Olericulture is a branch of horticulture that deals with production of vegetables. Importance of vegetables in human diet cannot be ignored these are major source of roughes that are helpful for digestion process. They also provide vitamins and minerals and also help to control cholesterol in our body. Many vegetables are famous for their low-caloric value being used by diet conscious people. Pakistani soils have capability to produce many vegetables; we have a long list of winter and summer vegetables. As with increasing population of the world and shortage of land for agricultural use coined the idea of producing vegetables in tunnels. This innovation is more useable for production of off-season vegetables. Hence production of vegetables out of their normal growing season. To produce winter vegetables in summer by creating an artificial environment is much costly so not practiced at high level in Pakistan. But production of summer vegetables in winter by providing them optimum environment in tunnels as the plastic sheets saves the energy of sun and does not allow them to go back and provides enough warmth for vegetable production. This technology is most famous with the name of tunnel technology. Normally the crops grown are cucumber, tomatoes, summer squashes, pepper and sweat pepper. By using this technology farmers can have their vegetable crop earlier and can earn more as compared to normal crop season. As potato and other vegetables from Sindh get more rate as compared to local varieties of different vegetables because winter season ends earlier and less chances of frost for optimum crop growth of many vegetables. Punjab agriculture department is also trying to enhance this technology by starting a project in Punjab. Main reasons to grow vegetables in tunnels to get more yields as compared to traditional methods of growing crops and particularly their harvesting before their normal growing season. These varieties having characteristic of growing vertical like hanging creeper are preferred, as they need less space to grow and flourish. Secondly this technology is more suitable for farmers having low holdings. By producing more vegetables in small area, we can meet our dietary requirements well and can also be able to export them. In last years we were forced to import many vegetables from India. It is shameful for an agrarian country to import basic necessitates rather than to produce in its own soil.
Environment of Punjab province is conducive for the production of many off-season vegetables. The optimum temperature range for tunnels production should not be less than 10c in coldest months of December and January. In these month crop growth become slow but with the onset of spring growth again comes to optimum level. Basic structure for tunnels varies in shape and sizes. Tunnels can be categorized in low and high tunnels mainly. Low tunnels cost less but not suitable for those areas, where the speedy air blows. These tunnels can be made by using mulberry sticks (shahtoot) and bamboo sticks. These tunnels are able to produce vegetable a month before their normal season. High tunnels are more permanent but they involve more capital. Structure of high tunnels can be made by using steel frame and also by bamboo structure. Height of this tunnel may be upto 12 feet. Their length are kept 130 feet and width 32 feet, row to row distance is maintained at 3 feet and plant to plant distance is kept 1.5 feet. In this way 8 tunnels can be made in a acre but if we change its specification to 30.180.12 (W.L.H) then 6 tunnels are made in a acre. In our local condition people use plastic sheets to cover the crop. Plastic costs less than glass and being used for a season but it serves the purpose. During foggy seasons the plant leaves remain wet for longer period and there are more chances for dissemination of disease. Proper fungicide should be used to avoid infection of various possible attacks. The main disadvantage of plastic green tunnel is that there is no way to regulate temperature, relative humidity and carbon dioxide level. For proper production of vegetables in tunnels fertile soils with PH range 5-7 are preferable. Well-decomposed organic matter should be added to increase fertility, porosity and water holding capacity of soil. Fertilizer requirements vary from crop to crop and type of soil but generally Phosphate should be given prior to planting, as plants need it in emerging stage. Nitrogen is applied at different level of crop growth, part of it as top dressing before planting along with phosphorus and potash. Fertigation is a term used for fertilizing along with watering is a good way to provide nutrients along with water. Proper irrigation is another important measure to obtain proper yield. But it mainly depends on crop and type of soil. In all circumstances it should be managed that plants may not bear water shock or water stress. For a uniform crop growth it is advisable to raise seedling in plastic bags and containers. Then these should be shifted to field in their appropriate season.
Production technology is different for different crops, but here for general information few important crops are discussed. Cucumber is most famous crop for tunnel production. It is being used as salad crop and famous for its low-caloric value. The fruits are picked before maturity and eaten fresh. Optimum germination time for its seedling is 3-4 days, and these are sown in last week of September for autmn crop. Its transplanting time in tunnels is start of October. Approximate time between its sowing and harvesting is 120 days. Its seed requirements for a kannal are 1800 seeds and sown in high tunnels. On an average one-plant yield 4 kg of fruit.6-8 tunnels/ acre are recommended. Though it is tough to maintain temperature in plastic tunnels, but the optimum temperature can be tried by opening tunnel opening at daytime for few hours. For proper growth of cucumber crop 21-24c day time temperature and 18-20c-night time temperature is required. If we maintain properly an acre of tunnel it may profit up to 2 lac rupees for a season. Recommended varities for cucumber are Rawa, Cannon, Speedy, Noble, Lona, Mansoor and Maxima.
Tomato is another important crop grown in tunnels; indeterminate hybrid cultivars are preferred for growing in tunnels. These are also sown in month of October – November . Optimum time between its sowing and harvesting is 120-150 days. Yield per plant ranges from 5-6 kg. High tunnels are recommended for tomato production. The side shoots are detached from main plants so that fruit may form at central branch. Recommended verities for tomato are Jewery, kolbery and Roma. In same season we can also grow tunnels for sweet pepper, pepper, and summer squashes. If we use high tunnel of iron structure along with drip irrigation system it may cost up to 120,000 rupees. But this system will be useful for almost 20 years. If we calculate all the tunnel expenditure excluding its structure those are not more than 50,000 rupees. On an average the cost of structure is fulfilled after 2 seasons. After initial investment one can earn more as compared to traditional way of farming. The utmost production in tunnels is also higher so these should be preferred to field cultivation of vegetables.
Tunnel farming is gaining popularity, and being practiced in many areas of Punjab like, Faisalabad, Mamokanjan, Gujranwala, Okara, Sahiwal. But still their cultivation is not at a level to be exported. Farmers are also unaware of their potential. Awareness programmes are helpful as Punjab government is already doing its effort to introduce this technology. But the goal is far ahead. Pakistani soils have capability to produce vegetable in such a huge amount that these can be exported. But it is impossible without practical help of Government, as vocational institutes should be established to promote such technologies and awareness programme should be launched to create importance of such practices. But an established market is needed to handle with production. As the farmers are increasing but markets are same. There should be some ways to manage higher future production. It should be thought that processing unit for waxing and packing of vegetables should be introduced at their production area so people may able to export their commodities as well as save them for longer use at local level. Progressive farmers in this field should be awarded to encourage them so they may utilize their enthusiasm for the future of the country. Still launching of cooling pads for production of winter vegetables is much costly to be afforded by farmers. Government should practically help the interested farmer and should provide them basic structure so that they might be able to increase vegetable production of Pakistan. If it will happen I assure Pakistan would one of the big exporters in field of agriculture and particularly in horticulture.