RESUMO Uma quinta parte da população mundial consome pouco zinco (Zn), causando deficiências que podem causar danos celulares, retardo no crescimento e diminuir o sistema imunológico. Nesse trabalho avaliou-se o efeito do tempo de condicionamento osmótico de sementes de beterraba em soluções enriquecidas com Zn sobre a fisiologia, o crescimento, a produção e a biofortificação da raiz. Dois experimentos em estufa foram conduzidos durante primavera de 2015 e outono de 2016. Em cada experimento foram testados 24 tratamentos os quais compreenderam as combinações de três concentrações de Zn (0, 10 e 30 mg mL-1), duas fontes de Zn (sulfato e cloreto) e quatro tempos (12, 16, 20 e 24 horas), sob arranjo de blocos casualizados com quatro repetições. A concentração de Zn, principalmente como sulfato, afetou todos os parâmetros avaliados nas plantas de beterraba, massa fresca e seca de raiz, fotossíntese e a concentração de Zn na raiz (biofortificação). Em comparação ao controle, a massa fresca da raíz incrementou 70 e 100 g por planta com 10 mg mL-1 Zn durante os experimentos de 2015 e 2016, respectivamente. A mesma concentração por 16 horas provocou a maior concentração de Zn nas raízes atingindo 121 e 42 mg kg-1 em 2015 e 2016, respectivamente. Assim, o condicionamento osmótico de sementes em soluções enriquecidas com Zn, melhora as respostas fisiológicas das plantas, promovendo incrementos no crescimento, na produção e na biofortificação das raízes de beterraba. Portanto, esse método pode ser utilizado para biofortificar agronomicamente plantas de beterraba, independente da fonte de Zn.

ABSTRACT One-fifth of the world's population consumes too little zinc (Zn) causing deficiencies that can damage cells, stunt growth, and decrease immune response. This study evaluated the effect of time on the priming of beet seeds, in solutions enriched with Zn, on physiology, growth, production, and root biofortification. Two greenhouse experiments were conducted during spring 2015 and autumn 2016. In each experiment, 24 treatments were tested which comprised various combinations of three Zn concentrations (0, 10, and 30 mg mL-1), two Zn sources (sulphate and chloride), and four time periods (12, 16, 20, and 24 h), arranged in a randomised block design with four replicates. The concentration of Zn, mainly as sulphate, affected all parameters evaluated in the beet plants, such as fresh and dry root mass, photosynthesis, and root Zn concentration (biofortification). Compared to the control, fresh root mass increased 70 and 100 g per plant with 10 mg mL-1 of Zn during the experiments in 2015 and 2016, respectively. The same concentration for 16 h produced the highest Zn concentration in the roots, achieving 121 and 42 mg kg-1 in 2015 and 2016, respectively. Priming seeds in solutions enriched with Zn, thus, benefited the physiological response of the beet plants by promoting increases in growth, production, and biofortification of beet roots. Therefore, this method can be used to biofortify beet plants agronomically, regardless of the Zn source.

RESUMO O objetivo do trabalho foi avaliar as características químicas, físicas e sensoriais dos frutos de banana (Musa spp.) cultivar Caipira e Pacovan Ken, resistentes à Sigatoka Negra (Mycosphaerella fijiensis Morelet), com e sem embalagem de polietileno de baixa densidade, associada à refrigeração durante o período de armazenamento pós-colheita. O experimento foi instalado em 2012, no delineamento de blocos casualizados em esquema de parcelas subdivididas no tempo, tendo nas parcelas um fatorial 3 x 2 referente aos frutos sem embalagem e com embalagem de polietileno de 10 e 16 µm e duas cultivares Caipira e Pakovan Ken, e nas subparcelas as avaliações em intervalos de seis dias (0; 6; 12; 18 e 24) e dois dias (0; 2; 4; 6 e 8), para frutos armazenados nas temperaturas de 12; 15 e 25 ºC, respectivamente. As variáveis avaliadas foram: sólidos solúveis, acidez titulável, relação sólidos solúveis/ acidez titulável, potencial hidrogeniônico, açúcares solúveis totais, coloração do fruto e análise sensorial. A embalagem de polietileno associada à refrigeração manteve os frutos armazenados por 24 dias, mantendo as características pós-colheita adequadas ao consumo. A cultivar Pakovan Ken destacou-se quando comparada à Caipira, apresentando valores superiores nos atributos dos frutos avaliados.

ABSTRACT The aim of this work was to evaluate the chemical, physical and sensory characteristics of the Caipira and Pakovan Ken cultivars of the banana (Musa spp.), resistant to black Sigatoka (Mycosphaerella fijiensis Morelet), both with and without low-density polyethylene wrapping and together with refrigeration during the period of post-harvest storage. The experiment was carried out in 2012, in a randomised block design and an arrangement of lots split over time. A 3 x 2 factorial scheme was used for the lots, consisting of fruit with no wrapping and fruit wrapped in 10 and 16 µm polyethylene film, and two cultivars, Caipira and Pakovan Ken. The sub-lots consisted of evaluations made at intervals of six days (0, 6, 12, 18 and 24) and of two days (0, 2, 4, 6 and 8), for fruit stored at temperatures of 12, 15 and 25 ºC respectively. The following variables were evaluated: soluble solids, titratable acidity, ratio of soluble solids to titratable acidity, hydrogen potential, total soluble sugars, fruit colouration and sensory analysis. The polyethylene film together with the refrigeration enabled the fruit to be stored for 24 days, maintaining post-harvest characteristics suitable for consumption. The Pakovan Ken cultivar stood out when compared to the Caipira, with higher values for the fruit attributes under evaluation.

