The pineapple is a tropical perennial plant widely cultivated for its edible fruit. As a native of warm regions, the plant’s entire life cycle, from vegetative growth to fruit maturation, is highly sensitive to its thermal environment. Temperature determines where this crop can be successfully grown and how quickly it develops.
The Ideal Thermal Window for Growth
The vegetative phase thrives within a specific thermal window. Optimal daytime temperatures hover between 25°C and 32°C (77°F–90°F), maximizing the rate of photosynthesis. Consistent temperatures in this range ensure efficient metabolic activity and rapid accumulation of biomass, leading to a large, healthy plant.
The plant benefits from a distinct temperature differential between day and night. Nighttime temperatures should drop to between 15°C and 20°C (59°F–68°F). This cooler period allows the plant to efficiently convert acids produced during the day into sugars via the Crassulacean Acid Metabolism (CAM) cycle. If temperatures remain too high at night, this metabolic efficiency decreases, slowing the plant’s overall growth rate.
Impact of Extreme Cold
Pineapples are intolerant of cold, and prolonged exposure to low temperatures can halt growth. The plant’s metabolic processes slow dramatically below 14°C (57°F), and growth essentially stops below 10°C (50°F). Sustained chilling conditions force the plant to divert energy away from growth toward survival.
Physical signs of cold stress manifest as reddening or purpling of the leaves, followed by leaf-tip necrosis. The most damaging effect on the fruit is Chilling Injury (CI), known as “black heart” or internal browning. This browning develops in the fruit’s flesh, often near the core, and may not become visible until the fruit is returned to warmer temperatures above 15°C (59°F). Freezing temperatures or frost are lethal to the pineapple plant, causing irreversible tissue damage and plant death.
Effects of Excessive Heat
While pineapples tolerate high temperatures better than cold, sustained heat above 35°C (95°F) introduces problems. Excessive warmth accelerates the plant’s respiration rate, causing it to consume sugars and energy reserves faster than it can produce them. This inefficient metabolism can lead to water stress and reduced overall plant health.
The developing fruit is susceptible to damage from intense heat and direct sunlight. Sun scald, a form of sunburn, appears as a bleached or pale grey area on the fruit’s exposed surface, which can deteriorate and become vulnerable to pathogens. Prolonged, intense heat can cause internal damage, described as “cooking” the fruit, which renders it unmarketable. Growers often employ strategies like tying the leaves over the fruit or using reflective materials to mitigate solar stress.
Temperature’s Role in Flowering and Fruiting
Temperature is a factor in triggering the transition from the vegetative stage to the reproductive stage. A drop in temperature, particularly a prolonged period of cool weather below 17°C (63°F), acts as a natural trigger for flowering, known as flower induction. This natural induction is often undesirable for commercial growers if it occurs before the plant has reached its maximum size, resulting in smaller, less valuable fruit.
Once the flower is induced, consistent, warm temperatures are required for the fruit to develop properly. Daytime temperatures between 21°C and 29.5°C (70°F–85°F) during the fruiting period promote the accumulation of sugars. This ensures the harvested fruit has the sweetness and flavor desired by consumers. Cooler temperatures during fruit development can slow the maturation process, potentially leading to a more acidic fruit and a longer time until harvest.