Increase in population has forced us to carry out continuous scientific experiments for the following reasons viz.
1. To develop more food crops
2. To increase quality in food crops and
3. To have sustainable food quality in food crops and assured food supply.
By introducing specialized technology, plant breeders are now able to develop more crops, which they multiply and supply them to the growers. Improvement in the genetic make up of plants is called plant breeding.
1. creation of useful variation in the cultivable crops.
2. selection of better crops.
3. conducting / carrying out breeding experiments to assess the quality of the crop and
4. release of a variety after their extensive multiplication.
The first and foremost aim in plant breeding is to create useful variation in the crop plant. This can be achieved by the following measures.
1. Bringing wild food crops to cultivation. (wheat, oats and many cereal crops were once wild plants which had now been domesticated).
2. Obtaining genes from desirable plants or related species (eg. as seeds from various parts of the world).
3. Introduction of plants from nearby regions or even from other countries for improvement of the crop. (eg. cauliflower, tomato, potato and soyabeans).
4. By employing certain plant breeding techniques, new varieties are developed. eg. maize, sorghum, cotton and sunflower.
5. Auto and Allopolyploid breeding.
6. By inducing mutations using physical and chemical mutagens.
7. Production of haploids by the application of plant tissue culture of anther and ovary.
8. Improvement of nutritional quality by genetic engineering (eg. Fortified rice - iron rich rice and carotene rich rice).
9. Development of disease, drought and environmental stress resistant varieties.
Present day crop plants are from wild species reared by careful domestication, cultivation and management. We have several wild varieties existing in nature just as in the case of salinity tolerant wild rice. Through gene manipulation, the gene for salinity tolerance could be cloned in a rice variety. In such of those areas where shortage of fresh water exists, rice can be cultivated using seawater and can even be grown in extreme saline soil. Similarly, we need many more such wild plants showing increased capacity to extremes of climatic conditions and disease resistance for plant breeding programmes. In order to safeguard the biodiversity and certain important valuable crops from going into extinction, scientists are protecting these crops by establishing gene or germplasm banks by preserving their seeds.