Anthocyanins increase most rapidly at temperatures between which two values?

• A. 15C and 25C
• B. 20C and 30C
• C. 25C and 35C
• D. 5C and 15C

Answer: (A)

Anthocyanin accumulation is highly temperature-dependent, because the enzymes driving the anthocyanin biosynthetic pathway work best within a moderate, not-too-hot, not-too-cold range. When temperatures move from cool toward this midsummer warmth, metabolic processes speed up and pigment synthesis accelerates, so the concentration of anthocyanins rises most quickly.

If temperatures are too cool, enzyme activity and overall metabolism are slower, so color development is gradual. If temperatures become too hot, stress and pigment degradation can blunt synthesis and even reduce net accumulation, so the rate of increase slows again. The fastest rise occurs in that middle, cooler-to-moderate range, where enzyme function and plant metabolism are optimized for pigment production.