By Gulzar Akhtar and Dr. Muhammad Aslam Khan
Hydroponics is a technique of growing crops in water instead of soil, containing all required nutrients for better plant growth because physiological requirements of the plants can be met without the use of soil and sunlight. There are two types of hydroponics, solution culture and medium culture. In solution culture no solid medium is used and plants roots are immersed in the solution. Solution culture method has three types static solution culture, continuous flow solution culture and aeroponics. In static solution culture, plants are grown in containers such as glass, jar, and tub containing the nutrient solution. These are may be aerated and unaerated. In unaerated static solution culture, solution level should remain below the plant roots so that roots above the solution can get oxygen. Nutrients level of the solution checked by electrical conductivity meter. If nutrient level is imbalance then fresh water or fresh nutrient solution is added to balance it. Clear containers are covered with aluminum foil, black paper or black plastic to prevent algae formation. In continuous flow solution culture, nutrient solution continuously flows from the roots of the plants. This is easier than static solution culture because of no need of regular adjustment of temperature and nutrient level of the solution. In this method, Nutrient film technique is used in which shallow water stream containing all required nutrients is continuously passed from the roots of the plants and provides adequate supply of water, nutrients and oxygen to plants. In Aeroponics no medium is required, plants roots are present in growth chamber and remains wet by mist of nutrients. Any plants can be grown in aeroponics for better growth and yield because it provides 100% supply of oxygen, carbon dioxide and nutrients to the roots, stems and leaves of the plant. In medium culture solid medium is used it also has different types, which named by the medium used. Rock wool, it is mostly used medium of hydroponics and free from action of microorganism, light in weight, have low cations exchange capacity making nutrients and water easily available. After usage rock wool can be used in bricks or to make new rock wool. Coco peat is also a medium made by outer shell of coconut after fiber removal. It is colonized with trichoderma bacteria for better growth and root protection. Perlite, a volcanic rock also used as good growing medium for hydroponic plants. It has properties similar to vermiculite but holds more air and less water. Gravels are also used as medium and these are same as used in aquariums. These are easy to wash, mange and inexpensive. Sand is a cheap easily available medium and has less water holding capacity.
Hydroponic techniques of growing crops are different from normal soil growing techniques. As in hydroponics inert and sterile growing media is used instead of soil, nutrients required for better growth are applied by dissolving in water, more plant growth and per area yield, decrease attack of insect pest and diseases, does not depends on climate, pH, nutrition level, light, temperature, humidity are controlled automatically.
Plant nutrients like N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, B, Mo and Cl are essential for plant growth and development. These nutrients dissolved in the water available in soil so plants easily take them by their roots. But in hydroponics soil is not used nutrients are dissolved in water to make solution and applied to the plants. The concentrations of nutrients maintained automatically according to plants requirement. Growth of plants can be increased or decreased by controlling carbon dioxide level and concentration of nutrients.
Hydroponics is very efficient technique to grow plants in water deficient and water saline conditions because in this technique rainwater is collected in big reservoirs where it clean to make it perfect for irrigation. Both water and nutrients are applied automatically to the plants. Light is also an important factor to control plant growth and development because in the absence of sunlight photosynthesis process will stop and ultimately plant growth will be stop. In hydroponics artificial light equal to spectrum and intensity of sunlight is provided to the plants for better growth. Other factors, which effect plant growth like temperature, humidity and carbon dioxide concentration are also maintained according to plant requirements.
Hydroponic is a good step to save our future because population is increasing day by day, which decreasing area under agriculture and increasing burden on agriculture to feed millions of hungry mouths. This situation can cause food shortage in future. To solve this problem we should search new ways to increase the quality and quantity of our agricultural products and make use of our barren lands. In Pakistan large areas of Thar desert, Thal and Cholistan in the provinces of Sindh and Punjab are barren due to absence of good quality water and soil. Normal agriculture is not possible in these areas but hydroponics is very suitable for growing good quality vegetables and other crops in these areas to fulfill the demand of local people and to export other country. In Pakistan hydroponic business is at embryonic stages to expand this business following should be taken in account.
Developing a well developed market for hydroponic products, creating awareness among the people, more short courses to produce skilled labour required for hydroponic business, more research to develop protocols of growing different crops by hydroponic techniques, government incentives to start hydroponic business, cooperation among private and government sector for increasing production and export of hydroponic products.