What are the temperature requirements for the growth of apple trees?

At what temperature are apple trees grown? Please introduce the physiological activities, biochemical reactions and growth and development of apple trees, which must be carried out under certain temperature conditions. Otherwise, its normal growth and development will be inhibited, hindered, victimized and even dead. Therefore, the planting network sorted out the apple tree temperature requirements, the following detailed list for netizens reference. Apple tree growth temperature: Apple life activities and growth and development of the required temperature, in terms of its physiological process, there are corresponding minimum, optimum and maximum three basic temperature. It is generally believed that the lowest temperature of apple is about 5.0℃, the optimum temperature is 13-25℃, and the highest temperature is about 40℃, and it varies according to varieties, organs, ages, growth periods, physiological processes and temperature changes, as well as other ecological factors. The optimum average temperature of different varieties was also different. 2. Temperature of apple tree flowering: Apple flowering date can be predicted by calculating accumulated temperature before flowering from accumulated temperature and flowering date. In temperate regions, the lowest effective accumulated temperature of 5℃ for tree growth is generally used to predict flowering. According to the research, the effective accumulated temperature above 5 ℃ is 160~180℃ on average from the temperature reaching 5℃ to the beginning of flowering, and there is little change among varieties. However, the length of flowering period is affected by temperature. Most varieties need about 50 days at 7-8℃, 40 days at 10℃ and 30 days at 12-13℃. The effective accumulated temperature required for most apple varieties from initial growth to flowering is 185±10℃, and the difference between years is as high as 101℃. Different varieties or the same variety in different areas and years required different accumulated temperature; different terrain and microclimate also have effects. 3. Temperature of flowering apple tree: Apple to achieve flowering, first need to reach a certain amount of accumulated temperature. Apple flowering is sensitive to temperature. Temperature is an important limiting ecological factor for flowering, pollination, fertilization and fruiting. Generally, the suitable temperature for apple flowering is 11.4~11.8℃, and the optimum temperature is 17~18℃. From the temperature required for pollinator bee activity, bees generally stop going out below 10℃, and become active gradually with the increase of temperature between 15 ℃ and 29℃, which is conducive to pollination and pollination. The temperature at flowering stage is an important condition for pollen germination and pollen tube elongation to complete fertilization. According to observation, different varieties require different suitable temperature, the suitable temperature for pollen germination is generally between 10~25℃, and the optimum temperature is 15~20℃; when it is higher than 30℃, pollen germination is obviously inhibited. 4. Effects of low temperature in spring on apple trees: Low temperature in spring: Because most apple producing areas in China belong to continental monsoon climate, spring temperature is unstable, often low temperature occurs, especially late frost damage is more common. Apple is in bud, flowering and fruiting stage in spring, and has weak tolerance to low temperature and sensitive response to temperature. Spring temperature is closely related to apple shape and appearance quality. After 15~16 days after flowering, apple fruit grows faster on vertical axis than on horizontal axis when the temperature is lower and the climate is cold. 5. Summer and autumn temperature effects on apple trees: Because summer and autumn are the periods when apple shoots stop growing, flower bud differentiation and fruit development mature, summer and autumn temperatures have great influence on flower bud differentiation, yield formation and quality. The results showed that the temperature in summer and autumn (June to September) was too high or too low, which was unfavorable to the above growth process of apple, and the most suitable monthly average temperature was between 16.5 ℃ and 22.85℃. If the temperature is too high in summer, the ecological reactions are: fruit shape index becomes smaller, coloring is bad, pulp is easy to develop, maturity consistency is poor, vitamin content is reduced, fruit aroma, flavor and storability are poor. Summer temperature and flower bud differentiation: the study pointed out that the apple flower bud differentiation initial stage and vigorous stage of the appropriate temperature for 20-27℃. The morphological differentiation period of flower buds of Marshal and Guoguang began after a certain number of days when the average temperature was stable above 20℃. 6. Effects of winter low temperature on apple trees: Apple enters true dormancy mainly due to low temperature, and is not sensitive to short days and dryness. A cool winter climate is also considered necessary to end true dormancy of buds. Cold temperature hours: that is, the number of hours experienced at low temperatures below 7.2℃. The starting point for cold temperatures is 7.2℃. Now scholars in various countries mostly take 7.2℃ as the standard of accumulated hours. Apples require CH values, which vary greatly from variety to variety. With the extension of modern cultivation area to lower latitudes, the CH value of apple demand tends to decrease gradually. From 1400-3684℃ in the early period to 500-1700℃ in the recent period. 12 pruning methods of apple trees Fertilization methods of apple trees