Physiological and biochemical responses for two cultivars of Pisum sativum (“Merveille de Kelvedon” and “Lincoln”) to iron deficiency conditions

The aim of this work was to compare the tolerance and the physiological responses to Fe deficiency of two Pisum sativum cultivars (“Merveille de kelvedon” and “Lincoln”) commonly cultivated in Tunisia. We studied the effects of Fe deficiency on: (i) chlorophyll content, relative growth rate (RGR) and Fe status, (ii) rhizosphere acidification, (iii) changes under Fe-deficient conditions in the activities of two root enzymes, the first related to the proton extrusion (H⁺-ATPase) and the second to iron reduction mechanism (Fe(III)-chelate-reductase: FCR). Three treatments were used: C, control, complete nutrient solution (CNS) containing 30 μM Fe; DD, direct deficiency, CNS without iron; ID, indirect deficiency, CNS containing 30 μM Fe + lime. Fe deficiency led to a significant decrease of chlorophyll content in both cultivars. The below reduction was observed in Fe-deficient plants of Merveille de Kelvedon. In addition, relative growth of shoots and whole plant was not affected by Fe deficiency. H⁺-ATPase and FCR activities were more stimulated in Merveille de Kelvedon than in Lincoln, under DD and ID Fe deficiency. The capacity of this cultivar to maintain plant growth and to preserve adequate chlorophyll synthesis under iron-limiting conditions is related to its better Fe-use efficiency, in addition to its high acidification and root reducing capacities. This allows us to suggest that Merveille de Kelvedon is more effective in overcoming Fe deficiency than Lincoln.