Photosynthesis & Crop Growth (Cambridge International IGCSE Environmental Management)

Optimum conditions for photosynthesis & crop growth

• Photosynthesis is the process where plants use sunlight, carbon dioxide and water to make glucose for growth

  • Glucose is used to build leaves, stems, roots, flowers and fruits

• The rate of photosynthesis directly affects crop growth and final yields

• Crops grow best when conditions allow photosynthesis to happen quickly and efficiently

Length of growing season

• Growing season—the part of the year when conditions are suitable for plant growth

• A longer growing season allows crops more time to carry out photosynthesis

  • Leads to larger plants and higher yields

• In colder climates, short growing seasons limit how long crops can grow

• Farmers choose crop varieties that fit the length of the local growing season

Optimum weather conditions

• Photosynthesis needs the right balance of sunlight, temperature and water
• Warm temperatures help enzymes work quickly, speeding up photosynthesis
• Adequate rainfall keeps soil moist so plants can absorb water
• Too much rain may cause waterlogging, reducing oxygen for roots
• Long periods of sunlight allow plants to make more glucose
• Extreme weather such as storms, heatwaves or frost can damage leaves and reduce photosynthesis

Daylight hours

• More daylight hours = more time for photosynthesis
• Summer has long days, allowing crops to grow quickly and efficiently
• Short winter days reduce the amount of light available
• Some crops need long daylight hours to flower or reach maturity, while others prefer shorter days
• Day length affects the timing of planting and harvesting

Exam Hint Always try to explain why a factor affects photosynthesis. For example, warm temperatures increase enzyme activity, which speeds up the reaction. This detail often earns extra marks.