Pollination Requirements of Macadamia

Abstract

The purpose of this work was to study the floral morphology and behavior of macadamia, especially regarding pollination; determine whether commercial varieties are self-fertile or self-sterile; seek suitable pollenizers if self-sterility was found; and determine the role of pollen vectors. pollen grains from a different variety, placed on marked style tips of an isolated self-incompatible variety and left unbagged, show a highly significant increase in initial set. This indicates that some measure of stickiness is present in either the pollen grain or stigma before the stigma becomes capable of causing pollen germination. Partial self-incompatibility was found in the majority of local trees of macadamia. However, several varieties were found which appeared to be almost completely self-compatible. In two orchards which were studied, the predominant pollen vectors of macadamia were insects. Wind pollination could not be wholly discounted, however, because enormous amounts of pollen are discharged by the flowers. The pollen-collecting honeybee is the most active insect on macadamia flowers. It is also the only insect that comes into regular contact with the stigmatic areas of the style.