Growth of peach as affected by decomposition of own root residues in soil

Abstract

The effects of decomposing peach root residues in soil on peach growth were determined in two pot experiments. In the first, peach root residues, despite their high C:N ratio and lignin content, largely decomposed under experimental conditions, leading to an immobilization of inorganic N. Shoot growth of peach seedlings was depressed by the addition of peach root residues, an effect that depended on their size and concentration: fine-textured root fragments (0.45–1.00 mm) resulted in more severe effects than medium sized ones (2–8 mm), while growth depression occurred only at concentrations higher than 0.35%. Peach root growth was depressed by root residues regardless of their size and amount. In the second experiment, where nitrogen was added to all pots to minimize the effects of immobilization of N during decomposition of root fragments, the growth of peach roots in residue-supplemented soil almost stopped. Pre-planting phosphate enrichment was very effective in stimulating growth of peach in virgin soil but did not offset the depression caused by peach root residues. It thus appears that besides mineral deficiencies, there exist alternative explantations of poor growth of peach in replant soils, including growth-inhibiting substances from decomposing root residues.