Important Definations
1. Stress:
Adverse conditions for crop growth and production caused by either environmental or biological factors or both.
2. Biotic Stress:
Adverse conditions for crop growth and production caused by biological factors such as disease, insects and parasitic weeds.
3. Abiotic Stress:
Adverse conditions for crop growth and production caused by environmental factors such as deficiency or excess of nutrition, moisture, temperature, and light, the presence of harmful gases or toxicants ,and abnormal soil conditions such as salinity, alkalinity, and acidity.
4. Genetic Resistance:
Ability of some genotypes to give higher yield of good quality than other varieties at the same initial level of disease or insect infestation under similar environmental conditions.
5. Vertical Resistance:
Resistance of a host to the particular race of a pathogen. Also called major gene resistance, oligogenic resistance and qualitative resistances.
6. Horizontal Resistance:
Resistance of a host to the particular race of a pathogen. Also called major gene resistance, polygenic resistance, minor gene resistance and nonspecific resistance.
7. Gene for Gene Hypothesis:
This hypothesis states that for each gene controlling resistance in the host, there is a corresponding gene controlling pathogenicity in the pathogen. Also called flor hypothesis after the name of the scientist who developed this concept.
8. Parasite:
An organism or virus which lives upon or within another living organism.
9. Pest:
Any animal or higher plant which parasitizes crop plants, E.g. insects, nematodes, birds and parasitic weeds.
10. Disease:
Disorders of crop plants caused by pathogen.
11. Pathogenicity:
Ability of a pathogen to attack a host.
12. Pathogen:
Various disease causing organisms such as fungi, bacteria, viruses, and mycoplasmas.
13. Immune:
Completely resistant plants.
14. Major Genes:
Genes with distinct and easily identifiable effect.
15. Minor Genes:
Genes with small effect on a character.
16. Field Resistance:
Resistance which gives an effective control of a parasitic under field conditions.
17. Durable Resistance:
Long lasting resistance.
18. Seedling Resistance:
Resistance exhibited by young seedlings.
19. Adult Resistance:
Resistance exhibited by adult plants.
20. Host:
The plant attacked by a disease, insect or parasitic weed.
21. Physiological Race:
Strain of a pathogen differing in pathogenicity , also known as pathotype.
22. Virulent:
A race of pathogen capable of attacking a host with specific resistance.
23. Avirulent:
A pathogen race unable to attack a host with specific resistance.
24. Hypersensitivity:
A host pathogen reaction which leads to death of infested tissues.
25. Epidemic:
Widespread uncontrolled incidence of a disease.
26. Gene Pyramiding:
Incorporation of two or more major genes in a variety for specific resistance to a pathogen.
27. Gene Deployment:
Planned geographical distribution of major gene for specific resistance to pests for use in varietal development and production.
28. Biotype:
Variant of new strain of an insect.
29. Non-preference:
Various features of host plant that make the host undesirable or unattractive to insects for food shelter or reproduction.
30. Antibiotics:
Adverse effects of the host on feeding, development and reproduction of insect pest.
31. Tolerance:
Ability of a host to reproduce well despite the establishment of a pathogen in the host tissue or attack of an insect or the ability of a variety to produce more yield than susceptible variety at the same level of insect attack.
32. Voidance:
Escape of a variety from insect attack either due to earliness or its cultivation in the season when insect population is very low.