RESUMONa análise das variabilidades espacial e temporal dos fatores inerentes à produtividade agrícola, a geoestatística constitui a base para a aplicação dos conceitos de agricultura de precisão. Assim, este estudo foi desenvolvido com os objetivos de avaliar a variabilidade espacial de atributos físico-hídricos do solo e delimitar zonas homogêneas para o manejo da irrigação em um cultivo de videira, utilizando ferramentas geoestatísticas. Um experimento de campo foi realizado em Petrolina, PE, no Vale do Submédio São Francisco, em um pomar de videira irrigada por microaspersão. Em uma área de 3,2 ha, foram coletadas 160 amostras de solo nas camadas de 0,0-0,20 e 0,20-0,40 m, em quatro transeções, as quais foram utilizadas para as determinações das frações granulométricas (areia total, silte e argila), curva de retenção de água no solo, densidade do solo e porosidade total do solo. Os dados foram submetidos às análises pela estatística descritiva e geoestatística. A variabilidade espacial dos atributos físico-hídricos do solo foi observada; foi realizada a interpolação por krigagem e geração de mapas de contorno para a delimitação de zonas homogêneas. Os atributos de solo analisados apresentaram baixa (densidade do solo, porosidade total e areia total) e média heterogeneidade (silte e argila). O índice de dependência espacial observado foi classificado entre moderado e forte para todos os atributos. A água disponível na camada de 0,2-0,4 m apresentou o maior alcance e foi considerada o atributo para delimitação de três zonas homogêneas, que receberam diferentes volumes de água de irrigação durante dois ciclos de produção da videira, em razão da umidade do solo medido em cada uma dessas zonas.Termos de indexação: água disponível no solo, geoestatística, dependência espacial.

Irrigation plays an important role for grape's yield as well as on its quality for winemaking. Thus, the effects of deficit irrigation strategies on yield and quality of wine grapes cv. Syrah were evaluated in Petrolina, State of Pernambuco, Brazil. Evaluations were carried out throughout the second and third growing seasons, which were from November 2010 to February 2011 (rainy season) and from May to September 2011 (dry season), respectively. Vines were drip irrigated and the experimental design was completely randomized with three treatments and four replications. The treatments were full irrigation (FI), performed according crop evapotranspiration; regulated deficit irrigation (RDI), in which irrigation was interrupted in phenological growth stage of bunch closure, but was occasionally performed according soil water monitoring of the root zone; and deficit irrigation (DI), when irrigation was interrupted from bunch closure to harvesting. Differences on leaf water content amo ng treatments were observed in both growing seasons and RDI and DI treatment plants presented moderate water stress. The number of bunches did not differ among treatments in both growing seasons; however, bunch weight per plant, average bunch weight and soluble solid content were higher in FI treatment during the dry season. Deficit irrigation strategies promoted water saving. KEYWORDS:Vitis vinifera L., soil water content, leaf water potential. IRRIGAÇÃO COM DÉFICIT EM VIDEIRA DE VINHO CV. SYRAH EM DOIS CICLOS DE PRODUÇÃO NO SEMIÁRIDORESUMO: A irrigação tem importante papel tanto na produtividade como na qualidade da uva para vinificação. Assim, este trabalho avaliou a influência de estratégias de irrigação na produção, em termos quantitativos e qualitativos, da videira cv. Syrah, irrigada por gotejamento, em Petrolina --PE, no segundo ciclo de produção de uva, entre novembro de 2010 e fevereiro de 2011 (período "chuvoso") e no terceiro ciclo de produção de uva, entre maio e setembro de 2011 (período "seco"). O delineamento utilizado foi o de blocos casualizados, em número de 4, com 3 tratamentos: irrigação plena (IP), em que a aplicação de água foi realizada durante todo o ciclo de produção, com base na evapotranspiração da cultura; irrigação com dé ficit controlado (IDC), em que a aplicação de água foi interrompida na fase fenológica de cacho fechado, porém irrigações foram realizadas esporadicamente, sendo o momento de irrigação determinado pelo monitoramento da água do solo na zona radicular; e irrigação deficitária (ID), em que a aplicação de água foi interrompida na fase fenológica de cacho fechado, permanecendo assim até a colheita. Diferenças entre os tratamentos ocorreram quanto ao potencial hídrico foliar, e as plantas dos tratamentos IDC e ID apresentaram um estresse hídrico moderado. O número de cachos não foi afetado em ambos os ciclos pelos tratamentos, mas o peso de cachos por planta, peso médio do cacho e sólidos solúveis foram maiores no tratamento IP, no ciclo do período "seco". As estratégias de irrigação co...

