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ROOT SYSTEM GROWTH AND CONFORMATION OF PEACH GRAFTED ON TWO ROOTSTOCKS IN HIGH DENSITY ORCHARDS
Root system growth and conformation, root density, volume of soil explored, canopy growth and carbohydrate partitioning were measured for four consecutive years.
Trees grafted on ‘Missour’ showed 40–50% greater growth of both roots and canopy than those on ‘Mr.S.2/5’. Soil volume explored by roots for ‘Missour’ was twice that for ‘Mr.S.2/5’. Trees on ‘Missour’ had explored all available soil by the end of the second year, while those on ‘Mr.S.2/5’ took four years to explore the volume available.
Root density expressed as root dry weight per unit of soil volume explored was practically the same for the two treatments in the first two years.
By the end of the fourth year, however, ‘Mr.S.2/5’ showed an increase of almost 100% while values with ‘Missour’ were around 30% higher than the previous years.
When root density is expressed as total root length per unit of soil volume explored ‘Mr.S.2/5’ gave considerably higher values for all 4 years of the trial.
With the plum clone, 70–90% of total root length was represented by roots less than 1 mm diameter compared to 40–70% with ‘Missour’. Relationship between roots length and canopy dry weight proved constantly higher with ‘Mr.S.2/5’.
A considerable accumulation of starch (% of dry weight) in the roots and high soluble solid content in the woody organs of the canopy emerged for both rootstocks. ‘Missour’ showed a greater starch and soluble solid content in roots than ‘Mr.S.2/5’.