RESUMO

This study evaluated leaf supply of zinc (Zn) and boron (B) using either soluble or sparingly soluble fertilizers in young sweet orange trees. Three experiments were set up in a greenhouse to compare two sources and four doses (control, low, adequate and high) of fertilizers as follows: (i) Experiment I (B): boric acid and calcium borate; (ii) Experiment II (Zn): Zn sulfate and Zn oxide; and (iii) Experiment III (B + Zn): boric acid + Zn Sulfate and Zn Borate. The sparingly soluble sources were effective in increasing the Zn and B leaf concentration. Dry matter of the aerial part increased 18 % with B applications in adequate concentration independent of the B fertilizer sources. In contrast, trees did not grow well with applications of adequate concentration of Zn as Zn Sulfate or high Zn concentration as Zn borate. Superoxide dismutase activity in leaves increased with applications of low concentration of Zn as Zn oxide and decreased with high concentration of Zn from either source. Polyphenol oxidase activity increased with application of adequate concentration of B as boric acid and high concentration of B as calcium borate. Furthermore, the upper concentrations of Zn were toxic in orange trees when the source was Zn sulfate. Increases in plant growth without damage to leaf tissue and positive responses of key enzymes of orange trees in a range of nutrient concentration applications demonstrated the practical use of sparingly soluble fertilizers to supplying B and Zn foliarily to plants.

Assuntos

RESUMO

This study evaluated leaf supply of zinc (Zn) and boron (B) using either soluble or sparingly soluble fertilizers in young sweet orange trees. Three experiments were set up in a greenhouse to compare two sources and four doses (control, low, adequate and high) of fertilizers as follows: (i) Experiment I (B): boric acid and calcium borate; (ii) Experiment II (Zn): Zn sulfate and Zn oxide; and (iii) Experiment III (B + Zn): boric acid + Zn Sulfate and Zn Borate. The sparingly soluble sources were effective in increasing the Zn and B leaf concentration. Dry matter of the aerial part increased 18 % with B applications in adequate concentration independent of the B fertilizer sources. In contrast, trees did not grow well with applications of adequate concentration of Zn as Zn Sulfate or high Zn concentration as Zn borate. Superoxide dismutase activity in leaves increased with applications of low concentration of Zn as Zn oxide and decreased with high concentration of Zn from either source. Polyphenol oxidase activity increased with application of adequate concentration of B as boric acid and high concentration of B as calcium borate. Furthermore, the upper concentrations of Zn were toxic in orange trees when the source was Zn sulfate. Increases in plant growth without damage to leaf tissue and positive responses of key enzymes of orange trees in a range of nutrient concentration applications demonstrated the practical use of sparingly soluble fertilizers to supplying B and Zn foliarily to plants.(AU)

Assuntos

RESUMO

Phytotechnical parameters, yield and fertilizer use efficiency are relevant to the rational management of fertigation, especially in cultivation of high technological level. Thus, the objective was to evaluate the influence and efficiency of nitrogen (N) and potassium (K) application on the phytotechnical parameters, yield and nutritional efficiency of yellow melon in a fertigation system. The experiment was conducted in the city of Bom Jesus-PI, Brazil, from January to April 2016, in a strip-block design with four replicates, and the treatments consisted of five N levels (0, 45, 90, 135 and 180 kg ha-1 in the form of urea) and five K levels (0, 60, 120, 180 and 240 kg ha-1 in the form of potassium chloride), applied through fertigation. Collar diameter, main branch length, leaf chlorophyll content, number of leaves, leaf area index, biomass accumulation, fruit yield, and N and K use efficiencies were evaluated. Applications of 180 kg ha-1 of N and 240 kg ha-1 of K, respectively, led to the highest growth of the melon, while maximum production was obtained with the use of 112.50 and 165 kg ha-1 of N and K, respectively. The efficiency of N and K use decreased with increasing levels.

As características fitotécnicas, de rendimento e de eficiência de uso dos fertilizantes são relevantes para o manejo racional da fertirrigação, especialmente em cultivo de elevado nível tecnológico. Níveis crescentes de N e K promoverão maior crescimento e produtividade do meloeiro. Neste sentido, objetivou-se avaliar a influência e a eficiência da aplicação de nitrogênio e potássio sobre as características fitotécnicas, de rendimento e de eficiência do meloeiro amarelo em sistema de fertirrigação. O experimento foi conduzido na cidade de Bom Jesus ­ PI, Brasil durante o período de janeiro a abril de 2016. O delineamento experimental adotado foi de blocos em faixas com quatro repetições, e os tratamentos constituídos por cinco níveis de nitrogênio (0, 45, 90, 135 e 180 kg ha-1 na forma de ureia) e cinco níveis de potássio (0, 60, 120, 180 e 240 kg ha-1na forma de cloreto de potássio) aplicados via fertirrigação. Avaliou-se os caracteres fitotécnicos, rendimento de frutos e as eficiências de uso do nitrogênio e do potássio. As aplicações de 180 kg ha-1 de N e 240 kg ha-1 de K promoveram maior crescimento do meloeiro, enquanto que a máxima produção foi obtida com o uso de 112,50 e 165 kg ha-1 de nitrogênio e potássio, respectivamente. As eficiências de uso do nitrogênio e do potássio diminuíram com o aumento dos níveis aplicadas.

