Inducing early flowering in mangoes

Amy Dobell, Technical Officer, Darwin

Mango trees require cool temperatures at the beginning of the Dry Season to induce flowering. This year the cooler weather took longer than usual to reach us; resulting in later flowering and thus later fruiting. This delay in cool weather allowed us to test the potential of growth promoting foliar sprays to initiate flowering. This technology could allow farmers to increase the reliability of their crop during years when weather conditions are not ideal.

Two experiments were conducted in a Kensington Pride mango orchard in Berry Springs. The first examined eight different growth inhibitor treatments to stop premature vegetative growth, which occurs in response to the lack of cool weather. Vegetative growth at this time further delays flowering even after the cool weather finally arrives. The second experiment examined six treatments of growth promotors that targeted bud break and early flowering prior to the late arrival of cool weather.

This year’s work indicates that the growth promoting foliar sprays worked only on certain parts of the trees. The most exposed parts of the canopy did not respond to any treatment, and flowering between the trees, in the cooler and less exposed canopy positions, had the strongest response to treatments.

This may indicate that there is a high temperature inhibition as well as a low temperature requirement for flowering. We also found that the conventional use of potassium nitrate was almost ineffective in triggering flowering during these periods of high night temperatures. Where there was a response to the growth promoting treatments, it occurred rapidly with growth after one week and flowers within two to three weeks.

These results demonstrate that specific floral promoters are able to initiate flower growth at temperatures when mango trees would not normally flower. With further work this could open the opportunity for mango production to occur from June all the way through to December.

Panoramic view of Senior Research Leader Cameron McConchie applying a growth promoter spray to mangoes at Berry Springs