Crop Improvement – I (Kharif)
UNIT-IV
Chapter 5
Major breeding objectives
The breeding objectives for crops can vary depending on the needs of different stakeholders, such as farmers, consumers, and the agricultural industry. However, some common breeding objectives for crops include:
- Yield: One of the most important breeding objectives is to increase crop yield. This can be achieved through the development of cultivars with higher biomass, better resource use efficiency, and improved resistance to pests and diseases.
- Quality: Another important breeding objective is to improve the quality of the crop. This can include traits such as improved taste, aroma, texture, and nutritional content.
- Adaptability: Breeding crops that can adapt to different environments and climate conditions is important for ensuring food security and reducing the impact of climate change. This can include developing cultivars that are drought-tolerant, heat-tolerant, and resistant to pests and diseases prevalent in specific regions.
- Stress tolerance: Breeding crops that are tolerant to environmental stresses such as drought, salinity, and extreme temperatures is important for sustainable agriculture and food security.
- Resistance to pests and diseases: Developing cultivars with improved resistance to pests and diseases is important for reducing crop losses and decreasing reliance on chemical pesticides.
- Efficient resource use: Breeding crops that can use resources such as water and nutrients more efficiently can improve the sustainability of agriculture and reduce environmental impacts.
- Processing and storage: Developing cultivars that are suitable for processing and storage can improve the value of the crop and reduce post-harvest losses.
Overall, the major breeding objectives for crops are to improve yield, quality, adaptability, stress tolerance, resistance to pests and diseases, efficient resource use, and suitability for processing and storage. Achieving these objectives requires a combination of traditional breeding techniques, such as selection and hybridization, and modern tools such as genetic engineering and genomic selection.
Breeding objectives for the development of hybrids and varieties can vary depending on the crop and the target market. However, some of the major objectives include improving yield, adaptability, stability, resistance to biotic and abiotic stresses, and enhancing quality traits such as physical, chemical, and nutritional attributes.
Conventional Breeding Approaches:
- Phenotypic selection: This approach involves selecting plants with desirable traits based on their physical appearance. Breeders look for traits such as height, yield, disease resistance, and other agronomic characteristics.
- Pedigree breeding: This method involves selecting parents with desirable traits and crossing them to produce offspring with improved traits. The process is repeated over several generations until the desired traits are fixed.
- Backcross breeding: This method is used to transfer a specific trait from one variety to another by crossing it with a recurrent parent, followed by several rounds of backcrossing to the recurrent parent.
Modern Innovative Approaches:
- Marker-assisted selection (MAS): This approach uses molecular markers linked to specific traits to select those traits in the breeding process. MAS can accelerate the breeding process by reducing the time and resources required for phenotypic selection.
- Genomic selection: This method involves using high-throughput DNA sequencing to identify specific genes and alleles associated with desired traits. These genetic markers are used to predict the performance of offspring and select desirable traits.
- Genome editing: Genome editing technologies like CRISPR/Cas9 can be used to precisely and efficiently modify specific genes associated with desired traits, allowing breeders to rapidly develop new varieties with improved traits.
Procedures
Breeding objectives and procedures for developing hybrids and varieties for yield, adaptability, stability, abiotic and biotic stress tolerance, and quality can vary depending on the crop and the specific objectives of the breeding program. However, here are some general concepts and approaches for each of these topics:
- Yield: Breeding for increased yield is a major objective for most crops. Conventional approaches include selection for high-yielding plants, while modern innovative approaches can include the use of genomic selection, marker-assisted selection, and genetic engineering to identify and manipulate genes associated with yield. Hybridization, which involves crossing two or more genetically distinct plants to produce offspring with improved yield, is another approach that can be used to develop high-yielding cultivars.
- Adaptability: Breeding crops that can adapt to different environments and climate conditions is important for ensuring food security and reducing the impact of climate change. Conventional approaches include selection for traits such as drought tolerance, heat tolerance, and resistance to pests and diseases prevalent in specific regions. Modern innovative approaches can include the use of genomic selection and marker-assisted selection to identify genes associated with adaptability.
- Stability: Breeding for stability involves developing cultivars that perform consistently across different environments and over time. Conventional approaches include multi-location testing and selection for cultivars with stable performance in different environments. Modern innovative approaches can include the use of genomic selection to identify genes associated with stability.
- Abiotic stress tolerance: Abiotic stresses such as drought, salinity, and extreme temperatures can have a significant impact on crop yield. Breeding for abiotic stress tolerance involves developing cultivars that can survive and produce a reasonable yield under such conditions. Conventional approaches include selection for traits such as root depth, water use efficiency, and osmotic adjustment. Modern innovative approaches can include the use of genetic engineering to introduce or enhance genes associated with abiotic stress tolerance.
- Biotic stress tolerance: Biotic stresses such as pests and diseases can cause significant losses in crop yield. Breeding for biotic stress tolerance involves developing cultivars that can resist or tolerate these stresses. Conventional approaches include selection for traits such as resistance to specific pests and diseases. Modern innovative approaches can include the use of genetic engineering to introduce or enhance genes associated with biotic stress tolerance.
- Quality: Breeding for quality involves developing cultivars with desirable physical, chemical, and nutritional characteristics. Conventional approaches include selection for traits such as taste, aroma, texture, and nutritional content. Modern innovative approaches can include the use of genomic selection to identify genes associated with quality traits, as well as genetic engineering to introduce or enhance genes associated with desired traits.
Overall, breeding for yield, adaptability, stability, abiotic and biotic stress tolerance, and quality requires a combination of conventional and modern innovative approaches. Conventional approaches rely on selection and hybridization, while modern innovative approaches use advanced technologies such as genomic selection and genetic engineering to identify and manipulate genes associated with desired traits. Understanding and implementing these approaches can lead to the development of new cultivars with improved yield, quality, and resilience to stresses and changing environments.