The Influence of Medium Heterogeneity and Three Rootstocks on Growth and Nutrient Levels of Greenhouse-grown ‘Valencia’ Orange Trees1

Abstract

Abstract One-year-old ‘Valencia’ orange [Citrus sinensis (L.) Osbeck] trees on rough lemon (C. limon Burm. f.), Carrizo citrange [Poncirus trifoliata (L.) Raf. × C. sinensis], and sour orange [C. aurantium (L.)] rootstocks were transplanted into 4 soil media and grown in the greenhouse for 2 years. Treatments were 1) the entire pot filled with 2 sand: 1 sphagnum peatmoss: 1 perlite (v/v/v); 2) the entire pot filled with 3 red clay: 1 sand (v/v); 3) the lower half of the pot filled with sand: sphagnum peatmoss: perlite and the upper half with clay: sand; 4) the lower half of the pot filled with clay: sand and the upper half with sand: sphagnum peatmoss: perlite. The trees were grown from February to October 1979 when the tops were cut off. A single shoot was allowed to regrow and the trees were harvested again in October 1980. The largest trees were on rough lemon rootstock; trees on Carrizo were slightly smaller, those on sour orange distinctly smaller. Trees on sour orange grew very poorly in treatments 1 and 4 when the whole medium or the upper layer was sand: sphagnum peatmoss: perlite. Trees on all rootstocks grew best in clay-sand over sand-sphagnum peatmoss-perlite. Rootstocks induced significant differences in 12 elements, the media in 10 of 14 elements determined in the leaves. They also affected K, Mg, Zn and water-soluble phenolics in wood and bark. There were rootstocks × medium interactions for growth, 13 elements in the leaves, and the 3 elements and phenolics in the wood and bark.