Many cultivated species of citrus derive from just three primary ancestors – citrons, pomelos and mandarins, all native to South and East Asia. — Photo from Pexels
SO many cultivated species of citrus derive from just three primary ancestors – citrons, pomelos and mandarins, all native to South and East Asia.
These three, plus a few minor parents, have the rare genetic combination of being sexually compatible and highly prone to mutations.
Such traits allow their genes to mix naturally or by human hands, resulting in what we have now – oranges, lemons, limes and grapefruits.
Research has suggested that citrus existed some seven million years in Hunan, China. Out of the thousands of wild types, only dozens have become commercial behemoths like the Navel orange, Eureka lime and Mexican lime.
Lemons
Lemons are used for culinary and other purposes, and are especially prized for their tart, lips-puckering juice. – Photo from Pexels
Lemon is a species of small evergreen trees from the family ‘Rutaceae’. It is used for culinary and other purposes, and is especially prized for its tart, lips-puckering juice. The pulp and rind are used in cooking and baking.
The juice contains six per cent citric acid with a pH of 2.2, and is used to make the ever-refreshing lemonade and the luscious lemon meringue pie.
The various types of lemons included the Bonnie Brae, which is oblong, smooth, thin-skinned and seedless.
The Eureka is the ‘Four Seasons’ (Quatre Saisons), with pink flesh, and variegated green-and-yellow outer skin.
The Italian source is called ‘Sorrento’ lemon, which has high content of lemon oils.
Limes
Limes are typically round and usually green in colour, containing acidic juice vesicles. – Photo from Pexels
Talking about limes, we refer to the three species of citrus with especially sour taste.
A lime is typically round and usually green in colour, containing acidic juice vesicles.
The large Key lime (Citrus aurantiifolia) is elongated in shape and has green skin that becomes pale yellow when ripe.
Limes are acknowledged in Bahasa Malaysia as covering ‘limau nipis’, ‘limau purut’ (kaffir lime) and ‘limau kesturi’ (calamansi). However, the Australian limes are known as desert lime, finger lime and blood lime. There are other hybrids or cultivars that are famous for their own superiority.
The calamansi is known as ‘limau kesturi’ in Bahasa Malaysia. – Photo from Pexels
Benefits of lemons, limes
Lemons and limes are different types of citrus fruits, but with very similar nutritional profiles and health benefits. Each contains vitamins, minerals and antioxidants that protect cells from damage. Vitamin C also helps the body absorb iron from foods, and it supports the immune system.
They both contain flavonoids that are phytochemicals with health benefits, especially for those suffering from heart diseases and metabolic disorders.
Flavonoids have anti-inflammatory, antidiabetic, cancer-fighting and neuroprotective properties too.
Lemons and limes both contain collagen – a nutrient crucial in achieving younger and wrinkle-free skin. Collagen delays the ageing process, while Vitamin C brightens the skin.
Lemon juice is also used to relieve the pains caused by bee sting.
Limes and lemons were used to prevent scurvy in sailors who spent a long time at sea without Vitamin C.
Pectin is a structural heteropolysaccharide that contains paracetamol, used to treat fever and mild pains and many would recognise it as the brands ‘Panadol’ or ‘Tylenol’.
Propagation
Citrus fruits such as lemons or limes do have seeds for propagation, but the nursery purpose is preferred, with grafting being able to produce true-to-type progenies.
Seed-grown plants tend to produce more thorns and slow to reach the flowering stage.
To get the grafting planting materials, one needs the seedlings to be grafted with the mother plant’s buds. This process may take three months, or one can do the ‘marcotting’ ( or air-layering, a way of getting clones) on the living branch.
The same materials can be obtained for field-planting after nursery for a short time to ensure the roots are well established. Direct cuttings from branches can be rooted using rooting hormone (root tone) in potting medium for initial growth before field-planting.
The soil texture can be improved using compost and dolomite, organic fertilisers and growth hormones to enhance growth, and should be able to bring it to flowering and fruiting in three years.
Pests, disease management
The citrus is susceptible to infestation by whitefly, aphids and scale insects.
Several other pests can also cause damage to the leaves and fruits.
The bacteria-caused citrus-greening disease is called ‘Huanglongbing’ and is transmitted by the citrus psyllid.
It is most devastating – an outbreak of the greening disease of oranges initiated intensive research on the origin of citrus by many countries: Taiwan, China and Malaysia, through their agriculture authorities, in the 1980s.
The disease had wiped out the sweet mandarin orange crops in the Samarahan and Kuching areas.
Happy Gardening!