Just looking at a citrus fruit at the supermarket compels one to reach out and buy it. Maybe it is because of the colours that seem to burst out and invite you to savor its rich flavour. Looking at a carton of orange juice at the supermarket, one feels a little delirious thinking about the juice in those orange peels. Garden Talk spoke to Assistant Director Research W. D. Lesly of the Fruit Research and Development Institute Kananwila, Horana on citrus fruits that rank high among fruit fanatics.
“In the citrus group, the main types are sweet orange, mandarin, pummelo, grape fruit and lime. But there are variations. Fruits in the citrus group are spread throughout the world. They are highly adaptable to different climatic conditions. The quality varies according to climate,” said Lesly.
Mandarin trees are smaller than pummelo. Oranges are in between. Their quality is high when grown in dry cool areas. They have a good taste as plants are highly adaptable to various conditions.
“Brazil is the main producer of sweet oranges. Japan is the highest producer of mandarin. These types are spread out from Pakistan to Australia, but the quality is different from place to place according to climatic and soil conditions. The taste and appearance, inside and outside are different in the fruits found in various parts of the world,” stated Lesly.
In Sri Lanka, the best areas to grow citrus fruits are dry and cool areas with higher elevations such as some parts of Badulla. Although we have limited dry-cool areas, we have enough land to cultivate in the dry zone such as Moneragala, Ampara and Anuradhapura.
“When growing citrus trees, the grafting technique is the best. Budding can be done as well. Cut a citrus plant (rootstock) off at the trunk, take a branch from a mother plant and fix it to the cut -off point (graft it). That is the union. Then you need to cover the plant in polythene that acts as a micro propagator. After 21 days, remove the polythene. Then new shoots come from the branch taken from the mother plant. When grafting, we wrap the union using polythene tape,” he said.
Lesly explained the budding technique. “When budding, remove a part of the bark of the rootstock plant (the plant chosen for budding). Then take the mother plant and choose a bud. When a leaf falls after maturity, there is a scar. That is the bud or a growing point. It can develop as a branch.
 W. D. Lesly. Picture by Sarath Peiris |
“Carefully cut off a portion of the mother plant containing the bud and fix it to the rootstock plant: to the place where the part of the bark was removed.
“Afterwards, it is covered in a polythene covering. After 21 days, the polythene covering can be removed. We cut off the trunk of the rootstock plant again just above the place it was budded. Then new branches develop,” explained Lesly.
Citrus is a highly cross-pollinated plant adapting to different climatic conditions. It is pollinated by the wind and insects. Natural mutation also occurs in the population. With mutation, we can obtain favourable characteristics.
“Flowering takes about two or three years. It depends on the growing conditions. Fruits appear in four to five months after flowering. It varies according to the variety. The citrus plant can be kept for almost 40 – 50 years,” added Lesly.
Nurseries are essential for grafted plants. Initially, they are grown in seed beds, consisting of only sand. Then seedlings or rootstock plants are transferred to pots containing compost, sand and top soil.
“In one week, plants appear in seed beds. Afterwards, in one or two months, they are transferred to pots. But before grafting and budding, the seedling plant must be of suitable thickness. Then grafting and budding is carried out,” pointed out Lesly.
Citrus plants usually have dark green leaves. They are hardy plants and highly adaptable. They are evergreen plants. In countries with seasons, the end of winter is the season for citrus. In our country, plants are induced into flowering in December and January. Flowers bloom in February and March. Fruits appear during May and June.
“In a nursery, there is no particular temperature that needs to be adhered to. But it should not be exposed to heavy sunlight. Over 80 percent shade is necessary. Before grafting, we apply enough water to the rootstock plant, because for 21 days, we are not opening the cover. Gradually, it has to be exposed to sunlight. About two or three months after grafting and budding, plants are transferred to fields,” elucidated Lesly.
The soil medium in the field should be sandy with good drainage. The width and depth of the hole must be 75cm. Then it has to be exposed for four to five days. Then the hole needs to be filled mixing organic manure and top soil. If the soil PH is below 5.5, then Dolomite needs to be added to the top soil.
“In the West, citrus is used for different value added products such as jellies, ice cream, drinks and other food. Citrus is a delicacy. Citrus juice is even added to coffee. Dried portions of citrus are also used. We import citrus on a mass scale,” summed up Lesly.
HEALTH FACTS ABOUT CITRUS
*It has more antioxidants due to the high content of Vitamin C
*It helps develop immunity in our body and combats many diseases
*Orange juice is ideal solution for fever
*A citrus drink before meals will help increase appetite
*Citrus fruits help reduce the risk of stomach cancer
*Citrus fruit juices such as orange, lime and lemon, may lower the risk of specific types of kidney stones.
*Lime juice and coffee citrus are used for stomach pains.
*Grapefruit can lower blood pressure as it interferes with the metabolism of calcium channel blockers
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