How Manganese Deficiency Manifests in Rapeseed: Symptoms and Diagnostics

When growing rapeseed on soils with a neutral reaction, experts recommend seed dressing combined with microelements: boron at 0.2 kg/t and manganese at 0.3 kg/t. According to Hryhoriy Hospodarenko, Doctor of Agricultural Sciences and professor at Uman National University, writing in The Ukrainian Farmer magazine, manganese is essential for photosynthesis and carbohydrate synthesis due to its ability to change valence in redox processes.

Even with a slight deficiency of this element, plant growth is inhibited without obvious visual deficiency symptoms. In autumn, roots lack assimilates, remaining short, while plants stay stunted, increasing the risk of stand loss. In early spring, such rapeseed crops resume vegetation very slowly.

In cases of significant manganese deficiency, fat synthesis is disrupted, which weakens cell membranes and makes tissues limp and vulnerable. From the beginning of budding and intensely after flowering, the deficiency reduces oil content and quality. Due to impaired fatty acid synthesis, chlorosis appears between the veins.

Manganese is a component of enzymes affecting secondary metabolism, so its deficit disrupts stem lignification. This creates a high lodging risk despite short plant stature, and increases susceptibility to diseases like gray mold and phoma. Fully formed leaves show yellowish necrotic spots, with slowed development and poor pod filling.

Deficiency typically occurs on high-humus soils with pH > 6.0 during cold and wet weather, especially in autumn when root systems are underdeveloped and soils dry. Plant diagnostics at the 6th leaf stage should show a manganese content exceeding 40 mg/kg of dry matter.