crop yield Flashcards
What factors is a plant’s rate of photosynthesis affected by?
creating ideal conditions for photosynthesis
- amount of light
- amount of carbon dioxide
- temperature
What is used to give the best level of factors for photosynthesis to maximise crop yield?
creating ideal conditions for photosynthesis
- glasshouses (/greentunnels)
- polytunnels
Why is a glasshouse good for plants?
creating ideal conditions for photosynthesis
- keeps out more pests and diseases
- can put in artifical light to allow plants more time to photosynthesise
- traps heat to keep plants warm. (In winter a heater may be used.)
- CO2 level can be increased by a PARAFIN HEATER, which makes CO2 as a by product when it burns
Why is increasing rate of photosynthesis good?
creating ideal conditions for photosynthesis
- plants grow bigger and faster
- crop yields will be higher
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why is fertiliser used?
fertiliser
- to provide minerals eg nitrogen, potassium and phosphorus for compounds like proteins
- if plants do not get enough, their growth and life processes are affected
Why can minerals be lacking in soil?
fertiliser
- Previous crop can use it up
- so fertilisers can replace missing minerals or provide more, increasing crop yield
Why does pest control improve crop yield
pest control
- less plants are damaged or destroyed
what are the two types of pest control
pest control
- pesticides
- biological control
whats the problem with pesticide use?
pest control
- can be poisonous to humans- have to be closely monitored in food
- can harm other wildlife
Define biological control
pest control
- used as an ALTERNATIVE to pesticides
- means using other organisms to reduce the numbers of pests by either:
- encouraging WILD organisms or adding NEW ones
remember the 3 Ps
State biological control types of microorganisms used with examples
pest control
- predators (ladybirds eat aphids)
- parasites (some flies lay their eggs on slugs, one day killing them)
- pathogens (bacteria that affects caterpillars)
PROS and CONS of biological control
pest control
PROS
* longer lasting effect
* less harmful to wildlife
CONS
* can cause problems (cane toads were introduced to Australia to kill beetles but poison the native species that eat them so are now a major pest)