Objective of the module



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IMPORTANCE OF HORTICULTURE

SOURCE OF FOOD

  • Society depends on horticulture for a substantial amount of its food. This is sourced from vegetables, fruits and nuts.

  • They supply carbohydrates, vitamins and minerals

ORNAMENTALS


  • Landscaping has become an important component of construction. Plants in landscape include shrubs, trees, bedding plants and grasses.

  • Public malls, playgrounds and cemeteries are places where plants are displayed for specific purposes.

  • Flowers are important on special occasions such as roses for Valentines Day, Mothers Day, Graduations, Reconciliation; poinsentias for Christmas and lilies for Easter.

JOBS

  • Directly provides jobs to the society. These include nurserymen, florists, greenhouse managers, extension officers, sales or marketing officers, teachers, lecturers, farm managers

  • Indirectly provides jobs in the following areas

Research, Chemical industry (extraction of pigments e.g. oleoresin), Machinery (engineers and designers of tools for planting, weeding, harvesting). Distribution (freight forwarders, transporters, drivers)

EXPORT MARKETS


  • Horticulture provides foreign currency through exports. Floriculture exports of 1985 totalled Z$3.1 million and continued to grow rapidly to $500 million for 1995/96 season.

CHARACTERISTICS OF HORTICULTURAL CROPS


  • Many have high water content, hence they are utilised mostly in their living state

  • Highly perishable

  • Constituent water is essential to their quality

  • Generally grown more intensively and returns per unit area are normally higher than with agronomic or forestry crops

  • Mainly consumed for the supply of micronutrients and vitamins and for their contribution to flavour (spices) and interest of food (garnishing)

  • They are generally not staple crops

  • Consumption levels depend on the selling price and the buyer’s income

  • Crops are normally traded in relatively small quantities, in free marketing systems where both supply and demand determine the price.

CLASSIFICATION OF HORTICULTURAL CROPS

Why classifying horticultural plants?


  • There are many horticultural plants in the world. A lot of knowledge has been gathered on the plants. Classification makes summarisation of information on the plants possible hence serves time in information sharing.

  • It is a means of identification and communication on horticultural plants

  • It facilitates prediction



TYPES OF CLASSIFICATION


    • There are two types of classification, which are natural and artificial.

    • Scientific plant classification falls under natural classification

Natural Classification


  • Classifies objects together on the basis of the sum total of all their characters (features which exist in the group of objects in two or more distinguishable different states e.g. hair colour, eye colour in human)

  • It puts together those that are more alike in most respects

Artificial Classification


  • Classifies objects together on the basis of only one or a very few specially selected characters and ignores all the characters that the objects might have.

  • It does not take into account the natural relations of plants.

  • However, it is useful in horticulture. Plants can be classified on the basis of their ability to withstand drought e.g. drought tolerant, drought prone etc., which is useful information for crop husbandry.



COMPARISON OF ARTIFICIAL AND NATURAL CLASSIFICATION


NATURAL

ARTIFICIAL

Basis of classification


Basis of classification

It utilises the sum-total of all the characters of its members

It utilises one or very few characters of its members that are especially selected

Advantages

Disadvantages

Groups together plants most alike in their hereditary constitution

May not group plants that are most closely related phylogenetically

Generally groups together plants most closely related phylogenetically

May fail to group plants that are closely related phylogenetically

Contains a lot of information about members of the group

Contains limited information about its members

Additional information of its members can easily be incorporated

More information about its members cannot be easily incorporated

Has a high predictive value

Low predictive value

Disadvantages

Advantages


Identification of members may be difficult

Identification of members is made easy

Placing of poorly known plants may be uncertain or impossible

Poorly known members may be definitely placed

It is liable to change as more information is gathered on the plants

Does not change with increase in our knowledge

Adapted from Jeffrey (1982)
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