Strategie sostenibili a confronto nella prevenzione della clorosi ferrica

Iron (Fe) deficiency-induced leaf chlorosis is the main nutritional constraint for successful production of pear orchard cultivated in calcareous soils when grafted on quince, depressing fruit yield and quality and shortening the orchard lifetime as well. The study was aimed to evaluate the effectiveness of sustainable strategies in preventing iron chlorosis in field conditions. A 3-year trial was carried out in a mature commercial pear orchard (cv Abbé Fetel/BA29) located in the Po Valley (Italy). The following soil-applied treatments were compared: 1) untreated control; 2) soil Fe-chelate; 3) compost; 4) injection of synthetic vivianite; 5) acqueous extract of A. retroflexus and 6) acqueous extract of A. retroflexus enriched with FeSO4. During the experiment, unfertilized plants showed severe leaf Fechlorosis symptoms effectively prevented by Fechelate and, to a less extent, by vivianite which increased the soil Fe concentration (DTPA). Compost increased significantly the leaf chlorophyll content, soil microbial biomass and soil Fe concentration. The supply of A. retroflexus extract improved tree Fe nutrition uptake, particularly when enriched with FeSO4. Fe-chelate supply increased yield, while fruit weight, leaf K and Mn concentration were decreased. With exception of compost and vivianite, all strategies raised fruit RSR at harvest