Effect of KNO3 sprays to flowering mango trees on fruit retention, fruit size, tree yield, and fruit quality.
Oosthuyse S. A.
Author Affiliation: Merensky Technological Services, PO Box 14, Duivelskloof 0835, South Africa.
: 359-366
Abstract : In South Africa, the mango cultivars Tommy Atkins, Kent and Heidi retain few fruits compared with Sensation, Irwin and Keitt. During 1993, the effects on fruit retention, fruit size, tree yield, and fruit quality of KNO3 applications to flowering 2- to 3-year-old Tommy Atkins, Kent and Heidi trees were investigated. A KNO3 spray at 2 or 4% was administered either once, when inflorescences were flowering, or twice, when inflorescences were actively extending and when they were flowering. In Tommy Atkins, the greatest increase in fruit retention occurred following a single 4% application of KNO3. In Heidi, 2 KNO3 applications of 4% resulted in the greatest increase, and in Kent, 2 applications of 2% increased fruit retention the most. In every cultivar, slight reductions in average fruit weight (final fruit size) were associated with the increases in fruit retention. KNO3 increased tree yield in each cultivar. The greatest increases in yield corresponded with the greatest increases in fruit retention. There was no apparent effect of the KNO3 sprays on fruit quality (ground skin colouration, total soluble solids content, pH or taste on ripening). Inflorescence application of KNO3 to the cultivars tested is now adopted commercially in South Africa.