GREEN FINGERS
A plant explorer’s work has benefited fruit tree and coconut farmers, and even tempered the effects of typhoons
A plant explorer’s work has helped fruit tree and coconut farmers while easing the effects of typhoons.
Unlike the Philippines, which is battered by no less than 24 typhoons a year, Thailand is hardly hit by typhoons. Thais, therefore, did not know what to expect when Typhoon Gay hit the Gulf of Thailand on Nov 3, 1989. With gale-force winds of 120kph, it killed 529 people, including fishermen and offshore oil rig workers, and rendered 160,000 homeless in the southern provinces of Chumphon, Prachuap Khiri Khan, Surat Thani and Nakhon Si Thammarat.
Receiving the brunt of the storm were Pathiu and Sawi districts of Chumphon, where the typhoon flattened nearly everything on its path. The only building left unscathed was the agricultural research station of the Thailand Institute of Scientific and Technological Research (TISTR), which was right by the sea.
Years earlier, Piya Chalermglin, PhD, then head of the station, planted 10 rows of casuarina trees along the shore. The trees, which grow up to a height of 35 metres, were only 10 metres high when the typhoon struck but they effectively served as a windbreak, sparing the station from any damage.
“As it was the only building intact, the late HRH the Princess Mother used it as headquarters when she came to provide relief for the typhoon victims,” Mr Piya recalled.
You met Mr Piya in last Sunday’s Green Fingers. During the course of his career as a plant explorer and researcher with the TISTR, he discovered 17 plant species new to science. During his stint in Chumphon, one of the country’s leading producers of coconut, in the 1980s, his research findings made it easier for coconut growers to determine whether their trees had produced macapuno.
Macapuno is a naturally occurring coconut mutant with soft, jelly-like flesh that is two or three times thicker than the regular coconut. In the Philippines, where it is more common than in Thailand, the flesh is grated and cooked in syrup, then sold in specialty shops wrapped in cellophane like candy.
In Thailand, it is mixed with desserts flavoured with palm sugar and coconut milk, like tubtim krob. Macapuno is valued by growers as it fetches a high price; in Thailand it sells 10 times more than the regular coconut.
Not all coconut trees produce macapuno, and even those that do produce macapuno do not bear only the coveted fruit. “Macapuno tends to develop only on inflorescenses facing west, but in one bunch, only one out of three fruits is macapuno. The rest are regular coconuts,” Mr Piya said.
Coconut trees are propagated by placing the mature fruit in a cool, shady place where it germinates. However, Mr Piya said the only way macapuno can be propagated is by tissue culture as the embryo won’t develop if planted the conventional way.
Plants developed from macapuno will produce only macapuno but they must be grown at least three kilometres from the nearest coconut trees to avoid cross-pollination, Mr Piya said. Otherwise the fruit will be a mixture of macapuno and regular coconuts like the mother plant.
The trees that produce nothing else but macapuno, however, bear few fruit. “Only around five per bunch,” he added.
Among the agriculturists who benefited the most from Mr Piya’s research work and technology transfer are plant nursery owners in Ban Phra, in the Muang district of Prachin Buri province, which now rivals Chanthaburi as the biggest source of fruit tree saplings. He taught them an innovative way of doing approach grafting, resulting in increased production and more income, and at the same time making the saplings cheaper for gardeners who want to grow them in their own orchards or gardens.
Grafting is the union of two separate stems. The upper part of the union is called the scion and the lower part is called the stock or rootstock. The usual technique is to take a stem with two or more vegetative buds as scion and attach it to the stock, which can be a seedling or a mature tree. The scion and the stock are prepared and attached in such a way that their vascular cambiums are in contact with each other, and these are fastened together until the two stems merge and grow together as one.
In approach grafting, the scion and the stock are joined while both are growing on their own roots. The plants used as rootstocks are potted or planted in polyethelene bags and placed close to the stems used as scions. An inch or two of the bark on one side of the stock is sliced away, and a similar cut is made on one side of the scion. The two cuts are then pressed together and bound with a tape or string to prevent the cut surface from drying and to hold the cambia close together.
The cambia of the scion and the stock produce a mass of parenchyma cells which intermingle and interlock with each other. A callus then forms, serving as a bridge of living tissue between the scion and the stock, making it possible for them to grow as one.
Water, hormones and essential raw materials pass from the stock to the scion, and the manufactured foods pass from the scion to the stock. Once the callus is formed, the scion can be severed from the mother plant, ready to be transplanted.
“In the past, nurserymen could only graft the lower branches as the potted rootstocks were heavy and had to be placed on the ground. By tying the containers to bamboo poles horizontally placed above the trees, all the stems can be grafted as the stocks can be raised or lowered to be close to the scion,” Mr Piya explained.
“Once the callus formed and the scion is severed from the mother plant, a new stem grows and this can be grafted again as scion. The method is so simple and economical, and nurserymen can keep on propagating their trees, using seedlings as stocks.” Trees grafted using this method include jackfruit, mango, tamarind and Garcinia schomburgkiana, known in Thai as madan. My husband paid 200 baht, or 25 baht each, for eight 70-80cm tall jackfruit saplings he bought for our farm.
Following his retirement two years ago, Mr Piya joined a company producing vanilla in Tahiti and Madagascar, and has since been dividing his time between the two countries and Thailand.
He also has his own vanilla experimental plots in Chiang Mai, with the hope that someday he will be able to transfer his know-how about vanilla production to Thai growers.
“My dream is to make Thailand a leading producer and exporter of vanilla,” he said. “If I can fulfil that dream, then I can retire for good.”