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.

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.

Resumo As condições de cultivo são fatores determinantes que afetam a qualidade das flores de corte. Diante disso, objetivou-se, neste estudo, avaliar o crescimento vegetativo, floração e vida de vaso de variedades de gladíolos comerciais no semiárido brasileiro, sob diferentes condições de sombreamento. Duas variedades de gladíolos (Jester e Rose Friendship) foram cultivadas em duas condições: sol pleno e 70% de sombreamento. Avaliou-se a biometria em 60 dias após o plantio e a taxa de crescimento da cultura aos 15-30, 30-45 e 45-60 dias para as variáveis: número de perfilhos, diâmetro do colo, número de folhas e altura da planta. Após 45 dias, avaliou-se a massa fresca, massa seca e conteúdo relativo de água total da parte área e da parte radicular das plantas. Após a colheita, as hastes foram mantidas em temperatura de 22±3 °C e umidade relativa (UR) de 60%. A cada dois dias, realizou-se avaliação visual, além de avaliação do pH da solução, variação no volume de água e perda de massa fresca. O cultivo com 70% de sombreamento resultou em maior acúmulo de biomassa na parte aérea das plantas de gladíolos, maior diâmetro do colo e altura. A variedade Rose Friendship resultou em maior translocação de massa seca para a parte aérea das plantas. Isso resultou em maior altura. Por outro lado, as hastes de gladíolos provenientes do cultivo nas condições de pleno sol resultaram em maior vida de vaso: 10 dias em condições de conservação a 22±3 °C e UR 60%.

Abstract Cultivation conditions are determining factors that affect the quality of cut flowers. The objective of this study was to evaluate the vegetative growth, flowering and vase life of commercial gladiolus cultivars under different shading conditions in the Brazilian semi-arid region. Two cultivars of gladiolus (Jester and Rose Friendship) were grown under two conditions: full sun and 70% shade. Biometrics were evaluated 60 days after planting and the growth rate of the crop was evaluated at 15-30, 30-45 and 45-60 days for the variables: number of tillers, stem diameter, number of leaves and plant height. After 45 days, the fresh weight, dry weight and total relative water content of the area and root parts of the plants were evaluated. After the harvest, the stems were kept at a temperature of 22±3 °C and relative humidity (RH) of 60%. Visual assessment, pH of the solution, variation in the volume of water and loss of fresh mass were measured every two days. Cultivation with 70% shading resulted in greater accumulation of biomass in the aerial part of gladiolus plants, greater neck diameter and height. The Rose Friendship cultivar underwent a greater translocation of dry matter to the aerial part of the plants, resulting in greater height. On the other hand, the gladiolus stems from cultivation under full sun conditions resulted in longer vase life, 10 days under conservation conditions at 22±3 °C and RH 60%.

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.

ABSTRACT Producers in the northeastern semiarid region of Brazil have been cultivating irrigated corn. The commercialized product comprises mainly green ears and silage. However, the irrigation of crops for dry grain has been questioned regarding costs and price competitiveness in relation to the same non-irrigated product cultivated in other regions. In recent years, the use of drip tapes and fertigation has spread among corn producers in the region. The aim of this study was to determine the N dose, via fertigation, which provides the maximum economic production of corn for dry grain, in two crop seasons (summer and winter), in the semiarid region of Brazil. The experimental design was performed in randomized blocks, with four replications. In both crops, the treatments consisted of four doses of N (0, 80, 160, and 240 kg ha-1) applied in the form of urea. In the hybrid corn (Bt Feroz), the N content was evaluated in terms of leaves, grain yield, gross and net incomes, the rate of return, and the profitability index. Independent of the crop season, the yield of dry grain (5,441.03 kg ha-1) was highest when the corn was fertigated with a dose of 104.05 kg ha-1 N. The highest net incomes of the dry grain were obtained with 80 kg ha-1 N in summer (R$ 1,190.78 ha-1) and 160 kg ha-1 N in winter (R$ 2,757.54 ha-1). The winter crop was more favorable to the economic production of dry grain.

