An explosive way to induce flowering of Longgan

Longgan farmers from Northern Thailand had observed that Longgan trees around where they exploded firecrackers flowered and fruited profusely, whereas the rest of the farm was normal. They deduced that there was something in the firecrackers that caused the trees to flower. By asking the firecracker makers the ingredients of the firecrackers, the farmers narrowed down the suspected inducer and theorized that it was the perchlorate that did the job of inducing the flowers. They started pouring perchlorate solution on to the soil and got their results. This is an excellent case of effective farmer-led research.

Over the years the Thai Longgan farmers have used this information to improve their production and revenue, way before researchers in the academe got hold of the information.

Perchlorates are highly explosive and may not be handled by lay people. An alternative was to use chlorates (as potassium chlorate). It is just as explosive but a lot easier to handle than perchlorates.

By 2003, The Horticultural Research Institute of the Department of Agriculture of Thailand, The Horticultural Science Society of Thailand and the Food and Agricultural Organization (FAO) published the book: Amazing Thai Longgan, where the protocols were outlined.

Prerequisites

Either sodium or potassium chlorate solution is effective provided the following conditions are satisfied:

•Water is available. This is the single most important factor.

•The recommended dosage is used.

•The Longgan leaves are mature. The leaf maturity may be tested by squashing the leaf in the hand. If it crackles on the dry side, the leaves are mature enough. If it just folds, leaves are not mature yet. The tree should be healthy and free of any chlorosis.

In Thailand, chlorate treatment is avoided if it will fall on the last week of February to March because the flowers will be out April when it is too hot and dry. The quality and quantity of fruit will not be good.

Application Methods

Soil Application: This is the most popular method the farmers use. The tree should have mature leaves but without new sprouts or young leaves at the tip of the stems. The trees to be treated should be very healthy. Remove the litters and grasses below the canopy to expose and dry. Pour the solution at a recommended rate of 60 to 80 grams of sodium or potassium chlorate per tree; 0.5 meter away from the base of the tree but under the canopy. After treatment the soil is kept moist with daily watering for 10 days to ensure the chlorates reach their target roots.

Foliar application. The chlorates are sprayed over and under the mature leaves as 0.2 percent chlorate solution (40grams sodium or potassium chlorate in 20 liters of water). The best time to do this would be during the dry month November or December. It does not work during rainy season and the warm month of March.

Fifteen days after either treatment, the flowers will appear. There should be enough water to sustain the fruits.