RESUMO

BACKGROUND: Nutritional disorders of phosphorus (P), due to deficiency or toxicity, reduce the development of Eucalyptus spp. seedlings. Phosphorus deficiency often results in stunted growth and reduced vigor, while phosphorus toxicity can lead to nutrient imbalances and decreased physiological function. These sensitivities highlight the need for precise management of P levels in cultivation practices. The use of the beneficial element silicon (Si) has shown promising results under nutritional stress; nevertheless, comprehensive studies on its effects on Eucalyptus spp. seedlings are still emerging. To further elucidate the role of Si under varying P conditions, an experiment was conducted with clonal seedlings of a hybrid Eucalyptus spp. (Eucalyptus grandis × Eucalyptus urophylla, A207) in a soilless cultivation system. Seedlings were propagated using the minicutting method in vermiculite-filled tubes, followed by treatment with a nutrient solution at three P concentrations: a deficient dose (0.1 mM), an adequate dose (1.0 mM) and an excessive dose (10 mM), with and without the addition of Si (2mM). This study assessed P and Si concentration, nutritional efficiency, oxidative metabolism, photosynthetic parameters, and dry matter production. RESULTS: Si supply increased phenolic compounds production and reduced electrolyte leakage in seedlings provided with 0.1 mM of P. On the other hand, Si favored quantum efficiency of photosystem II as well as chlorophyll a content in seedlings supplemented with 10 mM of P. In general, Si attenuates P nutritional disorder by reducing the oxidative stress, favoring the non-enzymatic antioxidant system and photosynthetic parameters in seedlings of Eucalyptus grandis × Eucalyptus urophylla. CONCLUSION: The results of this study indicate that Eucalyptus grandis × Eucalyptus urophylla seedlings are sensitive to P deficiency and toxicity and Si has shown a beneficial effect, attenuating P nutritional disorder by reducing the oxidative stress, favoring the non-enzymatic antioxidant system and photosynthetic parameters.

Assuntos

RESUMO

ABSTRACT: Cultivation of soybean and off-season corn is advancing in areas under restricted edaphoclimatic conditions, such as petric plinthosols, which have significant proportions of gravel and are deficiency in micro-nutrients such as copper (Cu) and zinc (Zn). The effects of Cu and Zn concentrations on soybean nutrition cultivated in petric plinthosol are unclear, and it is unknown whether the levels considered adequate for other soils are sufficient for gravely soils, or even if higher Cu and Zn rates can cause a toxic effect in soybean. The objective was to compare the response of soybean grown in petric plinthosol and ferralsol to Cu and Zn doses for identifying the changes induced by gravel soils and to evaluate the residual effect on off-season corn grown in ferralsol. Four experiments were carried out with Cu and Zn doses applied to soil with the soybean crop in ferralsol and plinthosol. The leaf tissues of soybean crops in the two soils showed the same rate of increase in Zn concentrations, for each kg·ha-1 of Zn applied, the increase in Zn was 0.7 mg·kg-1, suggesting no difference in the effect of Zn fertilization between soils with and without gravel. The dosages of Zn and Cu Oxysulfate applied to soil did not cause residual effects in the off-season corn. The highest doses of Cu and Zn did not have any toxic effects on the plants. The main criteria for interpreting Cu and Zn in soil analysis are thus also applicable to soybean crops grown in petric plinthosol.

