Horticulture

Horticulture is the more comprehensive term, embracing many forms of production from the soil. In common usage, it refers to commercial gardening which includes the growing of flowers, fruits and vegetables as crops for profit. The article on horticulture is divided into the following sections:

Horticultural science and its branches

Horticultural regions

Temperate zones

Tropical zones

Propagation

Seed propagation

Vegetative structure

Layering and cutting

Grafting

Tissue culture

Horticulture during historical period

Horticulture in Bangladesh

British period

Pakistan period

Bangladesh period

Horticulture Science and its branches Horticulture is the branch of agriculture science dealing with garden crops, generally fruits, vegetables, and ornamental plants. The word is derived from the Latin hortus, 'garden', colere, 'to cultivate'. Horticulture science is divided into the cultivation of plants for food (Pomology and Olericulture) and plants for ornament (floriculture and landscape horticulture). Pomology deals with fruit and nut crops and Olericulture deals with vegetables. On the other hand floriculture is related to the production of flowers and ornamental plants. Landscape horticulture includes plants for landscape eg. shrubs, trees, and climbers. The success of the growing of horticultural plants depends on many factors, namely, climate, terrain and other regional variations.

Horticulture regions Broadly horticultural regions are classified as temperate and tropical zones.

Temperate zones Temperate zones for horticulture cannot be defined exactly by lines of latitude or longitude. The areas in the temperate region where frost in winter occurs rarely may be regarded temperate zone for horticulture. Most parts of Europe, North America and northern Asia are included in temperate zone. In the Southern Hemisphere, practically all of New Zealand, a few parts of Australia, and the southern part of South America have temperate climates. Thus the temperate zones are very wide and the range of plants, that can be grown in them is enormous. Most of the great gardens of the world have been developed in temperate zones. Plants in the temperate zones benefit from a winter resting period while the tropical plants tend to grow continuously. Most of the famous gardens, namely, rose gardens, herbaceous borders, annual borders, woodland gardens and rock gardens belong, to temperate zone gardens.

Tropical zones There is no sharp line of demarcation between the tropics and the subtropics. Many tropical plants can be cultivated in the subtropics, so also many subtropical plans can be grown in the tropics. Elevation of a place and annual rainfall are important determining factors. In the tropics of Asia and parts of Central and South America the dominant features of the gardens are flowering trees, shrubs, and climbers. Among the fruits mango, jackfruit, banana, papaya, pineapple, guava, custard apples, and citrus fruits etc. are grown. A large number of vegetable crops are found in the tropics but they vary in kind and quality with the presence or absence of periodic dry seasons in certain areas. In the uniformly wet tropics, the choice of vegetables is limited to a few root crops and some leafy vegetables.

Propagation Propagation or multiplication of plants is the most basic of horticultural practices. Propagation can be achieved sexually by seed or asexually by utilizing specialized vegetative structures of the plant (tubers and corms) or by employing such techniques as cutting, layering, grafting, and tissue culture.

Seed propagation The most common method of propagation for self-pollinated plants is by seed. It is also used widely for many cross pollinated plants. The propagation through seeds is the least expensive and often the only means of propagation. The disadvantages to seed propagation are, firstly, genetic variation in seed from cross-pollinated plants because they are heterozygous. This means that the plants grown from seed may not be identical to its parents and may possess undesirable characteristics. Secondly, in some cases plants from seed takes a long time to come to maturity and the productivity is also less. Seed propagation is widely used for common vegetables such as the bean, pea, cabbage, tomato, onion, and others.

Vegetative propagation Asexual or vegetative reproduction is based on the ability of plants to regenerate tissues and parts. It is a completely natural process in many plants; in others artificial methods are used.

