Detailed Explanation of Hyacinth Bean Planting Techniques and Field Management Methods

The hyacinth bean, also known as the eyebrow bean, moth-brow bean, lotus bean, magpie bean, and fence-climbing bean, is a cultivated species in the genus Lablab of the kidney bean tribe in the legume family. It is an annual or overwintering herbaceous vine, and can be perennial in frost-free areas of the south. The tender pods or mature beans are eaten. It originated in Asia. It is mainly distributed in India and tropical countries. In China, it is cultivated more in the south, followed by North China. Under natural conditions in high-cold regions, it can flower but does not set pods. The hyacinth bean is a vegetable relatively high in protein and carotene, easy to cultivate, and plays a certain role in regulating the supply of vegetables during the summer and autumn off-season, but it has not yet formed large-scale production.

Characteristics and Traits of the Hyacinth Bean

1. Botanical characteristics. The root system is well developed with many lateral roots, strong in absorbing water and nutrients, and forms spherical root nodules through symbiosis with cowpea-group rhizobia. The stem is trailing, with two types: short-vine and long-vine. Short vines are about 60-150 cm long, much branched, and erect and clumping. Long-vine types have stems 2-10 m long that twine. The cotyledons emerge above ground; the first pair of true leaves is opposite, simple leaves, and thereafter all are alternate trifoliolate compound leaves. Racemose inflorescences are axillary, indeterminate. Flowers vary by variety and may be white, light purple, or purplish red. It is self-pollinating, but insect pollination results in a certain outcrossing rate. The pods are flat and thick, obovate-oblong or oblong-short-strip-shaped, with a curved beak at the tip. Pod colors include green-white, light green, blue-green, deep purple, and purple-edged. Each pod contains 3-7 seeds. Seeds are slightly flat, oval, smooth, with a half-moon-shaped white raised strophiole on one edge, resembling a white eyebrow. The seed coat is white, black, or brown. The hilum is white. The 100-seed weight is 30-50 g. Seed storage life is 2-4 years.

2. Requirements for environmental conditions. It prefers warmth and fears cold, and dies when exposed to frost. The suitable growing temperature is 20-30°C, the optimum temperature for flowering and pod setting is 25-28°C, and it can tolerate high temperatures of 35°C. At high temperatures of 35-40°C, pollen germination decreases, easily causing flower and pod drop. The suitable temperature for seed germination is 22-23°C. It is a short-day crop. Some varieties are insensitive to photoperiod, so they can be planted in both northern and southern parts of China. The hyacinth bean is relatively shade-tolerant. It is not strict about water requirements, and mature plants are extremely drought-resistant. It has wide adaptability to soil, with well-drained, fertile sandy loam being best. The suitable pH range is 5.0-7.5.

Cultivation Techniques for the Hyacinth Bean

1. Planting methods. It is mostly direct-seeded in late spring, and tender pods are harvested successively from summer and autumn until before early frost. It can be monocropped or intercropped with corn, using corn stalks as support, or relay-cropped with garlic, and can also be planted at field edges and corners.

① Sowing density: for short-vine early-maturing cultivation, plant spacing is 30-45 cm and row spacing is 65-70 cm; for long-vine cultivation with trellis training and pruning, plant spacing is 45 cm and row spacing is 100-130 cm; for A-frame training and pruning cultivation, make beds 133 cm wide, plant 2 rows, with plant spacing of 35 cm, and leave a working path of 66 cm between beds.

② Sowing method: drill sowing or hole sowing, sowing depth 5-7 cm, and after sowing it is advisable to cover with plant ash.

③ Sowing rate: 57-67.5 kg/hectare for monocropping, 6-16.5 kg/hectare for mixed cropping.

