Sunflower seed price per jin, germination time, and the reason they turn to follow the sun

The sunflower is also known as the "sun-facing flower" because its flower often faces the sun. Sunflower seeds are called kuihua zi (sunflower seeds); they are often roasted and eaten as a snack, are delicious, and can also be pressed to make sunflower seed oil for consumption. So, how much does a jin of sunflower seeds cost? How long after planting do they germinate? Why do they turn to follow the sun? According to what is known, sunflower seeds cost 10 yuan/jin, though prices vary from region to region.

How long after planting do sunflower seeds germinate?

Sunflowers need only 6-10 days to germinate at a temperature of around 25°C. Note that if the temperature is on the low side, the number of days will increase; conversely, if the temperature rises, the number of days decreases. But note that the sowing temperature can be neither lower than 20°C nor higher than 30°C.

Why do sunflowers turn to follow the sun?

1. Sunflowers contain a substance called auxin, which can make plants grow tall and large, but it is timid and afraid of sunlight. So, as soon as the auxin in the sunflower's neck sees sunlight, it runs to the shaded side to hide. But the auxin on the shaded side keeps increasing, and it prompts that side to grow especially fast, while the side facing the sun grows a bit more slowly, so the plant bends toward the side with light. As the sun moves across the sky, the plant auxin, like a game of “hide-and-seek,” keeps moving away from the sunlight.

2. When the sun rises, the east side of the dewy-green sunflower receives sunlight, causing the auxin to be distributed more on the shaded west side of the vigorously growing young stem tip. The cells on this side elongate longitudinally and grow quickly, which makes the young stem bend toward the slower-growing east side, that is, the sunflower's tip (flower head) bends east in the morning. As the sun moves across the sky, changing the direction of the light, the sunflower's tip (flower head) also keeps changing direction; when noon arrives, the sunflower is upright, and by the afternoon it bends west again. All of this is expressed as the phototropism of the stem tip bending.

3. Therefore, the plant bends toward the side with light, and as a result, the natural phenomenon occurs in which the flower head turns to follow the sun. In botany, this property is called phototropism, and because it always faces the sun, it is also called positive phototropism.

4. As the saying goes, all things grow by relying on the sun; without the sun, all plants and living things on Earth could not survive. Besides sunflowers, many plants' flowers or leaves can also grow facing the sun. Is it also because auxin is afraid of light? No. They grow toward the sun in order to get more sunlight and produce more nutrients, so that they can grow better.