Resumo Regiões semiáridas são caracterizadas pela elevada evapotranspiração e baixa precipitação pluvial, favorecendo o acúmulo de sais quando irrigado com água salobra. Objetivouse avaliar o efeito do cultivo de milheto com níveis de água salobra e fertilização orgânica nas propriedades químicas e físicas do solo. Adotou-se o delineamento de blocos ao acaso, com arranjo fatorial, em parcelas subdivididas, com três repetições. As parcelas foram constituídas por quatro lâminas de irrigação (25, 50, 75 e 100% da evapotranspiração da cultura) e as subparcelas foram compostas por quatro níveis de fertilização orgânica (0; 15; 30 e 45 Mg ha-1). No final do ciclo de produção do milheto, o solo foi coletado nas camadas de 0-0.20 e 0.20-0.40 m, para aspectos físicos (densidade do solo, densidade de partículas e porosidade) e químicos (CE, pH, K, Na, Ca, Mg, H + Al, SB, CTC, V). Não houve interação entre a água salobra e a fertilização orgânica nas propriedades químicas do solo. A água salobra reduziu o potássio na camada de 0,20-0,.40 m. Observou-se efeito linear negativo para densidade na camada 0,20 - 0,40 m sob níveis de fertilização orgânica. Níveis de água salobra e fertilizante orgânico no cultivo do milheto não altera as propriedades químicas e físicas do solo na camada de 0-0,20 m. Porém, o uso de água salobra reduz a concentração de potássio no solo e a aplicação de fertilização orgânica reduz a densidade do solo na camada de 0.20-0,40 m.

Abstract Semi-arid regions are characterized by high evapotranspiration and low rainfall, favoring the accumulation of salts when irrigated with brackish water. The aim of this study was to evaluate the effect of pearl millet cultivation with brackish water levels and fertilized with organic fertilizer on the chemical and physical properties of the soil. A split plot randomized block design was adopted, in a factorial arrangement, with three repetitions. Plots consisted of four irrigation levels (25, 50, 75 and 100% crop evapotranspiration) and subplots consisted of four levels of organic fertilizer (0; 15; 30 and 45 Mg ha-1). At the end of the pearl millet production cycle, soil was collected from layers 0-0.20 m and 0.20-0.40 m, for physical (soil bulk density, particle density and porosity) and chemical (EC, pH, K, Na, Ca, Mg, H + Al, SB, CEC, V) properties. There was no effect of interaction of brackish water levels and organic fertilizer levels on soil chemical properties. Brackish water reduced potassium on layer 0.20-0.40 m. A negative linear effect was found for density in the 0.20-0.40 m layer under different levels of organic fertilizer. Brackish water levels and organic fertilizer levels in the cultivation of pearl millet does not alter soil chemical and physical properties at the 0-0.20 m layer. However, the use of brackish water reduces the concentration of potassium in the soil and the application of organic fertilizer reduces soil density at the 0.20-0.40 m layer.

Abstract This study investigated the water and radiation use efficiencies by Erythrina velutina and Enterolobium contortisiliquum under four water regimes. The experiment was carried out in the municipality of Serra Talhada, PE, Brazil. The experimental design was completely randomized with a 2 x 4 factorial arrangement and three replications. The water regimes were imposed from water replenishments based on the reference evapotranspiration (25, 50, 75 and 100% ET0). Water and radiation use efficiencies were calculated to the 120 days of growth. E. velutina showed a greater accumulated dry biomass (4.89 g pl-1) than E. contortisiliquum (2.22 g pl-1). The 75% ET0 water regime can be adopted without damage to the growth of both species. E. velutina was more efficient in the conversion of water (0.42 g l-1) and radiation in dry biomass (0.028 g MJ-1), indicating high environmental resilience, which is important features to choose species more adequate for reforestation activities.

ABSTRACT It was evaluated how straw management modifies the development, growth, nutrient cycling and crop water productivity of sugarcane in the semiarid region of Brazil. The experiment was carried out using two plots with 5 ha each, being one without straw on the soil surface and one with 26 Mg·ha-1 covering the soil. Sugarcane growth and development and straw decomposition coefficient were evaluated, whereas the industrial yield, juice quality, dry matter partitioning, and crop water productivity were determined at harvesting. The straw decomposition coefficient was 0.0049 Mg·ha-1·day-1, and the remaining dry mass was equal to 24%. The straw affected the sugarcane growth and development until the first 100 days. The individual internode volume can be adopted as an indicator of the effect of straw on sugarcane growth because the internode volumes up to the sixth position in the with-straw treatment crop were lower than in the no-straw treatment, which was not observed in other variables of the stalks. Keeping straw on the soil surface reduced the crop lodging. Yield and juice quality were not affected, but crop water productivity was increased by keeping sugarcane straw in the field.

