Marginal chlorosis

Marginal chlorosis is a physiological disorder in plants characterized by the yellowing or bleaching of leaf margins. Unlike pathogenic infections, this condition is primarily driven by abiotic stress, nutrient imbalances, or toxicity issues, leading to the failure of the plant to maintain chlorophyll production at the periphery of the leaf tissue.

This condition frequently affects various crops, including legumes like the peanut. In peanuts, marginal chlorosis is often a diagnostic marker for potassium or magnesium deficiencies. When left unmanaged, the impairment of the photosynthetic surface area drastically restricts the plant's ability to allocate energy to seed development and pod filling.

The progression of the disorder typically begins at the tip of the leaf, moving steadily along the margins towards the base. If the stressor persists, the affected areas transition from yellow to brown, resulting in necrosis and tissue death. This process can significantly reduce the overall leaf area available for photosynthesis, especially during the peak growing season.

Several environmental factors catalyze the development of marginal chlorosis, most notably soil salinity, high pH levels that render nutrients unavailable, and water scarcity. Excessive application of certain fertilizers can also create an ion imbalance in the rhizosphere, hindering the uptake of vital micronutrients required for cellular homeostasis.

Effective management and protection strategies rely on identifying the root cause through soil and plant tissue testing. Key measures include:

• adjusting fertilization programs to correct specific nutrient deficiencies,
• implementing proper irrigation scheduling to maintain moisture,
• monitoring soil electrical conductivity to avoid salt stress,
• using foliar stimulants during high-stress growth stages.