Investigating the Relationship of Soil Properties and Leaf Element Concentration with Qualitative Characteristics of the Washington Navel Orange Fruit in Darab Region, Fars province

Many factors including climate, type of rootstock, soil properties, geological factors, plant nutrition and irrigation affect the quantity and quality of orange fruit. In this study, the relations between citrus orchards conditions, their soil properties and leaf elements concentration and fruit quality were evaluated. The experiment was conducted as a randomized complete block design and soil, fruit and leaf samples were collected from six different regions of Darab, Fars, Iran. After fruit sampling, land properties such as physiographic features, slope, gravel, altitude and soil physical and chemical properties such as percent of sand, silt, clay, organic matter, calcium carbonate, pH and electrical conductivity and also N, P, K, Fe and Zn availability were determined. Several morphological and qualitative characteristics of fruit including, rind and flesh weight, rind thickness, length, diameter, fruit granulation, flavor, sugar and fruit juice acidity were determined. The contents of N, P, K, Fe and Zn in the collected leaves were determined. Three random samples were taken for each orchard and each replicate consisted of one tree. Results showed that fruit weight was correlated with the land slope, soil pH, electrical conductivity, soil organic matter content, soil N, P and K and leaf K content. Rind thickness showed a significant positive correlation with parameters such as land slope, electrical conductivity, organic matter, silt, clay and soil N, P and Zn and leaf N and K content. However, there was a significant negative correlation between rind thickness and soil gravel and sand contents. The relations between fruit granulation and soils calcium carbonate, gravel, organic matter content and soil K concentration were significant. TSS to TA ratio in fruit juices had significant negative correlation with land altitude, soils silt, calcium carbonate contents and leaf K content. Generally, many soil properties had significant effects on fruit quality but it seems that soil texture, organic matter, pH, P and K were more effective on fruit quality.