The breeding of silk cotton wood can be divided into sowing and cutting. Now briefly introduce these two farming methods.
Sowing propagation
1. Seed-collecting treatment: the fruit of Tetrahedera mongolica 10 is ripe, and the best seed-collecting time is in the middle and late of 10/0. Generally, a strong mother tree with fast growth, early fruit bearing, good quality and no pests and diseases should be selected. The capsules should be dried in the sun first, then dried in the shade for 3 ~ 6 days after the peel cracks, and turned over. The seeds screened by this method have orange-red arils, which are easy to mildew and deteriorate, affecting the storage and germination of seeds. Soak in water for 3~5d, and make sure to change the water 1 ~ 2 times a day. After the aril is softened, the aril is removed by hand rubbing to obtain pure seeds, which are dried for a few days and stored in a ventilated place. In mid-February, the seeds were soaked in warm water at 30℃ for 24 hours, and then the seeds were evenly mixed with river sand at the ratio of 1∶3, and placed in the shade in layers, and covered with grass curtains for moisture retention. After the soil is thawed in mid-March, put the seeds in the leeward and sunny place, properly replenish water, raise the temperature, accelerate germination, and sow when 1/3 is exposed.
2. Generally, the flat bed is used to raise seedlings, and sandy loam with flat terrain, loose soil, good drainage and convenient irrigation conditions is selected.
3. Soil preparation and fertilization should be carried out at the end of last autumn. During soil preparation, 6000 ~ 8000 kilograms of organic fertilizer should be applied per hectare to improve the physical and chemical properties of soil and eliminate some harmful pests and diseases. Prepare the soil preparation in mid-March, make a ridge with a width of 1m, water it and rake it flat and thin.
4. Management of sowing and seedling raising: Late March to early April is the best sowing date, and early sowing is timely. Generally, the banners of silk cotton wood are wide, and ditches with a depth of 3-5 cm and a width of 6-7 cm are dug with a row spacing of 20-25 cm. Then the seeds are evenly spread into the ditch, and the covering thickness is about 1cm. Generally speaking, the sowing amount per hectare is about 120 ~ 150 kg. Emerge about 20 days after sowing. When the height of seedlings is 3 ~ 5~7cm, the spacing between seedlings should be appropriate, and the spacing between seedlings should be 5~7cm, and the soil should be loosened in time to weed. Before the true leaves grow and the seedlings grow rapidly, properly control the water and "squat the seedlings". After squatting, irrigate the seedlings for 2-3 times, and the irrigation amount depends on the rainfall. Reduce the irrigation times in the late growth period, prevent the greedy seedlings in autumn, and stop watering and fertilizing in September. Topdressing nitrogen fertilizer at the early stage of seedling growth to promote seedling growth; Applying phosphorus and potassium fertilizer in the later stage to promote the lignification of seedlings. Generally, the height of seedlings in that year is as high as 85 ~ 100 cm.
cutting
Cutting is usually carried out from late March to early April, sooner rather than later, usually before soil thawing and axillary bud germination.
1. Cuttings are collected from the dormant period from defoliation to juice outflow in spring, and branches with strong growth, full lignification and no disease are selected.
2. Storage of cuttings: cut the collected cuttings into about 15cm, choose a shady place with high terrain and good drainage, dig a ditch with a width of 1m and a depth of 60-80cm, lay wet sand with a thickness of 5cm on the bottom, bind the cut cuttings according to a certain amount and put them into the ditch in layers, and finally fill them with wet sand and cover them with soil to form a house.
3. Cutting: 6 ~ 8 days before cutting, soak the cuttings with running water until obvious irregular tumors appear at the incision, so as to improve the survival rate of cutting. After soil preparation and fertilization, first use a cutting tool to open a hole, insert cuttings along the hole, and fill the hole. Generally, the cutting depth is 2/3 of the cutting length, the row spacing is 40cm, and the plant spacing is kept at about 20cm. After insertion, water it.