Vegetative structure Many plants produce specialized vegetative structures such as tubers, corms, rhizomes, bulbs etc. which can be used in propagation. Bulbs commonly grown at ground level consists of a short stem base with one or more buds protected by fleshy leaves. They are found in such plants as the onion, daffodil etc. Corms are short, fleshy, underground stems without fleshy leaves. The gladiolus and crocus are propagated by corms and cormels produced from fleshy buds. Rhizomes are horizontal, underground stems that are compressed or slender. Tubers are fleshy enlarged portions of underground stem. The edible potato tuber is also used for propagation. The sweet potato and dahlia are propagated by tuberous roots.

Layering and cutting Layering is the development of roots on a stem while it is still attached to the parent plant. The rooted stem is then detached to become a new plant growing on its own roots. The stem that form roots is called a layer, and the practice based on this phenomenon is known as layerage. This may be a natural means of reproduction, as in black raspberries and trailing blackberries, or it may be induced by artificial methods as in guava, lime, litchi by air layering.

Cutting is one of the most important methods of propagation. In propagation by cuttings, a portion of a stem, root or leaf is cut from the parent plant and the plant part is placed under certain favourable conditions and induced to form roots and shoots, thus producing a new independent plant. It differs from layerage in that the parts used are detached from the parent plant before the development of any root. Cuttage is a cheap and convenient mode of propagation for the plant species that strike roots easily. It is used extensively in the propagation of ornamental plants, including deciduous types, broad-leaved evergreens, and coniferous forms. To achieve success with difficult-to-root plants special care is taken to control the environment and encourage rooting. A number of growth regulators are used to stimulate rooting.

Grafting involves the joining together of plant parts (from two different plants) by means of tissue regeneration. The part of the combination that provides the root is called the stock or rootstock. It is the lower portion of the graft, which develops into the root system of the grafted plant. It may be a seedling, a rooted cutting, or a layered plant. The other part which is the short piece of detached shoot containing several dormant buds comprises the upper portion of the graft is called the scion. It should be the desired variety and free from disease. When the scion consists of a single bud, the process is called budding. The basic technique in grafting consists of placing cambial tissues of stock and scion in intimate contact, so that the resulting callus tissue produced from stock and scion interlocks to form a living continuous connection.

In general, grafts are only compatible between the same or closely related species. The success in grafting depends on proper use of technique, optimum physiological stages of stock and scion, and proper care for a period of time after grafting. There are different methods of grafting and budding. In Bangladesh veneer and cleft grafting are commonly used in mango, epicotyl grafting in jackfruit. On the other hand, budding is used in jujube, citrus and roses.

Tissue culture Tissue-culture techniques utilizing embryos, shoot tips, and callus can be used as a method of propagation. The procedure requires asceptic techniques and special media to supply inorganic elements, sugar, vitamins, growth regulators and organic complexes. Embryo culture has been used to produce plants from embryos that would not normally develop within the fruit. This occurs in early ripening peaches. Embryo culture can also be used to circumvent seed dormancy.

A shoot tip, when excised and cultured, may produce roots at the base. The technique is used for the purpose of producing plants free of disease. There are many orchids which can be multiplied rapidly by this method.

Environment control The intensive cultivation practiced in horticulture depends on extensive control of the environment for all phases of plant life. The developed countries in the temperate regions are growing vegetables and ornamentals in greenhouses. Modern greenhouses have automatic temperature control. Other environmental factors are controlled through automatic watering, regulation of light and shade, addition of carbon dioxide, and regulation of fertility.

Horticulture during historical period Western gardening had its origins in Egypt some 4,000 years ago. Gardening was introduced into Europe through the expansion of Roman rule and second, by way of the spread of Islam into Spain. It is presumed that Roman villas outside the confines of Italy contained native and imported plants, hedges, fruit trees, vines and herbs for medicinal and culinary purposes. Fruits have been the man's food from time immemorial. There is mention of fruits in the Vedic literature, religious books and testaments. It is also said that the history of fruits is as old as that of Adam and Eve who were living in a garden where they had only to pluck the fruit for their food.

