Differential response of pea (Pisum sativum L.) genotypes to iron deficiency in relation to the growth, rhizosphere acidification and ferric chelate reductase activities

Calcareous soils are known problematic lands for agricultural systems because of the low availability of nutrients, particularly iron (Fe). The so-called strategy I plant (e. g. Pea, Pisum sativum L.) which groups dicotyledons and monocots other than grasses, developed root membrane activities that contribute to the improvement of Fe availability. Among the functions considered to be a critical phase in iron absorption is rhizosphere acidification by H-ATPase and Fe(III) reduced by Fe(III) chelate reducctase (FeCR). In order to experimentally investigate the importance of root FeCR in Fe nutrition, its relationship with rhizosphere acidification and the genotypic differences in response to iron deficiency in pea (Pisum sativum L.), a glasshouse experiment was conducted hydroponically on four genotypes Merveille de Kelvedon (MK); Lincoln (Lin); Douce de Provence (DP) and Alexandra (Alex). Plants of each genotype were distributed into two plots, the first one received full nutrient solution (+ Fe), the second one received nutrient solution devoid of iron (- Fe). Plant growth, Fe distribution, SPAD index and root acidification and ferric chelate reductase activities were evaluated. Fe deficiency decreased plant growth and SPAD index along with the significant increase of H-ATPase and FeCR activities. Some genotypic differences were observed as follows; Alex showed high tolerance to Fe deprivation as compared to other genotypes. Important H-ATPase and FeCR activities, high Fe use efficiency and adequate membrane efficiency are the main reasons for this tolerance. These physiological parameters could be used as tools of tolerance for further breeding programs