ABSTRACT Cowpea is one of the pulse crops that present the highest potential for growing in the Semiarid region of Brazil. Lowcost vegetable protein source, it has resilience to adverse conditions, however, in competition with weeds, its productivity can be strongly compromised. To overcoming this situation, it is essential for integrated management programs to determine the critical period for preventing interference. Thus, the objective of this work was to determine weed interference periods and the effect of coexistence periods on cowpea grain yield in the Semiarid region of the state of Minas Gerais, Brazil. The treatments were arranged in a 2×9 factorial scheme, as follows: cultivation in coexistence with weeds and cultivation under weed control, for nine crescent periods (0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56 and 0-63 days after crop emergence), in a randomized experimental block design with four replications. The weed community was studied through phytosociological survey and evaluation of dry matter production and cowpea was evaluated for dry matter production, 100-grain mass and grain yield. The interference periods were determined using a non-linear logistic regression model. The weed community found was composed of 70% dicotyledonous and 30% monocotyledon plants, distributed in seven families and ten species. The coexistence with weeds results in losses of up to 90% in cowpea grain yield. The critical period of weed control in cowpea crop in the Semiarid region of the state of Minas Gerais, Brazil, is 11 to 36 days after crop emergence.

RESUMO O feijão-caupi é uma das culturas de pulses com maior potencial de cultivo no semiárido brasileiro. Fonte de proteína vegetal de baixo custo, apresenta resiliência a condições adversas, entretanto, em competição com plantas daninhas, pode ter sua produtividade fortemente comprometida. Para superar essa situação, é indispensável aos programas de manejo integrado determinar o período crítico de prevenção à interferência. Assim, objetivou-se com este trabalho determinar os períodos de interferência de plantas daninhas e o efeito dos períodos de convivência sobre a produtividade do feijão-caupi no semiárido mineiro. Os tratamentos foram arranjados em esquema fatorial 2×9, da seguinte forma: cultivo em convivência com plantas daninhas e cultivo sob controle de plantas daninhas, por nove períodos crescentes (0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56 e 0-63 dias após a emergência da cultura), em delineamento experimental de blocos casualizados com quatro repetições. A comunidade infestante foi estudada por meio de levantamento fitossociológico e avaliação da produção de matéria seca e o feijão-caupi foi avaliado quanto à produção de matéria seca, massa de 100 grãos e rendimento de grãos. Os períodos de interferência foram determinados adotando um modelo de equação não linear logístico. A comunidade infestante foi composta por 70% de plantas eudicotiledôneas e 30% de monocotiledôneas, distribuídas em sete famílias e dez espécies. A convivência com plantas daninhas resulta em até 90% de perdas na produtividade do feijão-caupi. O período crítico de controle de plantas daninhas no feijão-caupi no semiárido mineiro é de 11 a 36 dias após a emergência da cultura.

ABSTRACT. Among the forage species, especially in semiarid ecosystems, cactus pear is exceptional because of its high tolerance to adverse conditions and high productivity. Due to this alone, several studies have been conducted to identify the main technologies for this crop. Despite being consolidated and integrated, the cactus pear production system has limited accessibility, technical assistance, and availability of information for those dedicated to its production. This study aimed to present a digital platform, website, and applications to provide technical information on the cactus pear and demonstrate the efficiency of these applications through experimental data. On this digital platform, applications were made available for predicting the productivity of cactus pear using artificial neural networks (ANN) on a computer with routines in the R software and by simple linear regression (SLR) on smartphones on the Android system of the MIT App Inventor 2 platform. In addition, using the smartphone app, it is possible to obtain the cladode area through multiple linear regression (MLR). It is also possible to obtain the estimates of the experimental plot sizes by the maximum modified curvature, linear and quadratic methods with plateau response, relative information, comparison of variances, and convenient plot size. The platform provides technical information associated with the cactus pear crop from different sources (dissertations, theses, articles) and formats (video classes and teaching resources), offline for applications, and online with download for publications, dissertations, theses and articles, video classes, and several didactic resources. The biomathematical models integrated with the applications were highly precise in predicting the phenomena, in which the variation explained by the models in the prediction of responses for future observations had R² values of 0.95, 0.72, and 0.92, respectively, for productivity with computer-ANN and smartphone-SLR, and for the cladode area with a smartphone - MLR.

