What crops are suitable for planting under trees? Prospects and techniques for understory planting

When carrying out landscape construction, planting and breeding under the forest has also been a relatively popular management method in recent years, because the tree planting density is not high, and the open space under the forest can be fully utilized for interplanting other crops. Sowhat crops are suitable for planting under trees? What are the prospects for understory planting?

I. What crops are suitable for planting under trees

1. Wild yam

(1) Propagation methods

Wild yam can be propagated by bulbils or tubers. The propagation of wild yam is closely related to dormancy. Yam tubers or bulbils that have not undergone sufficient dormancy cannot be used for propagation; even if sown, they will not sprout. In wild yam propagation, cultivation using bulbils is still rare, because propagation with bulbils generally takes 2 years. In the first year, seed tubers of 0.03-0.1 kg are first cultivated, and only after sowing in the second year can large yams be formed. Although propagation by bulbils takes a relatively long time, it can prevent degeneration and ensure high quality and high grade. Whether tubers or bulbils are used as seed tubers, yams with reddish-brown skin and pure white flesh must be selected as seed tubers.

(2) Planting time and methods

In the early growth stage of wild yam, it mainly relies on the nutrients stored in the seed tubers for sprouting, rooting and leaf growth. The soil temperature required for sowing wild yam is 10-12°C. For planting, the traditional planting method is used: dig a shallow furrow 8-10 cm deep with a hoe, place the bulbils longitudinally and flat in the furrow, spread the bulbils evenly at intervals of 20-25 cm, or the interval can be appropriately reduced, with the minimum interval being 5 cm, then cover with soil, fill level and press lightly. If conditions permit, base fertilizer can be applied into the soil layer. During planting, care must be taken to remove stones mixed in the soil, otherwise the wild yam tubers will branch severely, the root shape will be unattractive, and commercial quality will be reduced.

(3) Post-planting management

After wild yam seedlings emerge, the stems grow extremely rapidly, reaching 30-50 cm within 7-10 days, and then they begin to grow leaves. Wild yam stems are small, slender, crisp and tender. Trellising to guide the vines is an essential management task. Using trees as trellises to guide the vines is very firm, simple and labor-saving, and also reduces input. In forestland, the soil is fertile and moist, and there are basically no weeds, so generally no fertilization, watering or hoeing is needed during management. Wild yam is a drought-tolerant crop and fears waterlogging. In rainy seasons, ditches should be cleared and drainage carried out in time so that there is no standing water at the roots of the wild yam.

(4) Harvesting

By the end of October or early November, the aboveground part of the wild yam turns yellow and dies, and harvesting can begin. However, in order to meet the needs of the off-season market, wild yam can also be harvested in the middle of the peak growth period. Although the tubers harvested at this time have not fully grown, the selling price is relatively high, and the economic benefit is still good. When harvesting wild yam, dig in sequence one after another. This can effectively reduce the damage rate and avoid missing any. When digging, be as careful as possible not to damage the tree roots.

2. Gastrodia elata

(1) Site selection

The site for cultivating Gastrodia elata should be selected in soil areas with good drainage, loose soil and sandy texture. Broad-leaved sparse forestland, bamboo forest, and burned secondary wasteland on east-facing and south-facing slopes above 800 m elevation are preferable; north-facing slopes are not suitable.

(2) Cultivation of fungal wood

Fungal wood is log segments fully covered with Armillaria mellea. In new areas, old fungal wood should be used to cultivate new fungal wood. The method is to dig a pit trench 30-40 cm deep, 150-180 cm wide, and 200-300 cm or longer, line it with 5-10 cm of fine sandy soil, then place new wood and old wood in layers on top, fill the gaps with dead branches and fallen leaves, place old and new wood in alternating layers for 4 layers, and after placing the new wood cover with 10-15 cm of sandy soil. Cultivating fungal wood begins in August-September and is completed in November, for winter planting of Gastrodia elata.