Characterization of the spatial variability of vegetative vigor in vineyards can help improve the performance of site-specific management practices, or the management of vineyards with different rates. Characterization using canopy proximal sensing has been a widely disseminated technique; however, vineyards in southeastern Brazil, where the utilization of annual double pruning results in a winter harvest, knowledge of the role of variability in improving vineyard management has not yet been applied. This study aimed to determine if post-veraison mapping of a normalized difference vegetation index could be used to assess the variability in grapevine vigor, water status, physiology, yield and berry quality attributes at harvest in an irrigated vineyard in southeastern Brazil. This normalized difference vegetation index was measured with an active canopy sensor, and spatial distribution maps over two growing seasons of a vineyard, managed on an annual double pruning basis, were generated. Attributes of physiological and technological berry maturation, leaf water potential, gas exchange, production, and fresh pruning weight were calculated. These normalized difference vegetation index maps allowed for the determination of variability in vegetative vigor and the productive potential of the vineyard; however, high levels of rainfall during the maturation period may reduce the potential of using these maps for determining berry parameters.

RESUMOApesar da grande importância da adubação na qualidade das uvas, ainda existem poucos estudos sobre a fertirrigação em videira de vinho no Vale do Submédio São Francisco. Com o objetivo de avaliar a produção de uvas sob a influência de doses de potássio e de adubo orgânico, um experimento foi realizado na Embrapa Semiárido, em Petrolina-PE, com videiras (Vitis vinifera L.), 'Syrah', enxertadas sobre o porta-enxerto 'Paulsen' 1103 e cultivadas no espaçamento 3 x 1 m. As plantas foram irrigadas por um sistema de gotejamento, com um emissor por planta, com vazão de 2 L h -1 . Os tratamentos foram constituídos de cinco doses de potássio (0, 20, 40, 80 e 160 kg ha -1 ) e duas doses de adubo orgânico (0 e 7,5 m 3 ha -1 ). Estes tratamentos foram dispostos em parcelas subdivididas no qual o adubo orgânico constituiu as parcelas e as doses de potássio as subparcelas. Foram avaliados na colheita o número de cachos por planta, a produção total por planta, o peso médio dos cachos e o rendimento total das plantas. As diferentes doses de potássio aplicadas pelo sistema de irrigação e de adubo orgânico aplicados via solo não influenciaram significativamente as características avaliadas. Palavras-chave:Vitis vinifera L., irrigação, fertilizante. INTRODUÇÃOA vitivinicultura é uma das atividades agrícolas de grande importância para o Vale do Submédio São Francisco. A produção de vinho é responsável pela geração de renda e emprega direta e indiretamente em torno de três mil pessoas. Esta produção representa 15% do mercado nacional de vinhos de mesa finos, sendo ainda exportada para outros países (Instituto do Vinho do Vale do São Francisco, 2008).

The nutrients availability can lead to changes on grapevines physiological behavior, which results in a great importance of studies regarding the application of potassium doses. The aim of this research was to evaluate the ecophysiological behavior of grapevine cultivar ‘Syrah’ growing under different potassium doses by fertigation, according to the determination of gas exchange, chlorophyll a, fluorescence and pigments index. Five years old plants, grafted on ‘Paulsen 1103’ rootstock, in a trellis system and planted at theBebedouro Experimental Field, located in Petrolina, PE, Brazil, were evaluated. The experiment was composed by five potassium doses (0, 20, 40, 80 and 160 kg ha-1), applied by fertigation. The potassium sources were potassium sulfate, potassium nitrate and potassium chloride. The evaluations of the ecophysiologyical parameters were performed at four different times (07am, 10am, 1pm and 3pm) throughout the day on the flowering stage and the first and second fruit growth stages, determining gas exchange and chlorophyll a fluorescence and the pigments index was evaluated at the same grapevines leaves one time. Considering each evaluation period, it was observed that, according to the magnitude of the results for gas exchange, chlorophyll a fluorescence and pigments index, is not possible to indicate the best potassium dose. The climatic conditions during each period of evaluation influenced most the eco-physiological variables than the applied potassium doses, while the changes on pigments index were due to leaves development during the plant cycle.

