Hydroponics is the cultivation or growing crops in nutrient based water solution where the roots of the plants are exposed to the nutrient solutions. Growing plants in hydroponic culture can leads to more Biomass and Protein as compared to others growth cultures. Growing crops in hydroponics also takes lesser water and nutrients for their growth. It is also best way for cultivation of crops as they are probably less threatens by harsh climatic conditions.
Hydroponics Nutrients: Nutrients are one of the basic requirements of crops along with water, air, temperature, etc. They are directly affects the growth and development of plants. Their deficiency or toxicity can leads to changes in the plants and can be identified also. The plants grown in hydroponics are as much or more nutritious than the plants grown in soil because they are grown in sterile medium and precise control. They also require similar nutrients as the crops grown in the soil.
The major elements which are needed in hydroponics are N, P, K, Mg, P, Ca, Zn, Fe, B, Cu, S, Mn, Cl, Mo, Na, Ni, C, H, O. These elements are further divided into Macro and Micro nutrients.
The source of C, H & O is environment whereas other nutrients are absorbed from the nutrient solution in the hydroponics system.
C, H, O : Contains 90% of the total dry weight. These are the basic components of organic compounds. Plants take it in Co2, and H2O form.
Nitrogen (N): It is available 2-4% of total plant dry weight. It’s the major component of amino acids, proteins, coenzymes and nucleic acids. A plant takes it in form of Nitrate and ammonium.
Sulphur (S): It is available 0.50% of total plant dry weight. It is the major component of sulphur amino acids, proteins, coenzyme A. Plant takes it in form of Sulphate.
Phosphorus (P): It is available 0.40 % of total plant dry weight. It is the major component of ATP, NADP intermediate of metabolism, membrane phospholipids, and nucleic acids. Plants take it in the form of Dihydrogen phosphate, Hydrogen phosphate.
Potassium (K): It is available 2.00% of total plant dry weight. It is involved in enzyme activation, turgor and osmotic regulation. Plant takes it in the form of Potassium (K+).
Calcium (Ca): It is available 1.50% of total plant dry weight. It is involved in enzyme activation, signal transduction and cell structure. Plants uptakes it in form of Calcium (Ca 2+).
Magnesium (Mg): It is available 0.40% of total plant dry weight. It is involved in enzyme activation and it is also a component of chlorophyll. Plant uptakes it in the form of Magnesium (Mg 2+).
Manganese (Mn): It is available 0.02% of the total plant dry weight. It is involved in enzyme activation and essential for water splitting. Plant uptakes it in the form of manganese (Mn 2+).
Iron (Fe): It is available 0.02% of total plant dry weight. It is involved in redox changes, photosynthesis and respiration. Plant uptakes it in the form of iron (Fe 2+).
Molybdenum (Mo): It is available 0.00% of total plant dry weight. It is involved in redox changes and nitrate reduction. Plant uptakes it in the form of molybdate.
Copper (Cu): It is available 0.00% of total plant dry weight. It is involved in redox changes, photosynthesis and respiration. Plant uptakes it in the form of copper (Cu 2+).
Zinc (Zn): It is available 0.00% of total plant dry weight. It is involved as enzyme cofactor activator. Plant uptakes it in the form of Zinc (Zn 2+).
Boron (B): It is available 0.01% of total plant dry weight. It is involved in membrane activity and cell division. Plant uptakes it in the form of Borate (BO 3- ).
Chlorine (Cl): It is available 0.1- 0.2% of total plant dry weight. It helps in charge balance and water splitting. Plant uptakes it in the form of chlorine (Cl).
