Definition of Plant Breeding
Plant breeding can be defined as:
- An art, a science, and technology of improving the genetic makeup of plants in relation to their economic use for mankind.
- The art and science of improving the heredity of plants for the benefit of humanity.
- A discipline that deals with the genetic improvement of crop plants, also known as the science of crop improvement.
- The science of changing and improving the heredity of plants to enhance their utility.
Aim of Plant Breeding Plant breeding aims to enhance the characteristics of plants, making them more desirable agronomically and economically. The objectives may vary depending on the specific crop.
Objectives of Plant Breeding (Detailed Explanation) Plant breeding is a scientific approach to developing crop varieties with desirable traits to meet the needs of food production, industrial use, and environmental adaptation. Below are the detailed objectives of plant breeding:
- Higher Yield
The primary objective of plant breeding is to increase the yield of economic produce, whether it is grain, fodder, fiber, tubers, cane, or oil, depending on the crop type.
- Why important?
High-yielding crops ensure food security and economic benefits for farmers. - How achieved?
- Developing high-yielding varieties through selection, hybridization, and genetic modification.
- Examples:
- High-yielding varieties of wheat like HD2967.
- Hybrid maize varieties developed for higher grain production.
- Improved Quality
Quality improvement is essential for making the produce more suitable for consumption, processing, or industrial use. The definition of “quality” depends on the crop:
- Cereal crops:
- Wheat: Grain size, color, milling, and baking quality.
- Rice: Cooking quality, aroma, and grain length.
- Vegetable crops: Nutritive value, flavor, shelf life, and resistance to spoilage.
- Oilseeds: High oil content and better fatty acid composition.
- Fiber crops: Long, strong, and fine fibers in crops like cotton.
Breeding efforts focus on these specific traits for better market acceptance and consumer satisfaction.
- Resistance to Abiotic Stresses
Abiotic stresses such as drought, salinity, extreme temperatures, and frost significantly impact crop productivity.
- Why important; Many agricultural regions face erratic climatic conditions. Stress-tolerant varieties ensure stable yields.
- How achieved: Developing drought-tolerant rice and wheat varieties. Salt-tolerant rice varieties for coastal regions (e.g., CSR30 rice).
- Resistance to Biotic Stresses
Biotic stresses like pests and diseases cause significant crop losses. Genetic resistance is the most sustainable solution:
- Why important Reduces reliance on pesticides and fungicides, lowering input costs and environmental impact.
- How achieved: Incorporating resistance genes from wild relatives or through transgenic approaches. Example: Bt cotton, which is resistant to bollworms.
- Change in Maturity Duration / Earliness Breeding crops for shorter maturity duration has several benefits:
- Advantages:
- Reduces exposure to pests and diseases.
- Saves on crop management and labor costs.
- Allows for crop rotation and double-cropping.
- Extends cultivation to regions with shorter growing seasons.
- Examples:
- Wheat varieties for late planting in rice-wheat systems.
- Cotton: Maturity duration reduced from 270 days to 170 days.
- Pigeonpea: Reduced from 270 days to 120 days.
- Determinate Growth Determinate growth refers to controlled or restricted vegetative growth, making the plant more manageable for harvest.
- Crops: Pigeonpea, mungbean, and cotton benefit from determinate growth as it aligns the maturity of all plants.
- Dormancy Dormancy refers to a temporary inability of seeds to germinate.
- Why important?
- Prevent pre-harvest sprouting: In crops like barley, greengram, and pea, seeds may germinate prematurely due to rain.
- In some cases, dormancy needs to be removed for immediate germination.
- Desirable Agronomic Characteristics Certain plant traits make crops more desirable or easier to cultivate:
- Examples:
- Dwarf cereals: Reduce lodging and improve fertilizer response.
- Tall fodder crops: Provide higher yields for livestock feed.
- Profuse branching: Improves yield in crops like pigeonpea and cotton.
- Elimination of Toxic Substances Some crops naturally produce toxic compounds that must be removed for safe consumption:
- Examples:
- Khesari dal (Lathyrus sativus): Neurotoxin removal to prevent paralysis.
- Mustard: Removal of erucic acid to make oil edible.
- Cotton: Removal of gossypol to make seeds suitable for human and animal consumption.
- Non-Shattering Characteristics Shattering of seeds or pods leads to significant losses during harvesting.
- Example: Non-shattering varieties of greengram have been developed to minimize such losses.
- Synchronous Maturity Uniform maturity in crops simplifies harvesting and improves efficiency.
- Crops: Cotton, mungbean, and cowpea, where uniform maturity reduces multiple pickings.
- Photo and Thermo Insensitivity Sensitivity to light (photoperiod) and temperature limits the regions where a crop can be grown. Breeding for insensitivity allows expansion into new areas:
- Examples:
- Wheat: Now grown in West Bengal.
- Rice: Cultivated in Punjab.
- Wider Adaptability Wider adaptability ensures a variety performs well under diverse environmental conditions:
- Why important Stabilizes yields across regions and seasons. Example: High-yielding rice varieties adapted to both irrigated and rainfed conditions.
- Varieties for New Seasons Breeding has enabled some crops to be grown in non-traditional seasons:
- Examples:
- Maize: Traditionally a kharif crop, now grown in rabi and zaid seasons.
- Mungbean: Grown in summer in addition to kharif.