Resumo Nas últimas décadas houve mudança no sistema de colheita e manejo da palhada em canaviais de todo o Brasil, visando atender a legislação vigente e reduzir custos. A deposição de resíduos culturais sobre o solo, contudo, modifica as características micrometeorológicas do ambiente. Este trabalho reporta um estudo conduzido em Juazeiro-BA, para avaliar o efeito da manutenção da palhada no balanço de energia, emissão foliar e eficiência do uso da radiação da cana-de-açúcar. Medidas micrometeorológicas e da cultura foram feitas entre setembro de 2015 e julho de 2016. A magnitude e sazonalidade dos fluxos de calor latente, sensível e no solo foram afetadas pela presença da palhada (p<0,0001) com alteração na partição do LE/Rn de 84% para 64%, do H/Rn de 12% para 35% e do G/Rn de 4% para 2%, nessa ordem, para o cultivo sem e com palhada. A temperatura do ar foi maior no cultivo com palhada após o fechamento do dossel, enquanto, a umidade relativa do ar foi acrescida apenas nos primeiros meses. A modificação do microclima por causa da manutenção da palhada em campo alterou a velocidade de emissão foliar da cana-de-açúcar, mas, pouco afetou a eficiência do uso da radiação (~ 2,51 g MJ-1).

Abstract In recent decades there has been a change in the system of harvesting and management of straw in sugarcane fields all over Brazil, aiming to comply with current legislation and reduce costs. The crop residues deposition on the soil, however, modifies the micrometeorological characteristics of the crop environment. This work reports a study conducted in Juazeiro-BA to evaluate the effect of field straw maintenance on the energy balance, development and radiation use efficiency by sugarcane. Micrometeorological and crop measurements were made between September 2015 and July 2016. The magnitude and seasonality of the latent, sensible and soil heat fluxes were affected by the presence of straw (p < 0.0001) with a change in the LE/Rn from 84% to 64%, H/Rn from 12% to 35% and G/Rn from 4% to 2%, in that order, for the cultivation without and with straw. The air temperature was higher in the straw crop after the canopy closure, while the air relative humidity was increased only in the first months. The modification of the microclimate due to the maintenance of the straw altered the leaf emission speed of the sugarcane, but little affected the radiation use efficiency by crop (~ 2.51 g MJ-1).

ABSTRACT The accumulation of dry biomass, its partitioning and the adjustment of equations were assessed for the initial growth of Piptadenia stipulacea (Benth) Ducke and Anadenanthera colubrina (Vell.) Brenan under water availability variation. The experiment was conducted in pots arranged in a completely randomized design with three replicates. Water conditions were evaluated using the percentages of reference evapotranspiration. Samples of the biomass were taken at 10-day intervals and used for the achievement of partitioning data and model adjustments. The short period of water scarcity in the initial growth phase of P. stipulacea and A. colubrina does not affect the establishment of these species, but different water regimes alter their root growth dynamics. The A. colubrina allocates more dry matter to the roots, while P. stipulacea sends more dry matter to the aerial part. The Gaussian, Lorentzian, Log-Normal and Gompertz models had excellent adjustments for the biomass variables of the P. stipulacea species, whereas for A. colubrina, we recommend the Exponential model.

Resumo Objetivou-se comparar os fluxos de radiação e de energia entre uma área de caatinga preservada e um cultivo de cana-de-açúcar irrigada no Semiárido brasileiro. Para tanto, foram analisados os componentes dos balanços de radiação e de energia, os dados ambientais (umidade, temperatura do solo, e regime hídrico) e o índice de cobertura vegetal, entre junho de 2015 e maio de 2016. No centro de cada área foi instalada uma torre micrometeorológica equipada com sensores eletrônicos. Como resultados, constatou-se que as principais diferenças no balanço de radiação entre a caatinga e a cana-de-açúcar estão associadas ao albedo e a emissão de radiação de ondas longas pelas superfícies. O fluxo de calor sensível (H) foi sempre maior na caatinga, enquanto o fluxo de calor latente (LE) foi superior na cana-de-açúcar (p < 0,05). Na caatinga, as partições de energia para o H, LE e fluxo de calor no solo (G) foram 64%, 34%, e 2%, nessa ordem; enquanto na cana-de-açúcar, foi de 12% para o H, 85% para o LE e 3% para o G; com diferenças significativas entre as superfícies (p < 0,05). Essas diferenças podem acarretar modificações no clima local e/ou regional, logo, devem ser consideradas nos modelos de simulação hidrológicos e climáticos.