Resumen El objetivo de este estudio fue evaluar la interferencia y determinar el nivel de daño económico (NDE) de escoba dura infestando diferentes cultivares de soja. Los tratamientos fueron cultivares de soja (NS 6909, NA 5909, DM 5958, Brasmax ELITE, Brasmax LANÇA y SYN 13561) y las densidades de escoba dura (0, 2, 3, 4, 9, 15, 16, 23, 22 y 58; 0, 2, 3, 3, 6, 6, 10, 11, 18 y 47; 0, 3, 4, 7, 8, 10, 11, 13, 15 y 24; 0, 1, 4, 6, 12, 18, 19, 31, 44 y 50; 0, 4, 5, 6, 9, 13, 17, 20, 20 y 47; e 0, 2, 3, 5, 9, 11, 15, 18, 29 y 30 plantas m-2), respectivamente, para cada cultivar. Los cultivares NS 6909, NA 5909 y Brasmax Lança son más competitivos que DM 5958, Brasmax Elite y SYN 13561. Los valores de NDE varían de 0,55 a 0,95 plantas m-2 para los cultivares NS 6909, NA 5909 y Brasmax Lança, que mostraron mejor competitividad. Los valores más bajos de NDE varían de 0,26 a 0,61 plantas m-2 para los cultivares DM 5958, Brasmax Elite y SYN 13561, los cuales mostraron menor competitividad con la maleza.

Abstract This study aimed to assess the interference and threshold level (TL) of Sida rhombifolia, the arrowleaf sida, competing with different soybean cultivars. The treatments comprised different soybean cultivars (NS 6909, NA 5909, DM 5958, Brasmax ELITE, Brasmax LANÇA, and SYN 13561) and densities of arrowleaf sida plants per square meter (m-2) (0, 2, 3, 4, 9, 15, 16, 23, 22, and 58; 0, 2, 3, 3, 6, 6, 10, 11, 18, and 47; 0, 3, 4, 7, 8, 10, 11, 13, 15, and 24; 0, 1, 4, 6, 12, 18, 19, 31, 44, and 50; 0, 4, 5, 6, 9, 13, 17, 20, 20, and 47; 0, 2, 3, 5, 9, 11, 15, 18, 29, and 30, respectively) for each cultivar. Cultivars NS 6909, NA 5909, and Brasmax Lança were more competitive than DM 5958, Brasmax Elite, and SYN 13561. The TL values varied from 0.55 to 0.95 plants m-2 for cultivars NS 6909, NA 5909, and Brasmax Lança, which exhibited greater competitiveness with arrowleaf sida. The lowest values of TL varied from 0.26 to 0.61 plants m-2 for cultivars DM 5958, Brasmax Elite, and SYN 13561, which had less competitiveness with weed.

Resumen El objetivo de este trabajo fue evaluar la capacidad competitiva de cultivares de frijol tipo carioca, BRS FC104, BRS FC402, IAC Imperador, IAC Milênio, IPR Tangará y SCS Riqueza, bajo niveles crecientes de infestación de Alexandergrass (Urochloa plantaginea). Los experimentos se realizaron en condiciones de invernadero en un diseño completamente al azar con cuatro repeticiones. Los tratamientos se organizaron en proporciones de plantas de frijol y Alexandergrass de: 100: 0, 75:25, 50:50, 25:75 y 0: 100 o 40:00, 30:10, 20:20, 10:30 y 0: 40 plantas por maceta. El análisis de la competitividad de las especies se realizó mediante diagramas aplicados a experimentos de series de reemplazo y también mediante los índices de competitividad relativa. Treinta días después de la emergencia del cultivo, se midieron el área foliar (AF), la altura de la planta (AP), el diámetro de la planta (DP) y la masa seca de los brotes (MS), además de características relacionadas con la fisiología de la planta. Hubo competencia entre cultivares de frijol carioca en presencia de Alexandergrass, independientemente de la proporción de plantas, lo que provocó reducciones en el DP, AF, y MS. Básicamente, existe competencia por los mismos recursos ambientales entre el cultivo de frijoles y Alexandergrass.

