In which month is the sweet potato (sweet potato) of "Convolvulaceae" growing seedlings? What are the methods of raising seedlings? When can sweet potato seedlings be planted?

Seedling cultivation is the basic work of sweet potato planting, and it also plays a very important role in the quality and yield of sweet potato in the future. So, when do sweet potatoes usually grow seedlings? What are the methods of raising sweet potato seedlings?

Time for raising sweet potato seedlings

All sweet potato seeds should be bred from mid-February to mid-April.

Sweet potato seedling breeding is the most important link in sweet potato production. Due to the low temperature in early spring in the northern potato area of the Huang-Huai River Basin in China, potato farmers have created many local seedling breeding methods and seedbed forms. In a short period of time, a large number of potato seedlings were cultivated with fewer potato species for production and application. If you raise seedlings at the right time, you can plant them in the field without losing the opportunity. By raising sufficient and strong seedlings, we can avoid "spring potato planting in summer" and "summer potato planting in autumn", and achieve the goal of high yield. In the potato areas south of the Yangtze River, because of the favorable climatic conditions, the application of seedling means and techniques is much simpler.

The time of breeding potato seedlings should be linked up with the time of planting in the field, and it is not good to be too early and too late. Planting too early, because of the cold weather and difficult heat preservation, the seedling period is prolonged, manpower is consumed, and fuel is wasted. Moreover, after potato seedlings are raised, they cannot be planted in the field because of low temperature, resulting in the phenomenon of "seedlings and other places", which will not only prolong the seedling age, but also reduce the quality of potato seedlings. As the seedlings that have been bred can not be collected in time, it will inevitably affect the growth of the following seedlings. If the planting is too late and the seedlings emerge late, the seedlings will not be able to catch up with the need of timely planting, which will lead to the situation of "waiting for seedlings" and eventually reducing the yield of late planting. Where seedlings are raised with hot kangs or hotbeds, it is generally controlled to plant seeds 25-30 days before the appropriate time for planting. For example, the planting time of spring potato in Shandong Province mostly begins at the end of April, and the seedling stage is suitable at the end of March or early April. Those who have a lot of experience in raising seedlings can also postpone a few days appropriately to shorten the time of raising seedlings and save investment. The summer potato in the north is planted in the middle and late June. If the summer potato seedlings are propagated in the nursery, the first and third stubble seedlings bred in the hot Kang or hotbed are cut into the nursery; the spring in the Yangtze River basin is relatively warm, and the seedlings are planted in the hotbed in early March, and the open field seedling raising period usually begins in early April. In the summer 'autumn potato area and autumn and winter potato area in the south, the seed metering period for raising seedlings with potato blocks is in the middle of February.

Preparation of sweet potato seed

Although the work of raising sweet potato seedlings is carried out in spring, the preparatory work must be done well in advance. First of all, it is necessary to implement the planting area of spring and summer potatoes. The amount of seed used per mu varies with the method and time of raising seedlings. If the method of raising seedlings by heating is adopted, the amount of seed used per mu is generally not less than 75kg. Those who do not plant spring potatoes in summer and autumn should first plant a good nursery, and 1 mu of nursery can be used for more than 10 mu of summer potato seedlings. In order to save the area of seed potato and seedling bed and cultivate strong seedlings, each standard bed (5 meters long and 1.7 meters wide) is about 150 kg. That is, about 17,18kg of seed potatoes per square meter. The seedbed in the open field can be thinner. According to the planting area, the number of seed potatoes, the number of seedling beds or the materials needed for breeding land and bed construction, such as plastic film, grass grass, fuel, brewing heat and other appliances, etc.

The second is to choose the land of seedbed. The suitable conditions are leeward to the sun, high terrain, good drainage, close to the water source, and convenient management. Open field nursery or nursery selection of fertile soil, no salinity, at least two years have not planted sweet potatoes and made a seedling bed, such as the seedling bed is permanent, before use should be strictly sterilized, bed soil renewal, to avoid the spread of disease.

Sweet potato seedling raising mode

Sweet potato producing areas in China are all over the north and south, with different natural conditions, seedling raising methods and seedling bed patterns. It can be divided into four categories.

1. Open-field type: make use of local natural conditions and do not need special equipment and management. Commonly used are land border (sunny border), small high ridges and so on.

