ABSTRACT It is common for vineyards in regions of high altitude to have high organic matter content in soil. Furthermore, reduced miner alization of organic matter and decomposing residues is expected because of the low temperatures. Thus, soils may not provide enough mineral nitrogen (N) to meet the needs of the grapevines and so the application of N sources is necessary, but may affect yield and must composition. The study aimed to evaluate yield and must composition of grapevines subjected to N application in soil with high organic matter content and the relationship with temperature and rainfall. The study was conducted in crops sea sons 2011/12, 2012/13 and 2013/14 in a vineyard located in the city of Água Doce, state of Santa Catarina, southern Brazil. The treatments consisted of N doses (0, 20, 40, 80 and 120 kg N ha-1) supplied via urea. Leaves opposite to the cluster were collected at full flowering and at veraison. Afterwards, the leaves were dried, ground and submitted to N analysis. Parameters of yield and must composition were evaluated. The dose of maximum technical efficiency in Cabernet Sauvignon grapevines was reached with 46 kg N ha-1 year-1 in crop season 2012/13. Leaf N content was a sensitive parameter to the application of N doses in the soil and underwent seasonal variation in relation to rainfall distribution. The N doses reduced total soluble solids (TSS) contents in the must. Based on principal component analysis, we found a correlation between total N content in leaf and accumulated rainfall, as well as between yield and temperature.

RESUMEN Los viñedos ubicados en regiones altas poseen suelos con alto contenido de materia orgánica. Sin embargo, debido a la baja temperatura se espera menor mineralización de la materia orgánica. De esta forma, los suelos pueden proporcionar menos cantidad de nitrógeno (N) mineral, respecto a los requerimientos de la vid. Por eso, es necesaria la aplicación de nitrógeno que puede afectar la productividad de la vid y la composición de la uva. Este estudio tuvo como objetivo evaluar la productividad y la composición del mosto de la vid sometido a la aplicación de N en suelos con alto contenido de materia orgánica y la relación con la temperatura y la pluviometría. El estudio fue realizado durante las campañas de los años 2011/12, 2012/13 y 2013/14, en un viñedo ubicado en el municipio de Agua Doce, Santa Catarina, región sur de Brasil. Los tratamientos fueron diferentes dosis de N (0, 20, 40, 80 e 120 kg N ha-1), suministrados con urea. La dosis de máxima eficiencia técnica en la vid Cabernet Sauvignon fue alcanzada con 46 kg N ha-1 año-1 en suelos con alto contenido de materia orgánica. El contenido de nitrógeno en las hojas fue un parámetro sensible a la aplicación de dosis de N en el suelo es sensible a la distribución de las lluvias. El N reduce el contenido de sólidos solubles totales en el mosto. Con base en los principales componentes analizados, los resultados indican una correlación entre el contenido de nitrógeno total en las hojas y la precipitación acumulada, así como entre los rendimientos y la temperatura.

ABSTRACT A hydroponic experiment was carried out to investigate the effect of phosphorus (P) nutrition on arsenic (As) uptake and translocation within the seedlings of rice cultivars. The experiment occurred in three stages: I 5 days of acclimatization (nutritive solution); II 10 days under P (0.0 and 0.09 mM) and As (0.0 and 100 mM) treatments; III 5 days under recovery. The As exposure had significant effect reducing dry weights of shoots or roots, resulted in elevated concentrations of As in shoot tissues. BR-IRGA 409 showed the highest susceptibility to As in biomass production and root system parameters regardless the P level. This cultivar showed contrasting responses of As translocation to shoot tissue dependent on P levels, with the highest As concentration under low P and lowest under normal P levels. P nutrition was most striking on plants recovery for all cultivars under As exposure. Clearer separation of cultivars for phosphorus use efficiency (PUE) occurred at lower shoot P contents, that was, at higher levels of P deficiency stress. IRGA 424 showed higher PUE as compared to the others cultivars. Our results go some way to understanding the role of P nutrition in controlling the effects of As in rice shoots.