CROSS-pollination has proven critical for maximising yields in macadamias, according to a Hort Innovation R&D pollination project.
Hort Innovation R&D manager Ashley Zamek said DNA paternity testing of macadamia nuts was done to understand if they were self or cross-pollinated.
"Work showed cross-pollination occurs in the majority of macadamia orchards, with only 2-6 per cent of nuts tested coming from self-pollination," Ms Zamek said.
"This means cross-pollination is critical for nut production and maximising yields in macadamia orchards."
The project - Increasing yield and quality in tropical horticulture with better pollination, fruit retention and nutrient distribution - aims to increase the productivity, profitability and global competitiveness of Australia's horticultural industries by helping to optimise crop pollination efficiency.
Cross-pollination is the transfer of pollen from one flower to another flower on a different variety of the same species.
Cross-pollination ensures genetic diversity of offspring which in some horticulture produce, means more fruit per tree and a better-quality product.
"The key objective of the six-year project is to increase yield and quality through better understanding of crop nutrition during crop pollination and through improved understanding of the effects of cross-pollination on a range of horticultural industries," Ms Zamek said.
Professor Stephen Trueman from Griffith University said most nuts were only formed when macadamia flowers receive pollen from a different variety.
"However, the distance to another variety in large orchards is often more than 100m," Professor Stephen Trueman said.
"We need to inter-plant the different macadamia varieties more closely to ensure that bees transport enough pollen from one variety to another."
Australian Macadamia Society CEO Jolyon Burnett said maximising the Australian macadamia crop had proven challenging.
"This research is helping to put the pieces of the puzzle together. We're now beginning to understand the critical components," Mr Burnett said.
"There is a lot of interest from Australian macadamia growers because of the potential for better pollination to improve yields and increase kernel recovery."
Hort Innovation R&D general manager Dr Alison Anderson said the program would also help develop new international collaborations among pollination and plant physiology science groups in Australia, New Zealand and Germany, and support new students into the horticulture sector.
The project started in 2017 and will continue until 2023.