott stigmas 24 h before and after hand pollination. Pollen tubes were
counted 1, 3, and 5 days after treatment in longitudinal blue violet autofluorescence-stained sections. Of the
seven evaluated products, only sulfur had a strong inhibitory effect. Elemental sulfur (S 8 ) inhibited pollen tube
growth by 94-100%. This strong effect was observed regardless of sulfur being applied 24 h before or after
pollination, and on fixed flowers 1, 3 or 5 days after applications. Saccharose treatment seemed to have the
opposite effect: stimulated pollen tube growth, but the difference with the positive control was small and non-
significant. The sulfur effect could be useful for designing agronomic applications capable of preventing seed
presence in Nadorcott mandarin.
