Effects of spraying organic acid and foliar fertilizer on fruit quality of pitaya at harvesting period

【Objective】To explore effects of spraying organic acid and foliar fertilizer on the quality of pitaya，so as to provide reference for its application in actual production.【Method】The pitaya was used as the test material，organic acids （lactic acid，oxalic acid and citric acid），foliar fertilizers solutions（zinc，boron，calcium lactate，sugar alcohol chelated calcium and compound calcium fertilizer）were sprayed on the fruits and branches on the 3^rd，13^th and 25^th days after flowering and pollination，respectively，with spray water as the control（CK）to analyze its quality traits such as physical and chemical characteristics，edible characteristics，nutritional components and antioxidant capacity during the harvesting period.【Result】The results indicated that spraying zinc and sugar alcohol chelated calcium could significantly reduce the fruit cracking rate（P<0.05，the same below），increase the content of beet anthocyanins，total phenols and total flavonoids in pulp，enhance the total reducing power，ferric ion reducing antioxidant power（FRAP）and ABTS free radical scavenging capacity，and obviously improve the single fruit weight and fruit shape index. And the fruit cracking rate of pitaya treated with sugar alcohol chelated calcium decreased by 76.56%，the total reducing ability increased by 53.03% compared with CK，while the total flavonoids，total reducing ability and ABTS free radical scavenging ability of pitaya treated with zinc increased by 40.49%，49.54% and 42.21% respectively compared with CK. Spraying zinc also significantly reduced the titratable acid content of fruit，increased the sugar-acid ratio and DPPH radical scavenging ability. Spraying sugar alcohol chelated calcium could significantly increase citric acid content，increased the pectin content in pulp. Spraying lactic acid could significantly reduce fruit cracking rate and titratable acid content，and significantly increase sugar-acid ratio and DPPH radical scavenging ability. Spraying compound calcium fertilizer can increase fruit weight，fruit shape index，sensory score，reducing sugar content，sugar-acid ratio，total flavone content，significantly increase peel relative thickness，quinic acid，tartaric acid and citric acid content，and enhance the scavenging ability of FRAP and ABTS free radicals. Through principal component analysis，it was found that the comprehensive score of pitayas treated with compound calcium fertilizer was the highest.【Conclusion】The effects of spraying organic acid and foliar fertilizer on the quality of pitaya fruit are different. Comprehensive evaluation showed that compound calcium fertilizer was the best treatment，followed by zinc，sugar alcohol chelated calcium and lactic acid. In production practice，the compound calcium fertilizer can be considered to be mixed with other foliar fertilizers，and the effect is probably better.