(a) State six aims of crop improvement. (b) Explain briefly ‘introduction’ as a method of crop improvement.
Explanation
(a) Aims of crop Improvement are:
(i) To develop new plant varieties which will yield more per unit area of land than the existing varieties i.e crops with high yield capacity
(ii) To develop plant varieties of better qualities than the existing ones e.g. fibre, sugar content, oil content e.t.c.
(iii) To produce early maturing crops or crops with short gestation which will mature within a shorter period than the existing varieties.
(iv) To improve the harvesting qualities of crops. For instance crops with reduced heights to make harvesting easier have been developed e.g oil palm.
(v) To produce crops which are resistant to diseases.
(vi) To meet the needs of the growers.
(vii) To produce crops which are resistant to pests.
(viii) To produce crops which can adapt to the local environmental conditions such as drought, heat and cold.
(ix) to achieve some level of uniformity within a variety so that it becomes adaptable to mechanization.
(x) to produce crops which are more acceptable to the consumers than the existing ones e.g. taste.
(b) "Introduction" as a method of crop Improvement:
(i) Involves movement of crop from its origin or supposed centre of evolution to another region especially in area where it can adapt.
(ii) Crops with desired qualities are identified in their centres of origin and then procured.
(iii) Such crops are introduced into the breeders country for testing and multiplication.
(iv) Such imported crops are usually quarantined by the nation's plant quarantine service before introduction into the country.
(v) Quarantine prevents the introduction of foreign pests and diseases into the country or locality through laboratory examination of the seeds before they are introduced.
(vi) Introduction is usually carried out to upgrade the qualities of the local varieties of crops. It introduces variability which is not present in the existing crops.
(vii) Introduced crops must adapt to the soil and climatic condition of local environment for introduction to succeed.