Crop Improvement – I (Kharif)
UNIT-II
Plant genetic resources
Plant genetic resources refer to the genetic material of plants, including seeds, fruits, roots, and other plant parts, that are used for plant breeding and other research purposes. Plant genetic resources are important because they contain genetic diversity that can be used to develop new crop varieties with desirable traits such as disease resistance, high yield, and tolerance to environmental stresses.
There are several types of plant genetic resources, including:
- Wild relatives of cultivated plants: These are wild plant species that are closely related to cultivated crops and are found in their natural habitats. They contain genes that can be used to improve the traits of cultivated crops.
- Landraces: These are traditional varieties of crops that have been grown by farmers for many generations. They have adapted to local environmental conditions and contain genes that can be used to develop new crop varieties with improved traits.
- Breeding lines and hybrids: These are crop varieties that have been developed through plant breeding and contain desirable traits such as high yield, disease resistance, and quality characteristics.
- Genetically modified organisms (GMOs): These are plants that have been genetically modified using biotechnology techniques to introduce desirable traits such as herbicide resistance or insect resistance.
It is important to conserve plant genetic resources to ensure their availability for future generations. Plant genetic resources can be conserved in gene banks or seed banks, where they are stored under controlled conditions to maintain their viability and genetic integrity. In addition to conservation, plant genetic resources can also be used for research, plant breeding, and crop improvement programs to develop new crop varieties with improved traits.
Their Utilization
Plant genetic resources are utilized in several ways to improve the productivity, quality, and sustainability of agricultural production. Some of the common ways in which plant genetic resources are utilized include:
- Plant breeding: Plant genetic resources are used to develop new crop varieties with desirable traits such as high yield, disease resistance, and tolerance to environmental stresses. Breeding programs use genetic diversity from different sources to introduce new genes and traits into cultivated crops.
- Biotechnology: Plant genetic resources are used in biotechnology to develop genetically modified crops with desirable traits such as herbicide resistance, insect resistance, and improved nutrient uptake. Biotechnology techniques such as genetic engineering and marker-assisted selection are used to manipulate the genes of plants.
- Conservation: Plant genetic resources are conserved in gene banks and seed banks to ensure their availability for future use. Gene banks and seed banks maintain the genetic diversity of plant species by collecting and preserving seeds and other plant materials.
- Research: Plant genetic resources are used in research to study the genetics, physiology, and ecology of plants. Research can lead to the discovery of new genes and traits that can be used to improve crop productivity and quality.
- Medicinal and industrial uses: Plant genetic resources are used in the development of medicines, cosmetics, and industrial products. Plants contain compounds that can be used for the development of new drugs and industrial materials.
Overall, the utilization of plant genetic resources is essential for the sustainable production of food, fibre, and other plant-based products. It is important to conserve and use plant genetic resources in a responsible and sustainable manner to ensure their availability for future generations.
Conservation
Conservation of plant genetic resources is important to maintain the diversity of plant species and their genetic variability. This helps to ensure that plant genetic resources are available for future use in plant breeding, research, and other purposes. Plant genetic resources can be conserved through several methods:
- In situ conservation: This involves the conservation of plant genetic resources in their natural habitat. Protected areas, such as national parks and wildlife reserves, are established to conserve the genetic diversity of wild plant species.
- Ex situ conservation: This involves the conservation of plant genetic resources outside their natural habitat. Gene banks and seed banks are established to store seeds, tissues, and other plant materials in controlled environments. This method ensures that plant genetic resources are conserved in case of natural disasters, environmental changes, or other threats.
- On-farm conservation: This involves the conservation of plant genetic resources on farms. Farmers are encouraged to grow traditional crop varieties and landraces to conserve their genetic diversity. This method helps to ensure that plant genetic resources are available for local use and to maintain the diversity of plant species in agricultural ecosystems.
- Participatory plant breeding: This involves the involvement of farmers and other stakeholders in plant breeding programs. Farmers are encouraged to grow crop varieties and landraces and to select plants with desirable traits. This method helps to ensure that plant genetic resources are conserved and that crop varieties are developed that meet the needs of local communities.
Overall, the conservation of plant genetic resources is important to maintain the genetic diversity of plant species and their potential for use in plant breeding, research, and other purposes. It is important to conserve plant genetic resources in a sustainable and responsible manner to ensure their availability for future generations.
The study of the genetics of qualitative and quantitative characters
The study of the genetics of qualitative and quantitative characters refers to the examination of the genetic basis of traits that exhibit either discrete or continuous variation, respectively. Qualitative characters are those that show clear-cut differences in phenotype, such as flower colour, seed shape, or presence/absence of a trait. Quantitative characters, on the other hand, are those that exhibit a range of values, such as height, weight, or yield.
Qualitative characters are often controlled by a single gene or a few genes that exhibit dominance or recessiveness. These genes follow Mendelian inheritance patterns, which means that they are inherited from one or both parents in a predictable manner.
For example, in pea plants, the gene for flower colour has two alleles: one for purple flowers (dominant) and the other for white flowers (recessive). If a pea plant has two purple flower alleles, it will have purple flowers, while a plant with two white flower alleles will have white flowers.
In contrast, quantitative characters are typically controlled by multiple genes, each with a small effect on the trait. This type of inheritance is known as polygenic inheritance. The effects of the genes are also influenced by the environment, which can result in continuous variation in the trait. For example, plant height is a quantitative character that is influenced by multiple genes and environmental factors such as temperature, water availability, and nutrient levels.
To study the genetics of qualitative and quantitative characters, researchers use a variety of techniques, including genetic mapping, quantitative trait locus (QTL) analysis, and genome-wide association studies (GWAS). These techniques help to identify the specific genes or genomic regions that control the trait of interest.
Understanding the genetics of qualitative and quantitative characters is important for plant breeding and crop improvement. Breeders can use this knowledge to develop new crop varieties with desirable traits such as disease resistance, high yield, and improved quality. In addition, understanding the genetic basis of traits can also help to identify the underlying mechanisms that control plant growth, development, and adaptation to environmental stresses.