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प्रश्न
Define the term ‘stress’ for plants. Discuss briefly the two types of stress encountered by plants.
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उत्तर
A plant has to constantly interact with various biotic and abiotic factors. These factors may put stress on a plant. Two types of stress that a plant often encounters are as follows:
- Environmental Stress: Environmental stress is produced by unfavourable conditions; like salinity, drought, extreme temperatures, etc. Many crop plants are unable to survive extreme saline conditions or drought or extreme temperatures and hence, stay dormant during these phases.
- Biotic Stress: Biotic stresses come in the form of insects and pests. Weeds also represent biotic stress for plants. While pests and insects do direct harm to the plants, weeds do so by competing for available resources; like sunlight, nutrients and water.
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संबंधित प्रश्न
Write a short note on ‘Mutational breeding’.
Identify ‘a’, ‘b’ and ‘c’ in the following table:
| S. No. | Crop | Variety | Insect Pests |
| 1. | Brassica | Pusa Gaurav | ‘a’ |
| 2. | Flat bean | Pusa Sem 2 Pusa sem 3 |
‘b’ |
| 3. | ‘c’ | Pusa Sawani Pusa A-4 |
Shoot and fruit borer |
How has the breeding programme helped in improving the public nutritional health? State two examples in support of your answer.
What are transgenic plants? Explain with any two examples
In an agricultural field there is a prevalence of the following organisms and crop diseases which are affecting the crop yield badly:
- White rust
- Leaf and stripe rust
- Black rot
- Jussids
Recommend the varieties of crops the farmers should grow to get rid of the existing problem and thus improve the crop yield.
State one characteristic of millets that has been improved as a result of hybrid breeding so as to produce high yielding millet crops.
List the two steps the classical plant breeding involves.
Answer each question in ‘One’ sentence only:
Define stock and scion.
Wheat -Atlas 66 has high contents of ______.
Importing better varieties and plants from outside and acclimatizing them to the local environment is called
Explain the best-suited type followed by plant breeders at present?
Sonora – 64 is a variety of ______.
If a diploid cell is treated with colchicine then it becomes:
Lysine and tryptophan are ______.
In the area of plant breeding, it is important not only to preserve the seeds of the variety being cultivated, but also to preserve all its wild relatives. Explain with a suitable example.
Discuss the two main limitations of plant hybridization programme.
It is said, that diseases are spreading faster due to globalisation and increased movement of people. Justify the statement taking the example of H5N1 virus.
Name the improved characteristics of wheat that helped India to achieve green revolution.
Suggest some of the features of plants that will prevent insect and pest infestation
Give a reason for the following:
The continuous inbreeding of crops may lead to reduced fertility and productivity. However, the self-pollinated crops do not show the ill-effects of inbreeding.
