Absorção e mobilidade floemática de boro (10B) em caupi
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Data
2016-08-12
Autores
Silva, Sylvia Leticia Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A deficiência de boro pode afetar a eficiência nutricional e o crescimento vegetativo e reprodutivo, induzindo alterações celulares no feijão-caupi. A eficiência do fornecimento do B via foliar, na cultura pode depender da concentração adequada do micronutriente na calda de pulverização, e se associado ao sorbitol poderia potencializar a sua absorção e crescimento. Propôs-se avaliar os efeitos da deficiência de boro na planta e da adubação foliar com boro na ausência e na presença de sorbitol no crescimento e no acúmulo de boro na planta, na produção e sua mobilidade no feijão-caupi. No estudo foram realizados três ensaios no período de fevereiro/ 2014 a maio/2015. No experimento I, empregaram-se dois tratamentos com solução nutritiva sob ausência (-B) e presença de boro (+B) em dez repetições. No experimento II utilizou-se esquema fatorial 5x2, sendo cinco concentrações de B (0; 1,25; 2,5; 3,75 e 5,0 g L-1 de B), via foliar, na forma de ácido bórico, na ausência ou na presença de sorbitol (500 mmol L 1), com quatro repetições. No experimento III estudou-se a mobilidade do boro marcado (10B) absorvido pelas raízes e pelas folhas. Avaliaram-se os sintomas de deficiência de boro, o crescimento da raiz, a massa seca dos órgãos da planta e o teor de B e a produção de grãos. A deficiência de boro em plantas de feijão-caupi diminuiu a eficiência de absorção de B, embora tenha aumentado à eficiência de uso do nutriente, mas os maiores prejuízos ocorreram nas variáveis reprodutivas e no crescimento da raiz em relação à produção de folhas e caule. A deficiência de boro em plantas de feijão-caupi diminuiu a eficiência de absorção de B, embora aumente à eficiência de uso do nutriente. Os maiores prejuízos ocorrem nas variáveis reprodutivas e no crescimento da raiz em relação à produção de folhas e caule. A deficiência de boro induz alterações celulares como espessamento na lamela média e acúmulo de amido nos cloroplastos foliares que reflete nos sintomas visuais característicos para o feijão-caupi. A maior produção de grãos de caupi (90 – 100% da produção máxima) ocorre quando o B foi pulverizado a 2,62 g L-1 de B, sem sorbitol, tendo como fonte o ácido bórico, nas épocas V6, R1 e R2 e teor foliar de 35 mg kg-1de B. A adubação foliar com boro, associada com sorbitol, incrementou a absorção do micronutriente na parte vegetativa, mas não refletiu na produção do feijão-caupi. Há mobilidade de boro aplicado via foliar em plantas de caupi, havendo viabilidade da adubação foliar para atendimento da demanda desse nutriente no feijão-caupi durante o seu desenvolvimento vegetativo.
Boron deficiency can affect nutritional efficiency, as well as vegetative and reproductive growth, inducing cell changes in cowpea. Efficiency of B supply via foliar application in crops may depend on its proper concentration in spray solution, and when associated with sorbitol, it could enhance its absorption and plant growth. The aim of this study was to assess the effects of boron deficiency and foliar fertilization in the absence and presence of sorbitol on plant growth and production, and its accumulation and mobility in cowpea. In the study, three experiments were carried out from February 2014 to May 2015. Experiment I was composed of two treatments with nutrient solution under absence (−B) and presence (+B) of boron in ten repetitions. In the experiment II, a 5 × 2 factorial scheme was used, being applied via foliar five concentrations of B (0, 1.25, 2.5, 3.75 and 5.0 g L−1 of B) in the form of boric acid and in the absence or presence of sorbitol (500 mmol L−1 ), with four repetitions. In the experiment III, marked boron (10B) mobility was studied regarding its absorption by roots and leaves. Boron deficiency symptoms, root growth, dry weight of plant organs and B content and grain production were assessed. Boron deficiency in cowpea plants decreased B absorption efficiency, although it has increased nutrient use efficiency. The greatest losses occurred in reproductive variables and root growth in relation to leaves and stem production. Boron deficiency induces cellular changes such as thickening in the middle lamella and starch accumulation in leaf chloroplasts, which lead to characteristic visual symptoms for cowpea. The highest production of cowpea grains (90–100% of maximum production) occurred when B was pulverized at 2.62 g L−1 of B without sorbitol, having as a source the boric acid, on growth stages V6, R1 and R2 and foliar content of 35 mg kg−1 of B. Foliar fertilization with boron, associated with sorbitol, increased micronutrient absorption in the vegetative part, but it did not influence cowpea production. A mobility was observed for B applied via foliar in cowpea plants, showing viability of foliar fertilization to meet the demand of this nutrient during vegetative development.
Boron deficiency can affect nutritional efficiency, as well as vegetative and reproductive growth, inducing cell changes in cowpea. Efficiency of B supply via foliar application in crops may depend on its proper concentration in spray solution, and when associated with sorbitol, it could enhance its absorption and plant growth. The aim of this study was to assess the effects of boron deficiency and foliar fertilization in the absence and presence of sorbitol on plant growth and production, and its accumulation and mobility in cowpea. In the study, three experiments were carried out from February 2014 to May 2015. Experiment I was composed of two treatments with nutrient solution under absence (−B) and presence (+B) of boron in ten repetitions. In the experiment II, a 5 × 2 factorial scheme was used, being applied via foliar five concentrations of B (0, 1.25, 2.5, 3.75 and 5.0 g L−1 of B) in the form of boric acid and in the absence or presence of sorbitol (500 mmol L−1 ), with four repetitions. In the experiment III, marked boron (10B) mobility was studied regarding its absorption by roots and leaves. Boron deficiency symptoms, root growth, dry weight of plant organs and B content and grain production were assessed. Boron deficiency in cowpea plants decreased B absorption efficiency, although it has increased nutrient use efficiency. The greatest losses occurred in reproductive variables and root growth in relation to leaves and stem production. Boron deficiency induces cellular changes such as thickening in the middle lamella and starch accumulation in leaf chloroplasts, which lead to characteristic visual symptoms for cowpea. The highest production of cowpea grains (90–100% of maximum production) occurred when B was pulverized at 2.62 g L−1 of B without sorbitol, having as a source the boric acid, on growth stages V6, R1 and R2 and foliar content of 35 mg kg−1 of B. Foliar fertilization with boron, associated with sorbitol, increased micronutrient absorption in the vegetative part, but it did not influence cowpea production. A mobility was observed for B applied via foliar in cowpea plants, showing viability of foliar fertilization to meet the demand of this nutrient during vegetative development.
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Palavras-chave
Adubação foliar, Boro marcado, Micronutriente, Nutrição de plantas, Redistribuição, Vigna unguiculata, Foliar fertilization, Marked boron, Micronutrient, Plant nutrition, Redistribution, Vigna unguiculata