What are the key points of the training technique for Schisandra chinensis?
The vines of Schisandra chinensis are soft and cannot stand upright; they need to attach to a support and twine upward to grow. Therefore, its training work includes two tasks: setting up supports and pruning.
(1) Setting up supports
In the year of planting, Schisandra chinensis shows considerable variation in growth amount. Under conditions of poor seedling quality and poor management, plant height generally reaches only 50-60 cm, but after stumping pruning, the average growth height in the second year can reach more than 150 cm, and by the third year it can cover the trellis surface. So generally, supports can be set up in the spring of the second year (early to mid-May). The supports can use trellis poles and UV-resistant polyethylene cord. Bamboo poles are often chosen as trellis poles, with a length of 2.0-2.2 m and a top diameter of 1.5-2.0 cm; for the UV-resistant polyethylene cord, a thickness of 3 x 15 strands is more suitable, with the upper end fixed to the first wire at the top. According to the plant spacing, use 1-2 poles per plant. When the plant spacing is less than 50 cm, one pole per plant can be set, placed about 5 cm beside the plant; when greater than 50 cm, two poles per plant, evenly inserted or fixed on both sides of the plant. The part of the bamboo pole that goes into the soil is best coated with asphalt to extend its service life, and the trellis poles are fixed to the three trellis wires with thin iron wire. In a Schisandra chinensis orchard with good seedling quality and management, the plant's growth height in the current year can reach about 2 m. Therefore, in the year of planting, supports should be set up in late May to facilitate rapid plant growth.
(2) Training
The purpose of training Schisandra chinensis is, through human intervention and induction, to make it grow and develop according to the grower's requirements, so as to fully use the trellis space, effectively use light energy, rationally retain vines, regulate the relationship between vegetative growth and reproductive growth, and cultivate robust and long-lived plants, making them adapt to climatic conditions and facilitating farming, pest and disease control, pruning, and harvesting operations, thereby achieving the goals of high yield, stable yield, and high quality.
The tree form commonly used for Schisandra chinensis is a training method with one group or two groups of main vines, that is, each plant retains 1 group or 2 groups of main vines, which are respectively twined on evenly arranged supports. On each support, 1-2 fixed main vines are retained. Lateral vines and fruiting mother branches grow on the main vines, with each fruiting mother branch spaced 15-20 cm apart and evenly distributed. Fruiting branches and vegetative branches grow on the fruiting mother branches, as shown in Figure 5-3. The advantage of this training method is that the tree structure is relatively simple, and the training and pruning techniques are easy to master; cultivation can be carried out between plants and rows, making weed control convenient; the plant volume and load are small, and the requirements for soil, fertilizer, and water conditions are less strict. However, because the plant is relatively upright, it easily forms a condition of strong top and weak bottom with the fruiting position moving upward, so control needs to be strengthened.
Each tree generally needs 3 years to form its tree shape. During the training process, special attention should be paid to the selection and retention of main vines; branches with strong growth vigor, solid growth, and plump buds should be selected as main vines. The number of main vines in each group must be strictly controlled; too many main vines will cause adverse consequences such as tree weakening and chaotic retention of branch groups.