Sunflower sunrise reason:
1. Sunflower faces the sun from germination to disk flowering. During the day, its leaves and disk follow the sun from east to west, but not immediately. Botanists have measured that its disk direction is about 12 degrees behind the sun, which is 48 minutes. After the sun goes down, the sunflower tray slowly swings back, facing east at about 3 am, waiting for the sun to rise.
Under the irradiation of sunlight, the auxin content on the back of sunflower increases, which stimulates the cells on the back to elongate and rotate towards the sun. After the sun goes down, auxin is redistributed, which makes sunflower turn to the east again.
2. After the disc is in full bloom, it no longer turns to the sun, but is fixed in the east. Sunflower pollen is afraid of high temperature. If the temperature is higher than 30℃, it will be burned. So you can avoid direct sunlight at noon and reduce radiation. When the disk is exposed to sunlight in the morning, it helps to dry the dew condensed at night and reduce the possibility of being attacked by mold; In addition, the temperature is low in the morning, and the sunlight makes the sunflower tray a warm nest, which can attract insects to help pollinate.
Extended data:
New Discovery of Sunflower Sunward Orientation in China
Scholars in the late Ming and early Qing dynasties are recording sunflowers? At that time, they also specifically mentioned its Japanese orientation. 1688 published "Flower Mirror" in more detail: "Sunflower, a sunflower. One or two feet tall, with leaves larger than hollyhocks, narrow tips and many notches. Flowers bloom in June, and there is only one flower on the top of each pole. The yellow flower has a big heart. It is shaped like a plate. As the sun rotates, if the sun rises, the flowers face east, the flowers go straight up at noon, and the flowers face west when the sun goes down. "
China's original sunflower refers to sunflower, which is also Japanese. Poets in the Tang and Song Dynasties have repeatedly recited, such as Du Fu's poem: "Sunflowers depend on the sun, but their physical properties are hard to take away." Mei's poem "Sunflower" said: "This heart was not born with the rising sun, but it is willing to believe that many grasses can drown it." Liu Kezhuang's poem "Kwai" says: "The ancient walls are shaded, the gardens are barren and the vegetation is deep. Have you ever been exposed to rain and dew and never changed your heart? " It can be seen that "sunflower" has been closely linked with "Xiangyang" since ancient times.
References:
Baidu encyclopedia-sunflower