Key Technical Points for Double-Cropping Water Bamboo Cultivation: A Detailed Guide to Planting and Harvesting Times

Double-cropping water bamboo (Zizania latifolia) is rich in nutrients and delicious, making it one of the important vegetable crops in China. Many vegetable growers, recognizing its strong market value, have begun cultivating double-cropping water bamboo. To grow water bamboo well and achieve high yields, we need to understand the planting and harvesting times for double-cropping water bamboo, and what the key technical points for cultivation are.

I. Planting Time for Double-Cropping Water Bamboo

Double-cropping water bamboo is divided into spring planting and summer-autumn planting. Spring planting takes place in early April, and summer-autumn planting is established in late July. Double-cropping water bamboo is not demanding about sunlight and can produce shoots twice a year. In production, small arched sheds are used for seedling nursing and transplanting. For the summer crop, early spring mulching cultivation is used, along with cold water from reservoirs for continuous irrigation. When planting water bamboo at altitudes above 500 m, varieties with different maturity periods should be reasonably matched, and measures such as staggered planting times and careful management should be adopted to achieve multiple harvests per year, extend the supply period, and increase economic returns.

II. Harvesting and Marketing Time for Double-Cropping Water Bamboo

The autumn crop is harvested from September to November, with early harvests taken every 3-4 days and later harvests every 5-6 days, yielding 1000-1500 kg per mu; the summer crop is harvested from May to June every 3-4 days, yielding 1500-2000 kg per mu. The standard for maturity is that the shoot-bearing part is noticeably swollen, one side of the leaf sheath has split open, and the white shoot flesh is slightly exposed; the central leaves come together, and the two outer leaves close toward the shoot stem, forming a shape like a wasp's waist. When harvesting, the autumn crop should be twisted off at the stem tube, while the summer crop should be pulled up with the roots and the stem tube cut off. The shoot with the leaf sheath retained is protected by the outer husk, which helps maintain its white, tender quality and facilitates transport and storage.

III. Key Technical Points for Double-Cropping Water Bamboo Cultivation

1. Land preparation and fertilization

Deep plow 17-20 cm. Water bamboo plants are tall and have a long growing period, requiring large amounts of fertilizer, especially nitrogen. Apply 3000-5000 kg of organic fertilizer per mu (human and animal manure, pond and river mud, or green manure are all acceptable), 50 kg of superphosphate, 100 kg of plant ash, or 40-50 kg of compound fertilizer as base fertilizer. After fertilizing, plow, harrow fine, and level the field so that the field is flat, the mud is soft, and fertilizer is sufficient, which helps rooting and the extension of underground stems.

2. Seedling raising and transplanting

Water bamboo is propagated by division. Around December, cut off the aboveground residual stems and dead leaves, dig up whole clumps or split clumps with soil attached, and temporarily plant them in a corner of a seedling field or water bamboo field for easy management and to promote early growth and increase effective tillering. The planting depth should be such that the clump soil is level with the soil surface, and shallow water should be irrigated after planting. Apply topdressing once in early March, with 1500 kg of human manure per mu. For spring planting in the main field, clumps can be divided and planted directly in early to mid-April; for autumn planting, the clumps are first divided and kept in a seedling field for continued propagation, or when harvesting the summer crop, selected seed plants with swollen shoots can be planted in the water bamboo seedling field. When new water bamboo seedlings grow to more than 20 cm, dig up the clumps and use a knife blade to cut vertically along the tillers, dividing them into several small clumps, each with old stems and 2-3 healthy tiller seedlings, and plant them in the seedling field at a spacing of 25 cm × 25 cm. During planting, maintain a water layer of 1.5 cm; after establishment, maintain a water layer of 3-6 cm to promote early tillering and rooting. Water bamboo seedlings should be dug, divided, and transplanted promptly. Before planting, trim the leaf tips, keeping the plant height at about 30 cm, and plant about 1200 clumps per mu, with row and plant spacing of 60 cm × 70 cm. Irrigate shallow water before planting, and it is best to plant in the evening or on cloudy days. Plant 1-2 plants per hole. Summer-autumn planting is mostly done after early rice, late rice seedling fields, rush grass, and early lotus. Generally, it is established from late July to before the Beginning of Autumn. Before planting, remove the old leaves at the base and lift the clumps, pull apart the seedling clusters so that each plant has 1-2 tiller seedlings, and cut off the upper leaves. When using the summer crop as seed, select and retain seed clumps according to seed selection standards during the summer harvest, leave 4-5 water bamboo shoots at the edge of each clump, let the shoots mature, promote lateral bud sprouting, and then dig up the water bamboo with seedlings and plant them, 1 plant per hole.

