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The objective was to identify the species and quantify the importance value index of weeds in the cultivation of arabica coffee in two irrigation systems, at different times of the year, in the northern region of Minas Gerais. A phytosociological survey was carried out in each season of the year (spring, summer, autumn and winter) in an area cultivated with the species Coffea arabica, subjected to two irrigation systems (sprinkling and dripping). The coffee crop was implanted at a spacing of 3.5 m between rows and 0.7 meters between plants. The collection of weeds was performed using the standard method of the square inventory, which was launched between the lines of the crop. The identification of the species was carried out, the number of individuals was quantified, the dry mass, frequency, density, abundance, importance value index and coverage, and the similarity index. 33 weed species were identified, being the species with the highest IVI Euphorbia hirta, Brachiaria plantaginea, Digitaria horizontalis, Cyperus rotundus and Amaranthus spp. It was observed a higher occurrence of weeds from the monocot group in the sprinkler irrigation system while in the drip there were predominance of dicot plants.

Appropriate plot size is recognized as a means of maximizing experimental accuracy and contributes to efficient treatment assessment. This study aimed to estimate the optimal plot size for experiments with ‘Gigante’ cactus pears using the comparison of variances method (CVM). A uniformity trial was conducted to assess plant height (PH), number of cladodes (NC), yield (Y), cladode area index (CAI), cladode length (CL), width (CW), thickness (CT) and cladode area (CA) in a cactus pear crop. A rectangular-shaped plot consisting of 10 rows of 50 plants each was used, totaling 500 plants, with 384 basic units (BU), corresponding to the study area. A hierarchical classification approach was adopted, simulating a split-plot design in which each plant was denominated a basic unit (BU), and considering the effects of blocks (B), plots (P)/B, subplots (S)/P/B, rows (R)/S/P/B and plants (Pln)/F/S/P/B. This resulted in five plots sizes, consisting of 1, 12, 24, 48 and 96 basic units. Plots with 12, 24, 48 and 96 BU were statistically equal for the variables Y, PH, NC, CAI, CL, CW and CT, with lower variances than the plot with 1 BU. As such, 4.8 m² with 12 basic units is the optimal experimental plot size for ‘Gigante’ cactus pears.

The umbuzeiro is a native Brazilian semi-arid plant with great agroindustrial potential. The characterization of the fruit, as well as the development or improvement of technologies for value aggregation are fundamental for its conservation, dissemination and culinary expansion. The objective was to characterize physically and chemically fruits of umbu and to define the access with greater commercial potential. A completely randomized design was used, with 10 replications, in a total of 4 accessions of umbuzeiro. The fruits were selected prioritizing uniformity of fruit size and maturation stage. Fruit peel color was analyzed; diameter and length; mass of the fruit, the bark, the pulp and the seed; firmness of the fruit, soluble solids contents; pH; titratable acidity and solids/acidity ratio. The values of the pulp yield and the technological index were determined. Significance was verified for all variables, except for soluble solids and pH. The average value of the titratable acidity was 1.3 mg of citric acid 100 mL-1 of juice. The diameter of the fruits varied between 4.0 and 4.5 cm. Fruit mass varied from 33.00 to 43.62 g and access to EPAMIG-C06 was the heaviest. The accesses EPAMIG-C06 and EPAMIG-C18 presented the highest technological index. Based on the results, it was concluded that the accesses present potential to the pulp industry due to the size and characteristics of the fruits. The umbu accesses under study presented small variation for solubility and pH. For in natura consumption and/or processing, the access EPAMIG-C06 stands out due to attributes of commercial interest.

Behavior analysis and plant expression are the answers the researcher needs to construct predictive models that minimize the effects of the uncertainties of field production. The objective of this study was to compare the simple and multiple linear regression methods and the artificial neural networks to allow the maximum security in the prediction of harvest in ‘Gigante’ cactus pear. The uniformity test was conducted at the Federal Institute of Bahia, Campus Guanambi, Bahia, Brazil, coordinates 14°13′30″ S, 42°46′53″ W and altitude of 525 m. At 930 days after planting, we evaluated 384 basic units, in which were measured the following variables: plant height (PH); cladode length (CL), width (CW) and thickness (CT); cladode number (CN); total cladode area (TCA); cladode area (CA) and cladode yield (Y). For the comparison between the artificial neural networks (ANN) and regression models (single and multiple-SLR and MLR), we considered the mean prediction error (MPE), the mean quadratic error (MQE), the mean square of deviation (MSD) and the coefficient of determination (R2).The values estimated by the ANN 7-5-1 showed the best proximity to the data obtained in field conditions, followed by ANN 6-2-1, MLR (TCA and CT), SLR (TCA) and SLR (CN). In this way, the ANN models with the topologies 7-2-1 and 6-2-1, MLR with the variables total cladode area and cladode thickness and SLR with the isolated descriptors total cladode area and cladode number, explain 85.1; 81.5; 76.3; 74.09 and 65.87%, respectively, of the yield variation. The ANNs were more efficient at predicting the yield of the ‘Gigante’ cactus pear when compared to the simple and multiple linear regression models.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Outra Agência 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. O tamanho ótimo de parcela para palma forrageira ‘Gigante’ pode ser estimado por vários métodos; assim, visando em última análise a eficiência, uso simples e alta precisão, o objetivo deste estudo foi comparar métodos para estimar tamanhos de parcelas: método de curvatura máxima modificada, método de tamanho de parcela conveniente de Hatheway, modelos de platô de resposta linear e quadrática e método de comparação de variâncias para avaliação de características fenotípicas em experimentos com palma forrageira 'Gigante'. Os tamanhos das parcelas foram estimados através da realização de um ensaio de uniformidade. Os tamanhos ótimos estimados de parcela variaram com o método e a característica vegetativa. A regressão de platô de resposta quadrática estimou os maiores tamanhos de parcelas, enquanto o método de Hatheway estimou os menores tamanhos de parcelas. O método de comparação de variâncias estimou tamanhos de parcelas intermediários em comparação com os outros métodos para a maioria das características medidas. Os tamanhos de parcelas estimados pelo método da curvatura máxima modificada são mais consistentes com os resultados relatados por estudos sobre a palma forrageira ‘Gigante’. 10 tamanhos de parcelas de unidades básicas estimados pelo modelo de platô de resposta linear podem ser usados ​​com alta precisão e viabilidade prática para o cultivo de palma forrageira, melhorando assim o uso dos recursos.