About Lesson
Introduction
- Plant breeding can be defined as an art, a science, and technology of improving then genetic makeup of plants in relation to their economic use for the man kind.
- It aims to improve the characteristics of plants so that they become more desirable agronomically and economically.
- The specific objectives may vary greatly depending on the crop under consideration.
Objectives of Plant Breeding
- Higher yield:
- The ultimate aim of plant breeding is to improve the yield of economic produce.
- Improvement in yield can be achieved either by evolving high yielding varieties or hybrids.
- Improved quality:
- Includes improvement in quality like grain size, color, milling and backing quality in wheat. Cooking quality in rice, malting quality in barley, size, color and size of fruits, nutritive and keeping quality in vegetables, protein content in pulses, oil content in oilseeds, fiber length, strength and fineness in cotton.
- Abiotic resistance:
- Crop plants also suffer from abiotic factors such as drought, soil salinity, extreme temperatures, heat, wind, cold and frost.
- Breeder has to develop resistant varieties for such environmental conditions.
- Biotic resistance:
- Crop plants are attacked by various diseases and insects, resulting in considerable yield losses.
- Genetic resistance is the cheapest and the best method of minimizing such losses.
- Determinate Growth:
- Development of varieties with determinate growth is desirable in crops like Mung, Pigeon Pea (Cajanus cajan), Cotton (Gossypium sp.), etc.
- Dormancy:
- A period of dormancy has to be introduced in these crops to check loss due to germination.
- In some other cases, however, it may be desirable to remove dormancy.
- Desirable Agronomic Characteristics:
- It includes plant height, branching, tillering capacity, growth habit, erect or trailing habit etc., is often desirable.
- Elimination of Toxic Substances:
- It is essential to develop varieties free from toxic compounds in some crops to make them safe for human consumption.
- For example, removal of neurotoxin in Khesari (Lathyruys sativus) which leads to paralysis of lower limbs, erucic acid from Brassica which is harmful for human health, and gossypol from the seed of cotton is necessary to make them fit for human consumption.
- Non-shattering characteristics:
- The shattering of pods is serious problem in green gram.
- Hence resistance to shattering is an important objective in green gram.
- Synchronous Maturity:
- It refers to maturity of a crop species at one time.
- The character is highly desirable in crops like Greengram, Cowpea, and Cotton where several pickings are required for crop harvest.
- Photo and Thermo insensitivity:
- Development of varieties insensitive to light and temperature helps in crossing the cultivation boundaries of crop plants.
- Photo and thermo-insensitive varieties of wheat and rice has permitted their cultivation in new areas.
- Wider adaptability:
- Adaptability is an important objective in plant breeding because it helps in stabilizing the crop production over regions and seasons.
- Varieties for New Seasons:
- Traditionally Maize is a kharif crop. But scientists are now able to grow Maize as rabi and zaid crops.