The Subtropical and Mediterranean Horticultural Institute (IHSM) La Mayora of Malaga is investigating how to improve avocado pollination, as despite being one of the trees with the most intense flowering, less than one percent of the flowers are pollinated and produce a fruit. The research aims to find pollination mechanisms to optimize the productivity and increase fruit yields per tree.
The research is being carried out under the direction of Iñaki Hormaza, research professor and director of the Subtropical Fruit Group and honorary member of the Botanical Society of America.
Work on this project has made it possible to find a relationship between the nutritional status of the flower and the fruit setting. Thanks to such studies, it is known that flowers with higher starch contents are more likely to become fruits. With the research, it was discovered that most avocado flowers have little starch and therefore very few chances of eventually turning into fruit.
According to the researcher Librada Alcaraz, member of the Subtropical Fruit Growing team of La Mayora, gaining knowledge about the pollination of the avocado flower is a long-term project, since there are many factors that intervene in the fruit's setting, from the flower's own biology to the type of insect pollinator, and even the temperature.
For the studies currently being carried out, La Mayora uses state-of-the-art machinery and equipment, such as a phytochamber capable of reproducing the desired environment in controlled conditions, which makes it possible to study the fruit setting without interferences. This chamber allows researchers to study the effects of low temperatures in the fruit setting, or make crosses to evaluate which pollen is of higher quality.
According to Alcaraz, the avocado flower is hermaphrodite. "First it opens in a feminine state; then it closes and opens again the next day in a masculine state. This sexual mechanism, called protogynous dicogamy, prevents self-fertilization," he explains.
Striving to improve fecundation, the IHSM La Mayora is making use of several systems. One is the use of insect hotels in the plantations to encourage pollination by insects, other than honey bees (solitary and syrphid bees), as the European honey bee is not an optimal pollinator for avocados. Furthermore, La Mayora is studying how to increase the starch content of flowers to improve their quality and thereby increase the percentage of fruit setting.