There is a growing need to increase agricultural water use efficiency (EUA). Furthermore, when the product market value started to be considered, it was developed the concept of economic water productivity (PEA), defined as the value obtained per unit of water used (U$s/mm). This goal can be achieved through higher EUA or by producing crops with higher unit value. At EEA INTA Anguil, La Pampa, field experiments with several winter crops (wheat with different quality, barley, safflower, and canola) were carried out in order to identify those that have highest EUA and PEA. The results of the 2011 growing season indicated that barley had the highest EUA (14,4 kg/mm) and PEA (2,6 U$s/mm). Wheat showed EUA between 10,9 and 13,6 kg/mm, with highest values for group 3 quality crops, while no differences were found for PEA among qualities (1,5 to 1,8 U$s/mm). Oilseeds showed a good performance with EUA of 4,8 kg/mm in canola and 5,6 kg/mm for the sunfflowers, and PEA of both oilseeds was around 2 U$s/mm. Although these results are preliminary, winter-spring oilseeds appear as interesting alternatives to include in rotations. | El incremento de la eficiencia de uso de agua (EUA) en agricultura se ha convertido en un tema primordial. Asimismo, al comenzar a considerarse el valor económico del producto, se desarrolló el concepto de productividad económica del agua (PEA), definido como el valor recibido por unidad de agua usada (U$s/mm). Dicho objetivo puede alcanzarse ya sea por un incremento en la EUA como por la producción de cultivos de más elevado valor. En la EEA INTA Anguil, La Pampa, se están llevando a cabo ensayos con diversos cultivos invernales (trigos grupo de calidad industrial 1 y 3, cebada, cártamo y colza) con el objetivo de identificar aquellos que brindan la mejor EUA y PEA. Los resultados de la campaña 2011 demostraron que la cebada tuvo la más alta EUA (14,4 kg/mm) y PEA (2,6 U$s/mm). Los trigos presentaron EUA variables entre 10,9-13,6 kg/mm, correspondiendo los valores más altos al grupo 3, en cuanto a PEA no hubo diferencias significativas entre calidades (1,5 a 1,8 U$s/mm). Las oleaginosas demostraron muy buen comportamiento, con EUA de 4,8 kg/mm en colza y 5,6 kg/mm en el caso del cártamo, y la PEA de ambas oleaginosas fue de alrededor de 2 U$s/mm. Si bien los resultados son preliminares, las oleaginosas inverno-primaverales parecen alternativas interesantes para incorporar en las rotaciones.

Objetivando avaliar os efeitos de défices hídricos, em três estádios fonológicos da cultura da cevada (Hordeum vulgare L.), foi conduzido experimento em vasos, com delineamento em blocos ao acaso. Foram utilizados nove tratamentos decorrentes da combinação dos potenciais mínimos de água no solo de -0,05, -0,20 e -1,50 MPa, com os estádios fenológicos de máximo perfilhamento, florescimento e grão leitoso, permanecendo uniformizados durante o restante do ciclo, entre os potenciais de -0,01 a -0,05 MPa. Os resultados de produção, peso e teor de proteína dos grãos, tamanho de espigas, número total e número de espigas chochas, mostraram que os efeitos de défices hídricos variaram com a intensidade, duração e estádio fenológico da cultura, onde o estádio de florescimento mostrou-se mais sensível ao défice de água. A ocorrência de défice hídrico intenso, em cada um dos estádios, bem como ciclos repetidos de défices moderados ou intensos, levaram à diminuições significativas na produção de grãos, além de ocorrer tendência ao aumento do teor de protema dos grãos. O manejo da irrigação na cultura da cevada, quando se busca a máxima eficiência no uso da água, deve levar em conta os diferentes estádios fenológicos.<br>The experiment was carried out under greenhouse conditions, with the objective of evaluating the effects of water deficits in three phenological phases of barley crop (Hordeum vulgare L.). Pots were arranged in a randomized block design with nine treatments. They originated from the combination of minimum soil water potentials of -0,05, -0,20 and -1,50 MPa, with the phenological phases of maximum tillering, flowering and milky grain, having been hold uniformly along the rest of the cycle, between -0,01 and -0,05 MPa potentials. Weight of grain, protein content, spike sizes, spike total number and number of hollow spikes, showed that water deficit effects varied with the intensity, duration and phenological phase of the crop, where the flowering phase showed to be most sensitive to the water deficit. Ocurrence of intense water deficit in each phase, as well as repeated cycles of moderated or intense water deficits, led to significative reductions in grain production. Besides, a tendency to a higher grain protein content was observed. Irrigation manegement of barley crop, aiming to a maximum efficience in water consumption must take into account lhe different phenological phases.

