Manganese (Mn) deficiency

Manganese (Mn) deficiency affects photosynthesis and protein synthesis. Mn-deficient plants are often deficient in Phosphorus.

Mn deficiency is relatively rare especially in irrigated rice systems and also not common in rainfed or lowland rice because the solubility of Mn increases under submerged conditions.

It occurs frequently in upland rice. Soils particularly prone to Mn deficiency include acid upland soils , alkaline and calcareous soils with low organic matter status and small amounts of reducible Mn, degraded paddy soils containing large amounts of active Iron (Fe).

Damage by Mg deficiency, could be very severe throughout the growth stage of the crop.

Affected plants are more susceptible to brown spot disease. Also, Mn deficient rice plant also deficient in Phosporous as well.

How to identify (Symptoms)

• pale grayish green interveinal chlorosis spreads from the tip to the leaf base
• necrotic brown spots develop later and leaf becomes dark brown
• newly emerging leaves are short, narrow, and light green

Manganese deficient plants are shorter, with fewer leaves, less weight, and have smaller root system at tillering. Plants are usually stunted but tillering is not affected.

How to manage

 

• Apply farmyard manure or straw (incorporated or burned) to balance Mn removal and enhance Mn(IV) reduction in soils containing small amounts of Mn and low organic matter status.
• Use acid-forming fertilizers, e.g., ammonia sulfate [(NH4)2SO4] instead of urea.