What are the conditions for growing apples? A detailed explanation of the growing environment requirements
Apples originated in central and southeastern Europe, Central and West Asia, and China**, and have a cultivation history of more than two thousand years in China. The main producing areas in China include Baishui, Tianshui, Yantai, Jixian, Yiyuan and other regions. Now let us take a look at what the conditions for growing apples are!
Rainfall requirements
During the growing period, apples require about 180 mm of precipitation per mu of land. With natural precipitation, only about 1/3 can actually be used and absorbed by the fruit trees, so a growing-season precipitation of 540 mm is already sufficient. In areas where precipitation from April to September is below 450 mm, irrigation is needed. Precipitation in northern China is unevenly distributed, with 70-80% concentrated in July and August, while water is insufficient in spring. In inland areas with little precipitation, water is insufficient, so when selecting a site for an orchard, irrigation conditions and moisture-conservation measures must be taken into account, and drainage measures for the rainy season should also be considered.
Light conditions
Apple is a light-loving tree species and can only grow normally with sufficient light. According to measurements by Shandong Agricultural University, for Golden Delicious and Starkrimson in the Tai'an area, the light compensation point is 600-800 meter-candles, and the saturation point is 3500-4500 meter-candles. Within this range, as light intensity increases, photosynthesis also strengthens. Insufficient sunlight causes a series of reactions, such as excessive vegetative growth of branches and leaves, weakness, poor resistance to pests and diseases, fewer flower buds differentiated, less nutrient storage, low flowering and fruit-setting rates, affected root growth, low sugar content in fruit, and poor coloring.
Soil environment
Soil has a great influence on the growth, yield and quality of apples. The main factors are soil layer, soil aeration and soil texture. In short, apples need deep soil, good drainage, rich organic matter, and slightly acidic to slightly alkaline conditions.
Temperature conditions
The apple tree is a temperate fruit tree that prefers low temperatures and dry conditions, requiring winters without severe cold and summers without extreme heat. The suitable temperature range is an annual average temperature of 9-14°C, an extreme winter low not lower than -12°C, a highest monthly average temperature in summer not higher than 20°C, an annual accumulated temperature of about 5000°C at ≥10°C, an average temperature during the growing season (April-October) of 12-18°C, and 1200-1500 hours of low temperatures below 7.2°C in winter to successfully pass natural dormancy. It is generally believed that apples can be cultivated in areas with an annual average temperature of 7.5-14°C. The natural dormancy period of apples is relatively long. If winter temperatures are high and cannot meet the low-temperature requirements needed for the winter dormancy period, spring budbreak will be uneven.
Looking at the regions where apples are most cultivated in the world, only when the average temperature of the coldest winter month (January in the Northern Hemisphere, July in the Southern Hemisphere) is between -10 and 10°C can the low-temperature requirements of apples be met. The average January temperatures in China's main apple-producing areas all fall within this limit. An average temperature of 12-18°C during the growing period (April-October) and an average temperature of 18-24°C in summer (June-August) are most suitable for apple growth. If summer temperatures are too high, with an average temperature above 26°C, apple flower bud differentiation is poor. If heat is insufficient, flower bud differentiation is also poor, the fruit is small and sour, the color is poor, and it does not store well. As for autumn temperatures, when daytime is warm and nighttime is cool, the fruit has high sugar content, good coloring, thick skin, abundant bloom, and good storage quality.