The earliest fruit grown by man is said to be the date-palm which finds its record as early as 7000 BC. Pomegranate, fig, olive, grapes have been mentioned in ancient literature. In Indian sub-continent horticulture was an important avocation during the 4th century BC and also in pre-Buddhist period. Mango, banana, fig, grape and date-palm were grown during that period. Emperor Babar recorded in his memoirs the presence of some citrus fruits in the early 16th century. Towards the end of sixteenth century about 100 years after the discovery of America by Columbus, fruits indigenous to the New World (western hemisphere) were reported in Ain-i-Akbari, the record of the reign of the Moghul Emperor Akbar. The fruits were the pineapple and the custard-apple both from tropical America. Orcharding was the hobby of the Mughal emperor and the 'Lakh Bagh' which was supposed to contain one lakh (100,000) mango trees was established during the period of Akbar. The pineapple and papaya were probably introduced into India by the Portuguese. In the 19th century European settlers and missionaries to India introduced new varieties of fruits from the United Kingdom, France and the East Indies, and established commercial orchards. Introductions were also made from Japan, Australia and the United States. During the period of British rule in India, fruit culture started developing in some places rapidly because of improved irrigation, transport and other facilities. The temperate fruits were grown in the hills and citrus fruits in the plains, and their culture was developed in north India.

The Chinese have been the world's best gardeners for many centuries. They have developed a number of excellent fruits eg. the litchi, the persimmon, and several citrus. Horticulture has been a favourite subject for their poets and other writers, some of them writing more than 4,000 years ago. A treatise on the litchi written in AD. 1056 is said to be the first book in the world dealing only with fruit growing.

Horticulture in Bangladesh

British period Modern agricultural research requires skills and resources which led to the development of national agricultural research systems. Researchers develop technologies to help the farmers make better use of the natural resources and other inputs that are available to them. The Indian Department of Agriculture was established in 1905. A nucleus agricultural research laboratory was established at Tejgaon, Dhaka in 1908 to serve the provinces of Bengal and Assam. Agricultural research was confined to crops, namely, rice, jute, cotton, oilseeds, pulses and sugarcane. The horticultural crops did not get due attention. Education is an important element of the agricultural research process. In 1938, the Bengal agricultural Institute (BAI) was established at Dhaka where horticulture was a teaching subject. Horticulture improvement and development did not receive attention as it deserves even at the end of the British Colonial period in 1947.

Pakistan period' During Pakistan period (1947-1971), a programme of horticulture development was initiated by Dr. Rahim Choudhury an horticulturist and Director of Agriculture. Coconut Research Station, Rahmatpur, Barisal;. Fruit Research Station, Hathazari, Chittagong;. Citrus Research Station, Jaintiapur, Sylhet and two plant Introduction Centers at Dhaka and Chittagong were established. Higher education in agricultural sciences made a significant advance in 1962 with the establishment of the Bangladesh Agricultural University (BAU) at Mymensingh. The Bangladesh Agricultural University became Bangladesh's primary training institution for agricultural scientists and others. Horticulture department at BAU has research programmes on fruits, vegetables, spices and ornamentals in addition teaching to at undergraduate and postgraduate levels from its inception. Training in horticulture up to the PhD degree is offered in the Agricultural University. Post harvest studies have been carried out on a number of fruit crops at BARI and Bangladesh Agricultural University, Mymensingh which helped the fruit industry in the country.