Nickel (Ni): It is available 0.000005- 0.0005% of total plant dry weight. It is a major component of some enzymes, biological nitrogen fixation and also nitrogen metabolism. Plant uptakes it in the form of nickel (Ni 2+).
pH
pH is also very important part if nutrients are being discussed. In Hydroponics it is very important to monitor the pH of water which is used to prepare the solution and irrigation of plants. pH basically measures the relative acidity and the concentration of hydrogen ion and it has an immense effect in plant nutrients availability. Its Point scale varies from 0 to 14 where below 7 scale show acidity, above 7 shows basicity and 7 shows neutral pH. It is a logarithmic scale, and each unit represents a 10-fold change which means if there is a small change in the values can cause large changes. And the optimum pH for hydroponically growing vegetable crops is 5.0 to 7.0.
Alkalinity of water is also important to be considered. Alkalinity basically measures the capacity which is used to mater the capacity of the water to neutralize the acid. This is due to the combined effects of carbonate and bicarbonate, but sometime hydroxide, ammonium, borate, silicate and phosphate also contributes.
The water shows low buffering capacity when the total alkalinity is low which results in the pH changes depending on the what is added into it. If the total alkalinity is high, the pH of the water will be high and we need to inject acid with irrigation water to decrease the pH level of the water i.e. the alkalinity of water decides the amount of acid required.
Antagonism and Interactions in Nutrients
Plant takes up the nutrients roughly depending on its availability in the solution. If the nutrient is in excessive amount, the plants take up it in an excessive at the expense of another nutrient. This is known as plant antagonism.
However in case of hydroponics there is a possibility of having sufficient amount of nutrients in the nutrients solution.
For example, if we are preparing a nutrient solution for any particular crop and we failed to calculate it’s correct proportion then there is a possibility of deficiency of one nutrient while the others will be in the excessive.
| Nutrient | Antagonistic with |
| Nitrogen | Potassium |
| Phosphorus | Zinc |
| Potassium | Nitrogen, Calcium, Magnesium |
| Sodium | Potassium, calcium, Magnesium |
| Calcium | Magnesium, Boron |
| Magnesium | Boron |
| Iron | Manganese |
Problems in Hydroponics nutrient solution
Hydroponics farming shows less forgiving nature than the normal agriculture system. It shows symptoms immediately in any nutrient problem. Therefore, the Hydroponics system should be monitored regularly and the composition should be accurate. Moreover, we should properly check if there any symptoms. Some of the symptoms includes:-
Soluble salts Damage: The major causes of soluble salts damage are over-fertilization, poor quality of water, accumulation of salts over a time in aggregate media and inadequate leaching. Fertilizers are mainly the salts, which easily get fertigated in the hydroponics system. When the water gets evaporated, the soluble salts get accumulated in the aggregate media if they do not get leached. The water used for irrigation is also rich in salts contributes to this problem.
Symptoms: This can leads to Chemical induced drought when there is high accumulation of soluble salts. This results in wilting of plants despite adequate irrigation. The other symptoms may include greening in the foliage, dead and burned leaf margins and death of root system.
Detection: We can measure the soluble salts level by tracking the electrical conductivity of irrigation water, nutrient solution and leachate.
Cure: Leaching of soluble salts can be done with clear water. Firstly, we have to identify the sources of high soluble salts level and then correct it.
Nitrogen Deficiency: The causes of nitrogen deficiency can be under fertilization, imbalance in the nutrients or excessive of leaching.
Symptoms: Its first deficiency is visible as light green foliage and the complete plant gets stunted. Wilting, dead or yellow leaf margins can be seen.
Detection: We can measure the electrical conductivity of the nutrient solution for prevention from this deficiency and also adjust the EC level whenever they are low or high.
Cure: We have to focus on the source to correct it. That means we have to add more nitrogen to the nutrient solution.
Phosphorus deficiency: It happens due to cold environmental condition or excess of iron in the growing medium.
Symptoms: It will causes weakness in stems, leaf and root growth slows down, and flowers and seeds to be either malformed or not develop at all.
Detection: The effects of phosphorus deficiency will be first seen in older parts of the plants. The damaged leaves initially appears as dark green to bluish green patches and when the conditions goes severe the foliage starts turning a red- purple hue. And in new leaves, their veins turn dark green in colour.
