What follows is a description of visual symptoms related to specific nutritional deficiencies commonly found in crops. While useful as a starting point to diagnosing production problems, keep in mind that multiple nutritional disorders often occur simultaneously. To understand your soil better consider doing a soil analysis to determine which nutrients are deficient in your soil.
Why do plants need Nitrogen?
Protein is essential for all living organisms, and is required for growth and development. Nitrogen is one of the main elements in protein, Nitrogen is also a component of nucleic acid, DNA, RNA, genes, chromosomes, enzymes, chlorophyll, secondary metabolites (alkaloids), and amino acids. Nitrogen accounts for about 1 to 6 % of plant dry matter, depending on the species.
Nitrogen deficiency slows down the growth and development of plants. The plants appear stunted with light green lower leaves, while the upper leaves remain green, With prolonged N deficiency, yellowing (chloro-sis) of older or lower leaves occurs. This is followed by leaf tip death and leaf margins developing a brown discoloration (necro-sis). In some instances the leaves fall off. The plant sterns become woody.
Why do plants need Phosphorous?
Phosphorus provides energy in the form of ATP and NADPH for plant metabolism (photosynthesis and respiration). Addi-tionally, it is a component of DNA, RNA, nucleotides and cell membrane.
Initially, plants appear darker green with reduced growth affecting the leaf size and stem thickness. As the deficiency con-tinues, the older, lower leaves develop irregular spots of brown to dark brown dead tissue. In some plants, reddish to purple pigmentation may appear on the under or upper surface of leaf margins, lower leaves, and stems. Eventually. leaf death of older leaves may occur. In most cases, lack of phosphorus delays flowering in plants.
Why do plants need Potassium?
Unlike nitrogen and phosphorus, potassium is not a component of plant organic matter. Potassium is important for movement of sugars, starch formation, pH stabilization, drought tolerance, cell turgor, enzyme activation, and regulation of stomata opening and closing.
The leaves of potassium deficient plants are small and dark green. The plants have short internodes resulting in compact plant appearance. These symptoms are followed by a sudden development of irregular necrotic tissues along the leaf margins and tips of lower, older leaves and eventually covering whole leaves, making the leaves appear scorched. Also, leaves curl downwards.
Why do plants need Calcium?
Calcium is required for cell wall structure and cellular signaling. Calcium is important in cell division, cell expansion, building of cell walls, stomatal regulation, and cold tolerance.
Unlike other nutrients, lack of calcium generally affects the growing points and young leaves of the plants. The young leaves we-often twisted or wrinkled. The growth is reduced with tiny black spots appearing around the mid-leaf area of young leaves and on the tips of very young leaves. In some cases, these black spots appear o the growing points. Abortion of flowers c flower buds is common if calcium is unavailable during flowering. During fruiting lack of calcium can result in fruit cracking, water soaked tissues or blossom end rot. (tomato).
Why do plants need magnesium?
Magnesium is a core component of chlorophyll (pigment of photosynthesis). Magnesium is also important in enzyme and cofactor reactions. It is involved in the metabolism and movement of carbohydrates and stabilizing cell membranes.
Normally magnesium deficiency symptom appear in lower, older leaves with chloro. sis of greenish yellow to yellowish green developing along the leaf margins and tips which progresses inward between the lea-veins. As the deficiency prolongs, necro! develops between the veins and the leap, curl downwards, Eventually, leaf and pla death may occur if the magnesium defi-ciency continues.
Why do plants need sulfur?
Sulfur is essential in protein synthesis sir it is a constituent of some essential emir acids such as cystine and methionine. Sulfur is also involved in plant photosynthesis and respiration.
Initally, uniform chlorosis of light greenish yellow pigmentation develops anywhere between the young and mature leaves, but rarely on lower, older leaves. As the symptoms advance, uniform chlorosis spreads to rest of the leaf area.
Why do plants need Iron?
Iron is an important component of heme and sulfur proteins. DNA and RNA synthesis is restricted under iron deficient environment. Iron is also involved in chlorophyll formation. Iron is considered an immobile element in the plant, and as a result, iron deficiency symptoms develop on young leaves and shoots.