(3) Selection of seed tubers

In production, long tubers 4-8 cm in size are selected as seed tubers. Degenerated tubers that become smaller year by year are not suitable for selection as seed tubers. For cultivating Gastrodia elata, the best fungal wood tree species are hard miscellaneous woods such as red cork oak, sharp-toothed oak, five-point maple, elm and black locust. Other tree species such as cotoneaster and mountain peach, also hard miscellaneous woods, can also be used.

(4) Planting

In production, the tuber propagation method is mainly used, as follows.

Digging the pit: Dig a pit trench 150 cm wide, 30-40 cm deep, and 200 cm or longer, spread 5-10 cm of fine sand or fine soil at the bottom, and dig drainage ditches around the pit for later use.

Sowing: On the soil layer lining the bottom of the pit, place 1-2 cm of dead branches and fallen leaves, then place 1 layer of new wood. The new wood is 100-120 cm long. Use a knife or axe to cut slanted incisions into the fungal sticks to open infection points, called “flowering”. After the new wood is arranged, place another layer of new wood and fungal wood, arranged alternately with the ends exposed, fill the spaces with a mixture of dead branches, fallen leaves and sandy soil, take seed tubers and place them tightly against the edges of the fungal wood, with 4 seed tubers attached to each piece of fungal wood, cover with a 0.5 cm layer of a mixture of dead branches, fallen leaves, sand and soil, place all new wood on the topmost layer, and then plant Gastrodia elata again.

Artificial pollination: Gastrodia elata is pollinated by insects, and arrow tubers often receive insufficient pollination. Artificial pollination is a key technique in Gastrodia elata cultivation. Within the 5-15 d flowering period of Gastrodia elata, pollen mostly matures between 9 a.m. and 2 p.m. on the second day after flowering. When the pollinium becomes soft and swollen, the anther cap is slightly lifted, and pollen is slightly visible at the edge of the anther cap, this indicates that the pollen has matured. Use the left hand to hold the newly opened flower, and with the right hand use small tweezers to reach into the flower tube, flatten and spread the lip, and gently remove it to facilitate pollination. When the crown cap is seen lifted and the pollen loose, remove the anther cap and clip the pollen onto the stigma of the staminal column, which has mucus at the base of the flower, to complete pollination.

(5) Post-planting management

After planting, prevent rainwater accumulation, avoid rot of the fungal material and tubers, protect against heat and cold, provide timely shading, and strictly prevent trampling by people and livestock and contamination by miscellaneous fungi.

(6) Harvesting and processing

Harvesting: Gastrodia elata is harvested in autumn in November and in spring in March-April. Open and harvest pit by pit, prepare additional fungal wood and supplements in advance, harvest the tubers while adding new material, and carry out the second round of cultivation at the same time.

Processing: Wash the recovered fresh tubers clean, boil in 0.5% alum boiling water until thoroughly cooked through, boiling large Gastrodia elata for 10-12 min and small ones for 8-10 min. After removing, spread them on a mat, sun-dry until half dry, then frequently press lightly with a wooden board, and sun-dry until the center is solid and transparent and the shrinkage is uniform and flat, which is best.

II. What are the prospects for understory planting

Developing understory planting is of great significance for shortening the forestry economic cycle, increasing forestry added value, promoting sustainable forestry development, opening channels for farmers to increase income, developing a circular economy, and consolidating the achievements of ecological construction. The relatively long forest tree production cycle is an important restrictive factor for forestry development and for farmers to become prosperous after forest tenure reform. Only by letting forestland lay “golden eggs” earlier and better developing understory planting can forestry ecological construction and industrial development be better promoted, and can the achievements of forest tenure reform be better consolidated with good economic benefits, enriching the people while promoting forestry and promoting forestry while enriching the people.

Developing understory planting is an effective way to increase farmers' income, but what crops to plant under the forest must also be determined according to local planting conditions in order to achieve better economic benefits.