The Spatial Distribution of Root System in M9 Rootstock Is Affected by Apple Cultivar and Tree Age

Abstract

The aim of study was to evaluate how different apple cultivars affect root morphology and spatial distribution of rootstock. The experiment was conducted with three different cultivars; ‘Golden delicious’, ‘Gala’ and ‘Starking’ grafted on M9 dwarfing rootstock. Nine and fourteen years old, French vertical axe trained trees were included in the experiment. The trench profile method was chosen to study the morphology of root system and the counted root intersects were divided into three classes; fine roots (<2mm), medium-sized roots (2-5 mm), and coarse roots (>5 mm). To analyze the spatial distribution of root system, the respective cumulative number of fine roots at three successive distances from the base of tree trunk and the cumulative number of fine roots in three successive distances from soil surface were expressed as percentage versus the total fine roots. Significant effects of scion on the total number of fine roots, and as well, on their side and in depth distribution were found. The pattern of root distribution is changing over years, tending to shift the bulk of absorptive roots further from the tank and deeper into the soil. This tendency was more visible to high yielding and late maturity cultivars.