2, heating type: according to local conditions, use local materials, build a certain specification of heating seedbed, use firewood or coal as fuel to heat up the seedbed temperature, such as Huilong fire Kang, Sandaogou, Dunshuidon fire Kang, one fire multi-Kang and so on. Some are also heated by electric heating. Heating seedbeds are commonly used in northern areas where the temperature is low in early spring.

3. Heating type: using the heat produced by plant straw, livestock fresh dung and fallen leaves in the process of accumulation and fermentation to raise the bed temperature to raise seedlings. This method has a wide adaptability, as long as there are conditions and needs, it is more suitable for all places.

4. Film mulching: such as single film mulching, double film mulching and plastic film mulching, can accelerate the growth of potato seedlings and save energy. In addition, there are also the use of geothermal, hot springs, solar energy and other seedlings, are practical and effective good methods.

The advantages of raising seedlings with sweet potato plastic film are:

① increases the temperature of the seedbed: the microclimate in the film is more than 15 degrees Celsius higher than the temperature in the open field. Under the sunlight, the temperature of the seedling bed can be raised to more than 50 degrees Celsius. The soil temperature of the bed is 50.7 degrees Celsius higher than that of the open field. A lot of heat-making materials or fuel can be saved. The space temperature in the film is too high, which is disadvantageous to the growth of potato seedlings, so ventilation, sprouting and watering should be adopted. Increasing the moisture of bed soil can effectively maintain humidity, improve soil heat capacity and thermal conductivity, and thus increase soil temperature.

② retains moisture: the film is impervious and hydrophobic, and the water in the soil evaporates continuously through high temperature and sunlight, so that the water condenses on the film, resulting in water reflux and dripping onto the bed. According to the measurement, the reflux of water per square meter can reach 1.5 liters in one day, which plays a significant role in maintaining the moisture of bed soil and reducing evaporation. After 35 days of mulching, the soil moisture in the 2-5 cm soil layer under the bed increased, while the soil moisture in 5-10 cm and 10-15 cm layers decreased by 2.6% respectively. The same soil layer without film decreased by 13.2% and 23.5% and 14.6% and 35.5%, respectively. The dewdrops condensed on the film and the fog in the space in the bed will affect the transmittance. When the temperature in the bed is low, the method of frequently slapping the film can be used to shake off the water droplets, increase the light transmittance and improve the bed temperature. If the temperature is too high, the dew on the film can reduce the intensity of sunlight and protect the potato seedlings from being burned.

③ germinates quickly and produces a lot of seedlings: the use of film mulching increases the bed temperature and maintains humidity, which is very conducive to potato germination and seedling growth. To raise seedlings in the open field, the seedlings covered with film emerged 12-16 days earlier than those without mulch, and the number of seedlings increased by 24-35%, and seedlings could be collected 13-23 days in advance.

Planting time of sweet potato

The planting season and time of the corresponding sweet potato seedlings:

Spring sweet potato: from late March to early April.

Autumn sweet potato: around the middle and late August.

Winter sweet potato: around the first and middle of October.

The suitable time for transplanting seedlings is in the middle of April, when the temperature in early spring is basically stable, and the suitable time for planting seedlings is when the ground temperature of 10 cm is more than 15 ℃ after the end of late frost, ploughing and tanning early last winter or the beginning of the year, and then set up ridges when planting. The border belt is wide 50cm. In the first and middle of April, the seedlings were cut and planted according to the emergence speed of the seedling bed, and the line horizontal insertion method was adopted to increase the number of potato seedlings into the soil to increase the number of tubers. There are 3000 trees per mu, which is about the distance from 33cm.

The growth period of sweet potato

The growth period of spring potato is 160-200 days, and that of summer potato is about 110-120 days. According to the growth characteristics of sweet potato in the field and its relationship with climatic conditions, it can be divided into three growth periods:

(1) Prophase (from planting seedlings to sealing pots). Spring potato lasts about 60-70 days, summer potato about 40 days. In this period, the growth of stems and leaves is slow, and the root system develops rapidly, which is mainly the period of growing fiber roots.

(2) in the middle stage (from sealing basin to the peak of stem and leaf growth). It takes about 50 days for spring potatoes and 30 days for summer potatoes. In this period, the root expands slowly, and the stem and leaf grow fast, which is mainly the period of growing stem and leaf.

(3) the later stage (from the decline of stems and leaves to harvest). Spring potato is after late August and summer potato is after early September. This period is the main period of root expansion.

Time: 2019-03-19 Click: