HIGHLIGHTS:
Beet response to copper fertigation depends on the initial concentration of this micronutrient in soil.
Necrotic spots on beet leaves are characteristic of copper toxicity.
Postharvest characteristics of tuberous root of beet are not influenced by copper fertigation.
ABSTRACT
Copper is an essential element for beet; however, it needs to be made available in adequate quantities since this nutrient, which is a heavy metal, can cause toxicity to plants and/or humans. This study aimed to evaluate the agronomic performance of beet fertigated with copper in a semi-arid region of Brazil. Two experiments were carried out in complete randomized blocks, with five treatments (0, 1.5, 3.0, 4.0, and 6.0 kg ha-1 of copper) and four replicates. In 2019, the copper content was within the adequate range for beet. In 2021, fertigation with copper above 0.8 kg ha-1 led to contents in the phytotoxicity range, which may explain the reduction in total and tuberous root dry mass accumulation. Fertilization with copper increased marketable yield in 2019 (17.32 t ha-1 at the dose of 3.9 kg ha-1 of copper), while, in 2021, there was no fit of the equations. Copper fertilization altered the tuberous root pH but did not influence the other tuberous root quality components. Plants fertilized with copper accumulated more copper in the leaves than in the tuberous root, with a maximum accumulation of 6.0 kg ha-1 of copper in 2019 and 2021. Fertilization with 3.9 kg ha-1 suits soils with low copper content.
Key words:
Beta vulgaris
; heavy metal; micronutrient; postharvest
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** - Significant at p ≤ 0.01 by the F test; * - Significant at p ≤ 0.05 by the F test; ns - non-significant at p < 0.05. Vertical bars represent the standard error of the mean
** - Significant at p ≤ 0.01 by the F test; * - Significant at p ≤ 0.05 by the F test; ns - non-significant at p < 0.05. CV - coefficient of variation. Vertical bars represent the standard error of the mean
* - Significant at p ≤ 0.05 by the F test; ns - non-significant at p < 0.05. CV - coefficient of variation. Vertical bars represent the standard error of the mean
** - Significant at p ≤ 0.01 by the F test; * - Significant at p ≤ 0.05 by the F test. CV - coefficient of variation. Vertical bars represent the standard error of the mean
** - Significant at p ≤ 0.01 by the F test; CV - coefficient of variation. Vertical bars represent standard error of the mean