Plantas de cana-de-açúcar suplementadas com boro tem maior tolerância ao efeito tóxico do alumínio
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Data
2022-04-19
Autores
Sousa, Francisco Bruno Ferreira de
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Universidade Estadual Paulista (Unesp)
Resumo
A toxidez por alumínio (Al) é um dos principais fatores limitantes da produtividade agrícola em solos ácidos. Alguns relatos têm sugerido que o aumento do fornecimento de nutrientes como o boro (B) pode mitigar esse efeito, mas nenhum estudo foi realizado com cana-de-açúcar para confirmar. Portanto, o objetivo neste trabalho foi verificar se o boro atenua o efeito da toxicidade do Al em plantas de cana-de-açúcar. O ensaio foi conduzido sob delineamento inteiramente casualizado em esquema fatorial 3 x 4 x 3, sendo: 3 concentrações de B (15, 30 e 60 mmol L-1) na forma de H3BO3, 4 concentrações de Al (0, 20, 40 e 60 mg L-1) utilizando o AlCl3 e 3 épocas de suplementação de boro (antes, durante e depois da exposição ao Al), com 4 repetições. Após 30 dias da exposição aos tratamentos, foram medidas e avaliadas as variáveis biométricas, teores de açucares totais, sacarose, teor de boro e nitrogênio, aminoácidos, proteínas totais, rendimento quântico do fotossistema II e coloração das raízes com hematoxilina. Os dados foram submetidos à análise de variância pelo teste F e comparação das médias pelo teste de Tukey. Os resultados revelaram que o boro atenua o efeito da toxidade do alumínio sobre o crescimento das plantas de cana-de-açúcar, principalmente quando suplementadas antes e durante a exposição ao Al. Plantas que receberam baixa concentração de boro foram as mais afetadas pelo Al e o aumento da concentração de B proporcionou maior crescimento do sistema radicular e melhorias da parte aérea de plantas de cana-de-açúcar sob toxicidade de Al. A coloração das raízes com hematoxilina, revelaram menor acúmulo de Al nos ápices radiculares com fornecimento de boro. As concentrações de açúcares e sacarose nos tecidos foliares foram diminuídas com suplementação de 15 mmol L-1 de B. Efeito positivo do B foi observado no metabolismo de N, resultando em acúmulo de aminoácidos e proteínas.
Aluminum toxicity (Al) is one of the main factors limiting agricultural productivity in acidic soils. Some reports have suggested that an increased supply of nutrients such as boron (B) can mitigate this effect, but no studies have been carried out with sugarcane to confirm this effect. Therefore, the objective of this work was to verify whether boron attenuates the effect of Al toxicity on sugarcane plants. The assay was conducted under a completely randomized design in a 3 x 4 x 3 factorial scheme, with: 3 concentrations of B (15, 30 and 60 mol L-1) in the form of H3BO3, 4 concentrations of Al (0, 20, 40 and 60 mg L-1) using AlCl3 and 3 times of boron supplementation (before, during and after exposure to Al) with 4 repetitions. The data were submitted to analysis of variance by the F test and comparison of means by the Tukey test. Results The results revealed that boron attenuates the effect of aluminum toxicity on the growth of sugarcane plants, especially when supplemented before and during exposure to Al. Plants that received a low concentration of boron were the most affected by Al and the increase in B concentration provided greater growth of the root system and improvements in the aerial part of sugarcane plants under Al toxicity. The staining of the roots with hematoxylin revealed less accumulation of Al in the root apexes with boron supply. Sugar and sucrose concentrations in leaf tissues were reduced with supplementation of 15 mmol L-1 of B. A positive effect of B was observed on N metabolism, resulting in accumulation of amino acids and proteins.
Aluminum toxicity (Al) is one of the main factors limiting agricultural productivity in acidic soils. Some reports have suggested that an increased supply of nutrients such as boron (B) can mitigate this effect, but no studies have been carried out with sugarcane to confirm this effect. Therefore, the objective of this work was to verify whether boron attenuates the effect of Al toxicity on sugarcane plants. The assay was conducted under a completely randomized design in a 3 x 4 x 3 factorial scheme, with: 3 concentrations of B (15, 30 and 60 mol L-1) in the form of H3BO3, 4 concentrations of Al (0, 20, 40 and 60 mg L-1) using AlCl3 and 3 times of boron supplementation (before, during and after exposure to Al) with 4 repetitions. The data were submitted to analysis of variance by the F test and comparison of means by the Tukey test. Results The results revealed that boron attenuates the effect of aluminum toxicity on the growth of sugarcane plants, especially when supplemented before and during exposure to Al. Plants that received a low concentration of boron were the most affected by Al and the increase in B concentration provided greater growth of the root system and improvements in the aerial part of sugarcane plants under Al toxicity. The staining of the roots with hematoxylin revealed less accumulation of Al in the root apexes with boron supply. Sugar and sucrose concentrations in leaf tissues were reduced with supplementation of 15 mmol L-1 of B. A positive effect of B was observed on N metabolism, resulting in accumulation of amino acids and proteins.
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Acidez, Estresse abiótico, Mitigação, Saccharum spp, Acidez do solo, Mitigação de riscos