Growth, tolerance and zinc accumulation in Senna multijuga and Erythrina crista-galli seedlings

Douglas L Scheid,Robson Andreazza,Rodrigo F Da Silva,Clovis O Da Ros,André L Grolli,Rudinei D Marco

doi:10.1590/1807-1929/agriambi.v21n7p465-470

Douglas L Scheid, Robson Andreazza + Show 4 more

Open Access

https://doi.org/10.1590/1807-1929/agriambi.v21n7p465-470

Copy DOI

Abstract

ABSTRACT Zinc (Zn) is a micronutrient that is reaching toxic levels in the soil, with the intensification of agricultural and industrial activities. The objective of this study was to evaluate the growth, accumulation and tolerance of Erythrina crista-galli and Senna multijuga seedlings in soil with addition of increasing Zn levels. The study was conducted in a greenhouse for 120 days, using a completely randomized design in a 2 x 6 factorial arrangement, corresponding to two tree species (S. multijuga and E. crista-galli) and six doses of zinc in the soil (0, 200, 400, 600, 800 and 1000 mg kg-1) with six replicates. E. crista-galli and S. multijuga seedlings decreased root and shoot dry weight with increasing Zn doses. E. crista-galli and S. multijuga have low Zn translocation index and are capable to phytostabilize Zn in the roots. E. crista-galli had greater tolerance to Zn compared with S. multijuga. The species have potential for Zn phytostabilization programs in contaminated soil.

Highlights

Zinc (Zn) is a potentially polluting heavy metal, but it is a micronutrient that acts as enzymatic cofactor, in the maintenance of biomembrane integrity, metabolism of carbohydrates and in the synthesis of proteins (Broadley et al, 2007; Hooda, 2010)
Zn doses in the soil increased the pseudo-total contents of the metal in the soil and, from 400 mg kg-1 on, these contents were higher than that established as maximum limit value allowed for agricultural soils by the resolution no 420 (CONAMA, 2009), which is 450 mg kg-1 (Figure 1)
No symptoms of chlorosis were observed in S. multijuga and E. crista-galli seedlings, physiological alterations, such as iron deficiency with reduction in the synthesis of chlorophyll and degradation of the chloroplasts (Broadley et al, 2007), may have occurred, culminating in reduction of dry matter with the increase in the Zn doses added to the soil, and reduction in the amount of photoassimilates produced by the leaves, resulting in lower amount of biomass produced by the plants

Summary

Introduction

Zinc (Zn) is a potentially polluting heavy metal, but it is a micronutrient that acts as enzymatic cofactor, in the maintenance of biomembrane integrity, metabolism of carbohydrates and in the synthesis of proteins (Broadley et al, 2007; Hooda, 2010). According to the National Environmental Council (CONAMA, 2009), in agricultural soils of Brazil, Zn contents above 450 mg kg-1 pose potential risks, direct or indirect, to human health. In this context, soils with high contents of this chemical element require remediation actions to avoid problems for human health. Phytoremediation is an alternative to recover contaminated areas, but there are only few studies involving tree species native to Brazil for phytoremediation of contaminated soils. According to Domínguez et al (2009), the utilization of tree species is a strategy to recover areas contaminated with metals, because they have large biomass production along the growth cycle. According to Magalhães et al (2011), another advantage of using tree species is that they are able to absorb and retain metals in the roots, restricting their transport to the leaves, which is an interesting feature for projects of reclamation of contaminated areas

Objectives

Methods

Results