Ratoon sugarcane response to potassium is dependent on the environmental conditions of the region. Cropping systems that do not burn crop biomass after harvest leave crop residues on the soil, affecting the soil-plant nutrient dynamics system and fertilizer requirements. The objective of this study was to evaluate the effect of potassium fertilization of first and second ratoon sugarcane crops on potassium contents in the soil, in the plant, and yield and quality of stalksin an Oxisol under a conservation cropping system. The following potassium rates were tested: 0, 27, 54, 108, and 162 kg K ha-1, arranged in a randomized block design with five replicates. The application of potassium increased soil nutrient concentrations at six months, reaching 2.87 and 2.61 mmol c dm-3 with the highest rate in the first and second ratoons, respectively. The increase in available exchangeable-K content in the soil favored a greater plant uptake of this nutrient, reaching 12.1 and 10.0 g kg-1 in the first and second ratoons, respectively. The increase in potassium absorption by plants was reflected in the production of stems; the highest yields (87.0 and 132.9 t ha-1) were obtained with the application of 162 kg K ha-1 in the first and second ratoons, respectively.

The presence of mulch on the soil surface after the mechanical harvesting of sugarcane (Saccharum officinarum L.) enhances the cycling of nutrients, especially K, which can decrease K fertilizer recommendations for the crop. The aim of this study was to evaluate the effect of K addition to an Oxisol, with an initial concentration 0.07 cmol c K kg-1, in first and second ratoon (no-till) sugarcane cultures by a conservationist system, i.e. rational use of fertilizers, use of alternative inputs and especially the maintenance of residues in soil that was previously burned to facilitate cutting. The following K doses were tested: 0, 32.5, 65, 130, and 195 kg K2O ha-1, arranged in a randomized block design with five replicates. Potassium content in the soil and in the plant, as well as the yield and the quality of stalks were evaluated. Soil K application increased K concentration in soil and plant, and was reflected in the production of stalks, with higher production (87.5 and 107.5 t ha-1) with the use of 120 and 123 kg K2O ha-1 in first and second ratoon sugarcane, respectively. At the first 2 yr it was not possible to reduce the K fertilization in ratoon. Therefore, with the introduction of the conservationist system there was an increase (20 t ha-1) at the second ratoon regarding the first one with the same applied rate.

O selênio (Se) é um importante elemento ligado a processos fisiológicos na planta, microrganismos, animais e seres humanos. No entanto, para as plantas, seu modo de ação e sua essencialidade são ainda motivos de controvérsia. No Brasil, é relevante a falta de informações sobre o Se nas culturas agrícolas, havendo ainda indicativo de baixa ingestão desse elemento pela população. Assim, este estudo objetivou avaliar a influência da aplicação de selenato e selenito na biofortificação com Se e o efeito dessas formas de Se nos teores de macro e micronutrientes em cultivares de alface. Utilizou-se o delineamento experimental inteiramente casualizado, em esquema fatorial 5 x 3 x 2, sendo cinco cultivares de alface (Maravilha de Verão, Rafaela, Great Lakes, Veneranda e Vera), três concentrações de Se (0, 10 e 20 μmol L-1) e duas formas de Se (selenato e selenito), com quatro repetições. Os resultados encontrados mostram que, para o cultivo de alface em solução nutritiva, o selenato foi mais indicado para a biofortificação com Se, enquanto o selenito mostrou ser mais tóxico. A aplicação do selenato resultou em aumento no teor de S na parte aérea, enquanto o selenito reduziu o teor de P, e ambas as formas de Se diminuíram os teores de micronutrientes. Entre as cultivares de alface, não se observou variação genotípica para o teor de Se, e pequena variação foi verificada para produção de matéria seca da parte aérea e teores de S, Mg, Mn e Fe.

Selenium is an important antioxidant element associated with physiological processes in plants, microorganisms, animals, and humans. However, its mode of action and essentiality in plants are still disputed. In Brazil, information on Se in agricultural crops is extremely scarce, though there are indications that low levels of Se are being consumed by the population. The objective of this study was to evaluate the effect of selenate and selenite on yield, mineral nutrition and biofortification with Se of lettuce cultivars. The experiment was arranged in a completely randomized factorial design 5 x 3 x 2, with five lettuce cultivars (Maravilha de Verão, Rafaela, Great Lakes, Veneranda, and Vera), three Se concentrations (0, 10 and 20 μmol L-1) and two forms of Se (selenate and selenite), with four replicates. Results indicate that selenate application is more appropriate for biofortification of lettuce cultivars, while the effect of selenite proved to be more toxic. The application of selenate results in increased S shoot concentrations, while selenite reduced P concentrations, and both Se forms decreased micronutrient concentrations. No genotypic variation among lettuce cultivars was observed for Se concentration, and little variation was observed for shoot dry matter yield and S, Mg, Mn, and Fe levels.