Manganese fertilization for sweet cassava production under organic management system

Giuliano Marchi,Thomaz Adolpho Rein,Eduardo Alano Vieira,Josefino De Freitas Fialho,José Carlos Sousa-Silva,Douglas Ramos Guelfi Silva,João De Deus Gomes Dos Santos Junior,Juaci Vitória Malaquias

doi:10.1590/1983-40632020v5066133

Abstract

ABSTRACT Organic management farms in the Federal District, Brazil, usually present overlimed and overfertilized soils, with high content of organic matter and high pH. These conditions lead to a low availability of manganese to crops. Many sweet cassava (Manihot esculenta Crantz.) crops were diagnosed with Mn deficiency in the region, presenting low yields. In order to overcome such condition, an experiment was established comprising the following treatments: application of MnSO4 banded in rows; treatment of cassava cuttings with a MnSO4 solution before planting; application of MnSO4 and elemental sulfur (S0) banded in the rows, to acidify the soil, increasing the Mn solubility; and leaf spraying of a Mn solution. The best results were revealed when the Mn was applied by foliar spraying and using a combination of methods (treatment of cassava cuttings with Mn, and Mn and S0 applied to the soil before planting). This treatments provided a fresh root yield of 19.5 Mg ha-1, contrasting with the control treatment (3.6 Mg ha-1).

Highlights

Manganese (Mn) deficiency in sweet cassava crops has been noticed in many farms in the Federal District, Brazil, those that use organic management systems (Fialho et al 2020)
The sweet cassava plant height, fresh shoot and root yield and number of roots showed positive responses to the Mn treatments, except the single application of 4.28 kg ha-1 banded in rows (Table 2), which was not different from the control treatment
Phosphorus, nitrogen and copper were probably partially “diluted” with the cassava growth, due to the increase of the Mn availability, while Ca was gradually absorbed into the plants according to the plant growth, rendering negative correlations (Table 4). These results showed that the conditions existing for a high sweet cassava yield under Mn deficiency should be further studied

Summary

Introduction

Manganese (Mn) deficiency in sweet cassava crops has been noticed in many farms in the Federal District, Brazil, those that use organic management systems (Fialho et al 2020). Manganese deficiency is more common in soils with pH above 6.5 (Galrão 1999). This pH condition is common in soils under organic management in the region. Manganese deficiency causes cassava to present low yields and interveinal chlorosis of upper and middle leaves (Howeler 2002), due to the fact that the Mn functions as an enzyme activator for steps in photosynthesis (Broadley et al 2012). Cassava crops present yellowish tips when Mn is poorly translocated in the plant, and deficiency symptoms appear first on young leaves (Galrão 1999)

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