Hydroponics Cultivation of Wheat
Authors: Vanita Pandey, Sneh Narwal, Rinki, Priyanka Chandra, Om Prakash Gupta, Sewa Ram and Kamal Gandhi
1. Dr. Vanita Pandey, Dr. Rinki and Dr. Om Paraksh Gupta, Scientist ICAR-IIWBR, Karnal.
2. Dr. Sneh Narwal and Dr. Sewa Ram, Principal Scientist ICAR-IIWBR, Karnal.
3. Dr. Priyanka Chandra, Scientist ICAR-CSSRI, Karnal.
4. Dr. Kamal Gandhi, Scientist ICAR-NDRI, Karnal.
In India, agriculture with its allied sectors, is undeniably the largest livelihood provider where a good number of the industries also depend upon it for their raw materials. India from an importer of food grains has now become an exporter of agriculture produce. Now in order to fulfill diverse objectives, agriculture should be internationally competitive, produce products of high quality while also meeting the sustainability goals. Also, to remain competitive, agricultural producers need rapid access to emerging innovative technologies like innovations in mechanical technologies, including robots, computers, and improved tractors, plus innovations in the application of water, pesticides, and herbicides which in-turn will inÂcrease agricultural output.
Hydroponics is defined as the science of growing plants in the absence of soil by providing them with chemical solutions containing artificial forms of nutrients, which the plants generally obtain from the soil. In hydroponics all the essential nutrients are provided in the form of solution for the normal growth and development of plants. Hydroponics is now considered an established branch of agronomic science where nutrient elements are mixed in specific solutions and in the amounts and proportions as required by different plants. The solution is brought into direct contact with the plant roots. In most plants, 20-50% of their total weight consists of roots. In some cases when plants are stressed by insufficient water or mineral nitrogen, as much as 90% of the plant biomass is located in the roots. On the other hand, in plants grown hydroponically with adequate water and nitrogen, only 3-5% of the plant biomass is represented by the roots. So in the case of parent lines in a crossing program, this cultivation method could benefit above soil development of plants. Seedling emergence is also an important factor for a breeder, because limited time and space also means that a reduction in emergence percentage can result in unnecessary delays within a breeding program. The opportunity to make certain crosses at critical times may also be lost because of emergence problems. Growing wheat hydroponically for plant breeding purposes may hold emergence, yield and seed quality advantages compared to traditional planting methods.
The hydroponic system consists of a frame, growth troughs and aeration, lighting, cooling, irrigation, supernatant collection and control units where the frame is constructed of angle iron. It also contains three independent recirculating nutrient film technique (NFT) units which are placed in an air-conditioned greenhouse where growth conditions are set suitable for wheat. High-pressure sodium lamps provide 80% of the 900 to 1200 mmol m-2 s-1 of the photosynthetically active radiation (PAR) that plants received 16 h/day while 20% of PAR was provided by ambient daylight. Temperature and relative humidity ranged between 23 to 28 Â°C and 60% to 70% for day and night, respectively for the duration of the experiment. Twelve plant-growth trays are divided equally among the three NFT units such that two trays per NFT unit were on each of two vertically separated levels. Hydroponic solutions are composed of the following inorganic salts (in mM): 4.51 Ca(NO3).24H2O, 3.48 KNO3, 1.15 KH2PO4, and 1.75 MgSO4.7H2O; and (in mM): 0.04 H3BO4, 6.75 MnSO4.H2O, 4.59 ZnSO 4.7H2O, 3.5 CuCl2.2H2O, 0.007 (NH4)6 Mo7O24.4H2O, and Fe provided by equimolar concentrations (89.5) of FeCl3.6H 2O and diethylenetriaminepentaacetic acid. Nutrient solutions in each NFT system are independently maintained at pH 6 by automatic controllers with the addition of a 0.5% (v/v) aqueous solution of HNO 3. The initial conductivity of fresh nutrient solution is between 1500 and 1700 Scm-1. As evapotranspiration depleted the nutrient solution in each NFT system, fresh nutrient solution is added weekly to maintain a constant volume in each system. Seeds of wheat are planted 12.5 cm apart in each hydroponic system. A cooling unit was designed to continuously remove the heat produced by the lamps to avoid heating of the nutrient solution.
Wheat seeds are surface-sterilized in an aqueous solution of 2.5% NaOCl (v/v) and 0.01% Tween 20 (v/v) for 15 min and rinsed three times with sterile deionized water. Then seeds are planted 12.5 cm apart in hydroponic system at two seeds per cube before being transplanted into the NFT systems. Wheat seedlings are transplanted at 10 days old and after transplanting hydroponic trays were flooded with 2.5 cm of standing nutrient solution for 3 to 5 days to help initiate root development into the plant-growth trays; after 5 days, nutrient solution was recirculated through each tray.
Benefits of Hydroponics
The method of growing crops in hydroponics is beneficial over soil culture due to several reasons. Hydroponics has garnered interest due to greater yield as compared to soil culture. Firstly, soil is not needed and a large number of plant populations can be grown in a very small area. Secondly, under optimum condition of nutrients maximum production can be attained. Thirdly, nutrients, water and aeration can be controlled to the highest degree. Also, since plants are grown in green house under artificial environment the adverse weather conditions, poor textured soil with lack of nutrients do not affect yield. Water in a hydroponic system can be recycled - at its most efficient a hydroponic farm only uses 10% of the water a normal farm uses. Because it's a closed system, nutrients don't leach away - an efficient hydroponic farm may only use 25% of the fertiliser a regular farm uses. Plus, eutrophication isn't a problem. Soil pests are non-existent, and in enclosed greenhouses natural predators can be used to control insect pests - next to no pesticide is required. This level of regulated growth is very difficult to replicate in soil culture.
In vegetables, it has been found that growth in hydroponic systems was accelerated and, the quality was better than that of soil grown crops. The hydroponic system provided a better emergence environment compared to the soil culture, indicating that there is a higher potential number of plants that can be established to make crosses. For all the measured yield and yield components hydroponic cultivation methods were very effective and superior to the potting cultivation method. In terms of biomass and the realization of yield potential the effect of the biomass relates to all the yield components, suggesting that for a plant to produce at optimum levels, it should be in the optimum environment. Thus, by using a form of hydroponic method, the optimum conditions can be obtained and maintained. The hydroponics cultivation is no doubt a costly and labour intensive venture but it can be used for uniform germination of wheat seedlings where they can be further transplanted in fields to realize maximum benefits. This can be crucial for crossing blocks and for seed multiplication. It can therefore be concluded that the hydroponic system is more effective than pots with soil in terms of emergence and yield, to grow wheat in the greenhouse.
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