Temperature plays a crucial role in plant growth and development, as it influences nearly every physiological and biochemical process in plants. Each plant species has an optimal temperature range in which it grows best. Temperatures that are too high or too low can disrupt normal growth, affect reproduction, and even cause plant death.
Here’s how temperature affects plant growth:
• Enzyme activity:
Temperature controls the rate of enzymatic reactions inside plant cells. Within the optimal range, enzyme activity increases, promoting faster growth. However, extremely high or low temperatures slow down or even stop enzyme function, affecting all metabolic processes like respiration, photosynthesis, and nutrient absorption.
• Photosynthesis:
Photosynthesis works best within moderate temperature ranges (usually between 20°C and 30°C for most plants). If temperatures drop too low, photosynthetic enzymes become less active. At very high temperatures, photosynthesis declines because enzymes denature and stomata close to reduce water loss, limiting CO₂ intake.
• Respiration:
Respiration—the process that converts stored sugars into energy—also depends on temperature. Higher temperatures increase respiration rates, but excessive heat can cause plants to burn more energy than they produce, leading to reduced growth.
• Seed germination:
Temperature determines how quickly and successfully seeds germinate. Each species has a specific temperature range for germination. Low temperatures delay or prevent germination, while excessively high temperatures may damage seed tissues.
• Water balance and transpiration:
Warm temperatures increase transpiration (loss of water from leaves). Moderate transpiration helps cool plants, but excessive heat can cause dehydration and wilting. In contrast, low temperatures slow transpiration, which may reduce nutrient movement within the plant.
• Flowering and fruiting:
Temperature influences the timing of flowering and fruit development. Some plants require a period of cold (vernalization) to trigger flowering, such as wheat or tulips. High temperatures during flowering can cause pollen sterility, flower drop, or poor fruit set.
• Growth rate:
In general, plant growth accelerates as temperature increases up to a certain point (the optimum). Beyond that point, metabolic processes begin to fail. For example, cool-season crops like lettuce and peas thrive in cooler temperatures, while warm-season crops like maize and tomatoes grow best in heat.
• Cold and frost damage:
Freezing temperatures can damage cell membranes and cause ice formation inside tissues, leading to wilting, leaf burn, or death. Plants adapted to cold climates produce antifreeze-like substances to survive frost.
• Heat stress:
Excessive heat causes proteins to denature, photosynthesis to decline, and water loss to increase. Prolonged exposure may result in leaf scorch, reduced yield, and lower quality of fruits and vegetables.
In summary, temperature affects plant growth rate, metabolism, reproduction, and survival. Each plant has an ideal temperature range that supports optimal enzyme activity, photosynthesis, and respiration. Maintaining suitable temperature conditions ensures healthy growth, proper flowering, and high crop productivity.