What are the climate and ecological requirements for growing pineapple?

1. Temperature. Under conditions with an annual average temperature above 23°C and high humidity, pineapple grows and develops well. The most suitable daily average temperature for production is 24-27°C. At 10-14°C, production is slow, and below 10°C growth tends to stop, manifesting as new roots ceasing to grow, leaves unable to continue growing, and fruit development stopping; only when the temperature stabilises at 14°C does pineapple begin normal growth. Therefore, 14°C is the critical temperature for normal pineapple growth. When the temperature drops to 2-5°C, symptoms of low-temperature damage appear. If this lasts too long (1-2 days), leaf tips become dry and withered, leaf colour turns yellow, roots at a soil depth of 5cm die, and immature or already mature fruit rind partially blackens with flesh shrinking and other mild chilling injury; when the temperature falls to 0°C and lasts more than 1 day, it causes the plant's central leaves to rot, roots to freeze to death, and fruit to shrink and rot; therefore, 0°C is the critical temperature at which pineapple suffers severe chilling injury. If the temperature reaches -2°C, the plants almost all die. Excessively high temperatures are also unsuitable for pineapple growth and fruit development. When the leaf surface temperature reaches 40°C, not only is plant growth inhibited, but tender leaves or mature leaves on the sun-facing side are also scorched; for pineapple planted on sandy soil, when the leaf surface temperature exceeds 40°C, most leaves dry up and wither, and if drought persists, some plants will die. The above critical temperatures affecting pineapple are not absolute. As far as freezing damage is concerned, if there is ample sunshine from after autumn to before the Start of Winter, the climate is relatively dry, and the temperature declines gradually, the pineapple plant's leaves and stems accumulate more carbohydrates, the plant's tissues are relatively mature and aged, and cold resistance is stronger; if the temperature drops abruptly and rainfall is greater than in normal years, the plant's leaves and stems accumulate fewer carbohydrates, the tissues are relatively weak and tender, and cold damage is severe. In winter, if the number of consecutive days with a daily average temperature ≤8°C exceeds 3-5 days, accompanied by wind and rain, pineapple heart rot is more common.

2. Rainfall. Pineapple is not strict about rainfall requirements and is relatively drought-tolerant. In semi-arid areas with an annual rainfall of 510mm to tropical rainforest areas with rainfall of 5540mm, pineapple can grow and develop normally. In areas with annual rainfall of 1000-2000mm and relatively even distribution across the months, growth, fruiting, yield and quality are better. Pineapple leaves are an excellent indicator tissue for reflecting soil moisture and atmospheric relative humidity. When the water stored in the leaves is low, leaf colour gradually changes from dark green to light green or yellow-green; when it is even lower, after leaf turgor pressure disappears, the leaves change from light yellow to light red, and the leaf margins curl backwards. If water is supplied at this time, the leaves return to normal. If there is no rain for a long time, the pineapple plant's leaves gradually wither from the base to the central leaves. When there is excessive rain and the soil's drainage and permeability are extremely poor, the pineapple root system can also rot due to prolonged waterlogging and lack of oxygen.

3. Sunshine. Under conditions of sufficient light, pineapple photosynthesis is vigorous, carbohydrate accumulation is high, plants grow robustly, and yield is high with excellent quality; with insufficient sunshine, plants grow slowly, fruit is small, soluble solids content is low, and quality is poor. For example, plants growing under tree shade have fruit that is sour and bland, with no fragrance; under high temperature and strong sunshine, not only are some leaves scorched, but the sun-facing side of the fruit is also scorched; therefore, sunshine is an important ecological factor for plant growth and fruiting, as well as for fruit size and quality. Sunshine not only affects plant growth and fruiting, but also has a great influence on pineapple's stress resistance, especially cold resistance. During the overwintering period, sufficient sunshine is conducive to photosynthesis and increases carbohydrate (especially sugar) accumulation, thereby enhancing the plant's cold resistance. Practical experience from pineapple-producing areas in the southern subtropics shows that plants grown under tree shade often suffer a greater degree of chilling injury than plants without shade.

4. Wind. Although wind is a relatively secondary ecological factor affecting pineapple cultivation, in southern subtropical production areas with frequent windy days, due to high soil evaporation, it is also extremely unfavourable to plant growth and fruit development. In production areas with much wind and relatively high wind speed in winter, advective chilling injury is also commonly suffered. Therefore, wind damage should be taken into consideration when planning orchards.