RESUMO Avaliou-se em Coahuila, norte do México, o rendimento e a qualidade nutracêutica da cultivar de tomate Sahel sob malha sombreada. Foram utilizadas diversas misturas de substratos orgânicos consistindo das misturas utilizando areia (S), vermicomposto (VC), esterco bovino solarizado (SB), solo agrícola (AS) e composto mineralizado (MC). Os tratamentos foram: T1 (S:VC, 80:20), T2 (S:SB, 80:20), T3 (S:SB:AS, 80:15:05), T4 (S:VC:AS, 80:15:05), T5 (S:MC, 80:20), e um tratamento controle T6 (S, 100%) com solução de Steiner. Os resultados de produtividade mostraram que os melhores tratamentos orgânicos foram T5 e T4 com 3,48 e 3,33 kg planta-1, respectivamente; enquanto o maior rendimento foi obtido no controle com 3,71 kg planta-1. O maior teor fenólico nos frutos sob tratamento orgânico foi de 56,94 mg equivalentes de ácido gálico por 100 g de peso fresco para T5, enquanto o tratamento com adubação química obteve 49,82. A maior capacidade antioxidante foi obtida em T4, com 478,34 μM equivalente de Trolox/100 g de peso fresco. Foram avaliadas duas fases de amadurecimento nos frutos (amarelo e vermelho). O conteúdo de licopeno no tomate foi, em média, 32% maior nos frutos de cor vermelha que nos amarelos, com 3,12 e 2,24 mg de licopeno 100 g polpa-1, respectivamente. Para os vermelhos, o tratamento T5 apresentou o maior valor (3,52) e nos amarelos T1, 2,35, enquanto o T2 apresentou os menores valores para as duas cores. Adubos orgânicos à base de S:VC podem induzir boas quantidades de licopeno em frutos de ambas as cores, além de melhorar fenóis e antiOX.

ABSTRACT Yield and nutraceutical quality of Sahel tomato cultivar under shade net was evaluated using different mixtures of organic substrates in Coahuila, northern Mexico. The treatments consisted of mixtures using sand (S), vermicompost (VC), solarized bovine manure (SB), agricultural soil (AS) and mineralized compost (MC). The treatments were: T1 (S:VC, 80:20), T2 (S:SB, 80:20), T3 (S:SB:AS, 80:15:05), T4 (S:VC:AS, 80:15:05), T5 (S:MC, 80:20), and a control treatment T6 (S, 100%) with Steiner solution. Yield results showed that the best organic treatments were T5 and T4 with 3.48 and 3.33 kg plant-1, respectively; while the highest yield was in control (T6) with 3.71 kg plant-1. The highest phenolic content in the organic treatment of fruits was 56.94 mg equivalent of gallic acid per 100 g in fresh weight for T5, while the treatment with chemical fertilization obtained 49.82. The greatest antioxidant capacity was obtained in T4, with 478.34 μM equivalent of Trolox/100 g fresh weight. Two colors were evaluated (yellow and red) corresponding to two ripeness phases. Lycopene content in tomatoes was in average 32% higher in the red colored fruits than in the yellow ones, with 3.12 and 2.24 mg lycopene 100 g pulp-1 values, respectively. For the red ones, treatment T5 showed the highest value (3.52) and in yellow ones T1 reported 2.35, while T2 presented the lowest values for both colors. Organic fertilizers based on S:VC can induce good amounts of lycopene in fruits of both colors, as well as improve phenols and antiOX.

Abstract: Research on arsenic in the Lagunera region has focused on quality and recovery of extracted groundwater, which contains high concentrations (> 0.20 mg L-1) of arsenic (As). Several studies worldwide have established that the addition of phosphate fertilizers in agricultural soils favors As availability in the soil solution. However, knowledge of the behavior of this metalloid in agricultural soils of La Laguna is scarce. The objectives of this study were to determine the concentration of arsenic available in different soils of the region and to evaluate the behavior of arsenic in soil after adding phosphorus (P). Four different agricultural soil profiles were described. Soil samples were collected and three columns of each profile were used as permeameters to verify vertical movement of As after adding phosphorus and irrigation levels simulating agricultural management. The soils were characterized physically and chemically; initial As content and final available As of each horizon of the permeameter were determined by the hydride generation spectroscopic method as well as soluble phosphorous concentration. Data were subjected to analysis of variance and Tukey comparison of means (P ≤ 0.05). The results show that addition of P to agricultural soils of La Laguna can increase available As in the topsoil (0-30 cm) up to 662%, without exceeding levels permitted by Mexican Standards NOM-147-SEMARNAT/SSA1 2004. This study will provide the basis for future research.