Abstract The objective of this work was to evaluate the competitive ability of carioca bean cultivars BRS FC104, BRS FC402, IAC Imperador, IAC Milênio, IPR Tangará, and SCS Riqueza in the presence of Alexandergrass (Urochloa plantaginea) in different proportions of plants in association. The experiments were carried out in a greenhouse in a completely randomized design with four replications. The treatments were arranged according to the proportions of beans and Alexandergrass plants: 100:0, 75:25, 50:50, 25:75, and 0:100 or 40:00, 30:10, 20:20, 10:30, and 0:40 plants per pot. The competitiveness of the species was analyzed using diagrams applied to replacement experiments and also through relative competitiveness indices. At 30 days after crop emergence, leaf area (LA), height (HP), diameter (DP), and shoot dry mass (SM) of the plant shoots were measured, as well as variables related to the physiology of the species. There was competition among carioca bean cultivars in the presence of Alexandergrass regardless of the proportion of plants, causing decreases in DP, LA and SM. Basically, there is competition for the same environmental resources between beans and Alexandergrass.

RESUMEN Entre las malezas que interfieren en el crecimiento y desarrollo del sorgo dulce se destaca el amor seco, especialmente por presentar alta capacidad competitiva por los recursos disponibles en el medio. El objetivo de este estudio es comparar la capacidad competitiva del sorgo dulce (Sorghum bicolor) frente al papunga (Bidens pilosa), en función de la proporción de cultivo y planta. Los experimentos se realizaron en un invernadero en un diseño completamente al azar, con cuatro repeticiones. Los tratamientos se organizaron en series de reemplazo en las proporciones de 100: 0, 75:25, 50:50, 25:75 y 0: 100% (sorgo: maleza) que correspondieron a 20:0, 15:5, 10:10, 5:15 y 0:20 plantas por maceta con volumen de 8 dm3 de sorgo dulce (cultivares BRS 506, BRS 509 o BRS 511) contra B. pilosa. Cincuenta días después de la emergencia, se evaluaron el área foliar de la planta (LA), la masa seca de los brotes (MS), la fotosíntesis (A) y la transpiración (E). La capacidad competitiva se analizó utilizando el método de análisis gráfico, construyendo diagramas basados en la productividad total y relativa. También se determinaron la competitividad, el coeficiente de agrupamiento y la agresividad. Los cultivares de sorgo, en general, fueron menos competitivos en todas las proporciones de B. pilosa. Hubo pequeñas diferencias en la capacidad competitiva entre los cultivares de sorgo; BRS 509 demostró ser ligeramente más competitivo que BRS 506 y BRS 511 frente al B. pilosa a. Sin embargo, es poco probable que esto proporcione una ventaja competitiva para BRS 509 en los campos de producción, por lo que B. pilosa a debe controlarse de manera eficiente al principio del ciclo de cultivo para evitar pérdidas de productividad, independientemente del cultivar de sorgo.

ABSTRACT Among the weeds that interfere with the growth and development of sweet sorghum, beggar ticks stands out, because it has a high competitive capacity for the available resources. This study aims to compare the competitive ability of sweet sorghum (Sorghum bicolor (L.) Moench) against hairy beggarticks (Bidens pilosa L.), as a function of cultivar and plant proportion. Experiments were conducted in a greenhouse in a completely randomized design with four replications and six treatments. Treatments were arranged in replacement series in the proportions of 100:0, 75:25, 50:50, 25:75, and 0:100% (sorghum:weed) equivalent to 20:0, 15:5, 10:10, 5:15 and 0:20 plants per pot with 8 dm3 capacity of sweet sorghum (cultivars ‘BRS 506’, ‘BRS 509’ or ‘BRS 511’) against hairy beggarticks. Fifty days after emergence, plant leaf area (LA), aboveground dry mass (DM), photosynthesis (A), and transpiration rates (E) were measured. Competitive ability was analyzed by using the graphical analysis method and building diagrams based on total and relative productivity. Competitiveness, clustering coefficient, and aggressiveness were also determined. Sorghum cultivars, in general, showed losses independently of the proportion of hairy beggarticks. Statistical analysis showed small differences in competitive ability among sorghum cultivars; ‘BRS 509’ was also demonstrated to be slightly more competitive than ‘BRS 506’ and ‘BRS 511’ against hairy beggarticks. This, however, is unlikely to provide a competitive advantage for ‘BRS 509’ in production fields, and hairy beggarticks should be efficiently controlled early in the crop cycle to avoid productivity losses, independently of the sorghum cultivar.

