Impacts of Woody Residue Amendments and Compost on ‘Beauregard’ OrangeFleshed Sweet Potato ( Ipomoea batatas L.)

Abstract

Orange-fleshed sweet potatoes (OFSP) are valued for their bioactive compounds andability to thrive in nutrient-poor soils. This study investigated the short-term effects ofwoody residues and compost on OFSP, focusing on plant growth, storage rootproduction, and bioactive compounds. Conducted in a commercial orchard, theexperiment compared different organic fertilization treatments with a control. Fourtreatments were established: Treatment 1 (T1) received compost fertilization;Treatment 2, control, (T2) had no fertilization; and Treatments 3 (T3) and 4 (T4) werefertilized with high (150 t ha⁻¹) and low (75 t ha⁻¹) doses of woody plant residues,respectively. Although woody residue application initially hampered plant growth, itultimately enhanced biological nitrogen fixation, phosphorus availability, and reducedstress and senescence. Agronomic production did not differ between the compost andwoody residue treatments but was increased at the high woody residue dosecompared to control. At late growth stages, ascorbic acid decreased in all treatments.At this time, the total phenolic content in storage roots remained high in the woodyresidue treatments. Conversely, compost reduced the bioactive compounds, withoutaffecting growth, potentially due to oxidative stress in late growth stages. The lowercrop senescence index and comparable agronomic production to the composttreatment suggest that woody residues were beneficial for OFSP growth and bioactivecomposition. The superior quality of the crop produced with woody residues indicatesthat this is an effective organic fertilization method for sweet potato production that cancontribute to its resilience to environmental variations.