LETTUCE (Lactuca sativa L.)

Lettuce is included in the group leafy vegetable crops is known in the society. These vegetables contain nutrients, especially vitamins and minerals that are complete to qualify the nutritional needs of the society. Lettuce as food vegetables can be consumed in their raw form as fresh vegetables together with other food ingredients. Besides useful for groceries, lettuce is also useful for the treatment (therapy) of various diseases. Thus, lettuce has a very important role in supporting public health.

In Indonesia lettuce plants cultivated by people in areas of vegetable centers in lowland and upland with various varieties grown.

The lettuce has a name that is different in every country, for example, lettuce (Indonesia), mustard (Taiwan), and lettuce or head lettuce (International).

According to various published sources, lettuce plant (lactuca sativa) is native to Europe and Asia. The new plant to be cultivated to get attention after it has benefits as a food ingredient vegetable contains good nutrition. In addition, the lettuce plants known to also have benefits for the treatment (therapy) various diseases. Lettuce plants has begun cultivated since approximately 2,500 years ago, with the proven presence of ancient writings about plants (lettuce) about 500 years BC.

Wild lettuce types often have leaves and stems are thorny, do not form a head and leaves a bitter taste, and contains a lot of sap. This plant breeding may be emphasized in order to obtain plants that are not prickly, slow flowering, large seeded and does not spread, not gummy, and not bitter. Other aspects include fewer wild shoots, leaves and a large width, and shape of the head. That form is a head of lettuce cultivated plant more, which was first named as "cabbage lettuce" in 1543.

During this time, lettuce used as a vegetable leaf for salad and touted as the king salad because the texture is very fine. Lettuce consumed raw and can be found in a salad or hamburger.

Condition Of Growth

Lettuce plants can grow well in damp and cold weather or cool air that is at a temperature between 15-20 °C, with a soil pH between 5.0 to 6.5. The preferred soil type of lettuce is dusty loam, sandy loam, the soil still contains humus and no stagnant. Nevertheless, the lettuce is still tolerant of soils poor in nutrients as long as irrigation and organic fertilizers were adequate. The soil should be neutral reaction. If the soil is acidic, lettuce leaves turn yellow. Therefore, for acidic soils calcification should be done first before planting. These plants can be grown in lowland or highland, but the best result is grown in the highlands. Lettuce grown in the lowlands tend to be fast flowering and seed in it.

Description Of Lettuce

Lettuce plants (Lactuca sativa), including vegetable crops belong to the leaf and seasonal crops (short-lived). Plants grow shorter height ranges from 20 cm - 40 cm or more, depending on the type and variety. No lettuce plants that make up the crop (collection leaves closer together form the head) and there are varieties that do not form a crop. Leaf lettuce plant height ranging from 30 cm - 40 cm and head lettuce plant height ranges from 20 cm - 30 cm. Morphologically, the vital organs contained in lettuce plants is as follows.

Leaf of lettuce plant has a shape, size, and color vary depending on the variety. For example, the type of lettuce that make up the crop has a leaf shape or a round or oval with size or large broad leaves, leaves dark green, light green, and there is a rather dark green. While that does not form a type of lettuce crop, the leaves are elliptical, large, jagged leaf edges (curling), and leaves dark green, light green, and red. Lettuce has a petiole width and bones pinnate leaves. Petiole is strong and smooth. The leaves are soft and crunchy when eaten, and has a slightly sweet flavor. Lettuce generally has a length of 20 cm - 25 cm and a width of 15 cm or more.

Lettuce plant has a real trunk. On lettuce plants that make up the crop, stems are very short and barely visible and is located on the bottom inside the ground. Whereas lettuce that do not form the crop (leaf lettuce and stem lettuce) has a longer stem and visible. Stem is robust, sturdy, strong and with a diameter ranging from 5.6 cm - 7 cm (stem lettuce), 2 cm - 3 cm (leaf lettuce), as well as 2 cm - 3 cm (head lettuce).

Lettuce plants have a root system stable and fibers. Root fibers sticking, growing spreads, in all directions at a depth of 20 cm - 50 cm or more. While stable roots grow straight into the center of the earth. Lettuce plant roots can grow and thrive in soil that is fertile, friable, easily absorbs water, and soil depth deep enough.

Seeds of lettuce plants flattened oval, hairy little hard, brown, old, and very small, the length of 4 mm and a width of 1 mm. Lettuce seeds are enclosed seeds and dashed two, may be used for the propagation of plants.