RESUMEN ''Respuestas bioquímicas y fisiológicas del árbol Pterogine nitens (Fabaceae) a la deriva simulada de glifosato''. Introducción: En las últimas décadas, el área de dispersión natural de P. nitens, estuvo sometida a un cambio en el uso de la tierra. Se expandió la frontera agropecuaria, a expensas del bosque nativo, con la incorporación de sistemas productivos que utilizan altas dosis del herbicida glifosato. Se desconoce el el grado de tolerancia de la especie al herbicida, y su respuestas fisiológicas. Objetivo: Evaluar las respuestas bioquímicas y fisiológicas de Pterogine nitens a la deriva simulada de glifosato. Métodos: Hicimos ensayos en invernáculo, con plantas de un año de edad, en macetas. Simulamos la deriva de glifosato, en dosis de 0,65 y 130g e.a. ha-1. Veinte días después de la aplicación, medimos las concentraciones de shikimato, pigmentos fotosíntéticos, y la composición mineral. Resultados: El glifosato incrementó las concentraciones de shikimato, y disminuyó las concentración de pigmentos fotosintéticos. También redujo las cocentraciones de potasio, magnesio, calcio, zinc, manganeso y hierro. Conclusiones: El glifosato altera la etapa fotoquímica de la fotosíntesis, al diminuir la concentración de pigmentos fotosintéticos. También interfiere con la homeostasis de macro y micronutrientes.

ABSTRACT Introduction: In the last decades, the natural dispersal area of P. nitens has been subjected to a change in land use. The agricultural frontier has expanded, at the expense of native forest, with the incorporation of productive systems that use high doses of the herbicide glyphosate. The degree of tolerance of the species to the herbicide and its physiological responses are unknown. Objective: To evaluate the biochemical and physiological responses of Pterogine nitens to simulated glyphosate drift. Methods: Greenhouse trials were conducted with one-year-old plants grown in pots. Glyphosate drift was simulated at doses of 0,65 and 130g a.e. ha-1. We measured concentrations of shikimate, photosynthetic pigments, and mineral composition, 20 days after application. Results: Glyphosate increased concentrations of shikimate and decreased concentrations of photosynthetic pigments. It also reduced concentrations of potassium, magnesium, calcium, zinc, manganese, and iron. Conclusions: Glyphosate alters the photochemical stage of photosynthesis by decreasing the concentration of photosynthetic pigments. It also interferes with macro- and micronutrient homeostasis.

ABSTRACT The pineapple belongs to the family Bromeliaceae and is a slow-growing succulent monocot with a reduced superficial root system. For this reason, the interference of weeds in competition with this crop can cause significant losses to the production. One of the bases to elaborate a control strategy is the knowledge of the diversity of weeds that occur in the cultivated areas. The objective of this study was to identify the weed community during pineapple growth in a semi-arid climate region of Brazil. Weeds were collected 60, 120, 180, 240, 300, and 360 days after planting (DAP) the pineapple. These collections were made in three different plots every two months until floral induction, composed of three pineapple cultivars. The weed community found in the irrigated pineapple field, in semi-arid climate conditions, was mostly composed by species belonging to the families Amaranthaceae, Asteraceae, Convolvulaceae, Fabaceae, Malvaceae, and Poaceae. The highest diversity of weed species was found at 60 DAP. The species Ipomoea acuminata was present throughout the development of the pineapple and showed the highest importance value index in most of the periods evaluated during the pineapple growth.