RESUMO: O cultivo de soja e milho safrinha avança em condições edafoclimáticas restritivas, como nos PLINTOSSOLOS PÈTRICOS, que apresentam proporções consideráveis de cascalho no seu perfil e são deficientes em cobre (Cu) e zinco (Zn). Não se sabe os efeitos de doses de Cu e Zn na nutrição da soja cultivada em PLINTOSSOLO PÉTRICO, nem se os níveis considerados adequados para outros solos são suficientes para solos cascalhentos, ou ainda, se altas doses de Cu e Zn podem causar toxidez nas plantas de soja. O objetivo foi comparar a resposta a doses de Cu e Zn em soja cultivada em PLINTOSSOLO PÉTRICO e em LATOSSOLO, a fim de identificar alterações provocadas pelo solo com cascalho, e adicionalmente, avaliar o efeito residual da adubação feita na soja para o milho safrinha cultivado no LATOSSOLO. Quatro experimentos foram desenvolvidos com doses de Cu e Zn aplicadas via solo na cultura da soja em LATOSSOLO e em PLINTOSSOLO PÉTRICO. Houve a mesma taxa de incremento na concentração de Zn no tecido foliar da soja nos dois solos estudados, para cada kg ha-1 de Zn aplicado, o incremento foi de 0,7 mg·kg-1 demonstrando que não há diferença de um solo com ou sem cascalho para os efeitos da adubação. As doses de oxissulfato de Zn e Cu aplicadas via solo não causaram efeito residual no milho safrinha. As maiores doses de Cu e Zn não causaram efeito tóxico nas plantas. Os principais critérios de interpretação de Cu e Zn em análise do solo se aplicam para soja cultivada em PLINTOSSOLO PÉTRICO.

RESUMO

Cultivation of soybean and off-season corn is advancing in areas under restricted edaphoclimatic conditions, such as petric plinthosols, which have significant proportions of gravel and are deficiency in micro-nutrients such as copper (Cu) and zinc (Zn). The effects of Cu and Zn concentrations on soybean nutrition cultivated in petric plinthosol are unclear, and it is unknown whether the levels considered adequate for other soils are sufficient for gravely soils, or even if higher Cu and Zn rates can cause a toxic effect in soybean. The objective was to compare the response of soybean grown in petric plinthosol and ferralsol to Cu and Zn doses for identifying the changes induced by gravel soils and to evaluate the residual effect on off-season corn grown in ferralsol. Four experiments were carried out with Cu and Zn doses applied to soil with the soybean crop in ferralsol and plinthosol. The leaf tissues of soybean crops in the two soils showed the same rate of increase in Zn concentrations, for each kg·ha-1 of Zn applied, the increase in Zn was 0.7 mg·kg-1, suggesting no difference in the effect of Zn fertilization between soils with and without gravel. The dosages of Zn and Cu Oxysulfate applied to soil did not cause residual effects in the off-season corn. The highest doses of Cu and Zn did not have any toxic effects on the plants. The main criteria for interpreting Cu and Zn in soil analysis are thus also applicable to soybean crops grown in petric plinthosol.

O cultivo de soja e milho safrinha avança em condições edafoclimáticas restritivas, como nos PLINTOSSOLOS PÈTRICOS, que apresentam proporções consideráveis de cascalho no seu perfil e são deficientes em cobre (Cu) e zinco (Zn). Não se sabe os efeitos de doses de Cu e Zn na nutrição da soja cultivada em PLINTOSSOLO PÉTRICO, nem se os níveis considerados adequados para outros solos são suficientes para solos cascalhentos, ou ainda, se altas doses de Cu e Zn podem causar toxidez nas plantas de soja. O objetivo foi comparar a resposta a doses de Cu e Zn em soja cultivada em PLINTOSSOLO PÉTRICO e em LATOSSOLO, a fim de identificar alterações provocadas pelo solo com cascalho, e adicionalmente, avaliar o efeito residual da adubação feita na soja para o milho safrinha cultivado no LATOSSOLO. Quatro experimentos foram desenvolvidos com doses de Cu e Zn aplicadas via solo na cultura da soja em LATOSSOLO e em PLINTOSSOLO PÉTRICO. Houve a mesma taxa de incremento na concentração de Zn no tecido foliar da soja nos dois solos estudados, para cada kg ha-1 de Zn aplicado, o incremento foi de 0,7 mg·kg-1 demonstrando que não há diferença de um solo com ou sem cascalho para os efeitos da adubação. As doses de oxissulfato de Zn e Cu aplicadas via solo não causaram efeito residual no milho safrinha. As maiores doses de Cu e Zn não causaram efeito tóxico nas plantas. Os principais critérios de interpretação de Cu e Zn em análise do solo se aplicam para soja cultivada em PLINTOSSOLO PÉTRICO.

Assuntos