2. Selecting excellent varieties

Choose good varieties according to cultivation conditions. Existing hyacinth beans are divided by pod color into three types: white hyacinth bean, green hyacinth bean, and purple hyacinth bean. The main varieties cultivated in China are:

① Purple-edged hyacinth bean. Also called pig-ear hyacinth bean, trailing. Leaves dark green, veins and petioles purple, pods broad and flat, green and thick, with dark purple along one suture line. Pod flesh crisp and tender. Each pod contains 5-6 seeds; mature seeds black; after cooking they are mealy, with good quality and high yield. It is mid-to-late maturing, strongly heat-tolerant, weakly cold-tolerant, fond of water and fertilizer, and vigorous in growth.

② White hyacinth bean. Trailing, much branched, vigorous in growth. The whole plant is green. Flowers white; pods slightly narrow, long, flat, and thin, light green; pod flesh relatively thin and tender; seeds white; flavor good. Spring sowing has a whole growth period of 160-170 days. Extremely drought-tolerant.

③ Black-seeded white hyacinth bean. Trailing, vigorous in growth; stems light green with purple at the nodes; leaves dark green; flowers purplish red; high pod-setting rate; pods light green, narrow and long; each pod contains 5-6 seeds; seeds black. Drought-tolerant, tolerant of poor soil, heat-tolerant, cold-tolerant, with a long harvest period.

④ Purple hyacinth bean. Trailing, strongly branching; stems dark purple; leaf blades green; veins and petioles dark purplish red; inflorescences long; many pods set; pods narrow and long with thick flesh, purplish red, containing 3-5 seeds, soft and mealy after cooking. Late-maturing, heat-tolerant, cold-tolerant, drought-tolerant, with a long harvest period and high yield.

3. Field management

① Water and fertilizer management: water demand is relatively low at the seedling stage, and relatively high after the vines elongate and during pod setting. Generally, water once or twice during vine elongation, and during the flowering and podding stage water about once every 10 days when there is no rain. After watering, cultivate and weed, and combine with topdressing to prevent flower and pod drop and excessive vegetative growth. Cultivation should be shallow to avoid damaging roots. Before pod setting, organic fertilizers such as decomposed chicken manure can be applied. After pod setting, apply a small amount of chemical fertilizer as topdressing.

② Trellising, vine guiding, and pruning: set up trellises before vines begin to run, or after vines begin to run use ropes promptly to guide vines onto trees or roofs. Pinch the main vine when it has 5-6 compound leaves to promote more lateral vines; when lateral vines have 3-4 leaves, pinch again, which can advance flowering and pod setting, but yield is lower. Generally, if using trellis or A-frame cultivation, pinch the stem vine when it grows to the top of the trellis, which can promote early pod maturity.

③ Pest and disease control: hyacinth bean has relatively few diseases; the main insect pests are aphids and red spider mites, which can be controlled by spraying low-toxicity pesticides and by early prevention.

4. Harvest

The hyacinth bean has a long growth period (160-300 days). It flowers and sets pods 60-65 days after emergence, and tender pods can then be harvested successively. Harvesting can continue for 90-120 days. Generally, tender pod yield is 15,000-18,750 kg per hectare. Fresh tender pods and tender beans have a short shelf life. If stored at 85%-90% relative humidity and 0-2°C, fresh pods can be kept for 21 days, and tender beans in pods for about 7 days. For harvest of mature seeds, long-vine types take 150-210 days, and early-maturing short-vine varieties 60-75 days. When mature pods turn dry and yellow, harvest, dry in the sun, thresh, winnow clean, and store.

Pest and Disease Control

1. Control of hyacinth bean rust and brown spot: use 100 g of 70% thiophanate-methyl or 20 g of 37% difenoconazole per mu, diluted in 60 kg of water, and spray for control.

2. Control of hyacinth bean noctuid, small lycaenid, and tobacco budworm: use 15-30 g of 3.3% abamectin · beta-cypermethrin or 40-60 ml of 30% emamectin benzoate · chlorpyrifos per mu, diluted in 60 kg of water, and spray for control.