For the past few years, Thai consumers have been enjoying temperate fruit crops, vegetables and herbs like never before. Depending on the season, avocados, strawberries, peaches, pears, persimmons, plums and passion fruit, as well as aubergine, broccoli, brussel sprouts, cabbage, carrot, leek, peas, potatoes, tomatoes, zucchini and Japanese pumpkin, to name just a few, are available fresh from the highlands of northern Thailand.
Grown under the auspices of the Royal Project, which ensures the produce is safe from pesticides, the crops may be purchased at Doi Kham shops in Bangkok and Chiang Mai. The shops, located at airports as well as at Kasetsart University and beside the Farmer’s Cooperative Market at Chatuchak, sell Royal Project crops and products including fresh and canned fruits and vegetables, canned and bottled fruit juices, jams, and fresh and dried flowers and herbs, among many others.
In the past, hill tribes roamed the mountains of Chiang Mai, planting the only cash crop that they knew, opium poppies. They did this in the only way they knew how: by using slash and burn cultivation, destroying forests and water sources.
In 1969, His Majesty the King visited Doi Ang Khang in Fang district of Chiang Mai and came upon some land which had been abandoned by the hill tribes since it was depleted of nutrients following the continuous cultivation of opium poppies.
The few families who had settled in the area grew apricots, which thrived very well in the cold climate. Seeing this, His Majesty asked researchers to help improve the hill tribes’ livelihood by introducing improved varieties of apricot and other temperate fruit trees. This marked the beginning of the King’s Royal Project.
Foreign governments gave tree cuttings, seeds and seedlings of temperate crops, equipment and technical know-how. Volunteers from various government agencies and universities developed the land, provided irrigation, conducted agricultural research and taught the hill tribes to plant fruit trees. While the trees were growing up, they were encouraged to grow vegetables, flowers and mushrooms, which the Royal Project sold for them.
Today, the hill tribes no longer need encouragement to grow cash crops. No longer leading a nomadic life, with opium poppies now a thing of the past, they cultivate land they can call their own and many now drive pickups. Yet, research goes on in the Royal Project’s 38 agricultural stations to determine which new varieties can be grown successfully or to increase their productivity even more.
At the Royal Agricultural Station at Pang Da, in Samoeng district of Chiang Mai, researchers are studying more than 20 varieties of grapes, finding ways not just how best to grow them but what shape of support is best for more efficient harvesting. Research is carried out on both temperate and tropical fruit crops, vegetables, flowers and herbs, as well as on fast-growing trees and bamboos, and soil and water conservation. The Pang Da station is the centre for the production of tree saplings for distribution to the other stations as well as hill tribes and interested growers.
What interested me during a visit to the station recently, however, was how yields were increased by pruning and training. Whether it’s fruit trees such as fig, longan, lychee, mango, persimmon and starfruit, or shrubs like mulberry, the technique is almost the same. The crown is cut back to reduce the plant’s height. Inward growing and unproductive branches are then removed to let the sun penetrate the lower branches.
Many growers think that the bigger a tree and the more branches it has, the more fruit it will bear. Often, however, the tree only has fruit on the outer fringes, for it’s those parts that get the most sun; shaded branches are unproductive. And if the tree is too high, the fruit on top cannot be reached and therefore cannot be harvested. Reducing the tree’s height facilitates harvesting, and letting the sun penetrate the lower branches encourages fruit set and productivity.
At the Pang Da research station, pruning establishes trees with strong, straight trunks and well-positioned primary branches, which are trained to be in a 45-degree horizontal position by being tied to wires strung between posts. Forcing them to be in a horizontal position enables them to get optimum light and the tree to have an open centre. Out of these horizontal branches grow vertical branches, and since optimum light distribution is key to high productivity, keeping higher branches upright permits light to reach the lower limbs.
Mulberry bushes trained this way yield 20kg during their first year and 40kg or more thereafter, according to Chaya Chaiprasop, one of the researchers at Pang Da. He also assists in research on grapes, kiwi, mango, lychee and pomegranate. Mango, of the golden giant variety from Taiwan, is now widely grown by hill tribes as well as lowlanders in Chiang Mai.
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Lofty leaves: Only branches that get the most sun bear fruit. Right, a golden giant mango from the Royal Agricultural Station at Pang Da.