4. Post-cutting management: In order to keep the soil moisture sufficient, cover the seedbed with plastic film after cutting, and seal it all around, and set up a sunshade net on it to avoid direct sunlight. Generally, rooting begins in about 3 weeks, and then the plastic film is removed in turn after rooting. At the seedling stage, it can be watered with small water to slowly penetrate into the seedbed, usually for 3 ~ 5 days 1 time. After 40 days of cutting, some quick-acting fertilizers can be applied appropriately to promote the healthy growth of seedlings. From April to September, loosen the soil and weed in time, with shallow seedlings and deep seedlings. Stop loosening the soil and weeding before the seedlings harden.
cultivation techniques
1. Water and fertilizer management
Water and fertilizer management should be strengthened in the first three years after seedling planting. From April to June, every month 1 time, and timely loosen the soil to conserve moisture. During the rainy season, the amount of water should be determined according to the rainfall. In case of heavy rain, drainage should be done in time to prevent root rot. Before the frozen soil is frozen in late autumn, the antifreeze water should be poured thoroughly, and the thawing water should be poured in time before thawing in the next spring. Water was poured once a month from April to 10 in the first two years. In the third year, in addition to timely watering antifreeze and thawing water, water 1 time every month in April, June and September. Starting from the fourth year, antifreeze water and unfrozen water are mainly poured, and natural precipitation can grow without watering.
Silkworm is a fattening tree species. When planting, enough decomposed and fermented cow and horse manure should be applied as base fertilizer. Generally, urea 1 time should be applied in mid-May, and phosphorus and potassium compound fertilizer should be applied in mid-July. Before the frozen soil in late autumn, only cow and horse manure was applied. In June of the following year, topdressing compound fertilizer 1 times, and applying farmyard manure in late autumn. After the third year, only 1 farmyard manure should be applied at the end of autumn.
Pruning and remodeling
The pruning of silk cotton trees is generally carried out from winter to early spring before germination. When pruning young trees, attention should be paid to maintaining the trunk, wiping the buds in spring and summer every year, erasing the competitive buds at the lower part, selecting 3-4 branches with vigorous growth and uniform distribution at the top of the trunk as the main branch culture, and draining the branches near the lower part in winter and spring dormancy to maintain the height of the main branch. However, it is not advisable to smear buds too much at a time, and it should be gradually sparse, so as not to affect the normal growth of seedlings. When the main branch grows to a certain length, it should be cut short to promote the growth of side branches, and when the side branches grow to a certain length, it should also be cut short to promote the growth of secondary side branches. After 3 ~ 4 years of cultivation, a basic tree shape can be formed. In the future maintenance, we should focus on removing miscellaneous branches, pests and diseases, dead branches, keeping the tree beautiful, and keeping the canopy ventilated and transparent.
3. Pest control
There are few diseases of silk cotton wood, and the main pests are Venus borer and Pieris rapae. Every spring and summer, leaves are often harmed by these two pests.
Venus foot moth is distributed in most parts of China, and can reproduce three generations a year in North China. It overwinters in the soil as a pupa, and its eggs are very large. Adults have phototaxis, and larvae have suspended animation. In the usual cultivation management, we should combine the cultivation measures such as shaping, thinning branches, cutting branches with eggs, strengthening loosening soil, fertilizing and spraying protective agents to improve the growth environment of silk cotton trees. Silkworms are very sensitive to chemical pesticides. In larval stage, 500 times Bt emulsion or 7000 times 25% diflubenzuron suspension can be used to control larvae. You can also install a black light to trap and kill adults and manually remove egg pieces.
Spodoptera brassicae is distributed in most parts of China, with 2 ~ 3 generations in North China every year. Overwintering in the soil with pupae, it has the habit of lying in the daytime and coming out at night, and has strong phototaxis. Spring and autumn are periods of serious harm. If it happens, adults can be lured to death by black light and sweet and sour liquid, and 500 times Bt emulsion can be used to prevent and control larvae.