Detailed Explanation of the Key Points of the New Short-Cutting Tea Propagation Technology
At present, asexual propagation of tea plants mainly uses the short-cutting method with heart soil spread on the bed surface. Although this technique can effectively reduce diseases and weed damage during the propagation process, its heavy workload and high input cost have largely restricted the propagation and promotion of improved tea varieties. In recent years, through relatively large-scale trials, we have proposed a simple, reliable, labor-saving and material-saving cutting technique without heart soil. The land preparation production cost of this technique is only 300 yuan per mu. It not only saves costs compared with the traditional heart soil method, but the cutting survival rate can also reach about 85%, offering considerable value for promotion.
I. Preparation of the Cutting Nursery Site
1. Site selection. The nursery site should be close to a water source, with loose soil and flat terrain, and convenient for irrigation and drainage.
2. Planning and plot layout should be adapted to local conditions. Plots should be divided according to the natural drop of the land. Drainage and irrigation ditches should be set around each plot, with a ditch width of 60 cm and a depth of 40 cm. The bed is generally 10-15 m long, and an east-west bed orientation is preferable. The bed width is 1 m, and the operation ditch between beds is 40 cm.
3. Construction of the seedbed. After marking the lines around the bed surface, excavation begins. First dig 10 cm of topsoil, shovel all the topsoil aside, then dig 10 cm of subsoil and place it on the other side. Backfill all the topsoil and level it. After fully mixing the prepared insecticide, fungicide and base fertilizer, evenly spread them on the topsoil layer (per sq m use 8 g of carbofuran, 1.5 g of thiophanate-methyl, and 450 g of cake fertilizer). Then backfill the subsoil as the topsoil. After leveling, compact the surroundings.
4. Furrow irrigation. After the seedbed is prepared, carry out continuous furrow irrigation so as to kill insect eggs, allow the fungicide to fully penetrate the soil, and fully decompose the cake fertilizer. This process takes about 20 days.
II. Establishment of Shade Facilities
According to the practical results of the past two years, the shading effect of a 1.8 m high flat trellis is the best. To establish the high flat trellis, use each plot as a unit, mark lines and bury posts, with a horizontal spacing of 6-8 m and a longitudinal spacing equal to the bed length. About 25 posts are needed per mu. Moso bamboo can be used, generally 2.5 m long, buried 50 cm deep. Each post must be firmly buried by tamping layer by layer with stones and soil. After the posts are buried, fix them with No. 12 iron wire, and place shade netting on the wire.
III. Cutting
1. Taking shoots and cutting cuttings. The shoot material must be thick, semi-lignified branches with a reddish-brown color. Cutting the cuttings is best done in the morning, and after the branches are cut back, they should be inserted immediately. The length of the cutting is generally preferably 3.3-4.0 cm. For long internodes, cut one node (one leaf and one bud). For short internodes, two nodes can be used to cut one cutting. Remove the lower leaves, keep one upper leaf, and the small stub left above the leaf must not be too short, generally 3-4 mm. The upper cut should slope outward to avoid water accumulation and rot, and the lower cut should be made into a horseshoe shape.
2. Inserting the cuttings. 1-2 h before insertion, sprinkle water to soak the bed surface thoroughly, then mark lines. For small- and medium-leaf varieties, the row spacing is generally 7-10 cm. After marking rows on the bed surface, first spray with 170 ml of the herbicide butachlor per mu mixed with 55 kg of water, then insert the cuttings. The row and plant spacing should be such that the cuttings do not cover each other and no soil is visible after insertion. After insertion, press lightly between the short cuttings with the fingers. The insertion angle is generally preferably 35-45° between the leaf and the ground. The leaf should not lie flat on the ground, otherwise leaf respiration will be affected. After insertion, sterilize with a 1000-fold solution of carbendazim, which also serves to wash the leaves and better fix the cuttings. Finally, insert bamboo arches (2.2 m long) on the bed, with the center height above the ground not less than 50 cm. Cover the bamboo arches with plastic film and compact the surroundings with soil to form a small arch shed. This can preserve heat and moisture and is conducive to the healing and rooting of the cuttings.
IV. Nursery Management
1. Water management. After insertion, irrigate promptly, with furrow irrigation for about 20 h. Routine water management should depend on soil moisture, generally keeping the topsoil moist. Soil below one cun should be able to be twisted into a strip but not stick to the hand. If the topsoil is dry and loose, furrow irrigation should be carried out promptly.
2. Temperature management. Generally, tea areas north of the Yangtze River mostly use autumn cutting (August 20-October 20). At this time, daytime temperatures are still relatively high, and plastic film is also used for covering. The daytime temperature inside the small arch shed is 28-34°C, and the maximum temperature can exceed 42°C. If it exceeds 42°C, the leaves will be scorched. Therefore, ventilation and heat dissipation must be carried out promptly (open the film at both ends). After temperatures rise in spring of the following year (generally in late March), temperature changes should be observed at any time and adjusted promptly.
3. Removing flower buds. In summer and autumn cutting, there are many flower buds, which must be removed promptly. When removing flower buds, dissecting scissors or pointed scissors can be used, and the buds must not be damaged or the cuttings loosened. Removing flower buds can be done together with ventilation or spraying.
4. Fertilization is generally carried out in late April. As the temperature gradually rises, large numbers of new roots are continuously produced, and tea buds also sprout abundantly. At this time, large amounts of fertilizer and water are needed. After mid-May, once 85-95% of the cuttings have rooted, the plastic film of the small arch shed can be removed. The first application is foliar spraying with a 0.5% urea solution; the second application is foliar spraying with 1% urea plus Shibibao (at an interval of 7-10 days); the third application is spraying with 2% urea plus Shibibao. After mid-June, as the cuttings gradually grow and their resistance increases, organic fertilizer can be mainly applied. The method is: put 1 part cake fertilizer and 10 parts water into a pond and allow it to fully decompose (about 20 days), then take 1 part cake fertilizer water and add 10 parts water, and water it on with a watering can, applying once every 15-20 days. In this way, the seedling height in the same year can generally reach 50-70 cm.
5. Hardening seedlings. After entering August, temperatures gradually decline, and the shade netting above the high trellis should be gradually removed. In the Dabie Mountain area, there are often semi-cloudy days, and this opportunity can be seized to harden the seedlings.
6. Pest and disease control. Because cutting seedlings need heat and moisture preservation, many pests and diseases reproduce faster under high-temperature and high-humidity conditions. According to field observations, losses from diseases are far greater than those from insect pests. The main diseases include tea bud blight, red leaf spot, root rot, brown leaf spot, root cancer, gray blight, and anthracnose; the main insect pests include: tea green leafhopper, green plant bug, tea tarsonemid mite, tea tussock moth, tea geometrid, and tea small leaf roller. Therefore, the occurrence and changes of pests and diseases in the shed should be observed frequently and controlled promptly.
For the main diseases in autumn and winter, such as tea gray blight, anthracnose, and brown leaf spot, a 800-fold solution of chlorothalonil or a 1000-fold solution of carbendazim can be used for spray control; for bud blight, root rot, anthracnose and others occurring in spring, a 1000-fold solution of 70% thiophanate-methyl or a 800-fold solution of 50% carbendazim can be used for spray control.