RESUMEN La pina pertenece a la familia Bromeliaceae y es una mono-cotiledónea suculenta de crecimiento lento con un sistema radical superficial reducido. Por este motivo, la interferencia de las malezas en competencia con el cultivo puede provocar pérdidas importantes para la producción. Una de las bases para la elaboración de una estrategia de control es el conocimiento de la diversidad de malezas que se dan en las áreas cultivadas. El objetivo de este trabajo fue identificar la comunidad de malezas durante el crecimiento de la pina en una región de clima semiárido de Brasil. Las malezas se recolectaron 60, 120, 180, 240, 300 y 360 días después de la siembra (DDS) de la pina. Estas recolecciones se realizaron en tres parcelas diferentes cada dos meses hasta la inducción floral, compuestas por tres cultivares de pina. La comunidad de malezas que se encontró en el campo de pina irrigado, en condiciones climáticas semiáridas, estaba compuesta principalmente por especies pertenecientes a las familias Amaranthaceae, Asteraceae, Convolvulaceae, Fabaceae, Malvaceae y Poaceae. La mayor diversidad de especies de malezas se encontró a los 60 DDS. La especie Ipomoea acuminata estuvo presente durante todo el desarrollo de la pina y mostró el índice de valor de importancia más alto en la mayoría de los períodos evaluados durante el crecimiento de la pina.

RESUMO Objetivou-se com esse trabalho avaliar o desempenho agronômico e a eficiência do uso da água de sistemas de sucessão de culturas em preparo convencional (PC) e plantio direto (PD), em dois experimentos instalados na região norte de Minas Gerais. O experimento 1 foi constituído pelo plantio em sucessão de milho- grão / feijão-comum, e o experimento 2 constituído pelo plantio em sucessão de sorgo / milho-verde. Em ambos os experimentos, os tratamentos foram constituídos por dois sistemas de manejo (PC e PD), dispostos no esquema de faixas, em dois anos de cultivo, com dez repetições. Foram avaliadas a produtividade e os componentes de produção de cada cultura, além da eficiência no uso de água (EUA) pelas culturas instaladas nas safras de outono-inverno, dentro de cada sistema de sucessão. Os dados obtidos foram submetidos à análise de variância, e, no caso de significância, as médias foram estudadas pelo próprio teste F a 5% de significância. Os resultados obtidos permitiram concluir que na sucessão milho-grão / feijão-comum, o PD aumenta a produtividade do milho em 21.45%, contudo, não há diferença entre os manejos para a produtividade feijão- comum. Na sucessão sorgo / milho-verde, o PD proporciona aumento da produtividade da matéria verde e matéria seca de sorgo em 39.65 e 84.26%, respectivamente, enquanto que no cultivo do milho-verde, o PD aumenta em 11.99 e 21.80%, respectivamente, a produtividade de espigas totais e comerciais. Nos dois sistemas de sucessão, o PD proporciona aumento na EUA pelas culturas, nas safras de outono-inverno.

ABSTRACT The objective of this work was to evaluate the agronomic performance and water use efficiency of crop rotations under conventional system (CTS) and no-tillage system (NTS) through two experiments conducted in the Semiarid region of the northern state of Minas Gerais, Brazil. Experiment 1 consisted of a grain corn-common bean rotation, and experiment 2 consisted of a sorghum-sweet corn rotation. The treatments, in both experiments, consisted of two tillage systems (CTS and NTS) arranged in strip-plots, in two crop years, with ten replications. Yield and production components of all crops and water use efficiency (WUE) of crops grown in the autumn-winter seasons were evaluated within each crop rotation. The data obtained were subjected to analysis of variance and, when significant, the means were subjected to the F test at 5% significance level. The results obtained showed that the NTS increases corn yield in 21.45% in the grain corn-common bean rotation; however, the common bean yield present no difference between tillage systems. NTS increases the sorghum fresh and dry matter yields in 39.65% and 84.26%, respectively, in the sorghum- sweet corn rotation, and the sweet corn total and commercial ear yield in 11.99% and 21.80%, respectively. The NTS increases the WUE of crops grown in the autumn-winter season, in both crop rotations.

