Detailed Explanation of the Key Technical Points for Scientific Cultivation and Management of Lablab Bean
I think many people have eaten lablab beans. Although they look flat and their appearance is not very eye-catching, their beauty lies within. Lablab bean is a relatively common vegetable in our daily lives. Its taste is very good, and its market price is not very expensive either.
What Is the Lablab Bean
Lablab bean, Lablab purpureus (Linn.) Sweet, commonly known as bian dou, with aliases including huolian biandou, tengdou, yanli dou, quedou, chadou, and moon vegetable, belongs to the class Dicotyledoneae. There are also many varieties, such as: white lablab bean, purple lablab bean, oil bean, snake bean, and pig's ear bean (shaped like a pig's ear). It is a perennial, twining vine plant of the genus Lablab in the Fabaceae family. It is a type of leguminous plant. It is cultivated in tropical and subtropical regions around the world. Lablab bean flowers come in red and white, and the pods come in colors such as green-white, light green, pink, or purple-red. The tender pods are used as a vegetable, while the white flowers and white seeds are used as medicine. They help remove summerheat and damp pathogens and have the effect of strengthening the spleen and stopping diarrhea. At the same time, lablab bean also has a significant effect in reducing tumors.
The Plant Morphology of the Lablab Bean
Annual twining herb. Leaflets 3; terminal leaflet rhombic-broadly ovate, lateral leaflets obliquely rhombic-broadly ovate, length —10 cm, width 4.5—10.5 cm, apex shortly acute or gradually acute, base broadly cuneate or nearly truncate, both surfaces with white short pubescence along the veins. Racemes axillary; flowers 2—4, clustered on the nodes of the rachis; the upper 2 teeth of the calyx almost completely connate, the remaining 3 teeth nearly equal; corolla white or purple-red, the base of the standard petal with 2 appendages on both sides; ovary sericeous, base glandular, style with white bearded hairs near the apex. Pods flat, sickle-shaped or semi-elliptic, length 5—7 cm; seeds 3—5, flat, oblong, white or purple-black. Flowering and fruiting period is July—September.
The nutritional composition of lablab bean is quite rich, including protein, fat, carbohydrates, calcium, phosphorus, iron, and dietary fiber, provitamin A, vitamin B1, vitamin B2, vitamin C, cyanogenic glycosides, tyrosinase, and more. The B-group vitamin content in the seed coat of lablab bean is especially rich. In addition, it also contains phospholipids, sucrose, and glucose. Furthermore, lablab bean also contains hemagglutinin, which is a protein-type substance that can increase the synthesis of deoxyribonucleic acid and ribonucleic acid and inhibit immune reactions and the movement of white blood cells and lymphocytes. Therefore, it can activate lymphocytes in tumor patients to produce lymphotoxin, which has a nonspecific damaging effect on body cells, and thus has a significant effect in reducing tumors. Tumor patients should often eat lablab beans, which have a certain auxiliary dietary therapeutic effect. Lablab bean has a clear fragrance without being overpowering, a mild nature, and a slightly yellow color, making it most compatible with the spleen.
Scientific Cultivation and Management Techniques for Lablab Bean
I. Cultivating Strong Seedlings
1. Bed selection and fertilization. Choose a non-continuous-cropping field plot with high terrain, convenient drainage and irrigation, and relatively good water- and fertilizer-retention performance as the seedling bed for lablab bean. Carefully prepare the land 15-20 d before sowing and apply sufficient basal fertilizer. Generally, for every 3.5 sq m, apply 100-120 kg of high-quality decomposed human and livestock manure, 1.2-1.5 kg of cake fertilizer, and 0.5 kg of phosphate fertilizer (P2O5 12%), turn them into the soil, and achieve the requirement of no hidden clods and full integration of soil and fertilizer. Then make nutrient pots with a diameter of 7 cm, and at the same time set up a 4 m wide medium tunnel with bamboo strips and polyethylene non-drip film.