Cure: This problem can be corrected by adding more phosphorus through different sources like CSL and seabird guano can be used to provide large amount of soluble P when required
Potassium deficiency: The common cause of potassium deficiency is overwatering the plants as potassium moves freely within the plants from plants to the upper branches and leaves.
Symptoms: The growth rate of foliage, fruits and roots goes down. Browning and curling of the leaves starts and usually appears first on the lower leaves.
Detection: Potassium plays the major role in turgor pressure so by checking the turgor pressure in the plants we can detect the deficiency symptoms of the plant.
Cure: We can solve this problem by adding potassium bicarbonate or potassium hydroxide in 2.5 gallons of water. We can also add potassium in organic form by mixing water solution of ash, chicken manure or slurry of manure.
Calcium Deficiency : The deficiency of calcium usually affects the quality of new leaves or partially grown leaves . This deficiency may slows down the plant’s growth rate.
Symptoms: The deficiency of calcium starts with browning leaf margins of new plant growth or on the bottom of the fruit. Great examples of this are tip burn in lettuce and blossom end rot in tomato and pepper. As symptoms progress, you may see brown dead spots on the leaves.
Detection: It firstly observed in younger leaves and tissues, the growth is inhibited and plants will have the bushy appearance.
Cure: Raise the pH level of the solution, changes in the watering routine, or addition of calcium rich fertilizers, supplements or organic material.
Magnesium deficiency:Magnesium is related with the production of chlorophyll in plants which means leads to impact the plant’s ability to photosynthesise, which in turn directly affects the greenish colours of the leaves.
Symptoms: Cause inter-venial necrosis.
Leaf margins changes to reddish purple.
Reduced photosynthetic activity.
Reduction in enzyme activity.
Cause ageing of leaves.
Detection: The leaves will starts developing small yellow colour spots. Eventually the whole leaf will start turning yellow.
Cure: Adding solution of 1mL Humiboosta per 1L water to normal solution until the early flowering stage. To adjust the pH up to 6.0, a foliar spray of 1 mL CMX to 1L of water.
Sulphur deficiency: The effects of sulphur deficiency may appear first in the newer leaves and the tissues may have the stunted growth and a lighter green or even yellow appearance. This mainly affects the plant growth yield.
Symptoms: Reduction in protein and chlorophyll synthesis.
Young leaves become yellow from green colour.
Stem become spindly and short.
If not protected all plant become pale green.
Stunted growth of plant.
Detection: To test the sulphur deficiency the best analytical method is the plant tissue analysis.
Cure: Using sulphur based inorganic fertilizers such as Epsom salts for making the water solution.
Boron Deficiency : They are very rare in plants and occur often with the calcium deficiency. They mainly occurs in the plants which are under water conditions.
- Symptoms: Leaves develop dark brown colour.
Irregular lesion on leaves.
Whitish yellow leaves spots on the base of plants.
Stem become brittle and distorted.
Flower bud fails in flower formation.
Detection: It is detected by stunted growth and distortion of growing tips which leads to tip death, brittle foliage and yellowing of lower leaves.
Cure: The most common method is to add small amount of boric acid per gallon of water as a foliar spray.
Chlorine Deficiency: Deficiency of chlorine is leads to chlorotic and necrotic spotting along the leaves with abruption in its boundaries between dead and alive tissue.
Symptoms: Leaves margin become wilted.
- Highly branched root system.
- Spots on leaves.
- Having stubby tips.
- Leaflet tip blade wilting.
Detection : We can simply detect its deficiency by wilting of leaves at the margins. As the severity increases the leaves starts curling, bronzing, chlorosis and necrosis.
Cure: To cure chlorine deficiency in hydroponics we have to add chlorine containing fertilizers in appropriate amount.
Iron Deficiency:- It is one of the most common deficiency in hydroponics plants. It causes decrease in vegetative growth as well as marked decrease in yield and quality loss.
