Comparative Root Anatomy of Five Actinidia Species in Relation to Rootstock Effects on Kiwifruit Flowering

This study examined the root anatomy of five Actinidia specieswhich, when used as rootstocks, differ in their effects on flowerproduction of the 'Hayward' kiwifruit scion. The rootstock speciesexamined were A. hemsleyana, A. eriantha, A. rufa, A. deliciosaand A. chinensis. Roots of all the five species had similartissues and similar cell types in each tissue. The cortex andendodermis were retained and developed further during secondaryroot thickening. Each meriphyte of endodermal cells, derivedduring secondary growth, was enclosed in a suberin lamella.Crystalline idioblasts were present in the cortex and phloem.These idioblasts contained raphide crystals, often surroundedby mucilage. Roots of the five species differed significantlyin the total cross-sectional area of vessels in the xylem, inthe total cross-sectional areas of fibres and crystalline idioblastsin the phloem, and in the abundance of starch grains in parenchymaof all tissues. Roots of flower-promoting rootstock speciestended to have more and larger xylem vessels, more crystallineidioblasts, and more starch grains. These anatomical featuresmay be used as criteria for future selection of flower-promotingrootstocks in kiwifruit. The possible physiological link betweenroot anatomy and rootstock effect is discussed.Copyright 1994,1999 Academic Press Kiwifruit, Actinidia, root, anatomy, rootstock, flowering