RESUMO O objetivo deste trabalho foi realizar a seleção simultânea em genótipos de batata-doce e verificar a eficiência de sistemas fuzzy quando comparados ao método Mulamba & Mock (MM). O experimento foi em blocos casualizados, com 24 genótipos de batata-doce, quatro repetições e dez plantas por parcela. Os valores genéticos foram obtidos pela metodologia dos modelos mistos (REML/BLUP), e posteriormente estimados o índice MM e os ganhos obtidos pelos sistemas fuzzy desenvolvidos. Houve predomínio de efeitos ambientais sobre os efeitos genotípicos para todas as características. Essas estimativas sugerem expressiva contribuição do ambiente para esses caracteres e, consequentemente, maior dificuldade para o melhoramento genético. Através disso, os sistemas fuzzy se destacaram em relação ao método de MM, já que apresentaram ganhos de seleção superiores para os caracteres relacionados à alimentação humana e animal. Os genótipos com potencial para alimentação humana e animal selecionados pelo sistema fuzzy foram: UFVJM07, UFVJM05, UFVJM09, UFVJM40, UFVJM01, UFVJM25, UFVJM15. A lógica fuzzy foi eficiente na seleção simultânea de genótipos de batata-doce, permitindo a seleção de plantas semelhantes ao ideótipo desejável do que o método MM.

ABSTRACT The objective of this work was to perform simultaneous selection in sweet potato genotypes and to verify the efficiency of fuzzy systems when compared to the Mulamba & Mock (MM) method. The experiment was carried out in randomized blocks, with 24 sweet potato genotypes, four replications and ten plants per plot. The breeding values were obtained by the mixed model methodology (REML/BLUP), and then the MM index and the gains obtained by the developed fuzzy systems were estimated. There was a predominance of environmental effects over genotypic effects for all traits. These estimates suggest an expressive contribution of the environment for these traits and, consequently, greater difficulty for genetic improvement. Through this, the fuzzy systems stood out in relation to the MM method, as they presented superior selection gains for characters related to human and animal food. The genotypes with potential for human and animal food selected by the fuzzy system were: UFVJM07, UFVJM05, UFVJM09, UFVJM40, UFVJM01, UFVJM25, UFVJM15. The fuzzy logic was efficient in the simultaneous selection of sweet potato genotypes, allowing the selection of plants similar to the desirable ideotype than the MM method.

Resumo O objetivo deste trabalho foi avaliar a dissimilaridade genética entre cultivares e genótipos de soja para a seleção de genitores, bem como propor um novo método para a utilização de mapas auto-organizáveis de Kohonen (SOMs) e testar sua eficiência por meio da análise discriminante de Anderson. Foram avaliados os descritores morfoagronômicos de cultivares e genótipos de soja. Para análise dos dados, utilizaram-se redes neurais artificiais do tipo SOM. O método proposto permitiu a determinação da melhor arquitetura de rede de forma não subjetiva. Além disso, no início do treinamento, foi possível mitigar o efeito da aleatoriedade dos pesos sinápticos sobre os grupos formados. Foram formados seis grupos dissimilares; portanto, há dissimilaridade genética entre cultivares e genótipos de soja. As cultivares C25, C8 e C13 podem ser combinadas com as C36, C31, C32 e C33, por apresentarem bons atributos de produtividade e alta dissimilaridade. A metodologia proposta é vantajosa em comparação ao uso de SOMs tradicionais e se mostrou eficiente devido à consistência dos agrupamentos de acordo com a análise discriminante de Anderson.

Abstract The objective of this work was to evaluate the genetic dissimilarity between soybean cultivars and genotypes for the selection of parents, as well as to propose a new method for using Kohonen’s self-organizing maps (SOMs) and to test its efficiency through Anderson’s discriminant analysis. The morphoagronomic descriptors of soybean cultivars and genotypes were evaluated. For data analysis, SOM-type artificial neural networks were used. The proposed method allowed the determination of the best network architecture in a nonsubjective way. Furthermore, at the beginning of training, it was possible to mitigate the randomness effect of the synaptic weights on the formed clusters. Six dissimilar clusters were formed; therefore, there is genetic dissimilarity between soybean cultivars and genotypes. Cultivars C25, C8, and C13 can be combined with C36, C31, C32, and C33 because they show good yield-related attributes and high dissimilarity. The proposed methodology is advantageous in comparison with the use of traditional SOMs, besides being efficient due to clustering consistency according to Anderson’s discriminant analysis.

