Department of Agriculture and Animal Sciences, Tribhuvan University, Lamjung, Nepal
Received date: 03/12/2021; Accepted date:16/12/2021; Published date: 23/12/2021
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Plant nutrients are the elements that are either constituted in plant body in the form of metabolites or externally supplied to the plant for plant nourishment, growth and effective metabolism. Cucumber requires altogether 14 nutrients to complete one life cycle. Its Carbon and Hydrogen requirement is fulfilled from air while Nitrogen, Phosphorus and Potassium are major macronutrients; calcium, magnesium, sulphur, sodium, iron, molybdenum, copper, boron, zinc, manganese and chlorine are essential nutrients that Cucumber uptakes from soil. In Nepal, Cucumber is cultivated in all ecological belts primarily in lowlands than uplands and one of the reasons why agriculturists do not totally invest in commercial cultivation of Cucumber in larger scale in uplands is poor growth behavior as a result of poor soil nutrient. Nutrient deficiency symptoms can be clearly identified by planting crop varieties in Nutrient Omission Plots. If in case plant shows any nutrient deficiency symptom, specific nutrient must be externally supplied to the plant.
Macronutrient; Micronutrient; Metabolites
Cucumber, one of the most important members of cucurbits in Nepal, is very popular among Nepalese consumers as it is used in various forms, such as salad, pickle and cooked vegetable. At present, it has subsistence as well as commercial importance, but it is a potential crop for processing in the future. Generally, it is difficult to define absolutely the quantity of each individual nutrient which is optimal to assure growth and development of the plant. In fact, nutrient content in plant tissues varies with species, cultivar, growth stage, part of the plant, and composition (ratio between nutrients and chemical form) of the nutrient solution.
Roles of Nitrogen: In the cucumber, nitrogen absorbed before the harvest began was translocated to the secondary lateral branch that newly appeared in the fruit enlargement term. It can be considered that the nitrogen absorbed in the vegetative growth phase is important in the occurrence of the lateral branch in the fruit enlargement term, and that the condition of nitrogen nutrition before the harvest influences the occurrence of the lateral branch.
Deficiency symptoms: Growth is stunted and the foliage fades to yellowish green. The discoloration is most pronounced in the lower leaves. Occasionally the mesophyll around the main veins remains green for some time contrasting with the yellow veins. Flowers are relatively large. N severe deficiency the whole plant turns yellow to almost white; cotyledons and lower leaves die, and younger leaves stop growing. Cucumber fruits of variety Sporu were short, thick, light or grayish green and spiny, whereas normal fruits were dark green and smooth. Report short abnormally shaped, pale yellow fruits pointed at their blossom ends.
Reasons behind Deficiency: When the application rate is less than the threshold, the plants and soil microbes would compensate for the soil nitrogen and external input, hence the reactive nitrogen losses response is steady. When it exceeds the threshold, the surplus nitrate availability in soil leads to increasing nitrogen leaching; and enhances nitrous oxide emission because of increasing nitrification and denitrification.
Management: The doses of N were split among three applications at 15, 30 and 45 days after plant emergence. Each plot contained ten plants with 0.2-m spacing between plants and a 0.8-m spacing between rows. The four central plants in each plot were evaluated, and the following assessments were performed: leaf N content, relative chlorophyll index, stem diameter, fruit length, fruit diameter, number of fruits, fruit fresh mass, fruit dry mass, shoot fresh mass, production per plant and total yield.
Role of phosphorus: Leaf and main stem development, number of fruits per plant, and harvest index were enhanced by increasing P levels in all studies.
Deficiency symptoms: Phosphate starvation significantly decreased growth of shoots and mass of roots, whereas root elongation growth was enhanced (diameter of root decreased). Intensity of root elongation was most pronounced at the beginning of culture on P-deficient medium and remained similar even after transfer to full nutrient medium. Phosphate-deficient cucumber plants had higher acid phosphatase activity both in extracts from roots and leaves and in root exudates when compared to samples from phosphate-sufficient plants.
Reasons behind Deficiency: Application of P fertilizers is the most common practice to address the problem of low-P availability in agricultural soils. However, this practice is confronted with daunting challenges of immobilization/precipitation of applied P with soil constituents, depletion of nonrenewable P sources, and high cost of P fertilizers. Available P in most of soils may constitute < 0.1% of total soil P In P-deﬁcient soils, the use efﬁciency of applied P is very low and >80% of applied P may be ﬁxed on soil constituents or precipitation with Ca, Fe, and Al compounds and thus becomes unavailable to the plants
Dicarboxylic acid copolymer-coated fertilizer P product significantly improved crop yields compared to the normal P fertilizer source. Crop may experience a short-fall in P supply due to slow-release of the P. Main use of such products would be in situations where P is at risk of loss by leaching such as the coarse-textured soils in high rainfall regions and soils prone to P fixation.