3. Fertilization techniques

In addition to applying sufficient base fertilizer during land preparation, topdressing is generally applied 7-10 days after planting as a “seedling-promoting fertilizer” at 500 kg of human urine and manure or 5 kg of urea per mu; a second topdressing is applied at the early tillering stage at 2000 kg of human urine and manure, or 20 kg of urea, or 60 kg of ammonium bicarbonate per mu to promote tillering and growth of water bamboo; at the peak tillering stage, fertilize according to seedling condition. For fields with insufficient base fertilizer and poor growth, apply a jointing and stem-strengthening fertilizer once in late June at 15 kg of urea or 40-50 kg of ammonium bicarbonate per mu; after entering the shoot-bearing stage, when more than half of the plants have entered the flat-stem stage, heavily apply a “shoot-promoting fertilizer” once at 2500-3000 kg of human urine and manure, or 25-30 kg of urea, or 75-90 kg of ammonium bicarbonate per mu to promote shoot formation and increase yield. Topdressing for the summer crop should be early; apply the first topdressing before the Beginning of Spring at 3000-5000 kg of organic fertilizer or human urine and manure and 50 kg of superphosphate per mu to promote early sprouting and early tillering. Apply the second fertilizer in late March at 3000 kg of human urine and manure per mu; if manure is insufficient, it can be mixed with urea or ammonium bicarbonate; or apply 30-40 kg of urea or 100 kg of ammonium bicarbonate per mu.

4. Weeding and removal of yellow leaves

After the water bamboo has established or before the old water bamboo field closes its canopy, weed the field 2-3 times. When weeding, first drain the field water to a shallow level, combine it with topdressing, apply fertilizer first and then weed; after the plants close the canopy, stop weeding. For spring-planted water bamboo, remove yellow leaves 2-3 times, respectively in mid-to-late July, early August, and mid-to-late August; for autumn-planted water bamboo, remove yellow leaves 10-15 days after establishment, once every 7-10 days, for a total of 2-3 times. The removed yellow leaves should be stepped into the soil as fertilizer. When removing yellow leaves, care must be taken to protect the green leaves and avoid or minimize damage to the plants, so as not to affect shoot formation. After leaf removal, spray pesticides promptly to control pests and diseases.

5. Cutting dead leaves, thinning water bamboo seedlings, and pressing clumps

Water bamboo is not cold-tolerant. When the temperature drops to about 5°C, the aboveground part of the plant gradually withers. In December, drain the field water, keep the soil moist, and use a sharp knife to cut the clumps about 5 cm above the ground, while also digging out gray shoot clumps and male shoot clumps with their roots. After cutting dead leaves, immediately irrigate shallow water in the field to keep the plants moist through winter and promote early sprouting the following year. For the summer crop, when the seedlings are 20-30 cm tall in April, thinning is needed: remove dense ones and keep sparse ones, remove weak ones and keep strong ones, remove inner ones and keep outer ones, and pull out small, dense tillers. For early-maturing varieties, keep 25-30 strong seedlings per clump; for late-maturing varieties, keep about 20 strong seedlings per clump. Floating water bamboo seedlings have the advantages of early sprouting, fast growth, early shoot formation, and large shoot flesh, so care should be taken to retain them. During thinning, the tillers should be allowed to spread outward to promote ventilation and light penetration between plants.