Protected cultivation of squash and melons

A. Introduction

• Squash (Cucurbita pepo) and melons (Cucumis melo) are high-value cucurbit crops.
• Under open field cultivation, they are highly sensitive to temperature, humidity, and pest-disease fluctuations.
• Protected cultivation ensures off-season production, uniform quality, and higher returns.
• Both crops are well-suited for cultivation in polyhouses, net houses, and low tunnels.

B. Climatic Requirements

a. Temperature:

• Optimal range: 20–30°C.
• Fruit set reduces below 15°C and above 35°C.

b. Relative Humidity: 50–70 percent is ideal.

c. Light: High light intensity promotes photosynthesis, but shading nets (30–50 percent) are useful in summer to reduce heat stress.

d. Day length: Long days favor vine growth; balanced photoperiod improves flowering.

C. Suitable Structures

• Naturally ventilated polyhouse: For year-round and off-season production.
• Low-cost tunnels: Suitable for early-season production.
• Insect-proof net houses: Effective against viral diseases (common in cucurbits).
• Plastic mulching: Conserves moisture, suppresses weeds, and regulates soil temperature.

D. Varieties and Hybrids

a. Squash:

• Hybrid varieties suitable for protected cultivation: Hybrid Zucchini-1, Arka Tanu, Arka Vikram, Sungreen F1, Local Zucchini hybrids.

b. Melons:

• Suitable hybrids: Hara Madhu, Pusa Rasraj, Arka Jeet, Muskmelon hybrids (e.g., Kashi Madhu, Arka Rajhans, Super Sweet).
• In Nepal (Krishi Diary 2081): Recommended hybrids for cucurbits under polyhouse are high yielding F1 hybrids of muskmelon and zucchini.

E. Propagation and Nursery Management

• Seeds are sown in protrays/cocopeat media under protected nursery.
• Seed treatment with fungicides (Thiram/Carbendazim) prevents damping-off.
• Transplanting is done at 2–3 leaf stage (3–4 weeks old seedlings).

F. Planting and Spacing

a. Squash:

• Plant spacing: 60 × 60 cm (for bush types) or 1.0 × 0.6 m (for vining types).

b. Melons:

• Spacing: 1.5 × 0.5 m or 2.0 × 0.5 m depending on growth habit.
• Plants are trained on trellis/netting system to utilize vertical space.

G. Training and Pruning

Squash (Zucchini type): Usually not trained extensively; only side shoots and old leaves are removed.

a. Melons:

• Plants are trained vertically on nylon nets/strings.
• Pruning involves removal of lateral shoots up to 7th–8th node to encourage female flowers.
• Fruits are thinned, retaining 2–3 per vine for uniform size and quality
• Use of fruit nets/slings supports heavy fruits and prevents breakage.

H. Nutrient Management

• Soil is enriched with FYM (15–20 t/ha).
• Fertigation is commonly practiced under drip irrigation.
• Recommended dose (general):

a. N: 120–150 kg/ha, P2O5: 80–100 kg/ha, K2O: 100–120 kg/ha.

b. Split application: 8–10 weekly doses through drip.

• Foliar sprays of micronutrients (Boron, Calcium, Magnesium) improve fruit set and quality.

I. Irrigation Management

• Drip irrigation ensures efficient water use and prevents leaf wetting (reduces diseases).
• Irrigation frequency: every 2–3 days depending on crop stage and season.
• Mulching reduces evaporation and maintains soil moisture.

J. Pollination Management

• Both squash and melon require insect-mediated pollination.
• Under polyhouse:

a. Introduce honeybees (Apis mellifera) or bumblebees for effective pollination.

b. In absence of bees, manual pollination is practiced.

K. Pest and Disease Management

a. Major pests:

• Aphids, whiteflies, fruit flies, spider mites, leaf miners.

b. Major diseases:

• Powdery mildew, downy mildew, Fusarium wilt, viral diseases (CMV, ZYMV).

c. Integrated Management:

• Use of insect-proof nets.
• Yellow sticky traps for whiteflies.
• Neem oil sprays as prophylactic.
• Fungicide sprays: Wettable sulphur (powdery mildew), Metalaxyl + Mancozeb (downy mildew).
• Virus management through resistant hybrids and strict vector control.

d. Harvesting and Yield

a. Squash:

• Harvest tender fruits 5–7 days after fruit set.
• Yield potential: 20–25 t/ha under polyhouse.

b. Melons:

• Harvest at full slip stage (fruits detach easily) or 30–35 days after fruit set.
• Yield potential: 30–35 t/ha under protected cultivation.