Planting method of Chinese yam

The efficacy of yam yam, also known as yam, is a perennial twining herb. Chinese medicine believes that yam has many functions, such as invigorating spleen and lung, consolidating kidney and replenishing essence. As a nutritious food, Chinese yam contains a lot of starch, protein, vitamins, glucose, crude protein amino acids, choline and allantoin. Among them, yam soap, an important nutritional component, is the precursor of synthesizing female hormones, which has the functions of nourishing yin and strengthening yang and enhancing metabolism; Mucus and digestive enzymes contained in fresh tubers can prevent cardiovascular fat deposition and contribute to gastrointestinal digestion and absorption.

The planting method of Chinese yam has a good market prospect because of its high economic value. In recent years, vegetable cultivation has attracted the attention of farmers. The main cultivation techniques of yam are summarized as follows.

1. Biological characteristics of Chinese yam

Yam likes warm and humid, and avoids water and drought. Suitable for planting on sandy loam with rich and loose soil layer and good drainage. The stems and leaves like high temperature, dryness and frost, and the optimum temperature for growth is 25-28℃. Tubers are extremely drought-tolerant, so sandy loam with good drainage and high fertility should be selected. Clay tends to make tubers have many whiskers, large roots, irregular shapes and easy to have flat forks. Yam likes organic fertilizer, but the manure must be fully decomposed and mixed evenly with the soil, otherwise the tender tissue at the tip of the tuber will be bifurcated or even necrotic due to dehydration once it comes into contact with raw manure or dung. Nitrogen fertilizer should be supplied in the early stage of growth, which is beneficial to the growth of stems and leaves; In the middle and late growth stage, nitrogen fertilizer should be properly supplied to keep the stems and leaves from fading, and phosphorus and potassium fertilizer should be applied to facilitate tuber expansion. After emergence, the tuber does not need much water in the early growth stage, which is beneficial to the formation of deep soil layer and tuber, and the tuber can not be short of water in the peak growth period.

Second, the growth process

Yam can be divided into the following four periods from bud germination to tuber harvest:

1. Germination period: it takes about 35 days for yam seeds to germinate and 50 days for yam segments. The shoots are pulled up from the top of the buds, and the tubers are pulled out from the bottom of the buds. When the tuber grows to 1 to 3 cm, the bud will break through the ground.

2. Shoot-drying period: This period lasts for 60 days, and the growth is mainly stem and leaf, with little tuber growth.

3. The peak period of tuber growth: from budding to stem and leaf growth is basically stable, which takes about 60 days. During this period, stem and leaf growth and tuber growth are extremely vigorous, but the growth center is in tuber.

4. Dormancy period: The stems and leaves decline due to frost, and the tubers enter dormancy period.

Third, cultivation techniques.

1, the cultivation season of yam

Planting begins in early spring before the final frost and ends in late autumn, early winter and early frost.

2. Sowing materials

The main sowing materials of yam are: yam seeds, Duan Zi and Lai Ji. The original origin of yam comes from goodness. In the autumn of the first year, large-scale storage of Liangji was selected for the winter; In the following spring, drill in the open field half a month before the frost, or sow after the seedbed germinates. Yam tubers are easy to produce adventitious buds and can be cut into pieces for propagation. Most flat seeds can only germinate at the stem tip of tuber, so longitudinal cutting method is adopted when cutting into pieces, and the weight of cutting into pieces is about 100g. Any part of the long cylindrical seed block can germinate and propagate according to the length of 10- 15 cm, which is called yam segment. There is a hidden bud at the top of the long column seed block, so this section is often intercepted for seed use, commonly known as yam seed.

3. Soil preparation, soil preparation and sowing

When the tuber of yam grows deep under the soil, it should be turned deep or ditched on the spot. In rotation, the ditching distance 1 m, the width of 25 cm and the depth of 0.5- 1 m vary with varieties. Intercropping is ditching according to 2-3 meters. It is best to plow the ditch soil before winter, and turn the soil into the ditch in early spring with the thawing of the soil. Finally, make a border according to the width of 1 m for planting. The sowing method is: generally, single row drilling is adopted, a deep ditch of 10 cm is opened in the center of the border, and then yam seeds or segments are put into the ditch according to the plant spacing of 15-20 cm, and covered with 8- 10 cm.

