Guizhou Wild Hazelnut Seedling Cultivation Techniques

Hazelnut is one of the world's four major nuts, rich in nutrients and with a unique flavor. Plants of the genus Corylus are mostly shrubs, small trees or trees, with well-developed root systems, graceful form and luxuriant branches and leaves, making them excellent trees for landscaping and soil and water conservation, with good economic and ecological value. Guizhou has 4 species of plants in the family Corylaceae, genus Corylus, namely Corylus ferox var. thibetica, Corylus yunnanensis, Corylus heterophylla var. sutchuensis and Corylus chinensis var. fargesii, all of which are wild species [1]. The main propagation methods for hazelnut are division, layering, grafting and cuttings. This article describes the seed propagation and seedling cultivation techniques for wild hazelnut in Guizhou, hoping to provide a reference for the development and utilization of wild Corylus plants in Guizhou, the protection of germplasm resources, scientific research materials and expanded cultivation.

1 Seed collection

The ripening period of hazelnut is related to the species, the growing site environment and climatic conditions. In Guizhou, Corylus yunnanensis and Corylus heterophylla var. sutchuensis ripen in late July to early August of the lunar calendar, while Corylus ferox var. thibetica and Corylus chinensis var. fargesii ripen slightly later. Generally, those growing on sunny slopes or with better light conditions ripen earlier, and within the same clump, the top and the outer part of the crown ripen earlier. The hazelnut can be harvested once the color of the husk and the top of the nut changes from white to yellowish-brown. Corylus yunnanensis and Corylus heterophylla var. sutchuensis are clustered shrubs 1-5 m tall, making seed collection relatively easy. Corylus ferox var. thibetica and Corylus chinensis var. fargesii are small trees and large trees, requiring tools to assist with seed collection. For hazelnuts with a relatively concentrated distribution, the woodland can be cleared and the ground leveled, and after the nuts ripen and fall to the ground, they can be collected in a concentrated manner. It should be noted that hazelnuts must be fully ripe to be suitable for seed propagation and seedling cultivation, and nuts that fall to the ground should be collected promptly.

2 Seed treatment

For the fruits of Corylus yunnanensis, Corylus heterophylla var. sutchuensis and Corylus ferox var. thibetica, the nuts can be manually peeled from the husks after drying in the sun. The husks of Corylus chinensis var. fargesii are difficult to remove by hand, and since the fruits are hard, a modified corn thresher can be used to remove the husks. Its principle is to use an electric motor to drive a long cylindrical roller covered with many spikes, with a certain distance between the spikes; when rotating, it squeezes the nuts of Corylus chinensis var. fargesii out of the husks. The gap between the roller spikes ensures both that the nuts can be smoothly squeezed out of the husks and that the nut shells are not crushed.

3 Germination promotion

The pericarp, seed coat and embryo of hazelnut all contain substances that inhibit seed germination [2], so low-temperature stratification and hormone treatment are required. This mainly applies to the nuts of Corylus chinensis var. fargesii, with appropriate adjustments for the nuts of Corylus heterophylla var. sutchuensis, Corylus yunnanensis and Corylus ferox var. thibetica.

In late December of the year before sowing, soak the seeds to absorb water, changing the water once a day. After most seeds have absorbed water and sunk, remove them and drain, then soak them in an 80 mg/L gibberellin solution for 24 h, remove and air-dry the surface moisture, then place the seeds in layers in moist vermiculite or wet sand at 1 °C-5 °C, turning the seeds once a week, while opening for ventilation for 3-5 min, frequently checking the moisture status and replenishing water in time to avoid the seeds drying out. After about 80 d of stratification treatment, move them to room temperature and bury them in sand to promote germination, turning them once a day. Begin sowing when the radicle of the seed just breaks through the seed coat [3-5].

Outdoor natural stratification can also be used: open a 10 cm deep trench on the seedling bed, put the seeds into nylon mesh bags, then spread them flat in the dug trench, cover with about 5-8 cm of soil, cover with a small amount of straw and other litter, and sow one year later.

4 Selection of the seedling site

Choose loose, fertile sandy loam soil with flat terrain and a gentle mountain slope, and as far as possible choose a plot close to a water source, with convenient drainage and irrigation, sufficient light, and sheltered from wind and facing the sun.

5 Land preparation

Deep plow the sowing land 20-30 cm in the autumn of the previous year, and apply sufficient base fertilizer in conjunction with plowing, applying 3- m3 of coarse fertilizer per 667 sq m. The seedling bed is 120 cm wide and 15-20 cm high; rake the bed soil level and fine. Water thoroughly 3-5 d before sowing. For ridge planting, the ridge width is 60 cm.

6 Sowing

For spring sowing, sow as early as possible provided there is no danger of late frost damage. For ridge sowing, the spacing between adjacent seeds is 6-8 cm. For bed sowing: row spacing 20 cm, seed spacing 5-6 cm. First open furrows on the leveled ridge surface or bed surface, with a furrow depth of 5-6 cm, then scatter the pure seeds screened out from the wet sand into the bottom of the furrow according to the plant and row spacing, cover with 3-5 cm of soil, and press lightly.