Rind texture and juice acid content of Citrus spp. as affected by foliar sprays of mono-potassium phosphate (MKP), urea ammonium phosphate (UAP) and mono-ammonium phosphate (MAP)

Abstract

Rind coarseness of fruit of Citrus spp. is a general problem in the Citrusdal region of South Africa (Western Cape Province), often limiting the percentage of exportable fruit. Acid content of the juice of Citrus fruit is an important determinant of juice quality, and fruit with too high juice content are not preferred by consumers. The effects of foliar sprays of 1%, 3% and 5% mono-potassium phosphate (MKP), 2% urea ammonium phosphate (UAP) and 1% mono-ammonium phosphate (MAP) applied 4 or 6 weeks after full bloom (WAFB) on rind texture and juice acid content of selected Citrus spp. on rough lemon rootstock were evaluated from the 1998/99 to 2000/01 seasons. Foliar sprays of MKP and MAP reduced TA of ‘Thoro Temple’ tangor when applied 6 WAFB, and MKP, UAP and MAP improved rind texture of the tangors (‘Nouvelle’ and ‘Thoro Temple’) and oranges (‘Shamouti’ and ‘Valencia Late’) without affecting juice and SS contents.