Abstract The objective of this study was to compare the radiation and energy fluxes between an area of preserved caatinga and an irrigated sugarcane crop in the Brazilian semi-arid region. The radiation and energy components, the environmental data (soil moisture and temperature, water regime) and the vegetation cover index were analyzed between June 2015 and May 2016. In each area was installed a micrometeorological tower equipped with electronic sensors. As results, it was verified that the main differences in the radiation balance between caatinga and sugarcane are associated to the albedo and the emission of long-wave radiation on the surfaces. The sensible heat flux (H) was always higher in the caatinga, while the latent heat flux (LE) was higher in sugarcane (p < 0.05). In the caatinga, the energy partitions for H, LE and soil heat flux (G) were 64%, 34% and 2%, in that order; while in sugarcane, it was 12% for H, 85% for LE and 3% for G; with significant differences between the surfaces (p < 0.05). These differences can lead to modifications in the local and / or regional climate, so they should be considered in hydrological and climatic simulation models.

RESUMO Os fatores ambientais que afetam as características morfológicas de distintos gêneros de cactáceas são pouco conhecidos. Assim, objetivou-se analisar a contribuição de variáveis ambientais para o crescimento dos cladódios e da planta de clones de palma forrageira dos gêneros Nopalea e Opuntia. Os dados usados nesse estudo foram adquiridos de um experimento conduzido em Serra Talhada, Pernambuco, entre os anos de 2012 e 2013, onde os clones 'IPA Sertânia' (Nopalea), 'Miúda' (Nopalea) e 'Orelha de Elefante Mexicana' (Opuntia) foram submetidos a distintas lâminas (2,5; 5,0; e 7,5 mm) e intervalos fixos de irrigação (7; 14 e 28 dias). Características morfológicas dos cladódios e das plantas, e variáveis meteorológicas foram obtidas ao longo do tempo. Correlação de Pearson, seguida de análises de multicolinearidade, canônica e trilha foram aplicadas. Temperatura mínima, umidade relativa máxima e mínima, velocidade do vento e radiação solar foram as variáveis que mais afetaram o crescimento da palma. O gênero Opuntia revelou menor sensibilidade à variação da temperatura do ar quando comparado ao gênero Nopalea. As maiores intensidades de radiação solar global afetaram mais os clones do gênero Nopalea do que do gênero Opuntia. Conclui-se que há uma exigência ambiental diferenciada entre os gêneros Nopalea e Opuntia de palma forrageira.

ABSTRACT The environmental factors that affect the morphological characteristics of different genera of cacti are little known. The aim of this study therefore was to analyse the contribution of environmental variables to growth in cladodes and plant of forage cactus clones of the genera Nopalea and Opuntia. The data used in this study were obtained from an experiment conducted in Serra Talhada, Pernambuco, Brazil, between 2012 and 2013, where the clones 'IPA Sertânia' (Nopalea), 'Miúda' (Nopalea) and 'Orelha de Elefante Mexicana' (Opuntia) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and fixed irrigation intervals (7, 14 and 28 days). Morphological characteristics of the cladodes and plants and weather variables were obtained over time. Pearson's correlation, followed by multicollinearity, canonical and path analysis were applied. The minimum temperature, maximum and minimum relative humidity, wind speed and solar radiation were the variables that most affected growth in the cactus. The genus Opuntia showed less sensitivity to variations in air temperature compared to the genus Nopalea. The higher intensities of global solar radiation affected clones of the genus Nopalea more than the genus Opuntia. It can be concluded that there are different environmental requirements between forage cacti of the genera Nopalea and Opuntia.