Variation in the spatial distribution of leaf chlorophyll content associated with the progression of the phenological cycle of crops may occur in cultivated areas as a result of the variability of environmental conditions and of the intrinsic properties of the plants. The objective of the present study was to model the trend in variation and assess the temporal stability of index of chlorophyll a, b, and total chlorophyll (Chla, Chlb, and Chlt, respectively), and to characterize the spatial distribution of Chlt index in grapevine cv. 'Chardonnay'. The assessments consisted of in situ measurements made with a portable meter in a commercial vineyard located in the municipality of Espírito Santo do Pinhal, state of São Paulo, Brazil, in the period between flowering and fruit maturation. Descriptive statistics were applied to the indices and regression models were fitted to ascertain the relationship of their mean variation with time. The temporal stability of Chlt index was estimated using Spearman's rank correlation analysis and thematic maps were created using geostatistical analysis and spatial estimation by ordinary kriging. The Chlb and Chlt indices were non-linearly associated with cycle progression and their decrease after the start of maturation was estimated. The temporal stability of the Chlt index was low and variation in its spatial distribution was observed over the assessed period.

The monitoring of chlorophyll content in grapevine leaves allows us to evaluate their N status, assisting with the information for the decision make about nutrient rate and application time to the vineyard. The present work aimed to propose an easy-to-use procedure for the calibration of a chlorophyll hand-held meter based on the NDVI homogeneous zones in a vineyard for the device readings and leaf sampling. We evaluated the wine grape ‘Chardonnay’ growing under drip irrigation in a vineyard located in the Southeast region of Brazil. Readings of the relative chlorophyll indices (a, b, and total) were taken in situ four times throughout the 2019 growing season, with the device placed on two leaves of every 40 pre-selected target plants in two homogeneous zones of NDVI previously defined in the vineyard. Subsequently, the chlorophyll and leaf nitrogen contents were determined in laboratory to relate them to the chlorophyll meter readings through generalized estimation equations. The chlorophyll meter is capable of estimating the levels of chlorophyll a, b and total by the models generated with an error of 0.98, 0.58, and 1.47 µg ml-1 cm-2 for calibration and of 1.03, 0.67, and 1.49 µg ml -1 cm-2 for prediction, respectively. The functions developed for the leaf N content present calibration error of 1.49 g kg-1 and prediction error of 3.39 g kg-1, but capable of providing an estimate when error is less than the amplitude of nitrogen sufficiency.

Due to the increase in water and energy tariffs, in addition to the limited amount of these resources, the automation of irrigation can help farmers to increase the production of agricultural crops. Therefore, the objective of this research was to evaluate different irrigation managements between manual and automatic in the production of arugula in a protected environment, in order to determine the productive potential in the cultivation of vegetables. The experiment was conducted in randomized blocks with four irrigation management strategies, divided into automatic and manual managements: automatic irrigation management via soil (IAS); automatic irrigation management via climate (IAC); manual irrigation management via soil (IMS) and manual irrigation management via climate (IMC). The treatments were applied to the arugula (Eruca Sativa L.) crop during two production cycles, and their effect on biophysical aspects of plants and irrigation water productivity was evaluated. For the fresh mass variable, the IAC (17.75 g plant -1 ), IAS (12.38 g plant -1 ), and IMC (8.63 g plant -1 ) treatments, in the 1 st cycle, were statistically similar to each other, whereas in the 2 nd cycle, only the IAC (16.29 g plant -1 ) and IAS (19.80 g plant -1 ) treatments had this statistical similarity. Automatic managements can be recommended based on this research, however, considering the financial difficulties of the small farmer, IMC may be a desirable option in unfavorable economic conditions.