7.1 - Using crop plants to produce food
Why people grow crops
● Grown by people, mainly to provide food for people/animals
● ↳ Energy production, e.g.: trees/substantial (堅實) grasses
● ↳ Raw materials, e.g.: cotton/hemp (麻)
● In order to (increase) yield:
○ Water/mineral ions from soil
○ Carbon dioxide/light for photosynthesis
○ Suitable temperature for enzyme activities
○ → Reduce losses, e.g.: competition of pests/weeds, diseases
Glasshouses and polytunnels (plastic - polythene)
● Provide protection for crops\enclosed environment - controlled climate
● Small scale - in gardens/family vegetable plots (allotments [配給])/small
farms//commercial (e.g.: strawberries, tomatoes; peppers, cucumbers,
aubergines, lettuces; flowers)
● ALSO - protection enables early/out-of-season crops to be grown at times with
higher market prices (i.e.: profit ↑)
● Protected environment and (auto-)controlled climate
○ Light - transparent cover admits sunlight (increased beneficial greenhouse
effect); ALSO artificial lighting boosts light intensity for photosynthesis →
extra production
○ Temperature - ↑ due to greenhouse effect, rate of enzyme
reactions ↑ (photosynthetic-inclusive)
■ HOWEVER ensure ventilation/shading to prevent overheating
○ Water supply & control of humidity - controlled irrigation (too little/much
water can reduce plant growth); ensure humidity not too high (or else could
encourage spread of fungal/bacterial diseases)
○ Wind - physical protection from wind; reduced temperature fall, ↓ rate of
transpiration
○ Frost - ice crystals produced in frozen cells make them burst; reduced frost
damage to sensitive crops, e.g.: cucumbers
○ Carbon dioxide - carefully monitored; more CO2, more photosynthesis
(artificial supply of CO2 is more effective in glasshouse than polytunnel)
Use of fertilizer to increase crop yield
● Supply mineral ions (so as to maintain soil fertility - plants need mineral ions to
make amino acids\proteins)
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Why people grow crops
● Grown by people, mainly to provide food for people/animals
● ↳ Energy production, e.g.: trees/substantial (堅實) grasses
● ↳ Raw materials, e.g.: cotton/hemp (麻)
● In order to (increase) yield:
○ Water/mineral ions from soil
○ Carbon dioxide/light for photosynthesis
○ Suitable temperature for enzyme activities
○ → Reduce losses, e.g.: competition of pests/weeds, diseases
Glasshouses and polytunnels (plastic - polythene)
● Provide protection for crops\enclosed environment - controlled climate
● Small scale - in gardens/family vegetable plots (allotments [配給])/small
farms//commercial (e.g.: strawberries, tomatoes; peppers, cucumbers,
aubergines, lettuces; flowers)
● ALSO - protection enables early/out-of-season crops to be grown at times with
higher market prices (i.e.: profit ↑)
● Protected environment and (auto-)controlled climate
○ Light - transparent cover admits sunlight (increased beneficial greenhouse
effect); ALSO artificial lighting boosts light intensity for photosynthesis →
extra production
○ Temperature - ↑ due to greenhouse effect, rate of enzyme
reactions ↑ (photosynthetic-inclusive)
■ HOWEVER ensure ventilation/shading to prevent overheating
○ Water supply & control of humidity - controlled irrigation (too little/much
water can reduce plant growth); ensure humidity not too high (or else could
encourage spread of fungal/bacterial diseases)
○ Wind - physical protection from wind; reduced temperature fall, ↓ rate of
transpiration
○ Frost - ice crystals produced in frozen cells make them burst; reduced frost
damage to sensitive crops, e.g.: cucumbers
○ Carbon dioxide - carefully monitored; more CO2, more photosynthesis
(artificial supply of CO2 is more effective in glasshouse than polytunnel)
Use of fertilizer to increase crop yield
● Supply mineral ions (so as to maintain soil fertility - plants need mineral ions to
make amino acids\proteins)
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