Muhammad Umar
M.Sc Scholar Institute of Horticultural Sciences, University of Agriculture Faisalabad
Email: umar_1879@yahoo.com
Cell: 00923466520724
Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil (Anonymous, 2011a). Terrestrial plants can be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk. The hydroponic systems may be classified under eight headings like surface watering technique, sub-irrigation, wick system, grow bag technique, soak and drain, rockwool technique, drip feed technique and nutrient film technique. Generally seven types of cultures are commonly used in hydroponics including water culture, sand culture, gravel culture, vermiculaponics, horticultural rockwool culture, hydroculture and aeroponics (Anonymous, 2011b). There are several advantages of hydroponics production like less labour input, light manual operations than soil cultivation, lack of crop rotation, competition for nutrients, minimum wastage of water, no weeds, all seasons production and very less or no usage of pesticides. But along with advantages there are several disadvantages or limitations of hydroponics including high initial capital investment, high degree of management skills, difficult to manage at large scale, nonstop energy requirements to maintain system and very much dependent on nutrient solution temperature (Daha. 2006).
A variety of crops can be grown using hydroponics/soil-less culture. In vegetables lettuce, kang kong, tomato, egg plant, green bean, capsicum, bell pepper and cucumbers, in fodder crops sorghum, alphalfa, barley, in cereals rice, maize, in fruit crops strawberry, in ornamentals anthurium, merrygold, coleus, roses, carnations, orchids, chrysanthemums and in medicinal crops alovera can be grown by using hydroponics (Douglas.1975)
One must keep some precautions in his/her mind while dealing with hydroponics. First precaution is high temperature during mid afternoons in green/ net houses and under protective covers. Adoption of closed system of hydroponics where the solution is recycled to reduce such rise in temperature to some extent. Second precautions is less penetration of sunlight to inner rows of hanging bag and grow bag techniques resulting poor growth and low yield. Third precaution is pollination. As protected structures effectively prevent insects reaching crops, pollination by insects does not take place in the protected structures (Daha. 2006).
As experienced in normal crop husbandry, pests diseases also affect hydroponics plants and they also show physiological as well as nutritional disorders under unfavorable conditions. First and most observed physiological disorder in hydroponics is blossom end rot of tomato. It appears at the bottom end fruits, brown, sunken leathery spots appear. Second most important physiological disorder is concentric fruit cracking of tomato. Concentric cracks appear around the fruit stalk or cracks extending from fruit stalk appear. High day temperatures, large differences between day and night temperature and sudden change in growing media moisture content are the causes of this condition. Shrink cracks of bell pepper is also an alarming physiological threat in hydroponics. Fruit crooking of cucumber is a serious physiological disorder in cucumber. The curvature of known as fruit crooking begins at early stages of fruit development and may be caused by adverse temperature, excessive moisture in growing medium, poor nutrition, excessive fruit load or insect damage (Jones. 1977)
Increasing the temperature of water supplied to spinach during winter improved growth and yield of the crop. It has been reported that in hydroponics, root temperature can be controlled by warming the nutrient solution and thus providing the heat energy requirements for optimum plant growth and development (Calatayud et al., 2008)
Flooded I. aquatic plants produced plenty adventitious roots at the stem bases that promote oxygen diffusion to the roots and facilitate nutrients uptake (Yamamoto et al, 1995).
Use of plant uptake and plant-mediated conversions also has great potential for the removal of nutrients from nutrient enriched waters. Recently, there is an increased interest in integrating treatment systems and production systems based on the common-sense approach of conversion of wastes into products. By integrating these techniques, it is possible to reduce wastes and associated environmental impacts, and at the same time generate an additional crop (Naegel, 1977; Quillere et al., 1995; Rakocy et al., 2006).
Rate of growth of S. oleracea L. and biomass increased with increased water temperature, an indication for possible increase in yield when grown at higher temperatures during winter in controlled settings (Nxawe. 2009). Kankung and mukunuwenna in hydroponics, specially in NFT and Grow bag cultures, exhibit faster growth and greater marketable yield, giving a satisfactory turnover for the grower. (Weerakkody. 2002). I. aquatica and L. sativa are promising species to be included in integrated hydroponic and aquaculture facilities. Brassica varieties did not grow well at water-saturated conditions and therefore has less potential. (Trang et al., 2010)
Hydroponics or soil-less culture is relatively a new system of growing plants which helps reduce dependency on labour, threat of insect pest & diseases and efficient use of water. But due to certain limitations like high initial cost, some nutritional as well as physiological disorders and difficulties to maintain long term commercial hydroponic system, it is not well adopted to our country.
References:
Anonymous, 2011a. Hydroponics. http://en.wikipedia.org/wiki/Hydroponics. Retrieved on 23 October 2011 Anonymous, 2011b.http://www.techno-preneur.net/information-desk/sciencetech-magazine/2007/jan07/Hydroponics.pdf . Retrieved on 2 November 2011
Calatayud, A., E. Gorbe, D. Roca, P. F. MartÃnez. 2008. Effect of two nutrient solution temperatures on nitrate uptake, nitrate reductase activity, NH4 + concentration and chlorophyll a fluorescence in rose plants. Environ. Exper. Bot. 64:65-74.
Daha, M. 2006. Growing Edge: 9(2): 37-38
Douglas, S.J. 1975. Hydroponics: Bombay: Oxford UP. (5) pp:1-3
Harris, D. 1992 . Hydroponics (Key to sustain agriculture in water): New Holland Publishers
Jones, L. 1977. Home Hydroponics & How To Do It: Crown Publishers, Inc. New York, N.Y.
Naegel, L.C.A. 1977. Combined production of fish and plants in recirculating water. Aquaculture.10:17-24.
Nxawe, S., C. P. Laubscher and P. A. Ndakidemi. 2009. Effect of regulated irrigation water temperature on hydroponics production of spinach. Afr. J. Agric. Res. 4(12):1442-1446
Rakocy, J.E., M.P. Masser and T.M. Losordo. 2006. Recirculating aquaculture tank production systems: aquaponics-integrating fish and plant culture. SRAC Publication No. 454. Southern Regional.
Trang, N. T. D., H. H. Schierup and H. Brix. 2010. Leaf vegetables for use in integrated hydroponics and aquaculture systems: Effects of root flooding on growth, mineral composition and nutrient uptake. Afr. J. Agric. Res. 9(27):4186-4196.
Weerakkody, W.A.P., N.A.K.G.E. Kumari, W.M.S.M. Bandara, R. Drisa and O. I. Oladele. 2002. Appropriate hydroponic systems for growing leafy vegetables in greenhouse. Nig. J. Hort. Sci. 7(1):707-712
Yamamoto, F., Sakata and T. Terazawa. 1995. Physiological, morphological and anatomical responses of Fraxinus mandshurica seedlings to flooding. Tree Physiol. 15: 713-719.Aquaculture Center. Texas A & M University, Texas, USA.
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