Why do plants exhibit deficiency symptoms

Curling of leaves upward along margins. Light green color on uneven chlorosis of young leaves. Brown or black scorching of new leaf tips and die-back of growing points. Growing points of stems and roots cease to develop. Poor root growth and roots short and thickened.

Interveinal chlorosis of new leaves followed by complete chlorosis and or bleaching of new leaves. Interveinal chlorosis of new leaves with some green next to veins. Short internodes and small leaves.

Rosetting or whirling of leaves. Interveinal chlorosis of new leaves with some green next to veins and later with grey or tan necrotic spots in chlorotic areas. Toxicity symptoms include reduced growth rate and necrosis along the main veins.

Toxicity symptoms start on the lower leaves and work up the main stem. The leaves die back to the stem. Interveinal chlorosis of new leaves with tips and edges green, followed by veinal chlorosis. Leaves at the top of the plant wilt easily followed by chlorotic and necrotic areas in the leaves.

Dieback of terminal shoots in trees. Symptoms develop as a yellow-tinted band around the leaf margins. The chlorotic zone becomes necrotic and gray, while the major portion of the leaf remains green. Due to deficiency of N, Mg, P, S. Poor quality of crops, including differences in protein, oil, or starch content, and storage quality. Yield differences detected only by careful experimental work. The visual symptom may be caused by more than one nutrient.

For example, N-deficiency symptoms may be identified, although S may also be deficient and its symptoms may not be readily apparent. B deficiency is accompanied by a red coloration of the leaves near the growing point when the plant is well supplied with K. Deficiencies are actually relative, and a deficiency of one nutrient may be related to an excessive quantity of another.

For example, Mn deficiency may be induced by adding large quantities of Fe, provided that soil Mn is marginally deficient. Also, at a low level of P supply, the plant may not require as much N compared to normal or adequate P. It is often difficult to distinguish among the deficiency symptoms in the field, as disease or insect damage can resemble certain micronutrients deficiencies. For example, leaf hopper damage can be confused with deficiency in alfalfa.

A visual symptom may be caused by more than one factor. For example, sugars in corn combine with flavones to form anthocyanins purple, red, and yellow pigments and their accumulation may be caused by an insufficient supply of P, low soil temperature, insect damage to the roots, or N deficiency. The question, then, is how best to eliminate hidden hunger. Testing of plants and soils is helpful for planning or modifying plant-nutrient programs to avoid this problem in subsequent crops.

In both approaches, careful consideration must be given to past management practices. Plant Nutrition :: Mineral Nutrition.

Nutrient Deficiency Symptoms of Plants Growing plants act as integrators of all growth factors and are the products in which the grower is interested. Nutrient deficiency symptoms may be classified as follows: Complete crop failure at the seedling stage. Severe stunting of plants. Specific leaf symptoms appearing at varying times during the season.

Internal abnormalities such as clogged conductive tissues. Delayed or abnormal maturity. Obvious yield differences, with or without leaf symptoms. Precautions in interpreting nutrient deficiency symptoms include the following: The visual symptom may be caused by more than one nutrient.

Hidden Hunger Hidden hunger refers to a situation in which a crop needs more of a given nutrient yet has shown no deficiency symptoms. What are nutrient deficiencies? Symptoms, cause and remedy Nitrogen deficiency Symptoms: Spindly yellow plants or yellow leaves, sometimes with pink tints. Cause: Nitrogen promotes green, leafy growth and deficiency results in yellowing and stunted growth.

Nitrogen is very soluble, so is easily washed out of the soil in winter rains, leaving the soil deficient in spring, just when plants are putting on new growth. Nitrogen deficiency is a common cause of yellow leaves in spring. Remedy: In the long term, mulching with organic matter such as well rotted garden compost or manure provides a steady trickle of nitrogen to stabilise levels. In the short term, applying high nitrogen fertilisers such as sulphate of ammonia or poultry manure pellets will remedy the problem.

Potassium deficiency Symptoms: Yellow or purple leaf-tints with browning at the leaf edge and poor flowering or fruiting. Cause: Potassium is needed for controlling both water uptake and the process allowing plants to harness energy from the sun photosynthesis. Potassium promotes flowering, fruiting and general hardiness.

Shortages are more likely on light, sandy or chalky soils where potassium is easily washed away. Clay soils, by contrast, hold potassium within their structure. Remedy: Apply high potassium fertilisers such as sulphate of potash, tomato feed or certain organic potassium sources derived from sugar beet processing.

Phosphorus deficiency Symptoms: Slow growth and dull yellow foliage. Cause: Phosphorus is needed for healthy roots and shoot growth. Soil shortages of phosphorus are rare, but may occur in areas with high rainfall and heavy clay soil. Remedy: Apply fertilisers such as superphosphate or bone meal.

Magnesium deficiency Symptoms: Yellowing between the leaf veins, sometimes with reddish brown tints and early leaf fall. Magnesium deficiency is common in tomatoes, apples, grape vines, raspberries, roses and rhododendrons.

Cause: Magnesium is needed for healthy leaves and for plants to harness energy from the sun photosynthesis. Soil shortages of magnesium are more common on light, sandy soils. This is because many deficiencies will present symptoms that look very similar to one another. Also, it is quite easy to mistake a nutrient deficiency symptom for other abiotic problems, such as pesticide drift, or a biotic plant disease.

As a rule of thumb, biotic problems tend to appear with asymmetrical patterns, while nutrient deficiency symptoms tend to be distributed symmetrically over the plant tissue surface. Plus, if plants are under additional stress e. The first step to visual identification of a nutrient deficiency is to determine where on the plant the symptoms are appearing. This will be dictated by whether the nutrient is mobile or immobile in the plant. A nutrient is considered mobile if the plant is able to move it from one part of the plant to another as it is needed.

In contrast, immobile plant nutrients cannot move to different parts of the plant. Therefore, deficiency symptoms of mobile nutrients will appear first in older parts of the plant Figure 1 , while symptoms for immobile nutrients will be seen first in new growth Figure 2. For example, symptoms of N, P, K and Mg deficiencies will manifest in the old growth because they are mobile, while symptoms of Ca, Cu, B, Fe, Mn and Zn deficiencies will appear in the new growth because they are immobile.

The next step to visual identification of a nutrient deficiency is to determine the characteristics of the symptoms. For example, leaves may appear chlorotic or yellow in color Figure 1 or there may be necrotic or dead tissue Figure 3.

Symptoms may also present on the leaf margins or tips Figure 3 or be interveinal Figure 4. The dichotomous key can be used to aid in the visual diagnosis of common nutrient deficiencies in plants when symptoms present first in old leaves Figure 5 or new leaves Figure 6.

Once a nutrient deficiency symptom has been identified, corrective actions, such as applying fertilizers or lime, can be taken. Before fertilizers are applied to the soil, a soil test should be completed to determine the nutrient status and pH of the soil.