Flowers of lettuce plants yellow, grows dense in a series. Flowers have a long flower stalk that reaches 80 cm or more. Lettuce plants grown in temperate zones (subtropical) easily or quickly bear fruit.

Lettuce Varieties

Lettuce has long been known by the society. In the beginning, there are only a few varieties (types) of lettuce. With the development of human civilization and technology, has now found new varieties are superior to previous generations are countless more. Thus providing great expectations for increased production of lettuce in Indonesia and other countries. In addition, the issuance of new varieties whose production is higher than previous varieties also give great hope to increase the income and welfare of farmers.

In Indonesia there are lettuce from local varieties and imported varieties. However, in general, grown by farmers is imported variety, because the production of local varieties are generally still lower than the imported varieties. Imported varieties more outstanding in the Indonesian market from different countries yielding seeds, for example Peto Seed (USA, United States), Yasui (Taiwan), Known You Seed (Taiwan), Liong You Seed (Taiwan), Qiang Nong Seed (Taiwan), Sakata Seed (Japan), Takil Seed (Japan), Hungnong seed (Korea), Nunhems seed (the Netherlands), and so forth, all of which can give high yields. Every year continuous seed companies that produce new varieties. Each variety has different advantages. This difference can be seen in terms of the productivity of the plant (leaf production/crop), adaptability to the environment, resistance to pests and diseases, as well as the taste of the leaves.

There are types of lettuce categorized by head formation or leaf type. Each of these lettuce varieties offers a unique flavor and texture, and growing different types of lettuce will be a surefire way to generate interest in eating a healthy diet. Some lettuces also keep better than others and all these characteristics are described in detail below.

1.   Crisphead or Iceberg. Crisphead lettuce, more commonly known as iceberg, has a tight head of crisp leaves. This familiar pale green lettuce forms a tight, cabbage-like head. Often found in the local salad bar, it is actually one of the more difficult lettuce varieties to grow. This lettuce texture is crisp and its flavor very mild. This lettuce variety is not fond of hot summer temps or water stress and may develop rotting from the inside out. Start iceberg lettuce via seed directly sown 18-24 inches apart or started indoors and then thinned 12-14 inches between heads.

Some iceberg lettuce varieties include: Ballade, Crispino, Ithaca, Legacy, Mission, Salinas, Summertime and Sun Devil, all of which mature in 70-80 days.

2.   Summer Crisp, French Crisp or Batavian. Somewhat between the lettuce types Crisphead and Loose leaf, Summer Crisp is a large lettuce variety resistant to bolting with great flavor. It has thick, crisp outer leaves which can be harvested as a loose leaf until the head forms, while the heart is sweet, juicy and a bit nutty.

Different types of lettuce for this variety are: Jack Ice, Oscarde, Reine Des glaces, Anuenue, Loma, Magenta, Nevada and Roger, all of which mature within 55-60 days.

3.   Butterhead, Boston or Bibb. One of the more delicate varieties of lettuce, Butterhead is creamy to light green on the inside and loose, soft and ruffled green on the exterior. A head of Boston lettuce resembles a flowering rose. Bibb lettuce - also called limestone - forms a smaller, cup-shaped head. These different types of lettuce may be harvested by removing the entire head or just the outside leaves and are easier to grow than the Crispheads, being more tolerant of conditions. Less likely to bolt and rarely bitter, the Butterhead lettuce varieties mature in about 55-75 days spaced similarly to the Crispheads.

A butterhead lettuce can be recognised by its soft leaves which are arranged rather like the petals of an old English rose. Often the centre has a much crisper head but nothing as crisp as iceberg or the average Cos. The leaves have lots of taste to them and overall are sweet. A butterhead lettuce  have a soft “buttery” texture and a sweet, mild flavor.

Not only are butterhead lettuces tasty but they are easier to grow and faster to mature compared to Cos and Iceberg types. Their ability to withstand cold temperatures is also accompanied by an ability to withstand higher temperatures compare to the other types. Several varieties can be planted in the autumn for harvest in spring much earlier than most other lettuce varieties. So just a couple of varieties of butterhead lettuce and with a bit of planning you can be eating your very own lettuce for seven months of the year. There are many old varieties still available although in the 1950s the butterhead lettuce (and to some degree the Cos) was overshadowed almost completely by the ubiquitous Iceberg type lettuces. In the 90s though the butterhead lettuce started the comeback because of its superior taste, appearance and nutritional value.

