Fruit nutrient accumulation of four orange varieties during fruit development

Evaluation of nutrient accumulation trends in fruit during fruit developmen t and nutrient status in the leaves are important components defining nutri ent requirements. Such nutrient demand should be met by nutrient supply in order to develop optimal rate and timing of fertilizer application. In a 3- year study the citrus (orange) varieties, 'Valencia', 'Parson Brown', 'Haml in', and 'Sunburst' were fertilized with either 168, 224, or 280 kg N ha(-1 ) yr(-1) as a broadcast application of N:P:K dry soluble granular fertilize r. These rates did not significantly affect the fruit nutrient status, juic e quality, or nutrients concentrations in the spring flush. The concentrati ons of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magne sium (Mg) in the fruit decreased with their enlargement during June through November. However, micronutrient concentrations in the fruits increased fr om June through August or September and then decreased. Fruit dry weight wa s greatest in 'Valencia' followed by 'Hamlin', 'Parson Brown', and 'Sunburs t' varieties. Soluble solids concentration (SSC) were higher in 'Valencia' and 'Sunburst' fruit than in the other two varieties. Other juice quality p arameters were not significantly different among the varieties. This study indicated non-significant influence of fertilizer rates on concentrations o f various mineral elements in 6-month-old spring flush with most of those c oncentrations within the optimal ranges.