Research

Researchers compared flower structure, reproductive timing and pollen-tube growth in macadamia cultivars in Queensland. Differences in flower spacing and timing did not explain the groups' self-fertility. Microscopy showed growth stopping within the style in incompatible pollinations, with outcomes varying between particular crosses and their reciprocal combinations. The experiment measured pollen-tube progression, not harvested yield; pollen dosage was not precisely controlled. The findings support further compatibility research, rather than a universal orchard planting prescription.

Researchers genetically assigned pollen parentage to nuts from 19 macadamia cultivars at 23 sites in Australia, Brazil and South Africa. Cross-pollination accounted for 80–100% of sampled fruit at 17 sites; other sites showed substantial variation. Cross-pollinated nuts often had better measured quality than self-pollinated nuts. The results support considering cultivar arrangement and pollinator distribution, but do not establish one hive density, planting layout or guaranteed yield gain for every orchard.