GLASSHOUSES

Certain crops can be grown in glasshouses or in tunnels made from transparent polythene.

This increases their growth and maximises the yield, for the following reasons:

Transparent material allows natural light in for photosynthesis during the summer. Additional lighting gives a ‘longer day’ during the winter.

The ‘greenhouse effect’ traps longer wave radiation and the greenhouse heats up.

Burning fuels increases the temperature and carbon dioxide levels, increasing the rate of photosynthesis

It also adds water vapour to the air and the plant loses less water through its leaves.

Growing the plants in a mineral solution (hydroponic culture) provides the right balance of mineral ions for the crop being grown.

Growing crops in glasshouses increases their yield!

Soil Minerals Soil minerals are the source of the elements the plants need to manufacture the complex organic molecules they need

Importance of nitrate ions to plants As nitrates source of nitogen atoms for:  Amino acids and proteins  Nucleic acids  ATP  Component of chlorophyll molecule

Plants growing without nitrates typically stunted, yellow

Importance of magnesium ions to plants As Mg 2+ source of magnesium atoms for:  reaction centre for chlorophyll molecule  essential cofactor for certain enzymes

Plants growing without magnesium Typical yellow leaves