Flowering behaviour and subsequent productivity of mangoes

• Department of Agriculture, Thailand
• CSIRO Division of Horticulture, Australia

In Thailand, 440 280 tonnes of mango (Mangifera indica) were produced in 1988/89. The fruit is traded at the village level and is also exported to Malaysia, Singapore and Japan.

In Australia, the mango is also becoming increasingly popular and planting expanded from an estimated 65 000 trees in 1978 to 700 000 trees in 1990.

However, mango, which occurs in the tropics and subtropics, exhibits one of the lowest orchard efficiencies of any fruit, with sustainable yields of less than 8 t/ha.

In Thailand, annual yields fluctuate by as much as 150%. This inconsistent production pattern has hindered export trade development by both Australia and Thailand. In the tropics, inconsistent production has been associated with the failure of flowering. In the subtropics, flowering is profuse but fruit set is poor, cooler temperatures affecting pollination and fertilisation of the ovule.

The purpose of this project is to research mango growth and reproduction in different environments. To achieve this, scientists in Thailand and Australia will define basic physiological parameters which effect floral induction, fruit set and development, for a variety of cultivars. Growth events will be described in relation to environmental conditions in tropical and subtropical areas.

The annual phenological cycle (i.e. seasonal growth patterns including reproduction) in mango trees will be studied by scientists in both tropical and subtropical regions. Such parameters are to some extent environmentally driven because variation between different cultivars is an expression of the genotype x interaction.

Scientists will also define seasonal change in carbon dioxide assimilation, photosynthesis and other physiological processes relating to flowering and determine the effect of environmental stresses on these processes.

At CSIRO, Darwin, a highly effective chemical cincturing technique has been developed for floral induction in tropical environments. Tropical research teams will evaluate the technique, which has a strong genotype interaction, for each cultivar.

The temperature limits during flowering and fruit set for key Thai and Australian cultivars will be the focus for subtropical research based in Maroochy HRS in Australia and Chiang Rai HRC in Thailand. Scientists in both countries will collect detailed records of floral phenology associated with temperature records and yield assessments for each cultivar. These data will be used as the basis for more detailed studies carried out in controlled temperature glasshouse rooms at Maroochy HRS.

Training in the scientific techniques developed will be given to Thai scientists taking part in the project.