Heavy metal toxicity in rice and soybean plants cultivated in contaminated soil

Abstract

RESUMO Toxicidade por metais pesados em plantas de arroz e soja cultivados em solo contaminadoOs metais pesados podem-se acumular no solo, causando fitotoxicidade em plantas, apresentando alguns sintomas específicos. Por esta razão, este estudo avaliou os sintomas específicos, em plantas de arroz e de soja, causados por excesso de metais pesados no solo. As plantas de arroz e de soja foram cultivadas em vasos, contendo solos com diferentes quantidades de metais pesados. O delineamento experimental foi inteiramente casualizado, com quatro repetições, utilizando-se duas culturas e sete amostras de solos com diferentes níveis de contaminação. As plantas de arroz e de soja exibiram diferentes respostas às elevadas concentrações desses metais no solo. Por exemplo, altas concentrações de Zn disponível no solo causaram fitotoxicidade no arroz e na soja, principalmente cloroses e inibição do crescimento das plantas. As plantas de arroz acumularam maiores teores de Cu, Mn, Pb e Zn e foram mais sensíveis às concentrações elevadas desses elementos no solo, absorvendo-os mais facilmente do que as plantas de soja. Além disso, altas concentrações de Zn no solo reduziram a concentração de Fe na parte aérea das plantas de soja e de arroz para níveis considerados deficientes.Palavras-chave: contaminação, nutrição de plantas, sintomatologia, metal pesado, Oriza sativa L., Glycine max L.1 Engenheira-Agrônoma. Departamento de Agronomia, Universidade Estadual do Centro-Oeste, Rua Simeão Camargo Varela de Sá, 3, Vila Carli, 85040-080, Guarapuava, Paraná, Brasil. mlsousi@hotmail.com (autora para correspondência). 2 Engenheiro-Agrônomo. Departamento de Ciência do Solo, Escola Superior de Agricultura "Luiz de Queiroz", Avenida Pádua Dias, 11, Caixa Postal 09, 13418-900, Piracicaba, São Paulo, Brasil. gcvitti@usp.br 3 Químico. Departamento de Agronomia, Universidade Estadual do Centro-Oeste, Rua Simeão Camargo Varela de Sá, 3, Vila Carli, Guarapuava, Paraná, Brasil. aanrt@hotmail.com Heavy metal toxicity in rice and soybean plants cultivated in contaminated soilHeavy metals can accumulate in soil and cause phytotoxicity in plants with some specific symptoms. The present study evaluated the specific symptoms on rice and soybeans plants caused by excess of heavy metals in soil. Rice and soybean were grown in pots containing soil with different levels of heavy metals. A completely randomized design was used, with four replications, using two crop species and seven sample soils with different contamination levels. Rice and soybean exhibited different responses to the high concentrations of heavy metals in the soil. Rice plants accumulated higher Cu, Mn, Pb and Zn concentrations and were more sensitive to high concentrations of these elements in the soil, absorbing them more easily compared to the soybean plants. However, high available Zn concentrations in the soil caused phytotoxicity symptoms in rice and soybean, mainly chlorosis and inhibited plant growth. Further, high Zn concentrations in the soil reduced the Fe concentrat...

Divalent nutrient cations: friend and foe during zinc stress in rice

“…In plants exposed to excess Zn, the metal began to accumulate in both the roots and shoots by 3 DAT, and increased further with prolonged treatment at 14 and 21 DAT ( Figure 1G, H). Even at 3 DAT, the Zn concentration in the shoots was well above the 400 mg/kg DW previously reported as critical toxicity (Silva et al ., 2014). On the other hand, Zn deficiency did not significantly reduce Zn concentrations in the roots or shoots ( Figure 1G, H) but there was a slight decline, enough for the concentration in the shoots of Zn-deprived plants to fall below the previously reported 15 mg/kg DW critical deficiency concentration (Shanmugam, Tsednee & Yeh, 2012) at 14 and 21 DAT ( Figure 1G).…”

“…Rice plants starved of Zn therefore display symptoms such as bronzed leaves, short internodes, fewer tillers, delayed development, and low grain yields (Yoshida & Tanaka, 1969;Widodo et al ., 2010). On the other hand, Zn toxicity symptoms include leaf chlorosis and the inhibition of growth and flowering (Silva, Vitti & Trevizam, 2014). The production of gibberellin (GA) and indole-3-acetic acid (IAA) is repressed by Zn starvation in tomato (Solanum lycopersicum ) and maize (Zea mays ) plants (Takaki & Kushizaki, 1977;Sekimoto, Hoshi, Nomura & Yokota, 1997), whereas the application of exogenous GA alleviates growth attenuation in rice seedlings exposed to excess Zn (Nag, Nag, Paul & Mukherji, 1984).…”

Foliar Application of Zn Phosphite and Zn EDTA in Soybean (Glycine max (L.) Merrill): In Vivo Investigations of Transport, Chemical Speciation, and Leaf Surface Changes

“…The concentration of Zn in the leaves of soybean ranges from 50 to 80 mg kg −1 reaching up to ca. 600 mg kg −1 in plants grown in Zn-contaminated soil (Silva et al 2014), demonstrating that the experimental design adopted here allowed to quantitatively record the Zn concentration.…”

The Impact of Galena Mining in North-Eastern Nigeria on Nearby Food Crops

“…The concentration of Fe determined in spinach were above the WHO/FAO threshold limit of 425 µg/g. According to [26] the ratio of Fe/Mn in vegetal tissue should be between 1.5 and 2.5 since both elements are involved in metabolic processes hence, they must be present in suitable proportions for adequate plant growth. In the present study the ratio of Fe/Mn were 1.703 in spinach and 2.417 in tomato.…”