Control efficacy of Ca-containing foliar fertilizers on bitter pit in bagged Fuji' apple and effects on the Ca and N contents of apple fruits and leaves

BACKGROUNDThe preharvest application of Ca-containing foliar fertilizers can reduce the incidence of bitter pit (BP) in apples and improve fruit quality by increasing the Ca content and decreasing both the N content and the N/Ca ratio in fruits. In this study, we aimed to investigate the control efficacy of Ca-containing fertilizers on the incidence of BP and their effects on the Ca and N contents in bagged Fuji' apples by spraying foliar fertilizer containing calcium chloride (CaCl2), calcium nitrate [Ca(NO3)(2)] or calcium formate [Ca(HCOO)(2)] at an early stage, fivedays after full bloom (DAFB)and40 DAFB, and at a late stage, 80 DAFBand125 DAFB. RESULTSThe incidences of BP were reduced significantly by 43.2-73.0%, and the efficacy of spraying at an early stage was significantly higher than that of spraying at a late stage. The Ca content of bagged apple fruits increased whereas the N content and N/Ca ratio decreased after spraying Ca-containing foliar fertilizers; however, the Ca content, N content and N/Ca ratio of apple leaves were differentially influenced. CONCLUSIONFoliar fertilizer containing CaCl2, Ca(NO3)(2) or Ca(HCOO)(2) can be used at an early stage to control BP in apple and improve the quality of bagged apple fruits. (c) 2018 Society of Chemical Industry