ABSTRACT Variation in rainfall affects crops; therefore, agricultural practices become essential for forage production in semi-arid regions. This study aimed to evaluate the influence of different agricultural practices on phyllochron, structural characteristics of forage cactus and millet, and their relations with crop yield using the principal component analysis (PCA). The design was in randomized blocks, with six treatments: sole cropped cactus without straw mulching, sole cropped cactus with straw mulching, sole cropped millet without straw mulching, sole cropped millet with straw mulching, and cactus intercropping with millet, with and without straw mulching, each with four replicates. There were three cactus cycles and nine millet cycles (three cycles of cultivars BRS1501 and six of IPA Bulk-1-BF). Biometric parameters were evaluated monthly, while yield was determined after the crop harvest. Phyllochron was determined with the regression analysis. The PCA was applied to structural characteristics and yield. The systems adopted did not influence the structural characteristics of cactus and millet ( p > 0.05), except for cladode thickness, which increased with straw mulching. Phyllochron of the millet reduced when the crop was intercropped. The structural characteristics of cladode length, width, and thickness influenced crop yield, mainly in systems with straw mulching. Straw mulching and intercropping alter phyllochron of cactus and millet. The adoption of straw mulching has a more significant relationship with cactus yield, whereas biometric variables influence crop yield for millet, not the cropping system.

RESUMO A palma forrageira é uma cultura altamente resistente, e oferece benefícios em sua mucilagem para a indústria devido às suas propriedades físico-químicas. Objetivou-se analisar o efeito do manejos de irrigação, época de colheita, tamanho do cladódio e adição de ácido cítrico durante o processamento no rendimento agroindustrial e nas propriedades físico-químicas de mucilagem extraída de cladódios de Nopalea cochenillifera clone Miúda cultivados em sequeiro e irrigados. Foram medidos o rendimento, teor de sólidos solúveis, acidez titulável, pH, teor de K+ e Na+, e condutividade elétrica na mucilagem. As práticas de manejo no campo resultaram em alterações nos ftoquímicos estudados. No cultivo de sequeiro, a colheita noturna dos cladódios maiores aumentou os teores de K+ e sólidos solúveis. A adição de ácido cítrico à extração da mucilagem resultou em maiores quantidades de sólidos solúveis, acidez titulável e condutividade elétrica e menores valores de pH. A maior disponibilidade hídrica promoveu maiores rendimentos de mucilagem.

ABSTRACT Cactus is a highly resistant crop, and offers benefits in its mucilage for the industry due to its physicochemical properties. This study aimed to analyze the effect of irrigation managements, harvest time, cladode size and citric acid addition during the processing on the agro-industrial yield and physicochemical properties of mucilage extracted from cladodes of Nopalea cochenillifera Miúda clone cultivated under rainfied and irrigated conditions. The yield, soluble solids content, titratable acidity, pH, K+ and Na+ contents, and the electrical conductivity were measured in the mucilage. The management practices in the field resulted in changes in the studied phytochemicals. For the rainfied cultivation, the night harvest of the biggest cladodes increased the K+ and soluble solids contents. The addition of citric acid to the mucilage extraction resulted in higher amounts of soluble solids, titratable acidity and electrical conductivity and lower pH values. The highest water availability promoted higher mucilage yields.

Resumen El objetivo fue modelar la distribución espacial de las propiedades físicas del suelo a través de geoestadísticas en la región semiárida brasileña. El estudio se realizó en la Cuenca Experimental del Río Ipanema, Pernambuco, en una zona aluvial con malla regular y muestras de 40 puntos. Se realizaron pruebas de infiltración para evaluar la conductividad hidráulica y muestreos para determinar la textura del suelo y el carbono orgánico del suelo (COS). Las variables fueron sometidas a análisis estadístico descriptivo y de correlación, además del informe geoestadístico, que indicó alta variabilidad para la conductividad hidráulica del suelo. Los mejores ajustes se realizaron con el modelo esférico para las variables de conductividad hidráulica, arena, limo y arcilla, y el modelo gaussiano para el COS. Así, con la técnica de geoestadística, fue posible mapear y verificar las principales características físicas del suelo en la zona, proporcionando una mayor optimización en la planificación agrícola.

Abstract The objective was to model the spatial distribution of the physical properties of the soil through geostatistics in the Brazilian semi-arid region. The study was carried out in the Experimental Basin of Ipanema River, Pernambuco, in an alluvial area with regular grid and samples of 40 points. Infiltration tests were carried out to assess hydraulic conductivity and sampling was performed to determine soil texture and soil organic carbon (SOC). The variables were subjected to descriptive and correlation statistical analyses, in addition to the geostatistical report, which indicated high variability for the hydraulic conductivity of the soil. The best fits were obtained with the Spherical model for the hydraulic conductivity, sand, silt, and clay variables, and the Gaussian model for SOC. Thus, with the geostatistics technique, it was possible to map and verify the main physical characteristics of the soil in the area, providing greater optimization in agricultural planning.

