Soluble Solids and Titratable Acid Contents in Different Portions in Maturing Satsuma Mandarin Fruit as Affected by Water Stress

Abstract

The effect of water stress on soluble solids content (SSC) and titratable acid content in different portions of fruit was examined in maturing 'Okitsu' satsuma mandarin (Citrus unshiu Marc.). In the control fruit, the difference in SSC in the radial direction became greater as the fruit matured. The difference in acidity became smaller with maturation in the stylar end in the radial direction and at the outer portion in the axial direction. Water stress caused a 12% to 47% increase in SSC in all fruit parts, compared with the control fruit from 140 to 230 days after anthesis (DAA) ; it especially affected the stem end. Water stress caused an 11-17% increase in acid content in the central portion of the equator, and a 4-13% reduction in the outer portions from 190 to 230 DAA. Thus, it seems that overall water stress induces and increase in SSC and an increase or decrease in acid content in different portions of fruit.