Tropentag, September 16 - 18, 2026, Göttingen "Towards multi-functional agro-ecosystems promoting climate-resilient futures"

Storage root and stem yield of improved cassava varieties introduced to Liberia

United Nations Industrial Development Organization (UNIDO), Switzerland

Abstract

Next to rice, cassava is the most important food crop in Liberia. However, the local varieties are highly susceptible to cassava mosaic virus (CMV) and develop frequently severe symptoms of the disease. Further, planting methods are designed to furnish a high number of small storage roots, harvested sequentially from plants without uprooting them (milking). Two to three planting stakes are horizontally buried, causing delayed sprouting and strong internal competition, aggravating CMV, causing low root yields around 5 to 7 Mg/ha fresh roots. The UNIDO GROW2 project introduced TME419, an improved cassava variety to Liberia and conducted on-farm trials to evaluate yield response to fertiliser and lime application and the crop age at harvest in Margibi, Bong and Nimba counties. Planting material yield as stem length (m/ha) and fresh storage root yield (Mg/ha) were determined.
Cassava was planted in mid-November 2024. Single planting stakes were vertically inserted to 2/3 of their length. The local cassava varieties produced 3.896 Mg/ha fresh storage roots. Fertiliser application (60-28-48 kg/ha NPK) increased yield marginally to 3.921 Mg/ha. Variety TME419 produced 19.800 Mg/ha without inputs, 20.116 Mg/ha, with fertiliser and 24.016 Mg/ha with 1 or 2 Mg/ha lime as Ca(OH)₂.
Local varieties produced 17353 m/ha stem without fertiliser and 19101 m/ha with fertiliser. TME419 produced 23754 m/ha without inputs, 21604 m/ha with fertiliser and 28817 m/ha with lime. Yield gains were attained when the harvest was delayed by 2 months from 9 months after planting (MAP) to 11 MAP. TME419 produced 5.227 Mg/ha more without inputs, 5.873 Mg/ha more with fertiliser and 5.455 Mg/ha more with lime. Stem production increased by 4825, 2176 and 6483 m/ha in TME419 control, fertilised and limed, respectively. The local varieties experienced root yield losses of 0.721 Mg/ha without inputs and gains of 0.200 Mg/ha when fertilised. Stem growth gains were larger than in TME419 with 8694 m/ha without inputs and 9908 m/ha with fertiliser.
Average root yield gains of 5.518 Mg/ha and stem length gains close to 4500 m/ha indicate that the additional 2 months of growth are beneficial. Later harvests did not result in similar root yield gains.

Keywords: Cassava, fertiliser, Liberia, lime, root yield, stem yield, varieties

Contact Address: Stefan Hauser, United Nations Industrial Development Organization (UNIDO), 1214 Vernier, Switzerland, e-mail: s.hauserunido.org