RESUMO Objetivou-se avaliar o desempenho produtivo-econômico da consorciação palma forrageira e sorgo em relação ao sistema de plantio exclusivo da palma forrageira sob diferentes lâminas de irrigação com água salina. A pesquisa foi conduzida em Serra Talhada, PE, com delineamento em blocos ao acaso, arranjo fatorial com parcelas subdivididas (5×2), quatro repetições, sendo considerada como parcelas as lâminas de irrigação complementar com base na evapotranspiração de referência (0; 8,75; 17,5; 26,25 e 35% ETo), e as subparcelas, os sistemas de plantio: palma exclusiva e consórcio palma-sorgo. O experimento foi conduzido por um ano, sendo um ciclo de palma e dois ciclos do sorgo. Ao final foram obtidas as produtividades de matéria fresca e seca. A rentabilidade econômica foi analisada por meio da receita líquida (RL) e da relação benefício/custo (B/C) da palma destinada à venda tanto para forragem como “semente” para o plantio, e do sorgo para produção de forragem. Simulações de RL e B/C foram feitas ao longo da vida útil de oito anos do sistema de irrigação. As lâminas de água aumentaram a produtividade de matéria seca do consórcio, devido ao benefício gerado ao sorgo. Com base na RL e B/C, verificou-se que a palma e o sorgo destinados à venda como forragem mostraram mais vantagem quando consorciadas e maior rentabilidade a partir do 2º ano de implantação do sistema de irrigação. Conclui-se que, o consórcio palma forrageira e sorgo irrigado com água salina deve ser recomendado para a produção de forragem no Semiárido brasileiro.

ABSTRACT The objective of this study was to evaluate the productive and economic performance of a forage cactus and sorghum intercropping system in relation to a forage cactus single cropping system under different irrigation blades with saline water. The study was conducted in Serra Talhada, State of Pernambuco, in a randomized block design, consisting of a factorial arrangement with split-plot parcels (5×2) and four replications. The five plots were the irrigation depths based on the reference evapotranspiration (ETo) (0, 8.75, 17.5, 26.25, and 35% ETo) and the two cropping systems were single forage cactus cropping and cactus intercropped with sorghum. The experiment was conducted for one year, with one forage cactus cycle and two cycles of sorghum. Yields were obtained at the end of the cycles. Economic profitability was analyzed by means of net revenue (NR) and the benefit/cost ratio (B/C), with cactus forage sold as forage or as "seed" and sorghum as forage. Net revenue and B/C simulations were carried out over an eight-year useful life span of the irrigation system. Increasing irrigation depth increased the dry matter yield of the intercropping system because of higher sorghum yield. Based on the NR and B/C ratio values, forage cactus and sorghum produced as forage produced higher economic outcomes in the intercropping system and showed a higher profitability from the 2nd year of implementation of the irrigation system. Forage cactus and sorghum intercropping irrigated with saline water is therefore recommended for forage production in the Brazilian semi-arid region.

RESUMO O objetivo foi avaliar a influência das características morfológicas dos cladódios sobre a formação do dossel da palma forrageira. O estudo foi conduzido em Serra Talhada, PE, com os clones IPA Sertânia - IPA, Miúda - MIU e Orelha de Elefante Mexicana - OEM, os quais foram submetidos a três lâminas (2,5; 5,0; e 7,5 mm) e três intervalos de irrigação (7; 14 e 28 dias), no período compreendido entre março 2012 a agosto de 2013. Dados das dimensões dos cladódios e do dossel das plantas foram obtidos ao longo do tempo. A matriz de correlação de Pearson foi elaborada, e análises canônicas e de trilha foram aplicadas para avaliação da associação entre as variáveis. Verificou-se que, as características dos cladódios de 2ª e de 3ª ordens foram as que mais contribuíram na formação do dossel dos clones do gênero Nopalea (IPA Sertânia e Miúda), enquanto para a Orelha de Elefante Mexicana do gênero Opuntia foram as dos cladódios de primeira 1ª e 3ª ordens. Conclui-se que, a influência das variáveis dos cladódios sobre o crescimento do dossel da palma forrageira esteve mais associada às características do gênero, do que a peculiaridades dos clones.

ABSTRACT Here we aimed to evaluate the influence of cladode morphology on the canopy formation of forage cactus plants. The study was carried out in Serra Talhada, the State of Pernambuco, using the IPA Sertânia (IPA), Miúda (MIU), and Orelha de Elefante Mexicana (OEM) clones, which were submitted to three irrigation depths (2.5, 5.0, or 7.5 mm) and three irrigation intervals (7, 14, or 28 days) from March 2012 to August 2013. Cladode and plant canopy biometric data were obtained during the experimental period. We found that the characteristics of the second and third order cladodes contributed most to the canopy formation of clones of the genus Nopalea (IPA and MIU), whereas, for the genus Opuntia (OEM), the first and third order cladodes contributed most. Overall, we found that the influence of the cladode variables on the canopy growth of forage cactus is more associated with the characteristics of the genus than to the peculiarities of the clones.