Tissue-culture technology facilitates to hike yeild of tasty coconut

The tasty, popular coconut species of Thailand, kati, could not be produced in large scale because it is infertile. But scientists have now found a way to overcome its sterility

COCONUTS may look alike and most may even taste alike. But not the kati variety of Thailand, also known as the makapuno in the Philippines, whose thick, white and creamy texture makes it king of the crop -- and costs 20 times more than ordinary nuts.

Coconut fanciers throughout south and southeast Asia are quite aware some coconuts are much tastier than others and the kati variety tastes the best of all because it is thick, white and creamy and the flesh never hardens. Wherever they are put on sale, vendors know their appeal will allow them to unhesitatingly charge upto 20 times the cost of an ordinary nut. Now, scientists at Bangkok Flower Company (BFC) have found a way to increase the production of katis.

In the 1970s, Filipino researchers discovered kati nuts hqave a delectable texture because they do not contain an enzyme called D-galactosidase. All coconut flesh contains a substance called galactomannan, which is broken down by D-galactosidase into something called mannan -- the stuff that hardens coconut flesh.

Whatever it is that causes the lack of D-galactosidase in kati nuts, is controlled by recessive genes -- which are genes that normally do not express the traits they control. If neither parent carries the recessive gene then none of the nuts they produce will be kati, but if each parent carries one recessive gene, then three of four nuts produced will be ordinary but the fourth will be kati. However, coconut growers cannot cultivate the elite kati nuts by simple planting, because katis are infertile. No wonder then that Thai vendors will sell an ordinary coconut for 2 baht (Rs 2.25) but charge upto 50 baht (Rs 56) for a kati.

BFC scientists usually focus their efforts on creating new and more beautiful orchids, using tissue culture. They decided to apply tissue-culture techniques to propagate the recalcitrant kati. They began by cutting the embryos out of 2,200 choice kati nuts and putting them in small, glass jars containing liquid nutrient. A few months later the jars contained tiny kati plantlets. When these were sturdy enough, the plantlets were transplanted to pots and a couple of years later, to an area secluded from other species of coconut and nurtured under constant supervision. The isolation was necessary because stray pollen could destroy their pedigree and the fruit from these trees would then include only one kati nut in four.

So far, BFC has invested 1500 baht (Rs 1,680) on each sapling and by 1994, when the saplings mature, the total investment would amount to 15 million baht (Rs 16.8 million). But BFC is confident it will recoup its investment many times over, because each tree will produce only kati nuts and growers will pay handsomely for a tree that guarantees such a highly saleable harvest.

The first generation of tissue-cultue palms will be as different from each other as palms are in the wild. Some of the palms, will be tall, some short, some will produce large harvests and some meagre. The researchers hope to develop plants with characteristics that would attract even higher payments from growers such as short trunks for easy harvesting, disease-resistance, high-quality nuts and reliable bumper harvests. But it will require years of crossing the first-generation palms to yield a palm with all the desired characteristics. The prospect of heavy investment over the next few years does not unduly perturb BFC. Company officials are confident they can sell each kati palm for at least 1,000 baht (Rs 1,120).

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