Traditional Culture Encyclopedia - Weather inquiry - Is the climate in Shaoyang, Hunan suitable for planting sunflowers on a large scale?
Is the climate in Shaoyang, Hunan suitable for planting sunflowers on a large scale?
key property
(1) growth period and growth period
The growth period of sunflower refers to the days from emergence to seed maturity, which is generally more than 85~ 120 days. The length of growth period varies with varieties, sowing dates and cultivation conditions. The whole growth period of sunflower is divided into four growth periods: seedling stage, budding stage, flowering stage and mature stage.
1. The seedling stage from emergence to bud is called seedling stage. Generally, it takes 35 to 50 days, and sowing in summer takes 28 to 35 days. This period is the stage of leaf and flower primordium formation and floret differentiation. At this stage, the aboveground growth is slow, the underground root system grows rapidly, and a strong root system is quickly formed, which is the stage with the strongest drought resistance of sunflower.
2. A star-shaped body with a diameter of 1 cm appeared at the top of sunflower bud stage, commonly known as budding. It generally takes about 20 days from germination to flowering, which is the period of vegetative growth and reproductive growth, and also the most vigorous stage in life. During this period, sunflower needs fertilizer and water most, accounting for about 40%~50% of the total fertilizer and water demand. If the demand for water and fertilizer cannot be met in time during this period, the output will be seriously affected.
3. At flowering stage, 75% of plant tongue-shaped flowers open in the field, that is, they enter flowering stage. It usually takes 6-9 days for the disk to be put into the tubular flower from the tongue-shaped bloom. The flowering period of this inflorescence is from the second day to the fifth day. The number of flowers in these four days accounts for about 75% of the total. Most flowers bloom at 4-6 am and pollinate and fertilize the next morning. The unfertilized branches can keep 7~ 10 days without wilting. The self-pollination seed setting rate of sunflower is very low, only about 3%; Cross pollination has a high seed setting rate. However, if the temperature is high, the rain is heavy, the humidity is high, the light is insufficient, and the soil is dry, the seed setting rate will be greatly reduced; Therefore, adjusting sowing date, timely fertilizing and watering, controlling pests and diseases, and adopting measures such as releasing bees or artificial pollination can improve the seed setting rate.
4. From flowering to maturity, sowing in spring for 25-55 days and sowing in summer for 25-40 days. There are differences among different varieties. The seed formation period is about 15 days after flowering and pollination. It requires clear weather, large temperature difference between day and night, and suitable soil humidity.
(b) Relationship between growth and environmental conditions
1. temperature Sunflower is native to tropical areas, but it has strong adaptability to temperature, and it is a kind of crop that likes temperature and is cold-resistant. Sunflower seeds have strong low temperature tolerance and stable local temperature. When the temperature is higher than 2℃, the seeds begin to germinate. Seeds can germinate and take root at 4~5℃; When the local temperature reaches 8~ 10℃, it can meet the needs of seed germination and emergence. The optimum temperature for germination is 3 1~37℃, and the highest temperature is 38~44℃. As long as the temperature of sunflower is not lower than 10℃, the whole growth process can grow normally. In a suitable temperature range, the higher the temperature, the faster the development.
2. Water sunflower is a tall plant with many dense leaves, and it is a crop that consumes more water. Its water absorption is 1.74 times that of corn. However, because its growth and development are mostly synchronized with local rain and heat, the contradiction between supply and demand of water resources is not prominent. There are great differences in water requirements of sunflower in different growth stages. From sowing to budding, it is relatively drought-resistant and requires less water, which is only 1.9% of the total water demand. However, proper drought is beneficial to root growth and drought resistance. The peak of water demand is from bud stage to flowering stage, which accounts for about 43% of the total water demand. The lack of water in this period has a great influence on the output. This stage coincides with more rainfall, which can basically meet the water demand of sunflower growth and development. If it is too dry, it needs to be supplemented by irrigation. The water demand from flowering to maturity is also more, accounting for about 38% of the total water demand. If the water is insufficient, it will not only affect the output, but also reduce the oil content.
Sunflower is a short-day crop. But it is not very sensitive to sunlight. Under the sunshine condition in Tianjin, it can blossom and mature normally without special treatment. Sunflowers like plenty of sunshine, and their seedlings, leaves and discs have strong phototropism. Adequate sunshine and strong seedlings can prevent futile growth; Adequate sunshine in the middle growth stage can promote the vigorous growth of stems and leaves, normal flowering and pollination, and improve the seed setting rate; In the late growth stage, the sun is full and the seeds are full.
4. Soil Sunflowers have low requirements for soil, and all kinds of soil can grow, from fertile soil to dry land, wasteland and saline-alkali land. Strong salt and alkali tolerance.
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