Floriculture sector is generating higher income and employment opportunities, promoting domestic market and exports. The traditional flower crops grown for loose flowers under open field conditions have different nutrient requirements compared to cut flower crops like roses which are grown under protected conditions. One of the factors affecting the productivity of most of the floricultural crops is due to improper use of nutrients. To improve the productivity, adequate amount of fertilisers in balanced proportion should be used.
Integrated Nutrient Management (INM) including use of mulches, organic manures and bio-fertilisers along with appropriate dosage of fertilisers is cost effective method to achieve more yield and better quality crop, besides, improving the soil fertility.
Application of appropriate plant nutrients at proper time with suitable method is one of the strategies to reduce various losses of nutrients which, in turn, increase the nutrient use efficiency. Deficiencies of nutrient elements cause various physiological disorders in flower crops and can be corrected by the application of appropriate nutrients. It is imperative to make a mention that the productivity of flower crops can be very low because of improper use of nutrients, unavailability of quality planting material, lack of adoption of proper planting methods and other agrotechniques. One of the means to improve the productivity is to use adequate amount of fertilisers in balanced proportion which may be very expensive but must be given more attention by the flower growers or floriculturist. The available information regarding proper use of fertilisers is very much scattered in flower crops in particular.
It is well known fact that balanced nutrition is essential for the growth, development and flowering of crops. All the elements play important role both in the vegetative and reproductive growth and are indispensable for production of foliage and flowers. As nitrogen, phosphorus and potassium are required in large quantities and hence, affect plant growth more as compared to other mineral nutrients. In addition to these, secondary nutrients like calcium, sulphur and magnesium are also needed in fairly large quantities than the other essential elements such as iron, manganese, zinc, copper, boron, molybdenum and chlorine. Some of them e.g., nitrogen, phosphorous and sulphur are consumed in building up the plant architecture while calcium, potassium and magnesium have both tissue building and metabolic functions. However, other essential elements such as boron, iron, manganese, copper, zinc and molybdenum have metabolic functions in the plant life.
| Nutritional deficiency disorders in Roses | |||
| Crop | Nutritional Deficiency | Symptoms | Management |
| Rose | Iron |
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| Boron |
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| Magnesium |
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In general, the micro-nutrients are found naturally in the soil in sufficient quantities, whereas the macronutrients are deficient in the soil and needs continuous supply. The availability of these nutrients in soil depends upon the soil pH. Iron, zinc, manganese, aluminum and copper are available at low pH (5.0 – 7.0), whereas the availability of boron decreases at < 5 and > 7 pH. However, availability of molybdenum is maximum at pH6.5. Chelated compounds are used to increase the availability of micronutrients and make them available to the plants. Recommended manures and fertilisers are conventionally applied to the soil either as basal dose or top dressing. However, foliar nutrition is an effective method of applying nutrients for better production in floral crops. The metabolic function of all the elements required for the plant growth and development are well described.
Nutrient Deficiencies and Disorders Flower Crops
Deficiency leads to morphological variation, which results in low productivity of quality flowers. The deficiency symptoms of nutrients can be corrected through foliar feeding. The easy key for identification of deficiencies of macro and micro nutrients in general is summarised in Nutritional disorders are basically physiological disorders in the plants that affect the productivity as well as the quality of flowers. Disturbance in the plant metabolic activities resulting from an excess or deficit of environmental variables like temperature, light, aeration and nutritional imbalances result in disorders. Nutritional disorders have become widespread with diminishing use of organic manures, unbalanced NPK fertiliser application and extension of horticulture to marginal lands.
Therefore, proper application of nutrients/ fertiliser is important to prevent the crop from these disorders. Various disorders of flower crops and their symptoms is given.
| Table 2 – Elements, concentration and their role in plant metabolism | ||
| Elements | Quantity in whole plants | Function |
| Carbon | 45% | All cellular constituents |
| Oxygen | 43% | All cellular constituents |
| Hydrogen | 6% | All cellular constituents |
| Nitrogen | 3-5% | All living matter, amino acids, proteins |
| Potassium | 1.5-3% | Enzyme system in the change of sugar to starch, citric acid synthesis, in the change of amino acids to proteins, respiration, interaction with iron enzymes, photosynthesis, buffer |
| Calcium | 0.1-3.5% | Cell wall, cell permeability, buffer |
| Sulphur | 0.05-1.5% | All living matter, proteins, nodulations in legumes, allyl oils of mustards, chlorophyll synthesis |
| Phosphorous | 0.25-0.5% | All living matter, nucleo proteins, lipids, phosphorylation enzymes |
| Magnesium | 0.05-0.7% | A part of the chlorophyll molecule, enzyme activator of hexokinase, phosphorylase, carboxylase, dehydrogenase, peptidase, photosynthesis, buffer |
| Chlorine | 100-300 ppm | With Na and K it helps in maintaining cation anion balance |
| Iron | 10-1500 ppm | A part of the porphyrin compounds cytochrome enzyme system, chlorophyll synthesis |
| Manganese | 5-1500 ppm | Chlorophyll synthesis, stabilisation of H- atoms split from H-OH by hydrogenation in photosynthesis, reduction of nitrates to nitrites, activator of arginase, carboxylases and dehydrogenases |
| Zinc | 3-150 ppm | Tryptophan synthesis, phosphorylation enzymes, enzymes in chloroplasts |
| Copper | 2-75 ppm | Enzyme in synthesis of ascorbic acid, activator of polyphenoloxidase, lactase and oxidase |
| Boron | 2-75 ppm | Phosphorylation enzymes, glutamine synthesis, nodulation in legumes |
| Molybdenum | Very less | Nodulation in legumes, tannin synthesis, reduction of nitrates to nitrites |
Application
Both organic and fertilisations have beneficial effects on growth, development and flower production. The review on nutrition related work during last three decades indicate the significance of developing various technologies for increasing quality flower production. Each of the mineral elements is specific in its functions in plant metabolism. In order to maintain proper health and sustain production of roses, it is essential to apply the accurate fertiliser at correct time in appropriate amounts. The nutritional requirement varies with cultivars, soil type and its fertility status.
Nitrogenous fertilisers are more important in vegetative growth and phosphates help in production of more and good quality blooms. Although some soils are quite rich in potassium, the potash fertilisers in combination with others give good results.
Balanced feeding with nitrogen and phosphorous impart vigour to the plant, enhance flower yield and quality. The optimum dose of nitrogen and potassium and right amount of phosphorous provides a better vegetative growth with higher yield.
It is well known that nearly 60-70 per cent N of total nitrogenous fertiliser is lost during transformation of ammonical form of nitrogen to nitrate form. For increasing fertiliser, nitrogen use efficiency, there is a need to limit the rate of ammonium oxidation.
Although a number of nitrification inhibitors are available nowadays, but all of them have limitations in their usefulness in one or other way. Application of nitrogen along with encapsulated calcium carbide (CaC2), a nitrogen inhibitor, result in better utilisation of applied N by the rose plant and also markedly affect flowering, flower quality and flower yield.
The secondary nutrients also play an important role for the improvement in production of quality rose flowers. It is observed that, the soil application of calcium, magnesium and sulphur appreciably affect the vegetative growth of roses. Magnesium increases the stem length, bud size, flower diameter and number of petals per flower. Magnesium and calcium applications increase the longevity of intact flowers. Application of fertilisers in solution form to the soil or hydroponics or in fertigation is practiced for obtaining good exhibition blooms. The advantage of this method is that nutrients solution reaches the plant root for immediate utilization. Foliar application of nutrients not only rectifies the nutrient deficiency but also increase the flower production.