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Cereal Crops
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Cereal Crops • Visit our website: http://www.sliderbase.com/ • Free PowerPoint Presentations for teaching and learning • Cereals- the worlds staple foods • Cereals are all members of the grass family • Examples include rice, wheat, maize and sorghum • They are grown for their seeds (grains) which are high in carbohydrates and protein • The water content of the grains is low compared to other vegetables • Other benefits of cereals • Easy to store because the low water content helps prevent mould growth • Easy to transport because there is not a lot of wet bulk • There is a suitable cereal for each type of climate • Grown in areas of high temperature and high humidity • Small plants are planted out in flooded fields • Rice can grow in normal soil • Flooded fields reduce competition from weeds • Nitrogen fixing bacteria live on flooded rice roots providing nitrate. This reduces need for fertiliser • This is a cereal which is adapted to grow in arid (dry) regions and tolerate high temperatures and light intensities • Uses a quarter of the water needed by rice • Has a lower grain yield than cereals grown in areas where water is abundant but is often the only crop that will grow • Extensive root system • Thick cuticle (waxy layer covering leaves) reduces evaporation of water from leaves • Sunken stomata reduce water loss by evaporation • Stomata close during drought and reopen very quickly afterwards • Adaptions of Sorghum to heat • Sorghum plants can synthesis heat shock proteins rapidly when temperatures rise • These heat shock proteins prevent enzymes being denatured and make them more thermostable • C3 and C4 photosynthesis • In temperate regions like the UK most plants are C3 • This means that the first molecule made when CO2 enters the leaf cells has 3 carbon atoms • C4 photosynthesis is an advantage to plants in hot regions with high light intensity • Advantages of C4 photosynthesis • A different enzyme is used. C3 plants use the enzyme rubisco which is not very effective when CO2 concentrations in the leaf cells are relatively low. • C4 plants use the enzyme PEP this enzyme has a high affinity for CO2 even when concentrations are low, for example when plants close their stomata to reduce water loss • Another C4 plant which is able to photosynthesis efficiently at high temperatures and light intensities. • Needs more water than sorghum but gives a higher yield so the preferred crop wherever there is enough rainfall
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