Paulo Emílio Rodrigues Donato

A escolha e manejo de cultivares de palma forrageira em microclimas específicos no semiárido são essenciais devido às variações climáticas que afetam seu crescimento e produtividade. Objetivou-se avaliar o desempenho de cultivares de palma forrageira sob diferentes densidades de plantio nas condições do semiárido baiano, região de Guanambi-BA. O ensaio foi conduzido em delineamento em blocos casualizados com quatro repetições, em esquema de parcelas subdivididas com três cultivares (Cv) nas parcelas (Orelha de Elefante Mexicana (OEM), Miúda e Gigante) e quatro densidades de plantio (DP) (20.000, 40.000, 60.000, 80.000 plantas ha-1) nas subparcelas, totalizando 12 tratamentos experimentais. Após 600 dias, foram medidas características morfológicas e produtivas. As variáveis, altura da planta, índice de área de cladódio e número de plantas mortas apresentaram interação (p<0,05) entre os fatores. Com efeito, linear positivo para índice de área do cladódio e número de plantas mortas, a ‘Miúda’ e a ‘OEM’ apresentaram maior IAC, com valores de 25,6 e 21,5 m² m-2 respectivamente na DP de 80.000 plantas ha-1. A ‘Miúda’ apresentou perdas superiores a 50% do estande em todas as DP. As cultivares OEM e Gigante apresentam produtividades de matéria verde e seca semelhantes. Quando as condições ambientais e de manejo propiciam índices de área de cladódios acima de 5 m² m-² o aumento da densidade de plantio acima de 20.000 plantas ha-1 não influencia o teor de matéria seca, as produtividades de massa verde e matéria seca nas cultivares de palma forrageira Gigante, OEM e Miúda.

The objective of this work was to determine reference values for nutritional diagnosis of ‘Gigante’ cactus pear cultivated with organic fertilization under semi-arid conditions by boundary line approach. The contents of nutrients, determined in samples collected in newly mature cladodes, dry matter yield (DMY), and nutrient extraction of 72 plots of an experiment with ‘Gigante’ cactus pear, fertilized with cattle manure, were used to establish the reference values. The lower (L₁) and upper (L_u) limits of the reference values were determined by fitted regression of DMY (y) as a function of nutrient contents in cladodes (x), considering a percentage of the maximum dry matter yield (slope = 0). The reference values, established by boundary line approach for macronutrients and micronutrients, are accurate for the nutritional diagnosis of ‘Gigante’ cactus pear and determine classes for interpretation of nutritional status. The normal reference values established for macronutrients, in g kg⁻¹, are: N (≤11.2 – −1, are: B (≤21.6 – <33.5), Cu (≤1.7 – <4.8), Fe (≤49.0 – <125.4), Mn (≤0.0 – <680.4), Zn (≤28.3 – <80.6), and Na (≤19.3 – <72.2).

