Effects of olive shoot residues on shoot and root growth of potted olive plantlets

tDecomposition of olive shoot residue (OSR) from leaf shedding and pruning may provide nutrient toolive orchards, although beyond a phytotoxic threshold it can also hamper plant growth. We studiedOSR decomposition effects on plant growth, biomass partitioning and soil fertility. Four levels of OSR (0%,3%, 10% and 30% [v/v]) were mixed into the substrate and placed close to the roots compared on twoolive potted cultivars over 240 days using a destructive sampling approach. Organic matter, polyphe-nol and nitrogen contents in the substrate, fine root respiration and electrolyte leakage, leaf pigmentcontent, chlorophyll a fluorescence, biomass partitioning, fine root nutritional status were determined.OSR increased the content of organic matter, polyphenols and nitrogen in the soil. In the first 150 days,OSR beyond 3% induced autotoxic effects, and altered fine root respiration, and electrolyte leakage andbiomass allocation. After 240 days, OSR induced a stimulatory effect on fine roots and shoot growth andincreased shoot and fine root nitrogen content. Application OSR did not significantly altered leaf pig-ment content and chlorophyll a fluorescence. As a conclusion, above the threshold of 3%, olive cannotprevent autotoxicity during the early decomposition of OSR, but later soil fertility and plant growth canbe increased.