Effect of Different Fertilizer Application Levels on Texture of 'Hakuho' Peach (Prunus persica Batsch)

Abstract

Effects of different fertilizer application levels on the flesh texture of peach fruits were investigated. Four-year-old 'Hakuho' peach trees trained to a central leader system were supplied with complete liquid fertilizers comprising higher (160 ppm), medium (80 ppm), or lower (40 ppm) levels of N. The fertilizer levels were lowered to half for each at the stone hardening stage. The fruit harvested from the H treatment trees reached the shipping maturity stage 4 to 6 days later than the fruits from the L and M treatment trees. The flesh firmness of the H treatment fruit was significantly lower than those from the M and L treatment fruits when compared at the shipping maturity stage in each treatment. The flesh softening was apparently accompanied with increased ethylene emission from the fruit. The flesh of the H treatment fruits contained higher levels of water-soluble pectin and cellulose, and lower levels of HCl-soluble pectin and starch than those from the M and L treatment fruits at the pre-mature stage. In addition to that, a higher level of K and a lower level of Ca were analysed in the flesh of the H treatment fruit than the other treatments. These results indicate that the peach fruit grown under using a high amount of fertilizer application deteriorates the flesh texture at the time of harvest mainly because of the unbalanced mineral nutrition and delayed fruit ripening than the normally fertilized fruits.