engleski

Leaf macronutrient accumulation and fruit size in apples (Malus domestica L.) influenced by the year, nitrogen rate and fruit load

The influence of weather conditions, nitrogen fertilization and fruit load was investigated in apple orchard (cultivar Idared, grafted on M9 rootstock) on southern side of Baranja Mountain in eastern Croatia, during three years (2002-2004). Design of the experiment was split-plot with 4 nitrogen doses (0-control, 30, 60 and 90 kg N ha-1, starting in the year 2001) and 3 fruit load pattern (not regulated- control, 50 and 100 fruits tree-1 defined by hand after June drop). Macroelement (N, P, K, Ca, and Mg) concentrations in leaves as well as fruit diameter and fresh mass were determined at harvest. Drought conditions in the year 2003 led to the lowest N accumulation in leaf, stimulated K and Ca accumulation, and restricted fruit diameter and fruit fresh mass. Higher N doses and fruit load reduction significantly increased fruit size. Consequently, leaf N concentration showed positive relations to fruit size parameters. However, P and K concentration were negatively correlated while Ca and Mg showed no relations with fruit mass and diameter. This investigation pointed out the significance of climate conditions in the efficacy of nitrogen nutrition in apple orchards, whereas fruit load regulation can improve source-sink ratio and mineral supply in stressful environmental conditions.

apple ; fruit load ; fruit size ; mineral content ; nitrogen

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