Symptoms: Iron deficiency shows up in plants as yellowing between leaf veins. Look for this symptom to show up first on new growth.
Detection: The iron deficiency is first visible in the youngest or newer leaves. The area between leaf veins becomes pale yellow or white.
Cure: Correct the pH of the nutrient solution. hydroponic basil was severely affected by iron deficiency. Once iron was added to the water, the new growth will not get affected.
Copper Deficiency:- Copper is an immobile nutrient which means the symptoms are first visible in the younger leaves. This deficiency affects the male fertility, plants growth and seed set.
Symptoms:-
- Chlorosis in young leaves.
- Stunted growth of plants.
- Cause delay in maturity of fruits.
- Irregular patches on leaves.
- Cause problem in reproductive stages.
Detection :- It’s visible in the foliage which are severely stunted as well as chlorotic. Deficient foliage gets cupped and deformed (Tung), bleached (lettuce), flaccid and blue green with chlorotic margins (tomato), abscise early (walnut), and eventually become necrotic in the interveinal areas (Tung).
Cure : We can cure it by maintaining the correct pH level or direct foliar spray of the nutrient solution. Or we can add fulvic acid products directly in the plants.
Molybdenum Deficiency : Molybdenum Deficiency starts with the older leaves which are at the bottom side. The leaves starts getting yellow and sometimes the whole plant gets light yellow in colour.
Symptoms:- The plant becomes stunted and the leaves show symptoms of nitrogen deficiency, appearing pale green or yellowish green in colour between the veins . The older leaves may be more severely affected with scorched edges.
The root nodule bacteria of legumes need more molybdenum to fix atmospheric nitrogen than the legumes need to utilise nitrates. In lucerne, clover and other pasture legumes, the main symptoms are associated with an inability to fix atmospheric nitrogen. Again, the stunting and yellowing are identical with nitrogen deficiency.
Detection :- The plant becomes stunted and the leaves show symptoms as of nitrogen deficiency, appearing pale green or yellowish green in colour between the veins . The older leaves may be more severely affected with scorched edges.
Cure:- BIOMIN MOLYBDENUM was developed foliar applications in Hydroponics. Completely bio-available and non-phytotoxic to plants when applied in accordance to directions. Designed to prevent and correct Molybdenum deficiencies and to boost crops during critical or fast growing periods
Zinc Deficiency : Hydroponic crops rarely develop zinc deficiencies, and as such have demonstrated significantly higher yields worldwide.
Symptoms
Zinc deficiencies come with diverse symptoms that often affect the youngest growth. You’ll notice stunted leaves, chlorosis, deformed leaves, necrotic spots, and leaves with wavy outlines.
- New growth will develop orange/brown necrotic spots.
- Patchy yellowing (chlorosis) will start at the base of the leaf before spreading towards the tip.
- Interveinal chlorosis
- Stunted growth, smaller leaf formation.
- Severe primary symptom could cause entire leaf to go brown.
- Leaves wrinkled, twisted or kinking
Detection : It starts as chlorosis due to the deficiency of zinc and will be visible over the entire leaf; whereas chlorosis due to zinc deficiency will be patchy and inconsistent.
Cure :- A foliar spray of Vitalize can also correct this problem. Mix 0.1ml of Vitalize to 1L of water, adjust to pH 5.5-5.8.
Nickel Deficiency: Minor nickel deficiency displays no visual symptoms, but can reduce growth and yield of plants. Significant nickel deficiency will display visual symptoms typically in the old leaves of the plants
Symptoms:-Its deficiency symptoms are chlorosis and inter-veinal chlorosis in young leaves leads to necrosis.
Detection:– It begins as the diminished lignin production in the plants, which is a component of cell walls that strengthens plants and contributes to disease resistance.
Cure:- We can cure this very easily and by the most effective strategy to correct acute Ni deficiency by foliar spraying with a dilute solution of NiSO4 or other water-soluble Ni fertilizer.