ABSTRACT The use of irrigation can improve the productivity and nutritional quality of the forage cactus in environments with a water deficit, resulting in profit to the producer. The productive performance, bromatological composition and economic benefits of using irrigation were investigated in this study with forage cactus clones regulated deficit irrigation (RDI). The study was conducted in an experimental design of randomised blocks, in a factorial scheme with subdivided plots. The plots consisted of water regimes based on the crop evapotranspiration (ETc) (rainfed, 40, 80 and 120% ETc). The cactus clones [‘Miúda’ (MIU), ‘Orelha de Elefante Mexicana’ (OEM) and ‘IPA Sertânia’ (IPA)] comprised the subplots. The total number of cladodes per plant, the fresh and dry matter yields and the bromatological composition were evaluated. Economic viability was assessed using the net revenue and benefit to cost ratio (BCR). The irrigation depths did not increase the yield of the clones. The OEM clone showed 276 and 343% greater fresh and dry matter production, respectively, when compared to the IPA clone; however, when compared with the MIU clone, it was 63%, both on a fresh and dry matter production. The water regimes had no effect on the nutritional quality of the cactus. Only IPA showed no profit during the first cycle (BCR < 1). It can be concluded that planting one irrigated hectare with the OEM and MIU clones offer economic returns starting from the first production cycle (18 months).

Abstract The vegetation structure is a good indicator of the conservation condition of an ecosystem, since it reflects alterations caused by anthropic action. This study proposes to analyze the phytosociological aspects of the Caatinga domain under anthropic disturbance and their correlations with hydrological variables. Twenty-five 400 m 2 plots were sampled in the municipality of Floresta - PE, Brazil. Phytosociological parameters such as density, frequency and dominance were calculated. The seasonality of plant area index was analyzed for six species. The association between structural characteristics and hydrological variables (throughfall, stemflow and interception loss) in the species was evaluated by multivariate analysis. A total of 930 individuals, six families and 10 species were recorded. The abundance of the species Cenostigma pyramidale in the area may be an indicator of the degree of change in the vegetation. The structural characteristics of the species revealed little association with rainfall partitioning.

RESUMO Embora pertencentes ao mesmo grupo fotossintético (MAC - Metabolismo Ácido das Crassuláceas), a evapotranspiração de distintas espécies de palma forrageira pode responder de maneira diferenciada às variáveis meteorológicas, e depende da sua dinâmica do crescimento. Objetivou-se analisar a contribuição de variáveis meteorológicas e de características morfológicas dos cladódios e da planta sobre a evapotranspiração de espécies de palma forrageira dos gêneros Nopalea e Opuntia. O experimento foi conduzido em Serra Talhada, Pernambuco, onde as espécies ‘IPA Sertânia’ (Nopalea sp.), ‘Miúda’ (Nopalea sp.) e Orelha de Elefante Mexicana (Opuntia sp.) foram submetidos a distintas lâminas (2,5; 5,0; e 7,5 mm) e intervalos e irrigação (7; 14 e 28 dias). A evapotranspiração real e dados biométricos das espécies de palma, e variáveis meteorológicas foram obtidos entre março de 2012 e agosto de 2013. Matriz de correlação de Pearson e análises canônica e de trilha foram aplicadas aos dados. Verificou-se que a radiação solar global se destacou como a variável que mais influenciou na redução da evapotranspiração real (ET) das três espécies, e a velocidade do vento àquela que afetou a resposta da ET à variação da demanda atmosférica (ET/ETo) das espécies Orelha de Elefante Mexicana e ‘IPA Sertânia’. O aumento do índice de área do cladódio implicou na redução da ET dessas duas últimas espécies, enquanto os efeitos do número de cladódios de 1ª e 2ª ordens foram os mais importantes para a ‘Miúda’. Logo, a evapotranspiração da palma forrageira depende da sazonalidade das condições meteorológicas e das características morfológicas das suas espécies.

ABSTRACT Despite belonging to the same photosynthetic group (CAM - Crassulacean Acid Metabolism), evapotranspiration of distinct species of forage cactus may respond differently to meteorological variables and depends on its growth dynamics. The objective of this work was to analyze the contribution of meteorological variables and morphological characteristics of cladodes and the plants on the evapotranspiration of forage cactus species of the genus Nopalea and Opuntia. The experiment was conducted in Serra Talhada, State of Pernambuco, where the species ‘IPA Sertânia’ (Nopalea sp.), ‘Miúda’ (Nopalea sp.) and ‘Orelha de Elefante Mexicana’ (Opuntia sp.) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and intervals (7, 14 and 28 days). Actual evapotranspiration and biometric data of forage cactus species and meteorological variables were obtained between March 2012 and August 2013. Pearson correlation matrix and canonical and path analysis were applied to the data. It was verified that the global solar radiation stood out as the variable that most influenced the reduction of the actual evapotranspiration (ET) of the three species, and the wind velocity as the one that affected the response of ET to the atmospheric demand variation (ET/ETo) of the species ‘Orelha de Elefante Mexicana’ and ‘IPA Sertânia’. The increase in the cladode area index implied in the reduction of ET of the latter two species, while the effects of the number of 1st and 2nd order cladodes were the most important for the ‘Miúda'. Hence, forage cactus evapotranspiration depends on the seasonality of the meteorological conditions and the morphological characteristics of its species.