Detailed Explanation of Key Points for Pollution-Free Cultivation Techniques of Overwintering Cucumber
1. Variety Selection and Crop Rotation Arrangement
Varieties can include Jinfeng No. 2, Xintai Mici, Bonai No. 13, etc. Cucumber is most intolerant of continuous cropping and repeated cropping; each planting should be separated by three crop rotations, and the preceding crop should be any crop other than cucurbits, preferably alliums such as onions and garlic.
2. Raising Seedlings and Seedling Stage Management
Raise seedlings in early September, requiring 2200-2700 seeds per mu.
2.1 Seed Treatment First remove seeds that are not plump and have off colors as well as impurities, then sun-dry for 1 day. Wash off the sticky substance on the seed coat with 30°C water, treat the seeds using the warm water soaking method, then soak in a 1% potassium permanganate solution for 20 minutes, remove and rinse the seeds, drain off surface moisture, then wrap them in a damp cloth and place under conditions of 25-33°C for germination. When the seed embryo shows white, they are ready for sowing.
2.2 Nutrient Soil Preparation Thoroughly mix 4 parts decomposed organic fertilizer with 6 parts onion-garlic field soil, and after sieving, mix 10g of chlorothalonil and 10g of Ledan into 1m3.
2.3 Filling the Pots Fill the nutrient soil to 1cm below the pot rim, then place them in the seedling bed, and finally water the seedling bed thoroughly.
2.4 Sowing Place the germinated seeds in the center of the nutrient pots, then cover with 1.5cm of soil and water thoroughly.
2.5 Seedling Stage Management
1) Temperature management. Before emergence, control the air temperature at 25-35°C during the day and 18-20°C at night, with soil temperature controlled at 18-25°C; after emergence, maintain the air temperature at 20-28°C during the day and 13-17°C at night. Control soil temperature at 15-18°C.
2) Watering. Generally water on sunny days and not on cloudy days; most importantly, water according to soil moisture conditions, keeping it alternately dry and moist, and water as little as possible. Remove weeds in a timely manner, and when there are two seedlings per pot, keep the stronger and remove the weaker.
3) Disease prevention. When the seedlings grow to 2 leaves, mix 10g of thiophanate-methyl plus 5g of agricultural streptomycin plus 5g of potassium dihydrogen phosphate into 15kg of water and spray the seedlings; spray pesticide once 1 day before transplanting (same method as above).
2.6 Seedling Age Transplanting of overwintering cucumber generally takes place from late September to early October; the calendar seedling age is about 25 days, and the suitable transplanting time is when the physiological seedling age reaches 4 leaves and 1 heart.
3. Transplanting
3.1 Land Preparation and Application of Base Fertilizer Prepare the land 10-15 days before transplanting, applying per mu 2500kg of decomposed organic fertilizer, 20kg of superphosphate, 25kg of diammonium phosphate, 1kg of 50% thiophanate-methyl wettable powder and 1kg of poisoned grain, scattering all evenly over the field, then deep plowing 20cm and raking level.
3.2 Ridging and Film Mulching Ridge and cover with film 5-6 days before transplanting. Use subsurface irrigation under the film. The wide row spacing is 1.2m, the working row width is 0.5m, the ridge height is 5-8cm, the furrow depth is 15cm, and the single ridge width is 20cm. After ridging, water thoroughly once. When inserting the small arches, they must be inserted flat and level, and cover with 90cm-wide plastic film; the film must be pulled straight, pulled flat and pressed firm.
3.3 Transplanting Density The transplanting spacing is 35cm, with 2200-2400 plants per mu.
4. Management After Transplanting
4.1 Temperature Management From transplanting to the seedling revival stage, control the daytime air temperature at 30-35°C, with nighttime temperature not lower than 15°C. From after seedling revival to the fruiting stage, keep the daytime air temperature at 25-28°C, with nighttime temperature not lower than 12°C. During the peak yield period, control the daytime air temperature at 30-38°C, with nighttime temperature above 18°C.
4.2 Fertilizer and Water Management Water once 3-5 days after transplanting to help seedling revival and strengthen the seedlings. Afterward, water according to seedling growth and soil moisture conditions. After harvesting the root cucumber, apply topdressing together with watering, generally applying 500-750kg of well-fermented organic fertilizer liquid per mu. After that, each time cucumbers are harvested, apply topdressing together with watering using the same method as above, and at the same time spray 2-3 times with 0.3% potassium dihydrogen phosphate solution, which helps early maturity and high yield.
4.3 Ventilation The vents should go from small to large and from few to many; when the wind is strong, do not ventilate along the wind direction.
4.4 Hanging and Training Vines When the plants reach 25cm in height and begin to trail, pull strings and wind them around the stems to hang the vines. Timely pick the root cucumber, side vines and tendrils to avoid dragging down the plant. Cucumber grown in winter requires continuous lowering of vines to extend the growth period. When consecutive cloudy days last too long, remove cucumbers of medium size and above to ensure normal plant growth.
5. Pest and Disease Control
5.1 Powdery Mildew Autumn is a season with frequent powdery mildew; because of dryness after rain, high field temperature, extensive management, lack of fertilizer and water or excessive watering, poor ventilation, insufficient light and weak growth, powdery mildew can all be triggered. After onset, mainly spray with 40% myclobutanil 800-fold solution, 40% DuPont Fuxing 1000-fold solution, or 10% Shigao 1000-fold solution, with continuous control 2-3 times for better effect.
5.2 Downy Mildew Cucumber downy mildew is a fungal disease that mainly damages leaves, developing from the base upward to the upper leaves. In the early stage of onset, light yellow nearly circular to polygonal lesions form on the leaf surface, and it is prone to concurrent angular leaf spot; when the air is humid, frost-like mold layers form on the underside of the leaves and can sometimes spread to the leaf surface. In the later stage, the lesions die and merge into patches, appearing yellow-brown; in severe cases, all outer leaves wither and die. It is mainly spread through airflow, watering, farming operations and insects. High humidity inside the greenhouse and extensive management make it easy to develop. After onset, spray with 64% Sandofan 600-fold solution or 72% Kelu 800-fold solution or 64% Previcur 800-fold solution, etc.