Foliar application of molybdenum: effects on yield quality of the grapevine Sangiovese (Vitis vinifera L.)

Abstract

Field experiments with Sangiovese vines were carried out in the Chianti Classico region over a period of two years to examine the effect of molybdenum (Mo) foliar sprays on nutrient composition of leaves, petioles and berries, leaf gas exchanges, must composition, total yield, bunch size and pruning weight. Two Mo foliar doses and time sprays (Mox1: one application in early flowering; Mox3: three applications in early flowering, early fruit set and veraison) were applied. Basal sample of petioles, leaves and berries collected at fruit set (except berries), veraison and harvest for mineral analyses showed not relevant interactions between Mo and the main macro and micronutrients. Leaf gas exchanges monitored after the applications, as well as SPAD units, showed a higher activity in the Mox3-treated vines. Increased vigour was also confirmed by the slightly higher total yield, bunch size and pruning weight, as well as the delay in fruit maturation (lower sugar and polyphenol contents at harvest). No relevant discrepancy between Mox1 and the control was found, except for higher soluble solid and yeast-assimilable nitrogen contents (YANC) in the treated vines. YANC was positively influenced also in the Mox3 vines, however with no significant differences towards the Mox1 treatment. The application of Mo as a useful tool to stimulate nitrogen metabolism, as well as indications about dose and time of Mo application, are discussed.