How to grow konjac for high yield? A detailed explanation of key planting techniques
Konjac, also known as konnyaku, moyu, and ruotou, is a perennial herbaceous plant of the genus Amorphophallus in the Araceae family. China began cultivating konjac as early as more than two thousand years ago, and its history as a food is equally long. It is mainly distributed in Yunnan, Guizhou, Sichuan, southern Shaanxi and western Hubei. As konjac continues to be developed and utilized, its cultivation has good development prospects. Let us take a look at high-yield konjac cultivation techniques below!
Site selection and land preparation
Konjac has strict requirements for light, heat, water, fertilizer and other conditions, so we must insist on matching the site and soil to the crop and planting according to local conditions. Choose slightly acidic to neutral (pH 6.5-7) soil with deep, fertile, loose texture and good drainage, and gentle slopes with loam, light loam or bubble soil containing a small amount of gravel are most suitable for growing konjac. Before sowing in the konjac field, dig and aerate the soil as early as possible, and remove stones, weeds and residual plastic film from the soil.
Seed corm treatment
1. Seed corm production: To develop konjac production, we must first develop seed corm production and prepare enough seed corms. Achieve disinfection treatment of seed corms, separation of seed corms from manure, timely chemical control, and timely removal of diseased plants. Developing seed corm production means insisting on propagating seed corms locally, mainly by konjac farmers themselves. New growers must first develop seed corms, and established growers should allocate a corresponding area for seed corms. Improve the quality and safety of seed corms. The ratio of seed corms to field area is generally 1:3.
2. Seed corm disinfection: Disinfecting seed corms means eliminating pathogens on the seed corms at the source. First is sunning the seed: before sowing, spread the seed corms in the sun for 2 days. Second is soaking the seed: on a sunny morning, soak the seed corms in a 500 ppm streptomycin sulfate solution for 30 minutes, remove them, dry them in the sun and sow immediately, or mix the seed with stove ash (wood ash), dry in the sun and then sow. Where conditions permit, the sunned and soaked seed corms should be raised into seedlings and sprouted before transplanting to the field.
3. Sowing method: When sowing, keep the seed corms and fertilizer separated from each other and not in direct contact. Use the method of first opening the sowing furrow and placing the seed, covering with soil, and then applying manure, to ensure safe emergence of konjac seedlings. After the konjac emerges and before disease occurs, spray agricultural streptomycin or Mengkejun as a preventive protective agent. Once diseased plants appear in the field, choose a sunny day after the dew has dried, dig up the diseased plants together with their roots and the soil in the planting hole, bury them deep in a place far from cultivated land, and disinfect with lime. Never take diseased plants home to feed pigs as raw feed or throw them away at will, causing artificial spread.
Scientific fertilization
1. Fertilization principles: Konjac is a chlorine-sensitive tuber crop with a large fertilizer requirement. It likes fertilizer and fears poor soil, and likes potassium and fears chlorine. It needs the most potassium fertilizer, followed by nitrogen fertilizer, and then phosphorus fertilizer and trace elements such as calcium, zinc, magnesium and manganese. Therefore, we must adhere to the principle of mainly using base fertilizer and heavily applying farmyard manure.
2. Base fertilizer management: For konjac fields with relatively low soil fertility, apply more than 2000 kg per mu of farmyard manure such as bedding manure, high-quality soil-and-miscellaneous manure, and sod ash manure. In the base fertilizer, apply 2-4 jin of biological potassium fertilizer according to soil nutrient status, and apply appropriate amounts of urea and fertilizers such as superphosphate or calcium magnesium phosphate.
3. Fertilizer selection: It is strictly forbidden to apply farmyard manure carrying diseased residues, chicken manure, and chemical fertilizers containing chlorine, and excessive nitrogen chemical fertilizer must not be applied. Applying large amounts of farmyard manure and as little chemical fertilizer as possible not only helps build soil fertility and improve the soil, but also enables konjac to grow steadily and robustly and enhances disease resistance.