These varieties of lettuce include: Blushed Butter Oak, Buttercrunch, Carmona, Divina, Emerald Oak, Flashy Butter Oak, Kweik, Pirat, Sanguine Ameliore, Summer Bib, Tom Thumb, Victoria, and Yugoslavian red and are extremely popular in Europe.

4.   Romaine or Cos. Romaine varieties are typically 8-10 inches tall and upright growing with spoon-shaped, tightly folded leaves and thick ribs. Coloration is medium green on the exterior to greenish white inside with the outer leaves sometimes being tough whilst the interior foliage is tender with wonderful crunch and sweetness. ‘Romaine’ comes from the word Roman while ‘Cos’ is derived from the Greek island of Kos. In the UK it is commonly called Cos lettuce although in France and the USA it is called Romaine - there is no difference between the two other than the different names. Romaine lettuce is a key ingredient of the famous dish Caesar Salad.

The typical Cos lettuce has upright leaves which form a relatively tight head. The inner leaves are a much lighter green compared to the outer leaves because the sun has not reached them so easily. As far as nutrition is concerned this type is high in nutrients but only in the outer green leaves, the inner whiter leaves have almost no nutrient value at all. The inner leaves are crisp and crunchy with very little taste, the outer leaves are softer and have a sharp and sweet, slightly earthy taste.

For many years lettuce has not only been eaten raw but often quickly cooked, mainly grilled and Cos stand up to cooking better than all the other types.

Lettuce is a plant which does not like excesses of heat but the Cos is better than all the other types at growing in warmer conditions. As far as growing is concerned the Cos lettuce has no major drawbacks and is easily cultivated if a few basic rules are followed.

Some different types of this lettuce are: Brown Golding, Chaos Mix II black, Chaos Mix II white, Devil’s Tongue, Dark Green Romaine, De Morges Braun, Hyper Red Rumple, Little Leprechaun, Mixed Chaos black, Mixed Chaos white, Nova F3, Nova F4 black, Nova F4 white, Paris Island Cos, Valmaine, and Winter Density, all of which mature within around 70 days.

5.   Loose leaf, Leaf, Cutting or Bunching. This type of lettuce comprises a number of varieties that don’t form heads, but consist of large, loosely packed leaves joined at a stem. The Loose leaf have rows of leaves loosely arranged around the centre. Unless your appetite for salad is rather large the leaves, rather than the whole lettuce, are harvested as and when needed which allows more leaves to grow. Harvest these varieties either whole or by the leaf as they mature. Plant at weekly intervals starting in early April and again mid August and thin Loose leaf lettuce to 4-6 inches apart. Loose leaf varieties are slow bolting and heat resistant.

The leaves are either green or shaded to deep red at the edges, and may be ruffled or smooth. Their degree of crispness is midway between romaine and butterhead, their taste is mild and delicate. Red leaf and green leaf are popular varieties. Oak leaf, both red and green, forms smaller heads, with flatter leaves shaped like big, floppy oak leaves. For home gardeners, loose leaf lettuce has an advantage over other types: If you pick leaves individually instead of pulling the whole head from the ground, the leaves will continue to replace themselves throughout the season.

The beauty of loose leaf lettuce is the vast array of colours, textures, shapes and tastes. Probably the best way to grow loose leaf salads for the beginner is to buy a packet of mixed seeds. Mixing different types of loose leaf lettuce together for a salad allows you to cut a few leaves from each plant and gives them the chance re-grow.

A wide variety of colors and shapes guaranteed to stimulate the sight and the palate are available in the following lettuce varieties: Austrian Greenleaf, Bijou, Black Seeded Simpson, Bronze Leaf, Brunia, Cracoviensis, Fine Frilled, Gold Rush, Green Ice, New Red Fire, Oakleaf, Perilla Green, Perilla Red, Merlot, Merveille De Mai, Red Sails, Ruby, Salad Bowl, and Simpson Elite, which will all mature within a 40-45 day time period.

