Availability and zinc accumulation in forage grasses grown in contaminated soil

Abstract

Zinc is an important micronutrient to plant growth, but when present in large quantities it can become a toxic element to plants. This study was aimed to evaluate the growth, concentration, accumulation and availability of Zn to forage grasses (Megathyrsus maximus cvs. Aruana and Tanzania, Urochloa brizantha cvs. Xaraés and Marandu and Urochloa decumbens cv. Basilisk) cultivated in Zn contaminated soils. The experiments were conducted under greenhouse conditions over a 90-day evaluation period, and Zn rates were 0, 100, 300 and 900 mg kg of soil. The Zn rates in soil caused growth reduction in all evaluated forage grasses. The cultivar Aruana was generally more tolerant to Zn, while the Marandu was generally more susceptible to the addition of Zn. The cultivar Aruana proved to be superior to others due to its higher growth and higher critical level toxicity of Zn. None of the forage grasses evaluated can be considered a Zn hyperaccumulator. The extraction order was DTPA at pH 7.3 < Mehlich-1 < USEPA 3051 < USEPA 3052 in the soil independent of forage grasses cultivation. The USEPA 3051 extractor was similar to Mehlich-1 in predicting the availability of Zn in soil.

Are Grasses Really Useful for the Phytoremediation of Potentially Toxic Trace Elements? A Review

“…Zinc was much more accumulated in the roots than the shoots in Andropogon gayanus exposed to 142.3 up to 854.0 μmol Zn L –1 for 7 weeks ( Ribeiro et al, 2020 ). Nardis et al (2018) mentioned that in different genotypes of P. maximum , the Zn concentrations in the roots were higher than in the shoots. On the other hand, these authors also pointed out that in B. brizantha cv.…”

“…Root elongation in B. syzigachne , L. hexandra , N. reynaudiana , and P. fugax decreased due to Zn excess ( Deng et al, 2006 ). In P. maximum , B. brizantha , and B. decumbens , Zn toxicity also led to lower root growth ( Nardis et al, 2018 ). In A. gayanus , Zn toxicity induced the vesiculation, vacuolation, and withdrawal of the plasma membrane from the root cell wall ( Ribeiro et al, 2020 ).…”

Effect of zinc on phytoremediation potential and carbonic anhydrase and polyphenol oxidase activities of Lythrum salicaria L.

“…Only 0.2% of known plant species have been identified as heavy metal hyperaccumulators including Alyssum bertolonii, Pteris cretica, Thlaspi caerulescens, Azolla pinnata, and Lemna minor (Rascio and Navari-Izzo, 2011;Tangahu et al, 2011;Ali et al, 2013;Thayaparan et al, 2015). Zinc (Zn), one of the heavy metals that enter the environment through anthropogenic activities including industrial wastes, sewage sludge, and acid rains, is an important micronutrient for plant growth but it can become a toxic element for plants when present in large quantities (Rout and Das, 2003;Nardis et al, 2018). Zn is involved in several plant metabolic processes such as enzyme activation, protein synthesis, and carbohydrate and lipid metabolism (Escudero-Almanza et al, 2012;Tsonev and Lidon, 2012;Ackova, 2018).…”