Root growth of cultivated and "wild" olive in response to potassium mineral nutrition

Nutrient availability affects root growth. The effect of potassium (K) level on the root growth, weight, and elongation, as well as on nutrient content of the olive genotypes Megaritiki, wild olive, Chondrolia Chalkidikis, Biancolilla, and K utilization efficiency was investigated. For this purpose, a greenhouse experiment was carried out in the farm of the Aristotle University of Thessaloniki. Three treatments were used: T1, that is, 25% modified Hoagland nutrient solution without K in distilled water, T2: 25% modified Hoagland nutrient solution with 0.2mM K in distilled water, and T3: 25% modified Hoagland nutrient solution with 1.5mM K in distilled water. K concentration had no significant effect on root growth of olive genotypes. The maximum root elongation was observed in the wild olive, in the T3 treatment, and the minimum in Biancolilla, in the T1 treatment. K utilization efficiency significantly differed between K treatments for the same genotype, as well as among genotypes for the same K treatment, following the order: Megaritiki > wild olive > Chondrolia Chalkidikis > Biancolilla. Finally, significant differences were found with regard to the effect of K treatment and olive genotype on many macronutrient and micronutrient concentrations in leaves and roots.