Effect of Nitrate and Ammonium Ions on the Pigment Content (Xanthophylls, Carotenes and Chlorophylls) of Ramalina Capitata

Abstract

Thalli of Ramalina capitata were sprayed with deionized water, 10 mM solutions of KNO₃ or NH₄Cl, or maintained without any water supply, for 10 days under controlled conditions. The lichens without a water supply showed an increase n antheraxanthin, lutein and β-carotene. The samples treated with deionized water showed a significant increase in violaxathin, antheraxanthin and β-carotene. The lack of a significant difference in zeaxanthin could indicate the absence of de-epoxidation of violaxanthin to zeaxanthin via antheraxanthin. Those samples treated with nitrate solution showed a significant increase in all pigments except for antheraxanthin. In contrast, ammonium treatment did not induce changes compared to water alone, except that antheraxanthin decreased. The lichens treated with nitrate exhibited a significant increase in both chlorophyll a and chlorophyll b, but ammonium affected only chlorophyll b.