Role and deficiency symptoms of phosphorous in grape

1. Role and deficiency symptoms of phosphorous in grape Soil phosphorous is divided into two classes, organic and inorganic. The concentration of phosphorous in soil is very low. Since P is associated with various types of plant metabolism, P deficiency leads to metabolic disorders. To insure proper growth and yield of grapevines, it is important to supply P exogenously. For correcting the deficiency of P, it is important to know the deficiency symptoms of P in grapevine. Hence, it is important to apply phosphorous judiciously by both organic and inorganic source as per the requirement of P to get higher yield without affecting soil health.

2. Objective After completing this lesson, you will be able to : Learn the role and deficiency symptoms of phosphorous in grapevine.

3. Role of phosphorous in grape Phosphorus (P) is an essential part of the process of photosynthesis. It involved in the formation of all oils, sugars, starches, etc. It effects rapid growth It helps with the transformation of solar energy into chemical energy; proper plant maturation; withstanding stress. It encourages blooming and root growth

4. Role of phosphorous in grape Phosphorus (P) is involved in the transfer of energy within plant cells that facilitate metabolism constituent of the fatty portion of cell membranes and of compounds involved. It also helps in assimilation and metabolism of carbohydrates It constitutes approximately 0.1 to 0.3% of dry matter of the vine, equivalent to 1.3 lbs per ton of grapes.

5. Deficiency symptoms Symptoms of P deficiency first seen on older leaves and the margin of the leaves turned golden yellow to light brown Central parts of leaves remained normal green with chlorotic areas becoming necrotic late in the season In extreme deficiency whole leaf blade dried up

6. Deficiency symptoms The higher level of phosphorus in shoots of Dashehari found favourable for flower-bud formation. Development of necrotic areas on the margins of leaves which become chlorotic and sheds heavily. Phosphorous deficiency caused fall of bloom and basal leaves turn yellow

7. Deficiency symptoms Red dots on basal leaves are appeared especially on the mid or terminal lobes due to phosphorous deficiency At later stage, red dots line up at right angles to the secondary veins and form dark red bars Alignment of red bars at right angles to the veins is a unique and most distinctive symptoms of P deficiency

8. Deficiency symptoms Reduced growth, dull green leaves, premature defoliation and pre mature berry ripening also caused by P deficiency Larger dark green leaves and violet-red anthocynin pigments on the petiole is also seen due to P deficiency Deficiency of phosphorus in vines can result in reduced vine vigor and yellowing of the interveinal area of basal leaves

9. Deficiency symptoms In extreme cases, some red discoloration of the interveinal area of basal leaves may be observed, followed by early defoliation of these leave These symptoms may be confused with leaf roll virus but phosphorus symptoms occur earlier in the growing season (flowering) Symptoms of phosphorus deficiency in a basal leaf of grapevine (Treeby et. al. 2004) Poor bud initiation and fruit set may also be observed

10. Toxicity of Phosphorus Excessive phosphorus has not been shown to be a direct problem for grapevines; however it may limit the uptake of other essential elements, such as zinc.