Do you know about the resistance offered by the plants against its enemy.

Host plant resistance (HPR) Heritable characters possessed by the plant to avoid, tolerate and or withstand pest infestation without subsequent loss in yield compared to susceptible host at the same initial level of infestation under similar environment condition.

Major characteristic by which resistant can be measure;

1. Resistant is heritable and control by one or major gene.

2. Resistant is relative and can be measure only with comparing with susceptible variety of same species.

3. Resistant is measurable and magnitude can be determine quantitatively by insect establishment and qualitatively by analysis of standard scoring system.

 4. Resistant is variable and can be modified by abiotic and biotic component of environment.

Degree of resistance / Intensity of resistance

1. Immunity: A variety that cannot be injured or infested at all by a specific insect pest under any unknown condition. Therefore anything less than immunity is resistance.

2. High resistance: Varieties which suffer less damage by specific insect under given set of environment. E.g. wild plant genotype possesses high resistance.

3. Low resistance: Some variety show less damage than the average damage.

4. Susceptible: Variety which show average or more than average damage by insect. E.g. cross breed or hybrid.

5. Highly susceptible: A variety show much more damage than the average.

Mechanism of resistance:

1. Non – preference:

· It is also called antixenosis.

 · Due to presence of chemical substances

· Due to morphological character.

· Due to presence of allochemical

· Due to absence of chemical attractant or stimulus.

2. Antibiosis:

· Due to presence of toxic substances.

· Due to nutrient imbalance.

· Presence of metabolites enzyme.

· Smaller amount of Asparagine.

· Some variety of rice resistant to BPH.

3. Tolerance:

· It is the inherent ability of the plant to withstand and support normally destructive population of insect pest without subsequent loss in yield.

· Tolerance of BPH – Triveni variety

· Tolerance may be due to presence of color, hairiness, palatability, waxiness, morphology, etc.