2. Seedbed management. Select excellent varieties that are tolerant to low temperatures at the seedling stage, fast-growing, produce many and early pods, have tender pods with little fiber, crisp texture and good taste, and strong stress resistance, such as Shanghai white lablab bean and red-vein lablab bean. In early December of that year, choose sunny weather for sowing and seedling raising. After sowing, set up a small arch shed inside the medium tunnel for covering, and keep the temperature inside the small arch shed at about 25°C. If this temperature is exceeded, pay attention to ventilation to regulate the shed temperature, to prevent high-temperature seedling injury or the formation of leggy seedlings; when the outdoor temperature drops below 6°C, cover the small arch shed with straw curtains for insulation, uncovering them by day and covering them at night, to prevent low temperatures from forming old and stiff seedlings. Carry out pot-moving and seedling-hardening 15-20 d before transplanting. When the main vine grows 4-5 true leaves, timely top and prune to promote the growth of secondary vines. Generally, keep 3-4 robust secondary vines per plant.
II. Rational Fertilization
1. Fertilizer amount and scheduling. Lablab bean under multi-layer covering cultivation has a long growth period and a long flowering and pod-setting period, so it requires a large amount of fertilizer and has high requirements for nutrient ratios. Generally, for every 667 sq m, apply 20-25 kg of pure N, 10-12 kg of P2O5, and 18-20 kg of K2O; the ratio of organic fertilizer to inorganic fertilizer is 45:55; the ratio of basal fertilizer to topdressing is 60:40. Fertilizer scheduling: nitrogen fertilizer is distributed as one basal and three topdressings in a ratio of 6:1:1.5:1.5; phosphorus and potassium fertilizers are applied as one basal and one topdressing, with a distribution ratio of 6:4.
2. Fertilizer application and methods. According to the fertilizer requirements of lablab bean, the principle of fertilizer application is heavy basal fertilizer, light topdressing, and multiple supplemental applications of pod fertilizer, so as to meet its need for early inflorescence formation and early flowering and pod setting. Basal fertilizer is mainly organic fertilizer. Before planting, apply 1000-1200 kg of high-quality decomposed organic fertilizer (chicken manure mixture) per 667 sq m as basal fertilizer; after planting, apply seedling fertilizer as topdressing, with 300-500 kg of high-quality decomposed organic fertilizer (human and livestock manure water) and 2-3 kg of urea per 667 sq m; after the first batch of tender pods of lablab bean is harvested, apply 30-40 kg of sulfuric-acid-series compound fertilizer per 667 sq m (N:P2O5:K2O is 1:0.6:0.9, total nutrient content 40%) or apply a compound mixture of 10-12 kg of urea, 20-25 kg of phosphate fertilizer (P2O5 12%), and 8-10 kg of potassium fertilizer (K2O 50%), and after each subsequent harvest, supplement with 3-5 kg of urea according to seedling condition, to promote more inflorescences and more return flowers, and increase yield per unit area. For vigorous growth, the amount and frequency of supplemental application can be reduced. As for fertilizer application methods, basal fertilizer is applied to the soil by surface application followed by plowing and harrowing for land preparation, and topdressing is applied in furrow strips or holes 15-20 cm from the roots. At the same time, during the flowering and pod stage, spray foliar fertilizer containing trace elements such as boron and molybdenum 3-4 times per 667 sq m, with 100-120 g each time, at intervals of 7-10 d, to improve the quality of lablab bean.
III. Field Management
1. Timely planting. In order to strive for early marketing of lablab bean, plant at the proper time. The planting density is arranged with a row spacing of 1.6 m and a plant spacing of 0.5-0.8 m. For lablab bean planted in mid-February, use a 10 m wide double-layer large shed plus a small arch shed with three-layer covering for insulation; if the temperature is relatively low, cover the small arch shed with straw curtains at night for insulation. For lablab bean transplanted and planted in mid-March, use a 4 m wide medium tunnel plus a small arch shed for covering and insulation. After planting lablab bean, keep the temperature inside the small arch shed at 20-30°C, but it must not exceed 35°C.