Resumen: El estudio del arsénico (As) en la región Lagunera se ha centrado en la calidad y recuperación del agua extraída del subsuelo, que contiene altas concentraciones (> 0.20 mg L-1) del mismo. Diferentes investigaciones han establecido que la adición de fertilizantes fosfatados en suelos agrícolas, favorece la disponibilidad del As en la solución del suelo. Sin embargo, el conocimiento del comportamiento de este metaloide en suelos agrícolas de la región Lagunera, es escaso. Por lo anterior, los objetivos de esta investigación fueron determinar la concentración de arsénico disponible en diferentes suelos de la región y evaluar su comportamiento después de la adición de fósforo soluble. Se describieron cuatro perfiles de diferentes suelos agrícolas, con el fin de captar la mayor variabilidad del metaloide en suelos de la región; tres columnas de cada perfil fueron empleadas como permeámetros para verificar el movimiento vertical del As, después de adicionar fósforo (P) y láminas de riego simulando el manejo agrícola. Los suelos fueron caracterizados física y químicamente; el contenido de As inicial se determinó por el método de espectroscopía por generación de hidruros; así como el As disponible final de cada horizonte de los permeámetros; además de la concentración de fósforo soluble final. Los datos se sometieron a un análisis de varianza y a una prueba de medias con Tukey (P ≤ 0.05). Los resultados mostraron que al agregar P a los suelos agrícolas de la región Lagunera, el As disponible en la capa superficial (0-30 cm) se incrementó hasta un 662%; aunque este metaloide no rebasó los niveles permisibles que dañen la salud humana, de acuerdo a la Norma Mexicana NOM-147-SEMARNAT/SSA1-2004.

Abstract Nutrient solution leachate is associated with over-irrigation, which generates economic losses, drastic changes in pH and electrical conductivity (EC) of the solution, saturation of the culture medium, decreased photosynthesis, nutritional imbalances, growth of pathogens and poor quality fruit. The objective of this research was to determine the frequency of irrigation and substrate to reduce leachate volumes of nutrient solution and to relate tomato yield. Five different irrigation frequencies during the day (one irrigation at 8:00 h., two at 8:00 and 10:00 h, three at 8:00, 10:00, and 12:00 h, four at 8:00, 10:00, 12:00, and 14:00 h, five at 8:00, 10:00, 12:00, 14:00, and 16:00 h) and three substrates (sand, perlite, and a mixture of sand, vermicompost) were evaluated in three tomato phenological stages (vegetative, flowering, and fruiting). Leachate depended on the frequency of irrigation during the vegetative stage. The substrate type influenced the leaching of the stages of fruiting and ripening, leachate depended on the substrates used. The least amount of leachate was obtained when the total volume of irrigation water in a single day in the sand substrate. The leachate from the mix 75% sand and 25% of vermicompost showed higher EC. Efficiency in water use was 22.16 kg m-3, when the total volume applied daily, divided into four irrigation, this corresponds to a productivity of 6.38 kg m-2 of fruit. Soluble solid in fruit (°Brix) depended exclusively of substrate used.

Resumen Los lixiviados de la solución nutritiva se asocian al sobre-riego, lo que genera pérdidas económicas, cambios drásticos en el pH y en la conductividad eléctrica (CE) de la solución, saturación del medio de cultivo, disminución de la fotosíntesis, desequilibrios nutricionales, desarrollo de patógenos y frutos de mala calidad. El objetivo de esta investigación fue determinar la frecuencia de riego y sustrato que reduzcan los volúmenes lixiviados de solución nutritiva y relacionarlos con el rendimiento del cultivo. Cinco diferentes frecuencias de riego durante el día (un riego a las 8:00 h; dos a las 8:00 y 10:00 h; tres a las 8:00, 10:00 y 12:00 h; cuatro a las 8:00, 10:00, 12:00 y 14:00 h; cinco a las 8:00, 10:00, 12:00, 14:00 y 16:00 h) y tres sustratos (arena, perlita y una mezcla de arena-vermicompost) fueron evaluadas en tres etapas fenológicas de tomate (vegetativa, floración y fructificación). Los lixiviados dependieron de las frecuencias de riego durante la etapa vegetativa. El tipo de sustrato influyó en la lixiviación de las etapas de fructificación y maduración del fruto, los lixiviados dependieron de los sustratos utilizados. La menor cantidad de lixiviados se logró al aplicar el volumen total de agua en un solo riego al día en el sustrato arena. El lixiviado de la mezcla 75% de arena y 25% de vermicompost presentó mayor CE. La eficiencia en el uso del agua fue de 22.16 kg m-3, cuando se aplicó el volumen total diario, dividido en cuatro riegos; esto corresponde a una productividad de 6.38 kg m-2 de fruto.