CLEANING ROOT CROP PROPAGULES TO INCREASE FARM PRODUCTIVITY AND SUPPORT GAP SYSTEM

Abstract

The use of clean planting materials is a good agricultural practice to improve crop yield, quality and food safety. This is of particular importance for asexually propagated crops such as root crops. Sweetpotato (Ipomoea batatas L.), cassava (Manihot esculenta Crantz) and yam (Dioscorea alata L.) are usually propagated using vine cuttings, stem cuttings and tuber slices, respectively; as such, pathogen load accumulates and is passed on from one generation to the next. The systemic presence of pathogens within the plant has no visible symptom except for depressed vigor and yield which is usually misdiagnosed resulting in unnecessary use of additional farm inputs such as pesticides and fertilizers. In an attempt to produce clean planting materials, several ex vitro and in vitro methods were tested; among these methods, the serial application of greenhouse preconditioning, thermotherapy, and meristem culture was established to be the best technique. Virus indexing tests confirmed the disease-free nature of the plantlets which were then mass propagated for field evaluation in comparison to conventional propagules. Plants produced from clean propagules remarkably outperformed those from conventional propagules as they had better field performance and higher yields than the latter. It is strongly recommended that Good Agricultural Practice (GAP) for root crops and other asexually propagated crops should integrate the use of clean planting materials.