Estimating cactus pear yield is important for the planning of small and medium rural producers, especially in environments with adverse climatic conditions, such as the Brazilian semi-arid region. The objective of this study was to evaluate the potential of artificial neural networks (ANN) for predicting yield of ‘Gigante’ cactus pear, and determine the most important morphological characters for this prediction. The experiment was conducted in the Instituto Federal Baiano, Guanambi campus, Bahia, Brazil, in 2009 to 2011. The area used is located at 14° 13’ 30” S and 42° 46’ 53” W, and its altitude is 525 m. Six vegetative agronomic characters were evaluated in 500 plants in the third production cycle. The data were subjected to ANN analysis using the R software. Ten network architectures were trained 100 times to select the one with the lowest mean square error for the validation data. The networks with five neurons in the middle layer presented the best results. Neural networks with coefficient of determination (R2) of 0.87 were adjusted for sample validation, assuring the generalization potential of the model. The morphological characters with the highest relative contribution to yield estimate were total cladode area, plant height, cladode thickness and cladode length, but all characters were important for predicting the cactus pear yield. Therefore, predicting the production of cactus pear with high precision using ANN and morphological characters is possible.

This work aimed to subsidize experimental planning for the evaluation of phenotypic characters in banana. The experiment consisted of a uniformity trial with Tropical cultivar spaced of 3 m x 2 m, in a useful area with nine rows of 40 plants. Vegetative and yield aspects were evaluated in two production cycles. Plants and basic units (UB) were combined to form various plot sizes, from which the variation coefficient and the soil heterogeneity index were estimated. To define the experimental design, the Hatheway method was used. Variability, resulting from the soil anisotropy and other factors such as desuckering cultural practice increases between mother plant and daughter plant cycles, with effects on experimental design. The variation coefficient and number of replicates are the factors that most influenced the experimental design. For the same precision level required, the combination that maximizes efficient in the use of experimental area can be adopted, that is, smaller plot size and higher number of replicates or larger plot size and fewer replicates. Estimates of plot size and number of replicates are subsides for the design of experiments for the evaluation of phenotypic descriptors in banana.

The optimum plot size for ‘Gigante’ cactus pear can be estimated by several methods; thus, ultimately aiming for efficiency, simple use and high precision, the objective of this study was to compare methods for estimating plot sizes: modified maximum curvature method, Hatheway’s convenient plot size method, linear and quadratic response plateau models, and comparison of variances method for evaluating phenotypic characteristics in experiments with ‘Gigante’ cactus pear. Plot sizes were estimated by conducting a uniformity trial. Estimated optimum plot sizes varied with the method and vegetative characteristic. The quadratic response plateau regression estimated the largest plot sizes, whereas Hatheway’s method estimated the smallest plot sizes. Comparison of variances method estimated intermediate plot sizes in comparison with the other methods for most measured characteristics. Plots sizes estimated by modified maximum curvature method are more consistent with results reported by studies on ‘Gigante’ cactus pear. 10 basic unit plot sizes estimated by the linear response plateau model can be used with high precision and practical feasibility for growing cactus pear, thereby improving the use of resources.

ABSTRACT. Physiological potential of castor bean seeds treated with micronutrients. The objective of this work was to evaluate the effect of micronutrient application on the germination and vigor of castor bean seeds, cv. BRS 149 Nordestina. A completely randomized design was used, with four repetitions of 25 seeds. The treatments were control, immersion in water, immersion in B, immersion in Zn, immersion in Cu, immersion in Mn, immersion in Mo and immersion in Fe. The results obtained indicate there was an increase in germination and vigor with the application of micronutrients in castor bean seeds. B was the most harmful on germination and vigor, and increased the percentage of impermeable and dormant seeds.Key words: Ricinus communis L., germination, seeds, vigor, seedlings, nutrients. IntroduçãoA mamoneira (Ricinus communis L.) é uma oleaginosa de relevante importância econômica e social, cujo óleo possui inúmeras aplicações na área industrial com perspectiva de utilização como fonte energética na produção de biocombustível (SEVERINO et al., 2005).Para se obter altas produtividades é necessário que sementes de qualidade sejam semeadas e, para a produção destas, plantas produtoras devem receber tratamento adequado, como a adubação (SANTOS et al., 2008).A produção e a qualidade fisiológica das sementes estão diretamente associadas à boa disponibilidade de nutrientes à lavoura, por afetar a formação do embrião e dos órgãos de reserva, assim como a composição química e, consequentemente, o metabolismo e o vigor (CARVALHO;NAKAGAWA, 2000).O tratamento de sementes com micronutrientes baseia-se no princípio da translocação dos mesmos da semente para a planta. Assim, a reserva de zinco, boro e cobre torna-se importante fonte para a nutrição da planta, prevenindo o aparecimento de sintomas iniciais de deficiência. Por outro lado, estes micronutrientes apresentam ação fungicídica (RIBEIRO; SANTOS, 1996). De acordo com estes autores, a fertilização das sementes com altos teores de micronutrientes e sua transferência para as plântulas, durante o processo germinativo e o desenvolvimento inicial das mesmas, permitem suprir parcialmente e, em alguns casos, totalmente as necessidades da planta. Garantem ainda que, quando observaram que a mobilização do zinco ocorre durante o processo de germinação e semente carente neste nutriente, origina planta deficiente em zinco.Cada micronutriente exerce papel diferenciado nas plantas. As funções básicas do zinco na planta estão relacionadas ao metabolismo dos carboidratos, das proteínas e dos fosfatos e à formação da estrutura de auxinas, de RNA e de ribossomos (BORKET, 1989). Este autor completa ainda que a função do boro está relacionada ao metabolismo de

Proper plant nutrition is critical to increasing the yield of bananas. The objective was to establish the potential nutrient-response curves and sufficiency ranges using the boundary line approach (BLA) and the method proposed by Kenworthy (MK) to assess the nutritional status of 'Prata-Anã' bananas cultivated under two environmental conditions. The study was carried out using a database comprising leaf nutrient concentrations and banana yields grown at Missão Velha, Ceará, and Ponto Novo, Bahia, Brazil. The reference population consisted of high-yielding plants with yields greater than the mean yield plus 0.5 standard deviation. The database was divided into two datasets. One contained 253 leaf analysis results and a reference population with a mean yield greater than 39.81 t ha -1 yr -1 at Missão Velha. The other contained 147 samples and a reference population with a mean yield greater than 41.69 t ha -1 yr -1 at Ponto Novo. The sufficiency ranges obtained by the BLA for 'Prata-Anã' banana in Bahia and Ceará, respectively, are: a) for macronutrients (g kg -1 ):