Key Cultivation Techniques for Intercropping Bitter Melon in Greenhouse Cucumber
Bitter melon is a heat-tolerant crop with few pests and diseases. Using a solar greenhouse for intercropping cucumber with bitter melon makes full use of the greenhouse's idle period, improves the utilization rate of greenhouse facilities, and increases economic returns. Variety selection. For cucumber, use Xintai Mici as the scion and black-seed pumpkin as the rootstock for grafted seedling raising....
Bitter melon is a heat-tolerant crop with few pests and diseases. Using a solar greenhouse for intercropping cucumber with bitter melon makes full use of the greenhouse's idle period, improves the utilization rate of greenhouse facilities, and increases economic returns.
Variety selection. For cucumber, use Xintai Mici as the scion and black-seed pumpkin as the rootstock for grafted seedling raising. For bitter melon, choose varieties with strong growth vigor, heat tolerance, and few pests and diseases.
Seedling raising. Raise cucumber seedlings around October 15 using the root-cutting insertion grafting method. When the cucumber seedlings are 3-4 cm and the cotyledons have unfolded, grafting can be done. After grafting, insert the root-cut cucumber seedlings into a pre-prepared seedbed. The grafted seedlings require careful management and are ready for planting about 20 days after grafting. Sow and raise bitter melon seedlings around November 10. Before sowing, scald the seeds in 60°C warm water for 15 minutes, then soak them in 30°C warm water for 12 hours. Remove and wrap them in gauze, place them at 30°C to promote germination, and sow after 80% of the seeds have sprouted.
Fertilizing and land preparation. Before planting, apply 2000-3000 kg of decomposed chicken manure, 100 kg of cake fertilizer, and 50 kg of ternary compound fertilizer per 1/15 hectare. Deep plow 30 cm, level the soil, and form ridges running north-south. Use high-ridge cultivation with a ridge height of 10-15 cm.
Planting. When the cucumber has 3-4 true leaves unfolded, plant it out. The wide row spacing and narrow row spacing are 80 cm and 50 cm respectively, with a plant spacing of 27-30 cm. Every 4 rows of cucumber, leave 1 row as a bitter melon intercropping row, with a row width of 1.2 m, and plant bitter melon in the middle of the row. Plant bitter melon when it has 4 true leaves, with a plant spacing of 40 cm.
Temperature management. Keep the greenhouse at 25-30°C during the day and 15-18°C at night. To increase the plants' cold resistance, spray a 1% concentration of plant cold-resistance agent once each after seedling recovery, at the flowering stage, and at the young fruit stage.
Water and fertilizer management. After watering the cucumber to help it recover from transplanting, do not water generally until the early harvesting stage of the first fruit, focusing mainly on promoting roots and controlling vine growth. From the early fruit-picking stage through the entire peak fruiting stage, water more frequently, generally once every 10-15 days. Do not water on rainy, snowy, or cooling days. In low-temperature seasons, watering at around 12:00 is best, and well water is preferable. For bitter melon, avoid heavy watering before the vines begin to trail. As the plants grow and temperatures gradually rise, gradually increase the amount of watering. In hot seasons, watering in the morning and evening each day is best.
Generally, after every 1 watering with clear water, apply 1 application of compound fertilizer (or human manure and urine) by flushing with the irrigation water, using 10-15 kg per 1/15 hectare each time, and pay attention to increasing the application of carbon dioxide gas fertilizer.
Plant adjustment. Bitter melon has strong branching ability. The fruit-setting rate of female flowers on the main vine decreases as the node position rises, and the yield mainly depends on female flowers at nodes 1-4 setting fruit. The pruning method is to maintain the growth of the main vine. Remove all side vines below 1 m on the main vine. After the main vine reaches a certain height, leave 2-3 robust side vines to grow onto the trellis together with the main vine. For side vines that grow later, keep those with fruit and pinch off the growing tip at that node, and cut off those without fruit.
Disease control. The main diseases of cucumber include downy mildew, anthracnose, and phytophthora blight. The diseases of bitter melon include leaf spot and anthracnose. For downy mildew and phytophthora blight, use 52% chlorothalonil smoke agent, fumigating 250 g per 1/15 hectare each time, or spray with 64% oxadixyl-mancozeb at 400 times dilution. For anthracnose, spray with 80% anthracnose thiram at 800 times dilution.
Harvesting. The cucumber harvest period generally runs from the end of December to late May of the following year, and the bitter melon harvest period starts in early March and ends in October.