PLANT RESPONSES: Plant response to herbivory and abiotic stress [PART 1]

why do plants need to respond to the environment?

-to avoid abiotic stress

-to avoid herbivory

-to maximise photosynthesis

-to ensure seed germination

herbivory

animals eating plants

responses plants use against herbivory

physical defence

-thorns→ prevents animals from eating it

-plants fold when touched

chemical defence

-produce alkaloids→ are toxic or bitter→ deter or poison herbivores [DIRECT]

-produce pheromones [INDIRECT]

→affect behaviour of other plants of the same species, triggering defence responses

→ OR attract predators/parasites of the herbivore

plant responses to abiotic stress

-drought

→close stomata

→leaf drop

-cold temperatures

→close stomata

→produce anti-freeze chemicals

→leaf drop

-low light levels / short day length [autumn/ winter]

→close stomata

→leaf drop

→etiolation [plant grows in the dark]

[tip: all leaf drop]