A associação de fatores no sistema solo-água-planta-atmosfera, como adubação, espaçamento entre plantas e disponibilidade hídrica, pode influenciar a atividade fisiológica em palma forrageira nas condições adversas do semiárido. Assim, objetivou-se determinar a eficiência fotoquímica em cladódios de palma forrageira ‘Gigante’ cultivada sob diferentes espaçamentos e adubação mineral em região semiárida, no período seco e chuvoso. O experimento foi conduzido em blocos ao acaso em esquema fatorial 4 x 3 x 7, com três repetições. O primeiro fator foi constituído de quatro adubações (000-000-000; 000-150-000; 200-150-000 e 200-150-100 kg ha-1 de N-P2O5-K2O), o segundo, por três espaçamentos (1,0 x 0,5; 2,0 x 0,25 e 3,0 x 1,0 x 0,25 m) e o terceiro por sete horários de leitura (6; 8; 10; 12; 14; 16 e 18 h). Foram realizadas leituras de fluorescência da clorofila “a” em cladódios de palma forrageira nas épocas seca e chuvosa com auxílio de um fluorômetro de luz modulada. Verificou-se ajustes cúbicos para as variáveis de fluorescência da clorofila “a” ao longo dia com magnitude de respostas diferenciadas nos períodos seco e chuvoso. Os cladódios de palma forrageira ‘Gigante’ sofrem alterações no fotossistema II na época seca nas condições fisiográficas do semiárido baiano e na época de chuvas o rendimento fotossintético em cladódios de palma forrageira é considerado ideal com variações ao longo do dia. Palavras-chave: arranjo de plantas; Opuntia; plantas CAM. Photochemical efficiency in cladodes of ‘Gigante’ cactus pear cultivated under different spacing and mineral fertilization The association of factors in the soil-water-plant-atmosphere system, such as fertilization, spacing between plants and water availability, can influence the physiological activity in cactus pear in the adverse conditions of the semiarid. Thus, the objective was to determine the photochemical efficiency in cladodes of ‘Gigante’ cactus pear cultivated under different spacing and mineral fertilization in the semi-arid region, in the dry and rainy season. The experiment was conducted in a randomized block design in a 4 x 3 x 7 factorial scheme with three replicates. The first factor consisted of four fertilizations (000-000-000, 000-150-000, 200-150-000 and 200-150-100 kg ha-1 of N-P2O5-K2O), the second one, by three fertilizations (1.0 x 0.5, 2.0 x 0.25 and 3.0 x 1.0 x 0.25 m) and the third by seven reading times (6 a.m., 8 a.m., 10 a.m., 12 p.m., 2 p.m., 4 p.m. and 6 p.m). Fluorite readings of “a” chlorophyll were carried out in forage palm cladodes in the dry and rainy seasons with the help of a light modulated fluorometer. Cubic adjustments wereobserved for the fluorescence variables of “a” chlorophyll along day with magnitude of differentiated responses in dry and rainy periods. The cladodes of ‘Giant’ cactus pear alterations suffer in photosystem II in the dry season in the physiographic conditions of the Bahia semi-arid and in the rainy season the photosynthetic yield in cladodes of forage palm is considered ideal with variations along the day. Keywords: arrangement of plants; Opuntia; CAM plants.

The equilibrium and nutritional balance of plants are known to be of utmost importance to evaluate their yield potential and to comprehend the dynamics of nutrients in the soil-plant system. Hence, the present study determined the reference values for evaluating the nutritional status of ‘Gigante’ cactus pear cultivated with organic fertilization in semiarid conditions by Diagnosis and Recommendation Integrated System (DRIS) and Balanced Indexes of Kenworthy (BIK) methods. The cladodes nutrients contents and dry matter yield of 72 plots were employed. The database was classified into a high-yield and low-yield population, above and below 19.93 Mg ha-1 cycle-1, respectively. The five ranges of nutrient contents in cladodes were defined based on the standard deviation range(s) of the DRIS indexes of the high-yield population. Furthermore, the fixed BIK values made it possible to ascertain the lower and the upper limit of the reference values of nutrient contents in the cladodes. The reference values for all nutrients determined by the DRIS and BIK methods varied from each other and those reported in the literature. These methods were efficient in identifying the limiting nutrients for ‘Gigante’ cactus pear, with differences in the hierarchical order of limitation, due to lack or excess, and nutrients not limiting to productivity.

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Cactus pear is a crop adapted to the climatic conditions of the Brazilian semiarid region, so it has contributed to the socioeconomic development of this region. The objective of this study was to evaluate the response of ‘Gigante’ cactus pear cultivated at different population densities in a mechanizable arrangement. The experimental design was in randomized blocks, with six population densities: 22,857; 34,286; 51,428; 62,857; 80,000 and 95,000 plants ha-1 and four repetitions. The following variables were evaluated: plant height, number of cladodes, cladode length, cladode width and cladode area index, green and dry matter yields, extraction/export of nutrients and soil chemical characteristics. Increase in population density in a mechanizable arrangement decreases the number of cladodes and increases the cladode area index. The maximum green and dry matter yield of cactus pear cultivated in arrangement that allows mechanization is expected with populations of 69,111.79 and 64,445.91 plants ha-1, respectively. Maximum values of extraction/export of nutrients in cactus pear tissue are expected at intermediate population densities (62,721.52-74,741.93 plants ha-1). Soil potential acidity has maximum value with 64,525.51 plants ha-1.

The objective of this study was to evaluate the chemical attributes of the soil cultivated with ‘Gigante’ cactus pear under different doses of organic fertilizer, planting spacings and sampling times. Four doses of organic fertilizer with bovine manure (0, 30, 60 and 90 Mg ha-1 year-1), three spacings (1.0 x 0.5, 2.0 x 0.25 and 3.0 x 1.0 x 0.25 m) and three sampling times (0, 390 and 600 days after planting) corresponding to the periods prior to planting, growth and harvest of the first cycle, were evaluated in a randomized block design in a 4 x 3 x 3 factorial scheme, with three repetitions. The pH in water, macronutrients (P, K, Ca, Mg), micronutrients (B, Cu, Fe, Mn, Zn), variables of the soil sorption complex (H + Al, SB, CEC, T, V) and soil organic matter (SOM) were determined. Organic fertilization increased the values of SOM, P, K, Ca, Mg, SB, CEC, T and V and reduced H + Al in soils cultivated with ‘Gigante’ cactus pear at different times. The doses of manure increased pH and Mn, regardless of sampling time and spacing. The spacings did not influence the chemical attributes of the soil.