Potassium andRole of potassium: Potassium plays a key role in plants including activation of enzymes, water balance regulation, energy and protein synthesis, K is involved in photosynthesis and osmotic pressure regulation.
Deficiency symptoms: Early symptoms of K deficiency were observed two days after the omission of K in the nutrient solution. They were characterized by chlorosis in the blade’s apical edge of intermediary leaves from primary and secondary rods, progressing to the center of the leaf, in tissues located between the veins. Symptoms are those found by.
Reasons behind Deficiency: The maximum rate of potassium uptake was lowered by ammonia during both, long- and short-time treatment. The results indicated that the NH3 influence on potassium uptake was due to effects on metabolism and permeability of roots because changes of K uptake rate occurred immediately after starting the NH3 treatment. Furthermore, it is shown that ammonia inhibited respiration of roots.
Management: To promote vegetative growth and vigor-Decrease K N ratio by increasing N.Specifically, the proportion of ammonium-N can be increased to promote vegetative growth. However, ammonium-N should always remain less than 14% of the total N.
Role of calcium: Therefore, among macronutrients, Ca is in greater proportion in the middle lamella of the cell wall as pectate, contributing to cell expansion and elongation.
Deficiency symptoms: Ten days after the omission of Ca, with the development of the deficiency, there was an intense necrosis of the tissue located in leaf edges, forming a tip-burn, a characteristic symptom of Ca deficiency. In addition, it was possible to observe necrotic tendrils and symptoms of apical rot, a physiological deficiency of various fruit vegetables caused by an inadequate concentration of Ca in the affected tissues.
Reasons behind Deficiency: According to, Ca deficiency in fruit can also be due to various physical.
Physiological: firstly, the high temperature and solar radiation, which increase leaf photosynthesis and this increases the supply of photo-assimilates to the fruit, an increase in cell. Expansion of the fruit on the other hand, the deficiency of oxygen in the substrate, extreme temperatures, low supply of Ca, high contribution of NH4+, high concentration of soluble salts (EC), high N supply, low humidity, high breathability in the foliage, low Ca uptake by roots under the fruit Ca transport, restriction xylem development, little deposition of calcium in the distal the fruit.
Management: Uptake can be enhanced by applying calcium in the soluble form (i.e., calcium nitrate or calcium chloride, either of which is immediately available for uptake). With many rapidly growing crops, insoluble sources will not provide adequate calcium fertility.
Role of Mg: Magnesium is a plant activator of many enzymes. Almost all phosphorylases and kinases require Mg2+ activation. Mg2+ promotes the hydrolysis of ATP or ADP and releases phosphoric acid and energy. It also activates ATPases, promotes phosphorylation, and synthesizes more ATP.
Deficiency symptoms: The early symptom of Mg deficiency was observed five days after its omission from the nutrient solution and it was characterized by a slight chlorosis among secondary veins of intermediary leaves. (28)
In advanced stages of Mg deficiency, the chlorotic lesions among veins advance to the disintegration of the mesophyll. Therefore, only the unchanged external cuticle remains, causing the whitish appearance of leaves .
Reasons behind Deficiency: Magnesium deficiency which is coursed by excess fertilization and excess irrigation and leads to declining production and quality appears more and more frequently. The average magnesium content in the earth's crust is 219 g/kg. Due to the weathering of the magnesium-bearing minerals, magnesium is leached. Especially, long-term unbalanced crop fertilization (NPK) led to Mg2+depletion, cation competition, and subsequent Mg2+leaching. When potassium is high in soil or potassium is applied, inhibition of magnesium absorption may stem from two aspects: on the one hand, cationic competition effect, especially potassium, inhibits magnesium absorption. Because K+as a monovalent ion-pair colloid has a lower affinity for divalent Mg2+than exchangeable Mg and thus inhibits the utilization of Mg2+it reduces Plant-to-plant uptake when there is more K+in the soil Magnesium absorption; the other may be due to the Mg2+ from the root to the ground part of the transport process blocked.
Management: With large rainfall, the content of water-soluble magnesium in soil increases and the mobility of magnesium increases. When lime and superphosphate are used in soil, magnesium will reduce the speed of movement.
Role of Fe: Iron plays a significant role in various physiological and biochemical pathways in plants. It serves as a component of many vital enzymes such as cytochromes of the electron transport chain, and it is thus required for a wide range of biological functions. In plants, iron is involved in the synthesis of chlorophyll, and it is essential for the maintenance of chloroplast structure and function.
Symptoms: Interveinal chlorosis in younger leaves is a symptom of iron deficiency. Reasons behind Deficiency Furthermore, a C-N hydrolase family protein has been identified in cucumber roots, and its concentration increased under Fe deficiency
Management: Plants mainly acquire Fe from the rhizosphere. Although Fe is one of the most abundant metals in the earth's crust, its availability to plant roots is very low. Fe availability is dictated by the soil redox potential and ph. In soils that are aerobic or of higher pH, Fe is readily oxidized,