Generally young leaves develop interveinal chlorosis, from the base, but in some as from the tip. Over time, interveinal chlorosis intensifies and the pattern becomes less interveinal. Even the stems appear chlorotic. At this point, the chlorotic symptoms are irreversible even if correctional measures are taken. Eventually, yellow gives way to white. The bioavailability of Fe is pH dependent; the lower the pH higher the solubility and hence the ability of iron to plants.
Why do plants need Manganese?
Manganese plays a significant role in photosynthesis. The formation of free en radicals during water splitting and ultimately the release of oxygen is not possible under Mn-free environments. Mn is the only element that can contribute the necessary electrons for this biochemical process.
The young and recently matured leaves develop chlorosis followed by stippling of necrosis on recently matured leaves. Drastic reduction of shoot and root growth is common. Flowering is strongly inhibited. Environmental factors such as sunny summer months, greenhouses built close to traffic areas and ozonated water used in irrigation/fertigation may contribute to
Why do plants need copper?
Copper plays an important role in quenching the radicals produced during biochemical processes. It is also a component of proteins and enzymes that are critical in producing ATP the “Biological Currency’. Copper is required for lignification, especially xylem formation, and its mobility is moderate to immobile within the plant.
Initially, the young and maturing leaves appear stunted. In some species a tinge of bluish-green appears, especially over the veins. This is followed by impaired flower development that includes reduced size, premature abscission, or abortion. Sudden death of tissue, with symptoms similar to localized tissue dehydration, develops on recently mature leaves as a result of poor xylem tissue development. Chlorosis is generally not a distinguishing feature.
Substrate with high pH or alkaline water may contribute to Cu deficiency. Symptoms appear initially at the base of the leaf and spread toward the margins.
Why do plants need zinc?
Zinc is an integral component of protein; so far, over 80 zinc-containing proteins have been reported. One of them, referred to as “Zinc Fingers’, is actively involved in DNA transcription. This means protein synthesis requires Zinc.
Young and recently matured leaves develop puckering, veinal chlorosis, and necrosis. Some plants develop purple pigmentation. Shoot and root growth is reduced. A high level of P in the substrate induces Zn deficiency. Zn availability is reduced by high pH and bicarbonates (HCO3-).
Why do plants need Boron?
Boron is required in plants for cell division, cell wall formation and stabilization, ligni-fication, xylem differentiation, membrane integrity, auxin activity, inhibition of callose formation, nucleic acid metabolism, apical meristem function, pollination and repro-duction, and counteracting the toxic effects of Aluminum. The critical B concentration varies among species, and B requirement during the developmental stage is greater than vegetative stage. Almost 90% of plant B is contained in the cell wall.
Like Calcium, Boron disorders develop on the shoot and root meristem, and on young leaves. The symptoms develop on the roots 3 to 4 days earlier than the shoot. Overall, the roots are thick and short while primary roots develop thick swollen root tips with numerous short secondary roots develop-ing close to the tip giving a “witch’s broom” symptom.
Meanwhile, foliage becomes darker and glossy. Young and recently matured leaves become thick, leathery and brittle with se-vere distortions. Loss of apical dominance is a common symptom in the root and shoots. At this point, it is too late to take any correctional measures.
Why do plants need molybdenum?
The requirement of Molybdenum for healthy plant is only 0.1 ppm in the form of Mo(VI) and is available only at high pH (> 6.8). It is involved in the initial step of inorganic nitrate (NO3) assimilation. There-fore, Mo is critical when nitrate is supplied rather than ammoniacal (NH4- N) N. It is important in the biosynthesis of the phyto-hormone abscisic acid, which is required in drought conditions.
Generally, the symptoms appear on the middle and older leaves with interveinal mottling and marginal chlorosis. Eventually, the symptoms progress to upward curling and necrosis of leaf margins. The symptoms are accentuated whenever nitrate-nitrogen (NO3-N) is the sole source of N, and under such conditions, the symptoms of Mo deficiency are similar to N deficiency.
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Adopted from Floriculture Directory 2017 – 2018