Resumen El riego con agua contaminada con arsénico (As) es un riesgo para la salud humana, causa la acumulación de este elemento en el suelo y afecta el rendimiento de los cultivos. El objetivo de este estudio fue evaluar el efecto de la concentración de fósforo (P) en el agua de riego contaminada con As y su acumulación en el cultivo de cebada (Hordeum vulgare L.). La hipótesis fue que la acumulación de As por la planta de cebada es inversa a la concentración de P en el agua de riego. El efecto del P se evaluó con un diseño experimental multifactorial, con nivel variable de tipo 32. Cuarenta y cinco semillas se sembraron en pilas de suelo de 0.126 m2 de área, con 20.16 L de riego con soluciones acuosas de As (50, 200 y 400 μg L-1) y P (120, 210 y 300 μg L-1). El contenido de As en el suelo se determinó al inicio y final del estudio y en la planta a los 45 y 90 d después de la siembra. El análisis de los elementos se realizó por ICP-AES después de la digestión de los materiales con microondas. La acumulación promedio de As en la planta (14 101 ± 1 813 μg kg-1) del tratamiento con 400 μg L-1 de As fue 2.4 veces mayor que en el tratamiento con 50 μg L-1. En el tratamiento con concentración mayor de P (300 μg L-1) la planta acumuló en promedio 6 871± 1 051 µg kg-1, esto es 41.4 % menos As que el tratamiento con 120 μg L-1. Las concentraciones de P y As en el agua de riego tuvieron un efecto significativo (p≤0.05) en la acumulación de este último en la planta de cebada; además, el P inhibe la absorción de As en cebada. | Abstract Irrigation with water contaminated with arsenic (As) is a risk to human health since it causes the accumulation of this element in the soil and affects crop yield. The objective of this study was to evaluate the effect of phosphorus (P) concentration on irrigation water contaminated with As and its accumulation in the cultivation of barley (Hordeum vulgare L.). The hypothesis was that the accumulation of As by the barley plant is inverse to the concentration of P in the irrigation water. The effect of P was evaluated with a multifactorial experimental design, with a variable level of type 32. Forty-five seeds were planted in soil piles of 0.126 m2, with 20.16 L of irrigation with aqueous solutions of As (50, 200 and 400 μg L-1) and P (120, 210 and 300 μg L-1). We determined the content of As in the soil at the beginning and end of the study, and in the plant at 45 and 90 d after sowing. The analysis of the elements was carried out by ICP-AES after the digestion of the materials with microwaves. The average accumulation of As in the plant (14 101 ± 1 813 μg kg-1) with the treatment of 400 μg L-1 of As was 2.4 times higher than in the treatment with 50 μg L-1. In the treatment with higher concentration of P (300 μg L-1) the plant accumulated an average of 6 871 ± 1 051 μg kg-1, that is, 41.4 % less As than the treatment with 120 μg L-1. The concentrations of P and As in the irrigation water had a significant effect (p(0.05) in the accumulation of as in the barley plant; in addition, P inhibits the absorption of As in barley.

Objetivando avaliar os efeitos de défices hídricos, em três estádios fonológicos da cultura da cevada (Hordeum vulgare L.), foi conduzido experimento em vasos, com delineamento em blocos ao acaso. Foram utilizados nove tratamentos decorrentes da combinação dos potenciais mínimos de água no solo de -0,05, -0,20 e -1,50 MPa, com os estádios fenológicos de máximo perfilhamento, florescimento e grão leitoso, permanecendo uniformizados durante o restante do ciclo, entre os potenciais de -0,01 a -0,05 MPa. Os resultados de produção, peso e teor de proteína dos grãos, tamanho de espigas, número total e número de espigas chochas, mostraram que os efeitos de défices hídricos variaram com a intensidade, duração e estádio fenológico da cultura, onde o estádio de florescimento mostrou-se mais sensível ao défice de água. A ocorrência de défice hídrico intenso, em cada um dos estádios, bem como ciclos repetidos de défices moderados ou intensos, levaram à diminuições significativas na produção de grãos, além de ocorrer tendência ao aumento do teor de protema dos grãos. O manejo da irrigação na cultura da cevada, quando se busca a máxima eficiência no uso da água, deve levar em conta os diferentes estádios fenológicos. | The experiment was carried out under greenhouse conditions, with the objective of evaluating the effects of water deficits in three phenological phases of barley crop (Hordeum vulgare L.). Pots were arranged in a randomized block design with nine treatments. They originated from the combination of minimum soil water potentials of -0,05, -0,20 and -1,50 MPa, with the phenological phases of maximum tillering, flowering and milky grain, having been hold uniformly along the rest of the cycle, between -0,01 and -0,05 MPa potentials. Weight of grain, protein content, spike sizes, spike total number and number of hollow spikes, showed that water deficit effects varied with the intensity, duration and phenological phase of the crop, where the flowering phase showed to be most sensitive to the water deficit. Ocurrence of intense water deficit in each phase, as well as repeated cycles of moderated or intense water deficits, led to significative reductions in grain production. Besides, a tendency to a higher grain protein content was observed. Irrigation manegement of barley crop, aiming to a maximum efficience in water consumption must take into account lhe different phenological phases.