Round melon (Praecitrullus fistulosus) is also known as a round gourd, Indian squash, squash melon, and Indian baby pumpkin. It is monoecious, annual with creeping or trailing habit. The fruits are round 5-8 cm in diameter and light green or dark green with white flesh. It is an important summer vegetable cultivated extensively in north India (Western Uttar Pradesh, Haryana, Punjab, and Rajasthan). The fruits contain a high proportion (93.5%) of water.
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Climate and soil
It grows well under warm and dry climates but can be grown both under hot as well as mild climates. The temperature of 27-30°C during the daytime and 18°C at the night are optimum for seed germination. Seeds do not germinate at low temperatures. Therefore, round melon cannot be grown in seasons and areas with low temperatures.
Sandy-loam soil rich in organic matter is ideal for its cultivation. It gives a good crop in river-beds where water table is quite high. While growing in the field, soil drainage must be ensured. The pH between 6-7 is ideal for its cultivation.
There are several locally-grown cultivars in different areas. A few varieties were also released. Input varieties are described here.
Arka Tinda: This is an advanced pedigree selection of the cross between T-3-4 (a local selection from Rajasthan) and T-8-2 (a local variety of Punjab). It is an early-maturing summer variety with round fruits having light green skin with soft hairs and tender flesh at a marketable stage (60 g). It yields around 9-10 tonnes/ ha in 90-100 days.
Bikaneri Green: Fruits are round, medium-size tender, and green with hairs and look very attractive. Hissar Selection 1: Its fruits are oval, green with hairs, and look very attractive.
Punjab Tinda (S-48): It is a selection from a local. type is grown in Punjab. Its plants are vigorous bearing 8-10 fruits/vine. Fruits are medium in size, flattish round, and light green. The fruit surf is shiny and pubescent. The flesh is less seedy, white, tender, and good in cooking quality. It yields 4.5-6.0 tonnes/ha. The fruits become ready for picking in 60 days after sowing.
Sahapur Tinda: It is a traditional variety of tinda conserved by the Kir community in Rajasthan. It is being grown around Jaipur and mostly marketed in Delhi. It is famous for bharva (a dish made by tinda fruit filled with other consumable ingredients mixed) vegetable besides other dishes. Its fruits are flat shaped, greenish-white, and weigh around 100-200 g at the time of harvesting. Yield potential is around 20-25 tonnes/ha.
Tamil Nadu Selection: Its plants are vigorous with broader and dark green leaves. The fruits turn flattish towards seed maturity. It can be cultivated in the spring-summer and Kharif seasons.
Since it is a short-duration crop, it is planted in different seasons in different parts of the country. In north Indian plains, 2 crops are taken. The first crop is sown during February-March, whereas the second is during June-July. In western India, summer crop is sown in December-January and rainy season crop in July August. In south India, it can be sown in December January and rainy season crop in June-July. In hilly regions of north India, sowing is done in May-June and could be continued up to July.
Seed rate and method of sowing
Its seed rate is 3.5- 5.0 kg/ha in the ridge and channel method while 5-7 kg/ ha in the pit sowing method.
Two seeds/hill on both inner sides of furrows and 4 seeds/pit are sown.
The planting distance in the channel ridge method: 2-3 m; channel to channel-channel width: 60 cm; and 60-75 cm plant-to-plant.
In-pit sowing method distance recommended is 1.5 to 2.0 m; row-to-row, and 60-75 cm plant-to-plant.
Further, a spacing of 250 cm x 90 cm is optimum for summer crop if sowing is done on one side of furrows in Punjab and a spacing of 150-200 cm between rows and 60-120 cm between plants or hills is recommended for Bengaluru conditions.
Manure and fertilization
Round melon responds. well to organic manures. The application of farmyard manure @ 20-25 tonnes/ha should be done at the time of field preparation. It requires 25 kg N, 50 kg P, 30 kg K/ha as basal dressing, and 25 kg of N as top-dressing into 2 split doses at 30 (at the time of earthing) and 60 days after sowing. The higher dose of N improves vegetative growth and decreases yield.
Frequent hand-weeding should be done to keep the crop weed-free. First, weeding may be given 15-20 days after sowing and later as and when required. The use of black polythene mulch helps conserve soil moisture and suppress weeds. Selective herbicides like nitrofen (1.25 liters/ha) or alachlor (2.5 liters/ha) could also be used to keep weeds under control.
Pre-germinated/soaked seeds germinate in 5-6 days. First irrigation should be given at the time of seed germination. Later irrigation could be given at 5-8 days intervals depending upon soil type and climatic conditions. Round melon needs more frequent irrigation than other cucurbits because of its shorter root length. During the rainy season irrigation is generally not required. Drip irrigation is also useful as it improves fruit yield by about 28%, reducing water requirements compared with the furrow system.
Diseases and pests
An important pest is the red pumpkin beetle (Aulacophora foveicollis), while powdery mildew and fusarium are common diseases affecting round melon.
Harvesting and post-harvest management
The first fruit picking of round melons is done about 60-90 days from sowing and continued up to 90-120 days depending upon the cultivars and seasons. Fruits take 6-8 days from anthesis to edible maturity. A good crop can give 8-12 tonnes/ha green unripe fruits. Picking should be done when fruits are still immature and small in size. Large-size fruits are not liked in the market even if immature and soft. Therefore, picking should be done every third to the fourth day.
The initial one or two fruits set at basal nodes should be harvested/ nipped early to allow better vine growth so that the plant can bear more fruits later. Plant growth-promoting chemicals also influence the yield. The aqueous solution of maleic hydrazide (50) ppm) sprayed at the 2-4 leaf stage stimulates vine growth, giving more femaleness and enhance female flowering at lower nodes. All these factors improve yield by 50 60%.
After harvesting, fruits should be carried in smaller lots to avoid bruising during handling. Keeping its fruits in a cool environment without causing bruises to their surface help in keeping fruits for 3-4 days with frequent wetting of covering/packing material and keeping the produce under shade or cool temperature.
All deformed and damaged fruits should be sorted out and rejected. Healthy fruits should be graded according to their size. The produce is packed in baskets with some filler, preferably leaves with a soft texture and low moisture content. For distant markets, perforated cardboard boxes with fillers are used. Since fruits respire which liberates heat, there should be enough aeration between the fruits so that the warm air should go out otherwise the fruits turn pale and become unmarketable. For transporting, a rack system should be preferred rather than dumping in a truck or heaping in the carriage. Due to high water content, the fruits are likely to get spoiled early, therefore arrangements for fast transportation and quick disposal/consumption should always be kept in mind.