Influence of Several Nutritional Balances on Olive Plant Development in Hydroponic Colture

A. Troncoso Centro de Edafologia y Biologia Aplicada del Quarto Sevi 11 a Spagna Two-year old, selfrooted olive plants (cv. "Frangivento") were grown in sand culture for three years with 7 nutritive solutions,which differed from the relative balances of couples of elements. Hoagland's solution was utilised as reference. Each thesis consisted in 24 plants, randomly divided in groups of six. Growth and leaves number and blade area were measured; on the central leaves of one year shoots the analysis for N,P,K,Ca and Mg was made at vegetation end (November) Mineral nutrition proved able to regulate vegetative development, and is at times represented by the nutritional status of leaves. The complete thesis (thesis 1) induced a good and constant growth; but it was surpassed by thesis 7, which had higher levels of P and was S deficient. High dos es of N are phytotoxic and determined the distal leaf edge necrosis first, and plants death later; its deficiency, ready detectable as N contents in leaves, stops growth. Particularly rapid and lethal is Ca deficiency, that causes the death of young leaves and apices. The dose of 1 meq of Ca++ in nutritive solutions (40 meq) is not sufficient to halt the process when symptoms are evident. The results of growth and foliar analyses with K and P deficiency on the third year are not clear, and on this subject the research should be perfected.