What are the requirements of Ginkgo biloba for climatic conditions?
Ginkgo biloba is native to temperate and subtropical regions and is most suitable for growing in temperate and subtropical temperature conditions.
At present, the northernmost border of Ginkgo biloba distribution in China is Shenyang, Liaoning Province. The annual average temperature in Shenyang is 7.3℃, and the absolute minimum temperature is -32.9℃. Due to the low temperature, there is a phenomenon of freezing tip every year. In Dandong City, Liaoning Province, although Ginkgo biloba is rarely damaged by freezing, its high growth is obviously inhibited. For trees aged 50-60, the height of the tree shall not exceed15.0m.. The trunk is thick under the tree, thin on the tree and has a large taper. The southernmost boundary of Ginkgo biloba distribution in China is Guangzhou City, Guangdong Province, with an annual average temperature of 265,438 0.7℃. Because of the high temperature there, the growth and fruit of ginkgo biloba are also inhibited. In Qinghui Garden, daliang town, Shunde, south of Guangzhou, there is a ginkgo tree 120 years old, with a height of only 9.0m and a DBH of 68cm. However, the century-old ginkgo tree growing in the most suitable climate conditions can reach more than 24 meters in height and 100 cm in diameter at breast height.
The existing wild ginkgo reserves in China include West Tianmu Mountain in Zhejiang, Dabie Mountain in Henan, Shennongjia National Nature Reserve in Hubei, and mountainous areas in Guizhou. The annual average temperature in these areas is between 15 ~ 17℃, the absolute minimum temperature is generally not lower than -20.0℃, and the absolute maximum temperature is generally lower than 35℃. Under such temperature conditions, Ginkgo biloba shows the best growth state. Specifically, the trunk is tall and straight, the taper is small, the height of the tree can reach or exceed 30 meters, and the plants can germinate and renew repeatedly. In the vigorous growth period, the average annual growth of DBH can reach 1-2 cm.
From the central producing area to the north or south, the temperature is high and low, and the vegetative growth of Ginkgo biloba is partially inhibited, but it is beneficial to the formation of flower buds and flowering and fruiting. Here, the extreme maximum temperature and the extreme minimum temperature will not cause harm to the body. Therefore, ginkgo biloba in these areas often has the characteristics of early flowering and fruiting and high yield of dried fruits, making these areas a potential high-yield producing area of dried ginkgo biloba.
The observation of ginkgo phenology showed that ginkgo began to germinate when the temperature rose above 8℃, sprouted branches and leaves above 65438 02℃, and blossomed above 65438 05℃. In 10 cm soil layer, when the local temperature reaches 6℃, the roots of Ginkgo biloba begin to move. In 25 cm soil layer, when the ground temperature 15- 18℃, the root system is developed; When the local temperature is higher than 23℃, the root growth will be inhibited again.
Ginkgo biloba, which enters the dormant period, has strong cold resistance. Even in Shenyang, the short-term low temperature of -32.9℃ will not freeze its branches to death. Once the bud of Ginkgo biloba leaves germinates, even if the low temperature of-1-2℃ appears for a short time, it will cause serious freezing damage to its young branches and leaves. The newly sprouted leaves will all die, and sometimes even spread to last year's branches. Therefore, severe late frost weather is extremely unfavorable to the normal growth and fruit of Ginkgo biloba. In the north of China, especially in the northwest, due to the continuous invasion of Siberian cold wave, serious late frost often occurs, which is also an important reason why Ginkgo biloba is difficult to advance northward, especially to the northwest. Just because of the high temperature and the late germination of Ginkgo biloba, especially the regulating effect of the sea in coastal areas on the climate, the northern boundary of Ginkgo biloba distribution has been extended to Shenyang, Liaoning Province, which is one of the coastal provinces above 42 degrees north latitude in China.
In Ruyuan County, Guangdong Province, the annual average temperature is 19.8℃, the lowest temperature is 4-9℃, and the highest temperature is 36℃, which is also suitable for the growth of Ginkgo biloba. The ginkgo here, even in winter, retains some leaves. Under this ecological condition, Ginkgo biloba has become a semi-evergreen plant.
(2) Precipitation
Ginkgo biloba needs a humid environment, so precipitation also plays an important role in limiting the distribution, growth and fruiting of Ginkgo biloba.
At present, the driest place of ginkgo trees in China is Lanzhou, Gansu, with an average annual precipitation of 328 mm, followed by Zhangjiakou, Hebei, with an average annual precipitation of 360 mm, and Wubao, Shaanxi, with an average annual precipitation of 475 mm. Ginkgo trees in these places grow in gardens and generally have good irrigation conditions.
