Tropical and subtropical vegetables (2+1)

Preparation of field

• The field is ploughed four or five times. Various systems of cultivation have been adopted depending on the season. In rainy season, raised beds or mounds are made to facilitate drainage. The pits are filled with a mixture of farmyard manure (20-25 tonnes/ha) and top soil and basal dose of fertilizers are mixed with the soil. In summer season, pits of 60cm diameter and 45m depth are taken at a spacing of 2m in rows spaced at 4.5m. Furrows can also be taken at 4.5m spacing. Along these lines, long channels of 60cm width are formed for irrigation. Spacing The recommended crop spacing in Kerala is 4.5 x 2m. But in Tamil Nadu it is 2.5 x 2m. In Punjab it is 3m x 60cm. In West Bengal, the crop is sown at a spacing of 3.4m x1.8-2.5m.

Sowing
The recommended seed rate varies in different states. In Kerala and Tamil Nadu it is 1.0-1.5kg/ha, while in Punjab it is 3-5kg/ha. Two seeds per hill are sown on both sides of raised beds or furrows. In pits, 4-5 seeds are sown and pits are pot watered till germination. The seeds germinate in 7-8 days and after germination 2-3 healthy seedlings are left in each pit and other seedling are thinned out. After germination of seeds, the pits can be irrigated through channels once in three days.

Nutrition
The doses of manures and fertilizers depend upon the soil type, climate and system of cultivation. Various recommendations are furnished below:
Nutrients recommended for pumpkin in different states of India
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State Nutrients                                                                                          (kg/ha)
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                                                                                         N                                      P                                    K
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Punjab                                                                            100                                 50                                  50
Himachal Pradesh                                                         150                                100                                 50
Karnataka                                                                      100                                100                                 40
Madhya Pradesh                                                            60                                  50                                   50
Tamil Nadu                                                                     32                                   24                                   24
Assam                                                                               75                                  80                                   80
Kerala                                                                              70                                    25                                   25
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The remaining N is to be applied in two equal split doses at the time of vining and at the time of full blooming. Well rotten farmyard manure is applied as basal dose along with the full dose of phosphorus and potash and half dose of nitrogen. In general, high N under high temperature condition promotes maleness in flowering resulting in low fruit set and low yield. Excessive vine growth can be pruned manually to promote higher female to male ratio. This is not practiced in commercial growing and the best way to control the vine growth within reasonable limits is by adjusting fertilizer doses and frequency of irrigation. It is better to complete all the fertilizer applications just before the fruit set.

Irrigation
During flowering and fruiting stages, irrigation should be given on alternate days. During initial stages of growth, irrigation is given at an interval of 3-4 days Later irrigation may be given at 5-7 days intervals. Excessive irrigation at maturity is not desirable as it may adversely affect the storability.

Weed control
Regular weeding should be done. Herbicides can also be used for this purpose. According to Khurana et al. (1988), pre-plant incorporation of Besulide @ 4-6kg/ha or Alachlor 2.5kg/ha as pre-emergence can be used for weed control in pumpkin.

Use of Growth regulators
• A growth regulator, Ethrel can be applied to increase the female flower production which helps to increase the yield. The concentration of the chemical is very important. The recommended concentration is 250ppm (2.5m1 of Ethrel in 10 litres of water). The first spray has to be given when there are two-true-leaves (15 days after sowing). This is repeated once in a week for 3 more times.

Training
For trailing pumpkin, dried twigs are spread on the ground. During the time of manuring, raking of soil should be done. Then the plants are irrigated immediately.