Detailed Explanation of Greenhouse Tea Production and Processing Technology in Northern China

Rizhao green tea, as a successful example of "moving southern tea to the north," accounts for more than 50% of the total tea garden area in Shandong Province. It has the unique qualities of "beautiful taste, rich aroma, and resistance to repeated brewing," and is renowned both domestically and internationally. In recent years, with the adjustment of agricultural structure, as an important component of facility agriculture, greenhouse tea production has formed a certain scale, becoming a pillar industry for agricultural development in tea regions and an important way for farmers to increase income. The production and processing technology of winter tea in facility-cultivated greenhouses is introduced as follows:

1 Site selection and greenhouse construction

1.1 Garden site selection Rizhao is located at 35-38° north latitude, at the northern limit of tea tree growth. Areas south of this latitude can be used to establish gardens for planting tea trees. Site selection principles: First, sheltered and sunny gentle slope areas. Second, the soil layer must be thick to facilitate the downward growth of tea tree roots. Third, the soil pH value should be 4-6.5.

1.2 Greenhouse construction Generally, steel-frame pillarless single-slope semi-arched greenhouses are used, with a length of 60-100 m, a span of 7-9 m, and a ridge height of 2.4-2.8 m. The greenhouse film should be a drip-free film with high light transmittance, and the greenhouse surface should be covered with 5 cm thick insulating straw curtains.

2 Cultivation key points

2.1 Deep plowing and fertilization After greenhouse construction, the soil inside the greenhouse should be deeply plowed and fertilized. The plowing depth should be more than 80 cm, and then trenches should be opened along the planting baseline, with both trench width and depth of 40 cm. After trenching, apply an average of 5000 kg of farmyard manure and 50 kg of phosphate fertilizer per mu, then mix the soil and fertilizer evenly and backfill and level the ground.

2.2 Moderate close planting Varieties with strong cold resistance and suitable for making famous tea, such as Longjing 43, Baihaozao, and Xinyang 10, should be selected. To see benefits as early as possible, older tea trees from outside the greenhouse can be directly selected for transplanting. Single-row and double-row close planting should be implemented. For single-row planting, the row spacing is 80-100 cm and the hole spacing is 33 cm. For double-row planting, the large row spacing is 80-100 cm, the small row spacing is 35-40 cm, and the hole spacing is also 33 cm.

3 Greenhouse management

3.1 Fertilizer and water management Fertilization should achieve "sufficient base fertilizer," "frequent topdressing," and "regular spraying." "Sufficient base fertilizer" means applying sufficient base fertilizer around White Dew in autumn, opening a trench 25 cm deep and 25 cm wide in the center of the planting row, and applying 3000 kg of farmyard manure per mu or 30 kg of cake fertilizer plus phosphate fertilizer. "Frequent topdressing" means topdressing after each harvest round, using the standard amount of 12 kg pure nitrogen and 3 kg each of pure phosphorus and pure potassium per 100 kg of dry tea harvested, applied in trenches under the tree canopy. "Regular spraying" means frequently spraying foliar fertilizer during tea tree growth, evenly spraying the canopy with a 0.5% urea solution or tea tree Yipenzao diluted 180-200 times.

Tea trees are leaf crops, and their photosynthesis has a high demand for water. Ensuring water supply is an important measure for obtaining high yields. Greenhouse tea watering should follow the principle of "less spraying and frequent irrigation," replenishing water at any time, and micro-irrigation technology is better.

3.2 Temperature management During the day, the greenhouse temperature should be 22-28°C. When it exceeds 30°C, ventilation should be used to lower the temperature. At night, it should be kept at 10-15°C. When it is below 5°C, heating should be used for protection. In addition, tea trees prefer shady and humid environments, and the relative air humidity should be maintained at 70%-80%. In hot weather with strong light, shading measures should be taken.

3.3 Pest and disease control Most tea garden pests hibernate in winter, so they pose no threat to greenhouse winter tea and no pesticide application is needed. For some diseases such as tea red leaf spot, sprays such as benomyl and carbendazim can be used during the non-picking period for preventive protection. The use of highly toxic, highly toxic, or high-residue pesticides in tea gardens is absolutely prohibited to ensure the production of pollution-free tea that meets standards.

4 Harvesting and pan-firing

Greenhouse tea has excellent quality, good market demand, and a high price, and is mostly made into high-grade famous and fine tea. When harvesting, it is necessary to pick at the right time, use proper methods, strictly follow standards, and retain appropriate growth. On this basis, emphasize the word "early": when 5% of the new shoots on the canopy surface reach the picking standard (one leaf and one bud just unfolding), pick immediately.

According to market demand, tea can be made into different shapes. In the Rizhao area, it is often made into curly strip-shaped, flat-shaped, and needle-shaped tea. Each shape has its own unique production process, but they can roughly be divided into 4 parts: First, spreading and air-drying. Spread on bamboo mats or cement floors for 2-4 hours at a thickness of 3-5 cm. When the moisture content of fresh leaves drops to about 70%, it is ready. Second, fixation. To improve fixation quality and achieve even and thorough fixation, the principles must be followed: "high-temperature fixation, first high then low; combining shaking and covering, more shaking and less covering; old fixation for tender leaves, tender fixation for old leaves." Third, shaping. This includes manual shaping and machine shaping. Fourth, drying. Reduce the moisture content in the tea leaves to about 5%. Commonly used tea-making machines include the 6CSM-30 famous tea fixation machine, the 6CRM-25 famous tea rolling machine, the 6CH-3 automatic famous tea dryer, and the 6CD-42 famous tea multi-function machine. All are preferred models for developing tea mechanization technology and are worth vigorous promotion.