Scientists unlock secrets behind flowering of the king of fruits

Tokyo, Japan – Researchers from Tokyo Metropolitan University have discovered that around 15 days of dry weather can trigger the flowering of durian. Observations of 110 durian plants revealed that flowering occurred around 50 days after an approximately 15-day dry spell, independent of whether the plant was grafted or grown from a seed. The team’s work might not only impact the production of a valuable agricultural asset but deepen our understanding of tropical ecosystems.

Known in many countries as the “king of fruits,” the durian is known for its distinctive strong odor, large size, and thorny rind. Though its odor splits opinions, its widespread culinary use in Asia makes it an exceptionally valuable crop, accounting for the largest share of fruit in Malaysia by production, area planted, and quantity produced. Yet, there is much that is unknown about its cultivation, including how its flowering is triggered.

To uncover the secrets of durian flowering, a team of researchers led by Professor Shinya Numata and Aoi Eguchi from Tokyo Metropolitan University undertook an extensive survey of durian, observing 110 plants in the orchard of the University Technology Malaysia with local collaborators. Their study covered both seed-grown and grafted plants, focusing on the timing at which individual plants flowered, measured against an extensive survey of weather conditions.

The team found that durian plants flowered approximately 50 days after a prolonged period of dry weather. These dry spells needed to be long enough to show up in moving average traces, specifically periods where rainfall averaged over 15-day windows was less than 1 millimeter. Previous work had hinted at some correlation between either dryness or low temperature. This is the first time that the exact conditions had been pinned down with such accuracy, though they found no correlation with maximum or minimum temperature. Their work was found to apply to durian plants irrespective of their varieties, as flowering seemed to occur at the same time for both. The same was also found for both seed-grown and grafted plant types.

The team had proposed that there was some relationship between the flowering of durian and the more general burst of flowering seen in the tropics following long dry spells. However, such general flowering events require a longer dry spell of around 30 days to occur. This explains why durian tend to flower multiple times a year, while synchronized flowering across species occurs once every few years.

Given its commercial value, insights like these will inform effective agricultural practices to predict flowering and manage harvests. The team hope that their findings will also deepen our understanding of the southeast Asian tropical ecosystem.

This work was supported by a JSPS KAKENHI Grant Number 22J21299.