Course Content
Qualitative and quantitative characters (qualitative and quantitative characters in crops and their inheritance)
0/2
Biometrical techniques in plant breeding (assessment of variability, aids to selection, choice of parents, crossing techniques, genotype-by- environment interactions)
0/3
Selection in self-pollinated crops (progeny test, pureline theory, origin of variation, genetic advance, genetic gain)
0/5
Hybridization techniques and its consequences (objectives, types, program, procedures, consequences)
0/4
Genetic composition of cross-pollinated populations (Hardy-Weinberg law, equilibrium, mating systems)
0/4
Breeding methods in self-pollinated crops (Mass, Pure line, Pedigree, Bulk, Backcross, etc)
0/5
Learn Introductory Plant Breeding with Rahul
About Lesson

Defense mechanisms of host against pathogen/parasite

A) Avoidance

  • Reduces the possibility of contact between potential consumer and plants by morphology, phenology or smell
  • Eg: Erect leaf habit in cereals reduces the deposition of rust inoculation

 

B) Tolerance

  • host neither restricts parasitic contact nor the growth and development of the parasite after establishment.
  • As a consequence, it does not affect the number of damage/symptoms per unit quantity of parasite present. However, there is little loss in the economic yield.

 

C) Resistance

  • It is the ability of the host to reduce the growth and or development of the parasite or pathogen after contact have been initiated or established

➢ Race specific/vertical resistance/gene for gene resistance: A resistance that is effective to specific (avirulent) genotypes of a pathogen species.

➢ Race nonspecific/horizontal resistance/no gene for gene resistance: A resistance that is equally effective to all the genotypes of a pathogen species.

 

D) Immune:

  • Host does not show the symptom of disease is known as immune reaction.
  • Rate of reproduction of the pathogen is zero
  • Immune plants generally show hypersensitive reaction
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