Since Chinese cabbages are cool season crops they like short days and moderate to cool temperatures for their healthy growth. Hot weather with long days causes bolting (seed stalk formation), a physiological disorder commonly found in cruciferous vegetable crops.
Some early varieties take only 40 – 45 days from sowing to harvest while late varieties take about 75-80 days to reach maturity.
Well-drained, fertile, moist soils which are rich in organic matter are most suitable for growing Chinese cabbages. Ideal soil pH is 6.0 to 7.5. These plants can tolerate slightly alkaline soil. They need plentiful, consistent moisture supply for their healthy growth.
Propagation is done either by direct seeding or by transplanting seedlings. Direct seeding is recommended for small scale plantations, container growing and home kitchen gardens. Seeds may be sown directly ¼ to ½ inches deep and 3 inches to 4 inches apart.
Germination temperature is 50-800F (Fahrenheit). It takes about 4 to 7 days for seedling to emerge. Once seedlings get established, thinning is done to 15 inches to 20 inches apart.
Transplants or seedlings are raised in well prepared nursery beds for large scale plantations. Seeds are sown in nursery beds from the middle of September to the end of October in plains. In the hills seeds are sown from March to June. For an early crop 600 to 750 grams and for late crop 400 grams of seeds to be sown to cover one hectare of area. In other words, if you have one acre land, you can sow approximately 300-350grams of seeds for an early crop and 200-250grams for a late crop.
Seedlings are transplanted when 5 -6 weeks old. Site needs to be prepared well by ploughing and levelling. 15-20 tons of farm yard manure or compost or sludge or any other organic manures should be incorporated into the soil per hectare of area almost a month before transplanting. This will enhance the soil fertility.
NPK fertilizers, Nitrogen@60 Kg, Phosphorus@80 Kg and Potassium@40 Kg per hectare should be applied before transplanting.
Right time for planting Chinese cabbage seedlings is fall through early spring. Spacing for Pe-tsai types is 18 inches (plant to plant) x 24 inches (row to row) and for Pak choi types is 8-12 inches (plant to plant) x 24 inches (row to row).
Application of Nitrogen@60 Kg/ha is recommended as top-dressing about 6 weeks after transplanting (at the time of earthing up). Soil should be kept moist always by regular irrigations. An early crop needs to be watered at least twice a week while a late crop needs watering at least once a week. Irrigation frequency should be determined based on the prevalent soil and weather conditions.
Average yield per hectare varies from 20 to 40 tons depending on the cultural practices adopted and the prevalent climatic conditions. When first heads begin to get firm, harvesting may be done. Chinese cabbages are harvested by cutting the entire plant just above the soil surface.
Storage at 0°C (32°F) is required to optimize Chinese cabbage storage life. Optimum storage life at 0°C to 2.5°C (32°F to 36°F) with an optimum Relative Humidity of 95-100% is, 2 to 6 months, depending on cultivar. Freeze damage occurs if Chinese cabbage is stored below -0.6°C (31°F).
For transport and marketing, Chinese cabbages are packed loosely in crates in upright position with provision for plenty of air circulation.
Maturity Indices for Chinese Cabbages: Maturity is based on head compactness in case of head-forming varieties where the head is neither too compact nor too loose. A very loose head is immature and a very compact head is over mature. In case of non-head forming varieties, maturity is measured based on the tightness of cluster of leaves. If the cluster of leaf petioles is formed tightly, it is considered as at correct maturity level.
Quality Indices for Chinese Cabbages: Major quality indices that are to be considered for Chinese Cabbages are, compactness and firmness of heads or leaf clusters, weight of the heads/leaf clusters, and its freshness and hygiene. A detailed account of quality indices is as given below:
- Compactness and Firmness: Heads or leaf cluster should be compact and firm
- Weight: Heads or leaf cluster should be heavy for the size
- Fresh Appearance: Heads or leaf cluster should be free of insect pests; free of decay; free of seed stalk development; and free of any other defects. Leaves and heads should be crisp and turgid
Chinese Cabbages are affected by various physiological and pathological disorders during pre-harvest and post-harvest stages.
Physiological Disorders: Major physiological disorders of Chinese Cabbages are black speck, chilling injury and physical injury.
Black speck: This disorder is also known as pepper spot, petiole spot, and gomasho. Major symptom is appearance of very small to moderate size discoloured lesions on the midrib and veins of the leaves. It normally occurs when Chinese cabbages are exposed to low temperatures in the field and by harvesting over mature heads.
This may also occur because of improper transit and storage conditions. Exposure of Chinese cabbages to low storage temperatures followed by warmer temperatures is one of the reasons. Ethylene does not promote development of black speck in Chinese cabbage.
Chilling injury: In Chinese cabbages, chilling injury occurs during storage at 0°C (32°F) after 3 months or longer. The main symptom is midrib discoloration, especially on outer leaves.
Physical Injury: Various types of physical injuries are cracking, bruising and damage of freshly harvested Chinese Cabbages. Breakage of the midribs occurs during material handling and field packing processes. This, in turn, causes browning of the products and therefore the increased susceptibility of the products to product decay. Outer midribs of over-mature heads crack easily and hence careful handling is recommended.
Pathological Disorders or Diseases of Chinese Cabbages: Major pathological disorders of Chinese Cabbages are club root, powdery mildew, fungal rot, bacterial rot, mold rot, and leaf spot.
Club Root: This is a fungal disease commonly found in field-growing Chinese cabbages.
Powdery Mildew: Chinese cabbages are susceptible to powdery mildew also, another fungal disease found common in cruciferous vegetables.
Fungal Soft Rot: This is a common form of product decay found in stored Chinese cabbages. Major symptoms include watery soft rot. This is caused by a fungus called Sclerotinia spp.
Mold Rot: This is also characterized by product decay and is a fungal disease caused by fungus Botrytis cinerea.
Leaf Spot: Leaf spot is another fungal disease of Chinese Cabbages and it is caused by fungus Alternaria spp.
Bacterial Soft Rot: This is caused by various bacterial species including Erwinia spp, Pseudomonas spp, and Xanthomonas spp. Bacterial soft-rots result in a slimy breakdown of the infected tissue.
Control Measures: Both fungal and bacterial rots of Chinese cabbages may be controlled by cultural practices such as trimming of outer leaves and field sanitation. Proper post harvest practices such as rapid cooling of freshly harvested produce to remove field heat and low temperature storage are also effective in controlling a number of disorders and diseases in Chinese Cabbages. Rotenone and other pyrethrum based fungicides may also be used to control fungal infections.
Major Insect Pests: Cabbage worms, flea beetles, slugs and aphids are found to be affecting Chinese cabbages during growing as well as storage phases. These insect pests can be controlled by the application of recommended organic insecticides/pesticides or by IPM (integrated pest management) practices.
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