Bitter gourd (Momordica charantia) is one of the most popular vegetables in Southeast Asia. It is a member of the cucurbit family along with cucumber, squash, watermelon, and muskmelon. Native to China or India, the fast-growing vine is grown throughout Asia and is becoming popular worldwide. Depending on location, bitter gourd is also known as bitter melon, karella, or balsam pear. The immature fruits and tender vine tips are used in a variety of culinary preparations.
The fruits and shoots are soaked in salt water to remove some of their bitterness and then boiled, fried or pickled. The fruit of bitter gourd fruit is similar in nutritional value compared to other cucurbits, with the notable exceptions that it is much higher in folate and vitamin C. The vine tips are an excellent source of vitamin A. The medicinal value of the gourd in the treatment of infectious diseases and diabetes is attracting the attention of scientists worldwide. The following suggested cultural practices were developed at AVRDC in the Taiwan lowlands. Growers may need to modify the practices to suit local soil, weather, pest, and disease conditions.
Climate and Soil Requirements
Bitter gourd grows well under the same conditions preferred by other cucurbits. It is normally grown as an annual crop, but can perform as a perennial in areas with mild, frost-free winters. The plant thrives in the tropics from lowland areas to altitudes of up to 1,000 m. Bitter gourd requires a minimum temperature of 18°C during early growth, but optimal temperatures are in the range of 24-27°C. It is more tolerant to low temperatures compared to other gourds, but cool temperatures will retard growth and frost will kill the plant. The plant is adapted to a wide variety of rainfall conditions, but regular irrigation is needed to ensure high yield. Bitter gourd tolerates a wide range of soils but prefers a well-drained sandy loam soil that is rich in organic matter. The optimum soil pH is 6.0-6.7, but plants tolerate alkaline soils up to pH 8.0.
Choosing a Variety
Numerous hybrid and open-pollinated varieties are available. Hybrids usually produce higher yields, but their seeds are relatively expensive and must be purchased for every planting. Open-pollinated varieties have the advantage that their seeds may be saved and used for future plantings. The choice of variety depends on market preference in a certain region, and is based on fruit shape and color. Generally, there are three types:
- small, 10-20 cm long, 100-300 g, usually dark green, very bitter;
- long, 30-60 cm long, 200-600 g, light green in color with medium size protuberances, and only slightly bitter; and
- triangular fruit type, cone-shaped, 9-12 cm long, 300-600 g, light to dark green with prominent tubercles, moderately to strongly bitter.
Select a variety that is well adapted to your growing conditions and preferred by consumers. Growers are encouraged to compare the performances of different varieties during different seasons to identify superior types.
Preparing the Field
Thorough land preparation and a well-prepared bed is required. Plow, harrow and rototill the field. Form 2O-cm-high beds during the dry season and 30 cm or higher during the wet season using a plow or mechanical bed shaper. The distance between centers of adjacent furrows is about 150 cm with a 90-cm bed top.
Direct seeding is the most common method of planting. In cooler climates, it may be necessaryto start the seedlings in a greenhouse to ensure good germination.
Option 1. Direct seeding
Optimum plant density differs with variety and usually ranges from 6,500 to 11,000 plants per ha. In some intensively managed plantings, a closer spacing of 50 x 50 cm is used resulting in 40,000 plants per ha. On raised beds, sow two or three seeds per hole at a depth of 2 cm. Space holes 40-60 cm apart in rows spaced 1.2-1.5 m apart. Plant density using this spacing will range from 13,600 to 17,300 plants per hectare. When planted in warm soil, seedlings will emerge in a week or less. Thin to one seedling when they have four true leaves.