Tropical and subtropical vegetables (2+1)

Preparation of field

• Plough the field for 3-4 times. Apply 20-25 tonnes of farmyard manure at the last ploughing.

Spacing
Long channels of 60cm width are formed at a spacing of 2m. Along this channel, pits of 45cm are dug at a spacing of 1.5m. The package of practice recommendation of Kerala suggests making pits of size 60cm at a spacing of 2m.

Nutrition
Different recommendations for fertilizers and manures are available for different locations. Fertilizer recommendation for bitter gourd for different states is given below.
---
                                              States                                                      N                                      P                                          K (kg/ha)

---

                                                    Punjab                                                   100                                  50                                              50
                                                    Himachal Pradesh                               100                                   50                                             50
                                                    Karnataka                                              62                                    50                                               0
                                                    Tamil Nadu                                            20                                    30                                              60
                                                    Maharashtra                                         50                                    40                                                0 

---

• In the coastal regions of Karnataka N and P at 80: 30kgs/ha alone gave maximum yield of 17.12 tonnes/ha. In coconut gardens of Kerala (partially shaded conditions) maximum fruit set and yield were obtained at NPK 90: 25: 50kgs/ha. In Kerala, application of farmyard manure @ 18 tonnes + NPK 60: 30: 60kg/ha resulted in maximum yield and net returns.

Irrigation
Since bitter gourd is sown both in rainy and summer seasons, rainy season crop normally does not require much watering except during dry spells. Being a shallow rooted vegetable, roots are mostly concentrated at top 60cm soil layer. The crop should be irrigated immediately after planting in summer and subsequently at 2-3 days interval until flowering.

Weed control
The field should be free from weeds throughout cropping season. Glycophosphate at 4.5kg/ha if applied after weed emergence and before sowing, weeds can be effectively controlled.

Use of Growth regulators
Ethrel at 25ppm increases female flowers. GA at 60ppm reduces the ratio of male: female flowers. High levels of endogenous GA like substances occur between 45-60 days when the ratio of male: female flowers are low. MH at 150-250ppm when applied at 2 leaf stage in variety ‘Pusa Do Mousmi’ induced the formation of pistillate flowers at the lowest node. Seed treatment with B9 at 3-4 ppm for 20 hours gave the highest number of female flowers per plant. Application of growth regulators at 2-4 leaf stage play an important role in expression and sex ratio. MH at 50-150ppm and CCC at 50-100ppm increase female: male ratio and at a high concentration of 200ppm CCC it is reduced.
Application of cycocel at 250mg/litre gave the highest dry-matter, acetic acid and TSS content and flesh thickness. GA3 at 25mg/litre gave highest number of seeds/fruit at 75kg N/ha. Application of paclobutrazol at 100 ppm improves the fruit yield. Soaking of seeds in Ethrel for 20ha/ppm or GA3, MH, silver nitrate at 3 - 4ppm gave the highest number of female flowers and fruits per plant. Seed treatment with Boron 3-4mg/litre or foliar application @ 3-4mg/litre gave significantly higher yield.