Effects of Excess Phosphorus Application on Passion Fruit Quality

抄録

To determine the effects of excess phosphorus (P) application on fruit quality, three-year-old passion fruit plants grown in sand culture with nutrient application of sufficient P at 3.5 mM were subjected to regulated P application treatment of 0, 1.3, 2.5, or 10 mM for three months. Just after harvest, fruit weight, dimensions, and peel color were measured. After a 10-day storage, titratable acidity (TA), total soluble solids (TSS), juice content, wrinkling degree, and juice P content were measured. Leaf mineral contents and SPAD index were measured. TA was the highest and the sugar/acid ratio was the lowest at the highest P treatment where 10 mM of P was applied, although there was no relationship between TA and juice P content. TSS was the lowest at terminated P treatment. Excess P application worsened peel color, while the wrinkling degree was not affected. Fruit weight and juice content were the highest at the highest P. Leaf P content was 0.2 % at P terminated treatment, and 1.2-1.6 % at the highest P treatment. No visible signs of P deficiency or excess were observed. Leaf Ca and Mn contents were higher at higher P treatment. The SPAD index and leaf N, K, Mg, Fe, and Zn contents were not affected. These results indicated that excess P application resulted in a deterioration of passion fruit quality, both in palatability and external appearance.