2. Pruning and pinching. After transplanting and planting, when the secondary vines of lablab bean grow to 40-50 cm, timely set up a "ren"-shaped trellis to guide the vines onto it, and control the trellis height at about 1.5 m. For lablab bean under multi-layer covering cultivation, because it is sown early and has a long growth period, the branches and leaves are prone to excessive growth, so timely topping and pinching should be carried out to promote inflorescence development, early flowering, early pod setting, and early marketing; timely pruning during the peak pod-setting period is an important technical measure to extend the harvest period. The method is as follows: after planting lablab bean, when the secondary vines grow to 100-120 cm, pinch them in time to promote more tertiary vines and lateral buds on the lower part, more flowering, and more pod setting. When entering the peak pod-setting period, cut off old lower branches and leaves and lateral branches with few pods to improve field ventilation and light transmission. Especially when entering the high-temperature season, persist in pruning and pinching to control excessive plant growth, extend the pod-setting time, and improve yield per unit area and output benefits.
3. Removing film and regulating water. For lablab bean under multi-layer covering cultivation, remove the film and dismantle the sheds in stages in spring. In the middle and lower reaches of the Yangtze River plain region, remove the small shed when the temperature rises from late March to early April; remove the medium tunnel or double-layer large shed film when the first batch of lablab bean is harvested in early to mid-May. Because water has a relatively large impact on the growth and development of lablab bean, insufficient water supply at the seedling stage causes slow growth, and early seedlings cannot meet the requirement of early development; if water supply is insufficient during the flowering and pod-setting period, it affects flowering and pod setting, thereby affecting yield and quality. Therefore, when soil moisture is poor and plant leaves wilt at noon, pay attention to replenishing water to ensure normal growth and development of lablab bean and improve yield and quality. After the sheds are removed, lablab bean enters the open-field growth period. At this time, the middle and lower reaches of the Yangtze River region enter the plum rain season, with relatively concentrated rainfall. At this time, open a complete set of field ditches (horizontal, vertical, and surrounding) to prevent the harm of visible waterlogging and hidden waterlogging.
Pest and Disease Control of Lablab Bean
1. Control of seedling-stage diseases. The main seedling-stage diseases of lablab bean under multi-layer covering cultivation are damping-off and seedling blight. For seedbed soil disinfection control, mix 8-10 g of 50% carbendazim wettable powder per sq m with 0.5-1.5 kg of dry fine soil to make medicated soil. Before sowing, spread 1/3 of the medicated soil on the seedbed, and after sowing spread the remaining medicated soil over the seeds as a covering. In the early stage of disease occurrence at the seedling stage, spray seedlings and bed surface with 600 times dilution of 50% thiophanate-methyl wettable powder, once every 5-7 d, spraying 2-3 times.
2. Control of pests and diseases during the flowering and pod stage. The main pests and diseases during the flowering and pod stage include gray mold, leafminer, bean pod borer, and tobacco cutworm. Because gray mold infects quickly and the pathogen has strong resistance to chemicals, control should adopt a combination of agricultural control and chemical control. Agricultural control: strengthen the regulation of the shed environment, requiring suitable temperature and low humidity, strengthen ventilation and dehumidification, and promptly remove diseased leaves and diseased pods by hand and take them outside the shed for deep burying, which helps prevent the occurrence and development of the disease.
Chemical control: when scattered occurrence of gray mold on diseased leaves and pods is found, use 800-1000 times dilution of 50% procymidone wettable powder or 50% iprodione wettable powder, spray the whole plant on a sunny morning, and ventilate to reduce humidity, spraying continuously 2-3 times, with each interval of 5-7 d. For leafminer control, from the peak egg-laying period to the early hatching period, choose 1500 times dilution of 2.5% deltamethrin emulsifiable concentrate for application, spraying 2-3 times, with each interval of 5-7 d.
For bean pod borer control, the pesticides can be 1500 times dilution of 2.5% deltamethrin emulsifiable concentrate or 4000-5000 times dilution of 1.8% abamectin, sprayed on the inflorescences at 8-10 a.m. at the initial flowering stage and full flowering stage, spraying 2 times, with an interval of 5-7 d; during the pod stage, apply the pesticide in the evening when the pests are active. For tobacco cutworm, choose 1000 times dilution of 5% tebufenozide or 3000-5000 times dilution of 10% chlorfenapyr, and spray directly at the pods in the early morning or evening when the pests come out to be active. However, the last pesticide application time should be more than 20 d apart from the harvest time.
Although many people have eaten lablab beans, many people are not very familiar with its cultivation and growth. In the process of growing lablab beans, although mastering certain methods and techniques is important, certain pest prevention methods and techniques are equally important.