Effects of exogenous calcium on mineral contents in pomegranate leaves and pericarp during fruit development

Abstract:【Objective】Calcium is one of the essential macronutrients for plants and functions in signaltransduction and constituent of the cell wall. Add exogenous calcium timely can promote the absorption ofpotassium, phosphate and nitrate during plant growth and development. In this study，exogenous calciumwere sprayed on pomegranate leaf and pericarp to find the effects of exogenous calcium on contents of theother several essential nutrients，during the whole development period. Then provide some theoretical basis for production of fertilizer.【Methods】‘Taishanhong’pomegranate trees were sprayed with differentconcentration（1，5，10 g·L^-1）of calcium nitrate solution in the 4th weeks after full blooming for the firsttime，then once every 4 weeks. Both the leaves and fruits were sampled to detect contents of potassium，calcium，magnesium，iron，manganese，copper and zinc, respectively. Effects of different exogenous calcium concentration on the leaves and pericarps were compared with the control which sprayed with water on⁃ly during the growth period.【Results】Exogenous calcium can significantly increase the calcium contentin both of the leaves and pericarps，the calcium content increase with the exogenous calcium concentra⁃tion in a certain concentration extent. Exogenous calcium increased magnesium content in pomegranateleaves and pericarps，and the higher concentration of 10 g·L^-1 exogenous calcium nitrate had the most significant influence on magnesium content in leaf in all the growth period，while the medium concentration 5 g·L^-1 had more remarkable impact on magnesium content in the pericarps. Medium and higher concentration of exogenous calcium changed the curves of iron content in pomegranate leaves during the growthperiod，iron contents presented a tendency of straight climb with the growth period，iron contents increase significantly in the pomegranate leaf in later developmental stages，and it had no significant effecton the peel. Exogenous calcium reduced copper contents to a certain extent in pomegranate leaves.【Con⁃clusion】Effects of exogenous calcium were different on the element contents of pomegranate leaves andpericarps，with the concentration of exogenous calcium changed the influences were different in a certainconcentration range（1-10 g·L^-1）. Foliar spraying calcium fertilizer improved the calcium content in theleaf and fruit skin，it also had certain promotion or antagonism effect to the potassium，magnesium，iron，manganese，copper，zinc contents. It played different roles in pomegranate leaves and pericarps with differ⁃ent spraying concentration and spraying period.