Research findings on pollination of Hass avocados

At the 2017 SA Avocado Growers’ Association research symposium, University of Pretoria researcher, Mart-Mari Nieuwenhuizen, presented new findings on the best pollinisers for Hass avocados. She also explored the effectiveness of bees as pollinators. Alita van der Walt reports.

- Alita van der Walt

Avocado growers keep a close eye on the fruit set and fruit drop of their orchards from October to February. This is to help them estimate the yield that can be expected during harvesting from March to May.

If avocado flowers are not pollinated, no fruit will develop. To ensure optimal pollination, avocado growers place bee hives in orchards to help increase the number of pollinators available.

Researchers at the University of Pretoria are conducting an ongoing study to determine which cultivar of avocado is the best polliniser for the popular Hass cultivar. They are also investigating the effect of using bees as pollinators in avocado orchards.

The study, which started in the 2015/2016 season, includes in vitro trials, as well as various field trials. The 2017 harvesting data will also be included in the study.

For the in vitro trials, pollen from Ettinger, Fuerte, Bacon, Zutano and Hass cultivars were used to pollinate the Hass pistil. 

According to Mart-Marie Nieuwenhuizen, a researcher at the University of Pretoria, the research team focused mainly on pollen tube movement down the style during the in vitro trials. The pistils of the pollinised flowers were studied under a fluorescent microscope and evaluations were made with regard to the number of pollen grains on the stigma, the number of pollen tubes moving down the style, and the number of pollen tubes that reached the ovary and entered the ovule.