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Resumo -O objetivo deste trabalho foi determinar a influência da tensão de água e de atributos físicos e químicos do solo sobre a produtividade do arroz irrigado por aspersão, em terras baixas no Rio Grande do Sul. Na safra 2011/2012, foram avaliados os efeitos das tensões de água no solo de 20 e 40 kPa, durante todo o ciclo da cultura, bem como as de 40 e 20 kPa nas fases vegetativa e reprodutiva, respectivamente. Na safra 2012/2013, foram avaliadas as tensões de 10, 20 e 40 kPa, durante todo o ciclo da cultura, e as de 40 e 10 kPa nas fases vegetativa e reprodutiva, respectivamente. Em ambas as safras, utilizou-se a cultivar de arroz irrigado BRS Pampa. O gasto com água na irrigação por aspersão representou 48% do gasto com a irrigação por inundação. A produtividade do arroz correlacionou-se positivamente com a microporosidade e com os teores de fósforo e potássio disponíveis no solo; e negativamente com a macroporosidade e a saturação por alumínio. A avaliação conjunta da tensão de água e de atributos físicos e químicos do solo permite avaliar com mais propriedade a variabilidade na produtividade de arroz irrigado por aspersão em terras baixas no Rio Grande do Sul. A irrigação por aspersão possibilita melhor uso da água proveniente da precipitação pluvial, com efeitos positivos sobre a economia de água.Termos para indexação: Oryza sativa, economia de água, fertilidade do solo, física do solo, porosidade do solo, tensão de água no solo. Sprinkler-irrigated rice yield in lowlands as a function of water availability and soil attributesAbstract -The objective of this work was to determine the effect of soil water tension and physicochemical soil attributes on sprinkler-irrigated rice yield in lowlands of the state of Rio Grande do Sul, Brazil. In the 2011/2012 crop season, the effects of 20 and 40 kPa soil water tensions throughout the crop cycle were evaluated, as well as of 40 and 20 kPa during the vegetative and reproductive phases, respectively. In the 2012/2013 crop season, soil water tensions of 10, 20, and 40 kPa were evaluated throughout the entire crop cycle, and the tensions of 40 and 10 kPa were evaluated during the vegetative and reproductive phases, respectively. In both crop seasons, the irrigated rice cultivar BRS Pampa was used. Water costs with sprinkler irrigation represented 48% of that with flood irrigation. Rice yield was positively correlated with soil microporosity and phosphorus and potassium availability; and negatively correlated with macroporosity and aluminum saturation. The joint evaluation of soil water tension and soil physicochemical attributes allow a better evaluation of the variability of sprinkler-irrigated rice yield in the lowland areas of the state of Rio Grande do Sul. Sprinkler irrigation allows better use of rainwater, revealing positive effects on water economy.

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RESUMO -O objetivo deste trabalho foi avaliar o efeito da inoculação de fungos micorrízicos arbusculares (Glomus clarum Nicolson e Schenck, Glomus etunicatum Becker e Gerd, Gigaspora margarita Becker e Hall e Scutellospora heterogama Nicolson e Gerd) em mudas micropropagadas de mirtileiro da cultivar Woodard. O delineamento experimental utilizado foi o de blocos casualizados, com cinco tratamentos, quatro repetições por tratamento e seis plantas por parcela. As plantas inoculadas com G. margarita apresentaram maior altura e biomassa seca das raízes. Os tratamentos com S. heterogama e G. margarita apresentaram os maiores resultados para a biomassa verde das raízes. O desempenho foi relacionado com as taxas de colonização das raízes que, nas plantas inoculadas com G. margarita e S. heterogama, foram de 48,2 e 45,1%, respectivamente. Para os teores nutricionais, as plantas inoculadas com S. heterogama, G. etunicatum, G. clarum e G. margarita proporcionaram maiores teores de N e P na parte aérea das plantas. Termos para indexação: Micropropagação, Vaccinium sp., endomicorrizas, crescimento. DEVELOPMENT OF SEEDLINGS OF BLUEBERRY INOCULATED ARBUSCULAR MYCORRHIZAL FUNGIABSTRACT -The objective of this study was to measure the effect of inoculation with arbuscular mycorrhizal fungi (Glomus clarum Nicolson and Schenck, Glomus etunicatum Becker and Gerd, Gigaspora margarita Becker and Hall and Scutellospora heterogama Nicolson and Gerd) in seedlings of blueberry cultivars Woodard. The experimental design was a randomized block with five treatments, with four plots per treatment and six plants per plot. Plants inoculated with G. margarita showed greater height and dry weight of roots. The treatments with S. heterogama and G. margarita showed the highest results for the green biomass of roots. The performance was related to the rate of colonization of roots, plants inoculated with G. margarita and S. heterogama, were 48.2 and 45.1%, respectively. For the nutritional contents, plants inoculated with S. heterogama, G. etunicatum, G. clarum and G. margarita provided higher levels of N and P in the shoots.

SUMMARYOne of the largest strawberry-producing municipalities of Rio Grande do Sul (RS) is Turuçu, in the South of the State. The strawberry production system adopted by farmers is similar to that used in other regions in Brazil and in the world. The main difference is related to the soil management, which can change the soil chemical properties during the strawberry cycle. This study had the objective of assessing the spatial and temporal distribution of soil fertility parameters using principal component analysis (PCA). Soil sampling was based on topography, dividing the field in three thirds: upper, middle and lower. From each of these thirds, five soil samples were randomly collected in the 0-0.20 m layer, to form a composite sample for each third. Four samples were taken during the strawberry cycle and the following properties were determined: soil organic matter (OM), soil total nitrogen (N), available phosphorus (P) and potassium (K), exchangeable calcium (Ca) and magnesium (Mg), soil pH (pH), cation exchange capacity (CEC) at pH 7.0, soil base (V%) and soil aluminum saturation(m%). No spatial variation was observed for any of the studied soil fertility parameters in the strawberry fields and temporal variation was only detected for available K. Phosphorus and K contents were always high or very high from the beginning of the strawberry cycle, while pH values ranged from very low to very high. Principal component analysis allowed the clustering of all strawberry fields based on variables related to soil acidity and organic matter content.Index terms: Fragaria x ananassa Duch, soil fertility, multivariate analysis, temporal variability.(