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Las interacciones de los nutrimentos en las plantas pueden ser cuantificadas mediante las concentraciones nutrimentales en los órganos vegetales, sin embargo, hay pocos estudios que evalúen la interacción de más de un nutrimento en el mismo experimento, y escasos reportes de la interacción N/K en la solución nutritiva en el rendimiento y la composición mineral de papa (Solanum tuberosum L.). El objetivo de esta investigación fue evaluar en invernadero e hidroponía la interacción de tres relaciones porcentuales NO3-/aniones (40/100, 60/100 y 80/100) y tres de K+/cationes (15/100, 35/100 y 55/100) sobre la composición mineral de hojas, tallos, tubérculos y el rendimiento de papa cv Agatha. El diseño experimental utilizado fue completamente al azar con arreglo factorial de tratamientos 32. La interacción NO3-/aniones x K+/cationes fue significativa para las concentraciones de P, K, Ca y Mg en hojas; K, Ca y Mg en tallos; y Ca y Mg en tubérculos. Las relaciones NO3-/aniones y K+/cationes, y la interacción NO3-/aniones x K+/cationes no afectaron estadísticamente el diámetro de tubérculo, la materia seca del tubérculo, el número de tubérculos y el rendimiento. Estos resultados indican que la producción de papa en un sistema hidropónico cerrado y sustrato de fibra de coco las relaciones NO3-/aniones y K+/cationes no deben ser mayores a 60/100 y 15/100, respectivamente, ya que relaciones altas de NO3-/aniones (80/100) y K+/cationes (55/100) reducen el rendimiento de tubérculos 16.7% y 12.8%, cada una

A la relación NO3-/K+ en la solución nutritiva (SN) se le considera un factor clave para obtener altos rendimientos; sin embargo, por la falta de investigaciones al respecto, su importancia está sujeta a discusión. El objetivo de este trabajo fue evaluar en invernadero el efecto de tres relaciones NO3-/aniones (40, 60 y 80/100) y tres de K+/cationes (15, 35 y 55/100) sobre el crecimiento, composición mineral y el rendimiento de pepino (Cucumis sativus L. cultivar Luxell). El experimento constó de dos etapas: la 1, desde la siembra al trasplante, y la 2, desde trasplante hasta cosecha; en ambas etapas el diseño experimental utilizado fue completamente al azar con arreglo factorial 32. En la etapa1, los efectos de las relaciones NO3-/K+ sobre las variables de crecimiento no fueron significativos, aunque para las concentraciones de P, K y Mg en hojas hubo significancia. En la etapa 2, hubo diferencias (p≤ 0.05) en el rendimiento para la relación NO3-/ aniones y para K+/cationes, pero no para su interacción. El mayor rendimiento (90.56 t ha-1) se obtuvo con la relación intermedia (60/100 NO3-/aniones), mientras que para la relación K+/cationes el mayor rendimiento (83.40 t ha-1) fue obtenido también con la relación intermedia (35/100). Con relaciones altas de NO3-/aniones y de K+/cationes, los rendimientos disminuyen 9.98 y 31.84%, respectivamente, por lo que es indispensable hacer un manejo equilibrado de las relaciones NO3-/aniones y de K+/cationes en la SN para no alterar las concentraciones nutrimentales en las hojas y reducir el rendimiento de pepino cultivado en hidroponía.

The physicochemical parameters, mineral composition, and nutraceutical properties of ready-to-drink flavored-colored commercial teas were analyzed in the present study. The pH of samples was slightly acidic (3.72 to 4.11), titratable acidity was low (0.092 to 0.174%), and color parameters were wide variable (pink, yellow, brown, and red). Citrus-flavored tea obtained the highest content of manganese (0.281 mg·L−1), zinc (0.069 mg·L−1), magnesium (2.92 mg·L−1), potassium (62.65 mg·L−1), and sodium (271.74 mg·L−1), while lemon-, peach-, and blueberry-flavored teas obtained the highest levels of copper (0.035 mg·L−1), iron (0.246 mg·L−1), and calcium (18.21 mg·L−1), respectively. Citrus, lemon-, sangria-, and rose petal-flavored teas obtained the highest content in total phenols (211.56 mg·L−1), total flavonoids (65.46 mg·L−1), total catechins (640.79 mg·L−1), and total anthocyanins (640.79 mg·L−1), respectively. Lemon- and rose petal-flavored teas showed the highest and lowest antioxidant capacity levels in DPPH (1096.00 to 118.77 μmolTE·L−1), ABTS (1048.84 to 232.00 μmolTE·L−1), and FRAP (1269.20 to 147.70 μmolTE·L−1) assays. The levels of sodium reported in labels of all samples were lower than data obtained in our analysis. Also the levels observed for total phenols in blueberry-, citrus-, and rose petal-flavored teas were lower than our analysis, but total phenols of lemon-, peach-, and sangria-flavored teas were higher than the content reported in their labels. The results obtained in the present work give information to consumers for choosing flavored-colored ready-to-drink tea based on the physicochemical, nutritional, and nutraceutical properties.

