Durian Pollination and Fruit Set.
Low fruit production in a durian farm is a recurring major problem. This problem is generally associated with poor pollination and fruit set.
Durian pollen is released mainly in clumps, indicating that it is not distributed by wind. Moths may be involved in pollen transfer. It was shown that if more pollen lands on the stigmatic surface, a higher amount of fruit set will be the result. This knowledge has led to hand-crossed pollination being a common practice to improve fruit set in durian.
|Research study - Pollination by fruit bats Link|
When about 25% of total flower number on the whole tree flowers is at bloom,hand-crossed pollination using pollen from different varieties or from the same variety but different trees is recommended. The optimum time should start pollination is from 6:30 to 9:30 p.m. or later, which is the effective pollination period for durian. (Reference)
|1. Durian tree with with heavy flowering|
|2. Select durian flowers where the anthers have dehised to release their pollens|
|3. Cut the anthers from the stamens and collect the pollen grains in a glass container.|
|4. The sticky pollen grains at the bottom of the tube will cling onto the fine hairs of a paint brush|
|5. Flower with stigma protruding from the petals and receptive for pollination|
|6. Pollen grains are then brush onto the receptive stigma. Usually carried out about 3.00 to 7.00p.m.|
|8. Flowers that are successfully pollinated have set fruits|
|9. Tree heavily laden with fruits from successful pollination and fruit set|
Seasonal fluctuations in weather conditions were found to influence the flowering and fruiting phenology and reproductive biology of durian grown around Darwin. Manually assisted cross-pollination resulted in higher fruit set of 31% in contrast to < 10% by selfing, producing higher yields and better quality fruit. Self-pollination resulted in more fruit abortion and produced fruits that were mis-shapen, curved with lower numbers of arils/locule, arils/fruit and lower numbers of seeds which were usually shrunken and disfunctional. Evidence from these studies also confirmed that the self-incompatibility system in durian is gametophytically controlled and that cultivars could be totally self-incompatible, partially self-incompatible or totally compatible. The durian pollen was found to exert metaxenia effects that influenced the development of the fruit characteristics and also xenia effect on the seed.
Studies on hand pollination of durian (Durio zibethinus L.) cvs. Cha-nee and Kanyao by certain pollinizers 
Songpol Somsri Kasetsart Univ., Bangkok (Thailand). Graduate School [Corporate Author]
The percentage of fruit set in the 2 varieties as observed after 2 weeks of pollination. In Cha-nee they were 0-6 for open and self pollinated and 30.1-63.61 for cross pollinated. In Kanyao, they were 21.19 and 87.09-89.68 for open and cross pollinated. The fruits of Cha-nee pollinated by several varieties were oval shape, unaborted carpel, larger size and heavier weight than the open pollinated fruit whereas those of Kanyao as seed parent were round shape with unaborted carpel, small fruit size and lesser fruit weight due to heavy fruit setting. The fruits pollinated by several varieties in The Cha-nee and Kanyao were similar to the open pollinated fruits in terms of fresh texture, fresh color, but had more unaborted seeds and higher number of seeds than the open pollinated fruits. The results of the experiment appear to indicated that fruit set in durian could be improved by cross pollination.
It has been known for some time that some durian trees are self-incompatible (Coronel 1966); although crossing and selfing tests with named clones have been conducted (Jamil 1965), no details
seem to have been published. This is unfortunate as such information would be useful in determining good clonal mixtures for orchards and for the production of better clonal material in the future. The Malaysian clone D99 has been shown to be self-compatible (Zainal Abidin and Nik Masdek 1992). Clone D24 (Shaari et al. 1985), and the Thai cultivars Gumpun and Luang (Lim el al. 1992) have been demonstrated to be self-incompatible.
However, compatibility information for the many other clones/cultivars is not available.