Anatomical studies of stems, roots and leaves of selected citrus rootstock varieties in relation to their vigour

Abstract

The present studies were carried out to consolidate information on anatomical features of stem, root and leaves from different vigour groups of citrus rootstock varieties. Troyer citrange (Citrus sinensis × Poncirus trifoliata), rough lemon (Citrus jambhiri), swingle citrumelo (Citrus paradisi × P. trifoliata), sweet lime (Citrus limettioides), carrizo citrange (C. sinensis × Poncirus trifoliata), sour orange (Citrus aurantium) and flying dragon (P. trifoliata) were examined to investigate relationships between their internal structure and vigour. It was found that vigorous rootstock, rough lemon (C. jambhiri) possessed lower proportions of bark (phloem) in the stems and roots as well as larger vessel elements in the xylem, when compared with least vigorous rootstocks, flying dragon (P. trifoliata). Smaller but more vessel elements were found in stem cross-sections than root cross-sections of three month’s old rootstock seedlings. The possible mechanism of vascular differentiation induced by young leaf primordia, following the original polarity and developing toward the roots is discussed. Key words: Citrus rootstock, anatomical features, stem, root, leaves.