Improving the yield and nutritional quality of cassava (Manihot esculenta Crantz) in the rainforest agro-ecological zone of southeast Nigeria through agronomic biofortification with micronutrients

Abstract

Cassava (Manihot esculenta Crantz) is an important staple crop, especially for resource-poor populations. Cassava-based diets are rich in calories but grossly deficient in essential mineral elements. A field study in southeastern Nigeria aimed at increasing yields and concentrations of bioavailable mineral elements in a β-carotene cassava variety, UMUCASS 38 (TMS 01/1371), through agronomic biofortification. A randomized complete block design experiment in triplicate, with foliar application of Zn (3.0 kg ha⁻¹ Zn as ZnSO₄), I (4.0 kg ha⁻¹ I as KI), Se (0.25 kg ha⁻¹ Se as Na₂SeO₃) and Zn + Se + I in combination at vegetative, tuber initiation and bulking stages of cassava. Results indicated neither phytotoxicity nor altered physical and chemical soil properties. Application of Zn or Zn + Se + I at the vegetative stage significantly increased cassava tuber yields. More Zn, Se, and I accumulated in fresh and processed cassava tuber products (gari, lafun), especially when Zn + Se + I was applied at tuber initiation stage. The combined application of Zn + Se + I consistently outperformed sole applications indicating a synergistic interaction effect between the three elements. It is concluded that in the Zn-deficient soils of southeast Nigeria, yield of cassava root tubers can be significantly increased by foliar application of Zn-containing fertilizer at the vegetative stage, but for optimal accumulation of elemental Zn, Se, and I, a combined Zn + Se + I fertilizer be applied at the tuber initiation stage.

Keywords:

• Crop improvement
• food security
• hidden hunger
• root crop
• synergism
• trace element

Acknowledgments

The authors gratefully acknowledge the Tertiary Education Trust Fund (TETFund) for funding this study through the Institutional Based Research (IBR) Grant assessed through the University of Calabar in the 2019/2020 intervention session.

Disclosure statement

No potential conflict of interest was reported by the author(s).