HARVESTING TIME AND VIABILITY OF Ixora coccinea 'Dwarf Red Coccinea' POLLEN

The cultivated variety of the non-native I. coccinea,   Knowledge about pollen of Ixora coccinea, cv. ‘Dwarf Red Coccinea’ to be collected for basic investigations or plant breeding purposes is limited. Under a light microscope, I. coccinea, cv. ‘Dwarf Red Coccinea’ pollen was generally prolate in shape which was different from that of  I. congesta and I. arborea. In addition, the quantity, viability and germinability of pollen collected at different times from 8 am to 4 pm in a summer day from the flowers of I. coccinea, cv. ‘Dwarf Red Coccinea’ were investigated. Pollen quantity was determined using a haemacytometer while the viable and germinable pollen was examined after staining with 1% acetocarmine and germinating on a modified agar-gelled germination medium, respectively. The I. coccinea, cv. ‘Dwarf Red Coccinea’ pollen collected at 10 am exhibited the highest pollen density and germination percentage of 53.3×104 pollen/ml and 72.05%, respectively. When these pollen were germinated on the artificial medium supplemented with various sucrose concentrations, the highest in vitro '˜Dwarf Red Coccinea' pollen germinability was found on a medium containing 10% sucrose. It was concluded that the best time to collect I. coccinea, cv. '˜Dwarf Red Coccinea' pollen was at 10 AM. Further studies would be worthwhile to investigate more closely the effect of changes in the environmental factors (for example, ambient temperature and humidity) even within the same day on harvestable pollen quantity and quality as well as pistil phenology to develop a more complete breeding strategy for Ixora.