Basically, plants can grow normally without irrigation, and the areas that can bear normal fruits in general years are Beijing, Jinan and other places. The annual precipitation in Beijing is 644 mm, and that in Jinan is 685 mm These areas have loose soil and abundant groundwater. Ginkgo biloba planted here has developed roots and deep straight roots, and can blossom and bear fruit normally even without irrigation.
The precipitation in the original center of Ginkgo biloba is generally above 800 mm In mountainous areas, due to the influence of topography, the precipitation in the growth area of Ginkgo biloba can even exceed1500 mm. Ginkgo biloba in these areas grows vigorously and can blossom and bear fruit normally. As long as the soil is loose and the drainage is good, even if the precipitation greatly exceeds 1500mm, it will not endanger the growth of Ginkgo biloba.
The annual precipitation in Guangzhou and other places is as high as 1600 mm or more. High temperature, combined with too much rain, especially in continuous rainy weather, ginkgo trees growing on red loam with poor drainage are often damaged by too much water retention in the soil, resulting in yellow leaves, dead branches and even death.
It can be seen that Ginkgo biloba is most suitable for growing in vast areas with precipitation above 800 mm and below1500 mm. Of course, Ginkgo biloba can also be planted in arid areas with irrigation conditions and rainy areas with good drainage.
Because Ginkgo biloba has different water requirements in different growth and development stages, the distribution of precipitation sometimes seriously affects the normal growth and fruit of plants. It is rainy in the growing season, especially in the period of rapid seed expansion, which can obviously improve the quality of ginkgo seeds, ensure the normal differentiation of flower buds, and make them bear normal fruits in the next year.
From 65438 to 0986, the vast ginkgo producing areas in China suffered from a rare drought in history. From the end of July to the beginning of September, it was hot and rainy. At this time, it is the rapid expansion stage of ginkgo seeds, which seriously affects the yield and quality of ginkgo in that year. Take Wuxian County, Jiangsu Province as an example. From late July to early September of 1986, the total precipitation is only 105.0mm, which is only 30% of the annual precipitation. At the beginning of August, when it was hot and dry, the precipitation was zero. This makes the output of first-class ginkgo with less than 360 capsules per kilogram in that year drop from about 90% in the previous year to 20%-30%, and the output in the second year also drops to about 80% in the previous year. In the same year and the same place, some fruit farmers strengthened management and insisted on watering and fertilizing during the drought, which not only maintained the original level of seeds in that year, but also achieved high yield in the next year. It can be seen that choosing the climate type with more precipitation during the rapid development of ginkgo seeds as the new production base of ginkgo dried fruits is beneficial to the production of high-quality ginkgo fruits.
Air humidity is another humidity factor closely related to precipitation. Too dry climate will cause ginkgo biloba to dehydrate rapidly and excessively, and even the branches and leaves will dry up and die. This is the more important reason why Ginkgo biloba is difficult to expand to the arid northwest.
Normal pollination of Ginkgo biloba requires sunny and mild weather. Rainy flowering period will make it difficult for pollen to fly away, thus affecting pollination and fruiting. On the one hand, it will reduce the dry fruit yield of Ginkgo biloba, which is not conducive to the fruit production of Ginkgo biloba, but on the other hand, it is conducive to the growth of Ginkgo biloba plants. People can make use of this to create a fast-growing and high-yield ginkgo timber forest.
(3) Lighting
Ginkgo biloba is slightly resistant to germination in its infancy, and it needs sufficient light after entering the fruiting period, which is also a necessary condition to ensure the normal fruiting of Ginkgo biloba plants.
According to the actual measurement of Shandong Agricultural University 1987, it is found that the light saturation point and light compensation point of Ginkgo biloba are related to the specific conditions of the plant, such as variety, age and growth status. Above the light compensation point and below the light saturation point, the photosynthetic efficiency increases with the increase of light intensity.
In Taian City, Shandong Province, the photosynthetic intensity of Ginkgo biloba increased with the increase of light intensity and temperature in a day. During the four hours from 9: 00 a.m. to 1 p.m., the light intensity remained relatively stable. At 3 pm, photosynthesis can reach the highest value of the day, and then gradually decrease. Here, photosynthesis shows a smooth unimodal curve.
In southern China, during the high temperature in summer, the light intensity at noon can exceed 50,000 lux. Too high temperature and too strong light will inhibit the normal progress of photosynthesis. With the decrease of light intensity, after noon, the photosynthesis of plants will have a second peak. In those places, the photosynthetic intensity of ginkgo biloba is generally bimodal.