The increasing order of the mean concentrations of Cd, Cu, and Zn in the tissues of Mugil cephalus of seven coastal lagoons of Sinaloa State (NW Mexico) was liver > gills > muscle, while for Pb it was gills > muscle ≥ liver. There were no differences between the mean concentrations of Cd and Pb of the three tissues determined in the samples of the seven lagoons and, although there were some significant differences, there was no indication of a latitude-related trend in the distribution of Cu and Zn: the Cu content of the muscle tended to be higher in the northern than in the southern lagoons, although in the case of the gills the highest and lowest mean values indicated an opposite trend, with the highest and lowest values in one southern and one northern lagoon. In the case of the liver, there were no differences and no indication of a regional trend. There were no differences in the mean Zn contents of muscle and gills; in the case of the liver, one of the lagoons of the central part of the state had a significantly higher value than one of the southern lagoons and all the rest had similar values. In addition, there was no clear indication of season-related differences in any of the three tissues. According to our results, the metal contents of the muscle of this species are not of concern for human health, since the allowable ingestion would be in the order of 0.9 kg/day.

This study shows the concentrations of Cd, Cu, Pb, and Zn in the muscle and hepatopancreas of Pacific white shrimps, Litopenaeus vannamei, cultured during 2010 in 26 commercial farms of the three main producer states of the Mexican NW, Sonora, Sinaloa, and Nayarit and compares the results to those obtained in 2000 using samples collected in16 farms of the same states. No significant changes were detected in Cd concentrations, but the 2010 Zn levels were significantly higher in all states in the hepatopancreas and in Sinaloa in the case of the muscle. Cu showed a tendency to higher hepatopancreas values in 2010, but differences were significant only in Sonora and for the global mean value. In contrast, Pb was one order of magnitude lower in both organs in 2010, possibly because of the almost 15 years since leaded gasoline was discontinued in Mexico.

To assess if they were within the safety limits for human consumption, the Cd, Cu, Pb, and Zn contents of fish muscles, bought from separate stalls of the fish markets of nine cities of NW Mexico, were determined by atomic absorption spectrophotometry. Considering all fish and markets, the mean contents were Zn:23.23±5.83, Cu:1.72±0.63, Cd:0.27±0.07, and Pb:0.09±0.04 µg/g (dry weight). Cu, Zn, and Pb did not reach levels of concern for human consumption, but the high Cd values determined in Mazatlán (Mugil cephalus:0.48±0.15;Diapterusspp.:0.57±0.33;Lutjanusspp.:0.72±0.12; small shark:0.87±0.19 µg/g dry weight) indicate that this was the only metal of concern for human health because the daily individual consumption of fish muscle to reach the PTDI would be within 0.27 and 0.41 kg.

Litopenaeus vannamei is the most important shrimp species in the traditional fishery of the coastal lagoons of the State of Sinaloa (NW Mexico), and most of the landings are consumed locally. Since these lagoons receive important volumes of agricultural, industrial and urban effluents, consumption of this shrimp could pose risks to human health. The mean content of Cd, Cu, Pb and Zn determined in the hepatopancreas of shrimp from commercial landings from six lagoons of Sinaloa were higher than those of the muscle. There was a weak correlation between the Zn content of the two tissues (P≤0.05) and the correlations were not significant for Cd, Cu and Pb (P>0.1). The concentrations found in the shrimp muscle were comparable or lower than those determined in commercial landings of different crustaceans from other geographic areas. According to our results the consumption of local shrimp poses no risks to human health.