Bangladesh periods During early seventies Bangladesh Agricultural Research Institute (BARI) was established at Joydebpur and there was a Division of Horticulture under it. Later on horticulture research has been reorganized as Horticulture Research Centre under BARI with one Central Station at Joydebpur and four other Regional Horticulture Stations at Rahmatpur (Barisal), Hathazari (Chittatong), Akbarpur (Moalvibazar) and Nababgonj (Rajshahi). At present the Horticulture Research Centre is working with large number research programmes on fruits, vegetables, spices, ornamentals to develop appropriate production technology, new varieties according to the needs of the farmers. Bangladesh Agricultural University, Mymensingh is providing training on advanced horticulture to the personnel employed in horticultural organisations, interested entrepreneurs, nurserymen, officials of Extension Directorate. In 1983, a graduate study institution named as 'Institute of Post-graduate Studies in Agriculture (IPSA)' was established at Salna, Gazipur. The institute developed facilities for offering MSc (Ag) and PhD degrees in horticulture. The institute was made an university and renamed as Banghabandhu Shiekh Mujibur Rahman Agricultural University in 1998, and it included undergraduate studies where horticulture was a subject of study. It was felt that more institutes for higher agricultural education should be set up in different regions of the country. Dumki (Patuakhali) Agriculture College, in the southern part and Hazi Danesh Agriculture College, Dinajpur in the northern part of the country were established in 1978 and 1988 respectively. The colleges at Patuakhali and Dinajpur have been reorganized as the University of Science and Technology with a faculty of Agriculture in each location. The Bangladesh Agricultural Institute upgraded to university in 2001 and named Sher-e-Bangla Agricultural University. In addition to teaching, the Horticulture Departments at the universities of Shere-e-Bangla Agricultural University, Dhaka; Patuakhali University of Science and Technology, Patuakhali; Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur have started research work on different horticultural crops, post harvest handling and processing of fruits, vegetables, spices and flowers.

Floriculture a part of ornamental horticulture is gaining importance in the country. Studies have established that the income from flower production is twice as much as can be obtained from rice per unit area. The export promotion Bureau (EPB) of Bangladesh recognized the potential of floriculture as a viable export earning sector. The growth of the trade in floriculture products has started in 1988 and it is expanding. The Horticultural Research Centre (HRC) have 133 rose varieties, 54 gladiolous, 2 tuberose, 30 chrysanthemum. The National Botanical Gardens, Mirpur (Dhaka) and Bangladesh Rifles, Dhaka, have also more than 200 rose varieties in their collections. A few tissue culture units, both in the public (BARI/DAE) and private sector (BRAC, German Krishi Foundation and proshika) have initiated the work on micropropagation.

Bangladesh is a country where the daily per capita supply of calories, protein and important nutritional elements is low in comparison with even many developing countries. Most of the population cannot afford meat, egg, milk, fish which are comparatively more expansive. The supply of fruits and vegetables can play a significant role in the nutritional requirements of the people. Fruits and vegetable farming have not been established as large scale commercial enterprises in the country. These are grown usually in and around the homesteads of 68,000 villages of Bangladesh. During the recent past, a trend has developed among some farmers to engage exclusively in the commercial cultivation of fruits and vegetables. With the development and expansion of communication system in the country, fruit and vegetable farming are also getting priority to the farmers of different regions of the country.

Bangladesh has climate and soils on which a large number of horticultural crops such as fruits, vegetables, potato, tropical tuber crops, mushroom, ornamental, medicinal and aromatic plants, plantation crops and spices are grown. We give major emphasis on cereals to attain self-sufficiency in food production. The need for diversification of crops is now well acknowledged. To make agriculture more profitable through efficient use of land, horticulture industry can play a vital role for agriculture development in the country. Growing of horticultural crops are highly remunerative for replacing subsistence farming and thus alleviate poverty level, provide higher employment opportunity and nutritional security. The crops have high potential for foreign exchange earnings and make higher contribution to GDP. Thus, it can be said that horticulture industry can help to provide health, wealth and prosperity to the poverty stricken Bangladesh. [Azizul Haque]

Bibliography Bangladesh Agricultural Research Council (BARC) and Bangladesh Academy of Agriculture (BAAG). Agricultural Research in Bangladesh in the 20th Century. Dhaka, 2001; Hudson T. Hartmann and Dale E. Kester. Plant Propagation: Principles and Practices. New Delhi, 1968; ICAR. Handbook of Horticulture, New Delhi 2001; The New Encyclopedia Britannica. Vol. 19: 672-690.