Assuntos

RESUMO

The objective of this study was to assess quantitatively and qualitatively the degree of use fertilizers, limestone and irrigation, as well as the management practices of pasture. A survey was carried out with 232 farmers and technicians of rural extension about the adoption of technical conservation and soil fertility, leaf and soil analysis, irrigation, fertilizers use and limestone, as well as costs of these techniques on production. The results pointed to an usual use of soil analysis, lime, micronutrients and soil conservation practices by 96%, 97%, 78% and 99% of interviewees. Regardless of the soil analysis, most of them used N, P2O5 and K2O formula (NPK) in pasture fertilizatiat are: 400kg ha-1 of 8-28-16 at planting, and 700 kg ha-1 of 20-5-20 at topdressing rates. However, 93.8% of the producers did not realize leaf analysis. For the interviewed an adequate price relationship for fertilizer use is 1t per 1000 milk liters and 1t per 195 meat kg (13@).

O objetivo deste trabalho foi avaliar quantitativamente e qualitativamente a utilização de fertilizantes, corretivos e irrigação bem como as práticas de manejo de pastagens. Foi aplicado um questionário junto a 232 pecuaristas e técnicos relacionados à pecuária para levantar o grau de utilização de técnicas de conservação e fertilidade do solo, irrigação, análise foliar e de solo, uso de fertilizantes e corretivos e o custo do uso dessas técnicas sobre a produção. Os resultados indicaram que a utilização de análise de solo, calcário, micronutrientes e de práticas de conserva- ção do solo são usuais em 96%, 97%, 78% e 99% dos entrevistados. Independentemente da análise de solo, as formulações N, P2O5 e K2O (NPK) mais utilizadas são: 400kg ha-1 de 8-28-16 no plantio, e 700kg ha-1 de 20-5-20 na cobertura. No entanto, 93,8% dos produtores não realizam análise foliar. Para os entrevistados, a relação de preço adequada para o uso de fertilizantes é de uma tonelada para cada mil litros de leite e de uma tonelada para cada treze arrobas de carne.

RESUMO

The objective of this study was to assess quantitatively and qualitatively the degree of use fertilizers, limestone and irrigation, as well as the management practices of pasture. A survey was carried out with 232 farmers and technicians of rural extension about the adoption of technical conservation and soil fertility, leaf and soil analysis, irrigation, fertilizers use and limestone, as well as costs of these techniques on production. The results pointed to an usual use of soil analysis, lime, micronutrients and soil conservation practices by 96%, 97%, 78% and 99% of interviewees. Regardless of the soil analysis, most of them used N, P2O5 and K2O formula (NPK) in pasture fertilizatiat are: 400kg ha-1 of 8-28-16 at planting, and 700 kg ha-1 of 20-5-20 at topdressing rates. However, 93.8% of the producers did not realize leaf analysis. For the interviewed an adequate price relationship for fertilizer use is 1t per 1000 milk liters and 1t per 195 meat kg (13@).

O objetivo deste trabalho foi avaliar quantitativamente e qualitativamente a utilização de fertilizantes, corretivos e irrigação bem como as práticas de manejo de pastagens. Foi aplicado um questionário junto a 232 pecuaristas e técnicos relacionados à pecuária para levantar o grau de utilização de técnicas de conservação e fertilidade do solo, irrigação, análise foliar e de solo, uso de fertilizantes e corretivos e o custo do uso dessas técnicas sobre a produção. Os resultados indicaram que a utilização de análise de solo, calcário, micronutrientes e de práticas de conserva- ção do solo são usuais em 96%, 97%, 78% e 99% dos entrevistados. Independentemente da análise de solo, as formulações N, P2O5 e K2O (NPK) mais utilizadas são: 400kg ha-1 de 8-28-16 no plantio, e 700kg ha-1 de 20-5-20 na cobertura. No entanto, 93,8% dos produtores não realizam análise foliar. Para os entrevistados, a relação de preço adequada para o uso de fertilizantes é de uma tonelada para cada mil litros de leite e de uma tonelada para cada treze arrobas de carne.