4. Reasonable topdressing
(1) For the first seedling topdressing, when about 80% of the konjac has emerged, if the base fertilizer was insufficient, apply a heavy seedling fertilizer, using 20-30 dan of human manure and urine per mu diluted with 40 dan of water for irrigation; if the base fertilizer was relatively sufficient, use about 5 jin of urea and 5 dan of human manure and urine per mu diluted with water for irrigation.
(2) For the second topdressing, from late June to early July, mix high-quality farmyard manure such as bedding manure or sod ash manure with 6-8 jin of urea and 15-20 jin of potassium sulfate and spread it lightly on the bed surface, combined with shallow earthing up.
(3) For the third topdressing of tuber expansion fertilizer, from late July to early August, use 20-30 jin of potassium sulfate per mu, apply it in holes and cover with soil, and from August to September spray the leaves 2-3 times with a 0.2% potassium dihydrogen phosphate solution.
Field management
1. Mulching management: After sowing konjac, vigorously collect various crop stalks, pod shells, dead leaves and other mulch materials. Long ones are best chopped up and spread evenly, firmly and tightly over the konjac field, meeting the standard of "no clumps of grass and no bare ground." Generally about 2000 jin of mulch is needed per mu. After September, pay attention to removing mulch that has not decomposed.
2. Weed removal: Konjac roots are distributed shallowly. To prevent intertillage and hoeing from cutting and injuring the developing young roots and underground stems and affecting normal plant growth, weeds can be removed by hand. However, note that a person can only squat in the furrow to pull weeds and should not step on the bed surface, to prevent crushing and injuring the underground rhizomes.
3. Clearing ditches and earthing up: Konjac fears both drought and waterlogging. Therefore, during the rainy season, especially after heavy rain, go to the field to inspect the planted plots, dredge ditches and drain water, and ensure the water channels are unobstructed. Along with clearing the ditches, cultivate the fine soil from the ditches onto the bed surface. Earthing up 2-3 times during the growth period helps the formation and expansion of the corms and keeps the daughter corms from being exposed, and can also enhance konjac's wind resistance and lodging resistance.
Pest and disease control
1. Soft rot
[Symptoms] Mainly affects petioles, corms and leaves. After infection, the tissues turn black, soften, and give off a foul odor, and may even cause the fruits to rot in patches and lodging, resulting in major losses.
[Control] Strengthen cultivation management for well-planted konjac, regularly carry out deep plowing and land preparation, drainage and ventilation. When selecting seeds, carefully choose seed corms that are free of rot and wounds, and properly store and transport them. In addition, when planting, note that konjac must not be continuously cropped or intercropped with certain vegetable crops, such as those in the Solanaceae family. Before sowing konjac, soak it in an appropriate proportion of agricultural streptomycin solution, remove it and then dry it.
2. Southern blight
[Symptoms] Mainly affects the base of the petiole, thereby damaging the petiole or corm. When the base of the petiole is infected with southern blight, dark brown spots appear and continuously expand, eventually causing white silky mycelium to grow on the petiole and take on a pale red color.
[Control] For southern blight, strengthen garden cultivation management and promptly drain standing water. When planting, do not continuously crop or intercrop with peanuts, Solanaceae plants or soybeans. At the same time, an appropriate proportion of Bordeaux mixture can be used to spray and disinfect the area around where the petiole contacts the soil surface during the period from konjac corm transition to corm swelling.
3. Leaf blight
[Symptoms] Mainly harms leaves. The pathogen overwinters in the soil and can splash onto leaves with rainwater. It can also invade through wounds or stomata and can spread through wind and rain. Therefore, the pathogen of leaf blight has extremely strong infective ability, causing konjac to wither and die in patches.
[Control] The prevention and treatment measures for leaf blight are basically the same as those for soft rot.
4. Insect pests
[Symptoms] The main insect pests affecting konjac growth include sweet potato hornworms, konjac nematodes, bean hawk moths, and others.
[Control] To control these insect pests, clear weeds and dead leaves during winter and spring, and adopt the method of intercropping konjac with corn in the field, which plays an important role in pest control. In addition, insecticides can also be used manually to eliminate pests, and when using farmyard manure, be sure to choose fully decomposed farmyard manure.