SS3 Lesson Note on Crop Improvement

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TOPIC:  CROP IMPROVEMENT

CONTENT:

1. Meaning, Aims, and Methods of Crop Improvement
2. Methods of Crop Improvement continued
3. Genetic Terms and Mendel’s Laws of inheritance

SUB TOPIC 1: Meaning and Aims of Crop Improvement

Crop Improvement refers to the ways of developing and breeding of crop varieties which are better than the pre-existing cultivars in a number of characters like taste, height, colour, etc for a better yield.

Crop improvement is defined as the science that deals with the development of new crop varieties with superior quality and quantity.

AIMS OF CROP IMPROVEMENT

1. To improve the quality of produce
2. To increase crop yield
3. To adapt crops to adverse climatic conditions
4. To induce resistance to pests and diseases in crop plants
5. To conserve land resources
6. To breed crops with uniform growth and maturity
7. To meet the particular needs of growers and consumers
8. To improve harvesting qualities thereby harvesting is done with ease
9. to meet the needs of consumers (processors or industrialists)

METHODS/PROCESS OF CROP IMPROVEMENT

A. INTRODUCTION: involves the movement of the plant(s) from the Center of origin of a supposed center of evolution to another place where they can adapt and survive. Such imported crops are usually guaranteed by the nation’s plant quarantine service before introducing it to the country.

 ADVANTAGES

1. It is used to upgrade the qualities of the local varieties
2. It brings about varieties adaptable to the soil and climatic conditions of the new area
3. it enhances greater productivity
4. It performs better under good climatic and soil conditions
5. It helps in controlling pests and diseases

DISADVANTAGES

1. There is the possibility of introducing new crop disease
2. The introduced crop may not adapt to the environmental conditions of the new place

B. SELECTION: This is the process of picking from a number of individuals in the field found to possess desirable characteristics for further cultivation. Selection has number of methods:

1. Mass Selection-this is a selection of crops that have desirable traits from a large group of crops. It is based on the performance of crop
2. Pure line Selection-it is a situation in which only one crop plant with desirable character is selected. A pure line is an offspring of a single self-pollinated individual due to a high degree of homozygosity which leads to the production of individuals that are alike
3. Pedigree Selection-crop plants are selected on the basis of their ancestors performance. It also means selection within the offspring of certain lines
4. Progeny Selection-plants are selected on the basis of the performance of their offspring or progenies.
5. Bulk Selection– the segregates are bulked for five generations or more before the homozygous lines are separated out
6. Recurrent Selection-this involves several cycles of selection as well as various degrees of progeny testing

ADVANTAGES OF SELECTION

1. It increases uniformity in the performance and quality of any desired traits
2. It eliminates undesirable plants from a population
3. It reduces the spread of pests and diseases
4. Seeds from best stands are multiplied for distribution

DISADVANTAGES OF SELECTION

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