TUNNEL farming is the production of off-season vegetable crops and fruits, which is rare in Pakistan.

Over the last few decades, the area of growing off-season vegetables under tunnel farming had increased, with Punjab having 40,000 acres out of 55,000 acres across the country. Now the acreage is falling. Recently, tunnel faming area in Punjab dropped to 30,000 acres owing to abrupt changes in weather and product quality concerns.

The purpose of tunnel farming is to grow vegetables inside the polythene tunnels so that proper atmosphere may be given to plants for their maximum growth and yield when these are impossible to be grown in open fields from December to February due to low temperature and high frost levels.

However, plant growth and produce of tunnel farming is correlated with environmental factors such as light, relative humidity, temperature, carbon dioxide, water and nutrients. Fluctuations in any of the environmental factor whether in low level or in excess results in reduction in plant vigour status and poor quality produce.

Sunlight is the major source of energy for plant growth. However, this not a problem in Pakistan unless dirty plastic/glass covers are used or winter is prolonged with foggy conditions. In foggy conditions, carbon dioxide shortage may occur when tunnels/ glasshouses are 100 per cent sealed off from the outside which could produce poor yield and quality even though harvested earlier or later.

Controlling the environmental factor completely needs miracle of science but can raise serious quality concerns. There are many quality concerns of vegetable produce via tunnel farming.

• Polythene sheets will retain more of the greenhouse gases to increase the inside temperature of tunnels for earlier production of vegetables. This results in improper/tender product within a short period of time. Each crop has specific time for its development and in this mode the time period is artificially reduced.

• Growers of tunnel farming claim that it is ‘environmentally friendly produce’ which is not exactly right because in open conditions, soil and crops emit certain gases back to the atmosphere when the fertilisers, pesticides and other agro-chemicals are used. In case of tunnels, all the toxic concentration of gases remains inside the tunnels which affect the vegetable produce and human health, consequently. If one wants to produce environmentally friendly crops, one has to focus on organic agriculture in open fields.

• The two stated factors result in improper photosynthetic or organic compounds and can be tasted when cooked. For example, cauliflower grown in open fields and those from tunnels will definitely taste different.

No doubt, tunnel farming is advantageous in controlling diseases, resulting in high yield and earning but produce quality is not up to the mark because it is affected by pollution. Therefore, the issues should be addressed properly and focus should be on modern organic agriculture rather than costly investment in tunnel farming.