Fruit production and nutrient status in grapefruit on five rootstocks

A trial was conducted during two years (2000/01 and 2001/02) on two sites using 'Shambar' grapefruit trees grafted to five rootstocks. The sites were located on the Greek island of Kos to evaluate the effect of rootstock and location on fruit production and leaf mineral composition of 'Shambar' grapefruit. Results indicated that yields were higher in 2001/02 than in 2000/01 and these differences were greater at site 2. Leaf nitrogen (N), potassium (K), zinc (Zn), and to some degree phosphorus (P) content was slightly deficient to deficient for the majority of the samples taken. Calcium (Ca) and magnesium (Mg) levels ranged from normal to high. The copper (Cu) and iron (Fe) leaf contents and the manganese (Mn) content of most samples were in the optimum range. The interactions between rootstock, site, and year upon yield and nutrient content were statistically significant. There were also significant correlation coefficients between yield and nutrient content as well as among the nutrients.