4. Tian Tuan management

(1) sparse seedlings

When several seedlings are cut into pieces or segments, weak seedlings should be thinned as soon as possible, and 1~2 strong seedlings should be left. The lateral branches at the base of the main stem hinder ventilation and light transmission and should be removed. In order to avoid excessive consumption of nutrients during the formation of a large number of Reiyoshi, a part can be removed as soon as possible.

(2) Fertilization

After sowing, the base fertilizer can be applied before the shed is set up, with the available nitrogen fertilizer. Topdressing 1 ~ 2 times at the time of emergence to ensure the need of emergence. When buds appear, stems, leaves and tubers begin to grow vigorously, and NPK compound fertilizer should be applied again.

(3) intertillage weeding

Combined with topdressing and watering, the intertillage should be shallow, and weeds near the plants should be pulled out by hand to avoid damaging the roots.

4. Water

Keep the soil moist during the tuber vigorous growth period. Yam is a drought-tolerant crop, but it should be watered properly if it is to produce high yield. Generally, before and after 1 topdressing, if the soil turns white after a long drought, it should be lightly watered 1-2 times until the soil surface is wet. At the turn of summer and autumn, if the dry and hot weather lasts for more than 1 week, cold water should be poured in the morning to fight drought: yam is afraid of waterlogging, and the ditch should be cleared and drained in time in rainy season to ensure that there is no water in the field.

(5) Pest control

① Anthracnose: Yellow spots appeared on the leaves of Dioscorea opposita in the early stage of anthracnose, then expanded into irregular spots with brown edges and scattered small black spots in the center, and some spots were perforated in the later stage. Umbilical spores and conidia of pathogenic bacteria overwinter on diseased leaves, and the disease is serious from June to August, and plants often wither and fall leaves. Prevention and control methods: when harvesting in winter, remove the residual leaves of diseased plants, and open the drainage ditch at ordinary times to reduce the humidity in the field. It can be protected by spraying 1: 1: 100 bordeaux solution before onset, and 50{bf} thiophanate methyl 1000 times solution can be sprayed at the initial stage of onset.

② Brown spot disease: The brown spot disease of yam, also known as "dead leaf disease", is an important disease of yam. At the early stage of the disease, yellow or yellow-white lesions with inconspicuous edges are produced on the lower leaves, and the periphery of the lesions turns brown in the later stage, and the central part is light brown with scattered black particles, sometimes broken and perforated. A large number of diseased spots will turn the whole leaf brown and die. It overwinters with mycelium or sessile fungi attached to the affected area, and forms spores after the spring of the following year, which spread with the wind and rain. Generally, the disease begins in the middle and late July, and it is seriously harmful in August, and it is easy to get sick under wet and rainy conditions. Control method: implement crop rotation. Clean the countryside and eliminate the source of wintering bacteria. Cut off the diseased leaves immediately after the onset of the disease, and then spray 65{bf} zineb and/kloc-0 every 7 days for 2~3 times continuously, which can achieve certain control effect.

③ grubs: during the growth period of yam tuber, they often bite the tuber. After being killed, the tuber didn't grow much, and it turned yellow-brown after being scraped. The cooking is not bad, the taste is bitter, the drying is hard and the quality is worse. Prevention and control methods: 30kg tea seed cake can be sprinkled per mu during soil preparation, and if wax damage occurs during the growth period, it can be poisoned by 1000 times of 90{bf} trichlorfon concentrate.

④ Red spider: Adult mites often gather on the back of leaves to suck juice, which makes the leaves turn from green to yellow and finally fall off, leading to early plant atrophy. Control method: Spraying 25{bf} of Komeiling 1500~2000 times at the initial stage of the disease, and spraying 35{bf} acaricide 1200 times/KLOC-0 times after five days can kill eggs and mites.