The objective of this study was to evaluate nutrient concentration and nutritional efficiency in ‘Gigante’ cactus pear under different chemical, organic and organomineral fertilizations, planting configurations and spacings, during three production cycles. Seventy two treatments, involving two types of configuration in the plots, three spacings in the subplots and 12 types of fertilization in the sub-subplots were arranged in a split-split-plot scheme, in a randomized block design, with three repetitions. At the time of harvest of each production cycle, 40 cladode tissue samples were collected per treatment to determine dry matter mass and nutrient concentration, which were used to calculate the coefficients of biological utilization of nutrients. Organic fertilization reduces Mn concentrations in cladodes to levels below the sufficiency range. The nutritional efficiency of N, S, P, Mn and Zn is higher with organic and organomineral fertilizations and are associated with higher dry matter yields, whereas K nutritional efficiency is higher with mineral fertilization. The absence of fertilization or application of 30 Mg ha-1 year-1 of bovine manure is insufficient to ensure nutritional status and dry matter yield above 15 Mg ha-1 in ‘Gigante’ cactus pear.

The objective of this work was to establish DRIS norms for evaluation of nutritional status of cactos pear of the Gigante cultivar grown under organic fertilization in semiarid conditions. Cladode macro and micronutrient contents and dry matter yield of 72 plots were evaluated. The experiment was conducted in a randomized block design with three replicates, using a 4×3×2 factorial arrangement consisted of four bovine manure rates (0, 30, 60, and 90 Mg ha-1 ano-1), three spacings (1.00×0.50, 2.00×0.25, and 3.00×1.00×0.25 m), and two production cycles (600 and 930 days). The data were separated into high-yield population (HYP) and low-yield population (LYP), above and below 19.93 Mg ha-1 cycle-1, respectively. The mean, standard deviation, coefficient of variation, variances, and variance ratios of all bivariate relations between nutrients were calculated for the establishment of DRIS norms, considering the direct (A/B) and reverse (B/A) form. The selection of direct and reverse relations between nutrients to compose the DRIS norms was based on the variance ratio between LYP and HYP (S2b/S2 a). The sixty-six relations between cladode nutrient contents that presented the higher ratios between the variances in the LYP and HYP (S2b/S2a) were chosen. The DRIS norms established make viable the use of leaf diagnosis as an evaluation method of nutritional status of cactos pear of the Gigante cultivar grown under organic fertilization in semiarid conditions.

Cactus pear is adapted to semi-arid conditions. In this study, the objective was to evaluate the water use efficiency and green and dry mass yields of the cultivar Gigante under different fertilization rates and sources in three production cycles, spacing and planting arrangement. Seventy two treatments, involving two types of arrangements in the plots, three spacings in the subplots and 12 types of fertilization in the sub-subplots were arranged in a split-split-plot scheme, using randomized block design with three repetions. Dry mass content decreases while water use efficiency and green mass and dry mass yields increase from the first to the third cycle. It is feasible to use planting arrangements in triple or quadrupling rows which allow increasing the mechanization index of the crop. Organomineral fertilization with 30 or 60 Mg ha^-1 year^-1 of bovine manure combined with 150-300-600 kg ha^-1 year^-1 of N-P₂O₅-K₂O and 300-300 kg ha^-1 year^-1 of P₂O₅-K₂O, respectively; organic fertilization with 90 Mg ha^-1 year^-1 of manure; and mineral fertilization with 300-300-600 kg ha^-1 year^-1 of N-P₂O₅-K₂O ensure green mass and dry mass yields greater than 200 and 15 Mg ha^-1 cycle^-1, respectively, and water use efficiency greater than 20 kg ha^-1 mm^-1 in ‘Gigante’ cactus pear. It is concluded that yields of this magnitude are ensured with application of about 300-300-300 kg ha^-1 year^-1 of N-P₂O₅-K₂O using organic, organomineral or mineral sources.