6.   Stem lettuce or Asparagus lettuce. Stem lettuce type has the characteristics, the plants do not form the crop, the leaves are large and long round with a length up to 40 cm and a width of about 15 cm, leaves ravel, petiole width, leaf there is a dark green, and there are light green (depending on the variety), the bones of pinnate leaves. Plant stem length ranging from 30 cm-40 cm, large and sturdy with diameters ranging from 5.6 cm - 7 cm, white greenish or whitish green, smooth and crisp. It is widely grown in China, and is also known as Chinese lettuce. The only variety available in the United States is called celtuce. Stem lettuce has a mild flavor that is sometimes described as “nutty cucumber.” Stem lettuce is good in salads, but can also be cooked like a vegetable. This type is resistant to heat and cold conditions, so it can be cultivated in lowland and upland.

The descriptions of some varieties of lettuce that has a good market and high economic value of the four types of lettuce above is as follows.

a.   Georgia

This variety is a hybrid type and the kind of head lettuce. Plants grow compact and have little outside leaf. The crop is large, dense, greenish white, and short center. Heavy crop ranged from 1 to 1.3 kg.

b.   General

This variety is a hybrid type and including Head lettuce types such as Georgia. Plants grow faster, cercospore leaf spot disease resistance, heat resistance. The crop is large, dense and uniform.

c.   Red Rapid

This variety is hybrids type and the kind of leaf lettuce type (Cutting lettuce or Leaf lettuce). Flowering plants is slow, so the harvest period grew longer. Broad leaves and large, the edges wavy leaves, and the leaves are red to dark red.

d.   Grand Rapid

This variety is a hybrid type and the kind of leaf lettuce. Plants grow faster, broad adaptability, can grow well in winter. This type is heat resistant and can be grown throughout the year. Green leaves.

e.   Sueh-Li-Hung 2

This variety is a hybrid type and the kind of leaf lettuce. Plants grow very strong, heat resistant and cold resistant, highly branched, is not easy flowering, disease resistance of wet rot and viruses. Green leaves and serrated. Harvesting plants 20 days after transplanting. Potential production reached 1.8 kg per plant. The leaves are suitable for sauerkraut.

f.    Sueh-Li-Hung

This variety is a hybrid type and the kind of leaf lettuce. Plant grow strong, branched, fertile, disease resistant, and pests. The leaves are straight and serrated leaf edge. The leaves are suitable for sauerkraut.

g.   Celtuce

This variety is a hybrid type and the kind of steam lettuce. Plants grow strong, easily grown, disease resistance, and short-lived. Large stems of plants with stem diameters of 6 cm and a length of 30 cm, white-green, light green flesh, smooth and crisp. The leaves are elliptical, large, stemmed wide, bright green, straight and serrated leaf edge. The leaves can also be used as a vegetable.

h.  Beseeming

This variety is a hybrid type and the kind of stem lettuce. Plants grow fast and strong, large-sized trunk midline 5.6 cm and a length of 30 cm-40 cm, white-green, and light green flesh-colored stems, as well as light blight disease-resistant plants. Leaves the plant has a size of approximately 40 cm long and 15 cm wide, elliptical with flat leaf edge. Potential production of 0.5 kg/plant. The stems can be cooked in soups, pickles, and leaves can be used as a vegetable.

i.    Majesty

This variety is a hybrid type and the kind of stem lettuce. Plants grow fast and strong, cercospore leaf spot disease resistant, resistant to cold and hot weather. Sturdy stems, light green, large with a diameter of about 7 cm, whitish light green flesh, crispy and suitable for sauerkraut. The leaves are elliptical with flat leaf edge. Young leaves can be used for vegetables.

j.    Bau-Sin

This variety is a hybrid type and the kind of head lettuce. Plants grow shorter, crop is large, smooth, crisp, and tastes good. The lettuce is suitable to be cooked, and sauerkraut.

k.   King Mustard

This variety is a hybrid type and the kind of leaf lettuce. Plants grow big and cold resistant. The leaves are wide, straight, thick, fibrous soft, green and purple.

l.    Other varieties

In addition to the varieties mentioned above, there are many varieties of other, for example, Dabota, Alps, Marina, Kaisser, Gento, Great Lakes, Okayama salad, Ontario, All the Year Round, Webb's wonderfull, Tom Thumb, Ballade, Santa Maria, Great Lakes 54, and so on which are hybrids and include the type of head lettuce. Paris Island, Paris White Winter Density, Barcarolle, and so is the type of hybrid and including fragile lettuce types. New Red Fire, Salad Bowl, Sunglow, Prize Head, Vulcan, Plato, Green Wafe, Vit, Red salad bowls, Eland, and so on which are hybrids and include the type of leaf lettuce.