Quicklime sterilization of planting holes and topsoil enhances Sacha inchi yield and suppresses root rot in tropical conditions

Sacha inchi ( Plukenetia volubilis L.), a perennial oilseed crop native to the Andean tropics, is increasingly cultivated in China for its omega-rich seeds. However, the increasing incidence of root rot, primarily caused by Fusarium oxysporum , poses a significant threat to its productivity and industry viability. The study aimed to evaluate the effects of different cultivation practices—including soil amendment, intercropping, and mulching—on soil health, root disease incidence, and the yield of Sacha inchi under tropical field conditions. A three-year randomized block field experiment (2020–2023) was conducted to test five treatments: S1 (monoculture control), S2 (intercropping with soybean), S3 (quicklime sterilization of planting holes and topsoil;), S4 (sulfur fertilization), and S5 (plastic film mulching). Among all treatments, quicklime application (S3) produced the most significant improvements. It reduced abundance of Fusarium , and root rot incidence (44.44 %) compared to the control (77.78 %) and enhanced soil pH, increased exchangeable calcium (Ca) and magnesium (Mg), and reduced exchangeable aluminum (Al). Yield under S3 (6065.4 kg ha –1 ) was 48.99 % higher than the control (S1), and notably higher than all other treatments. However, S3 also reduced soil-available copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe). Overall, our results demonstrate quicklime application to planting holes and topsoil is a practical strategy to manage root rot and boost Sacha inchi productivity in tropical cropping systems, thereby ensuring the sustainable development of the Sacha inchi industry. Quicklime sterilization of planting holes and topsoil layers significantly enhanced Sacha inchi yield. • Lime sterilization significantly increased Sacha inchi yield under tropical field conditions. • Liming reduced the abundance of Fusarium in the soil and lowered root rot incidence. • Liming improved soil pH and increased exchangeable calcium and magnesium levels. • Liming depleted soil micronutrient, suggesting the need for supplementation. • Lime sterilization is a promising strategy for managing soil-borne disease and enhancing Sacha inchi productivity.