RESUMO Com o conhecimento da distribuição do sistema radicular da palma forrageira é possível aprimorar o seu manejo, já que podem ser definidas áreas do solo mais propícias para a aplicação de fertilizantes e a instalação de sensores de umidade do solo em condição irrigada. Assim, objetivou-se avaliar a distribuição radicular de genótipos de palma forrageira sob percentagens de reposição de água no solo. Para isso, desenvolveu-se experimento de campo envolvendo dois materiais genéticos de palma forrageira (Gigante - Opuntia fícus-indica Mill. e Miúda - Nopalea cochenillifera Salm-Dyck) e seis percentagens de reposição de água no solo, com base na evapotranspiração de referência - ET0 (T1, sem irrigação; T2, 15%; T3, 30%; T4, 45%; T5, 60% e T6, 75% da ET0), dispostos no esquema de parcelas subdivididas, ficando os tratamentos de irrigação nas parcelas e os materiais genéticos nas subparcelas, no delineamento em blocos casualizados, com três repetições. Aos 390 dias após o plantio deu-se início à coleta de raízes das cultivares para análise da densidade de comprimento de raízes (DCR). Constatou-se que a DCR muito fina diminui com o aumento da distância da base da planta e profundidade e a DCR total, fina, pequena e média aumentam com maiores reposições de irrigação; 75% da ET0 próximo à base da planta incrementa a DCR; todas as classes de raízes se concentram entre 0-0,20 m de distância e 0,10 a 0,25 m de profundidade, e a percentagem da DCR é maior no genótipo Gigante e o genótipo Miúda apresenta melhor distribuição.

ABSTRACT Knowledge of the cactus pear root distribution system can improve management of the plant by defining the areas of soil best suited to fertilizer application and the installation of soil moisture sensors under irrigation. Thus, the aim of the present study was to assess the root distribution of cactus pear genotypes under different water replacement levels. To that end, a field experiment was conducted in a randomized block design, using genetic material from two cactus pear genotypes (Opuntia fícus-indica Mill. and Nopalea cochenillifera Salm-Dyck) and six water replacement levels based on reference evapotranspiration - ET0 (T1, no irrigation; T2, 15%; T3, 30%; T4, 45%; T5, 60% and T6, 75% of ET0), arranged in split-plot, with irrigation treatments allocated to the plots and the genetic material to the sub-plots, and three replicates. The roots of the cultivars were collected for analysis of root length density (RLD) 390 days after planting. The RDL of very fine roots declines as depth and distance from the plant base increases and total, fine, small and medium RDL rise at higher water replacement levels; 75% of ET0 near the plant base increases RDL; all the root diameter classes are concentrated at a distance of 0-0.20 m from the plant base and depth of 0.10 to 0.25 m; the RDL percentage is higher for the Gigante genotype and Miuda exhibits better root distribution.

Resumen El objetivo fue evaluar el tamaño mínimo de parcelas experimentales para el frijol común (Phaseolus vulgaris L.) utilizando el método de curvatura máxima modificado. El experimento consistió en una prueba de uniformidad en un suelo Latosol amarillo-rojo con la temporada de lluvias marcada por el verano con el cultivar BRSFC-402 sembrado a un espaciamiento de 0,5 m entre hileras de plantas y 10 plantas por metro dentro de la hilera. Para las mediciones se consideraron 20 hileras centrales de 20 m de longitud, totalizando 4.000 plantas en un área de 200 m². Se evaluó el rodal final de frijol, el número medio de vainas por planta, el número medio de granos por vaina, el peso medio de 100 granos y el rendimiento de grano. En las evaluaciones, cada fila con 10 plantas se consideró una unidad básica (0,5 m²), que asciende a 400 unidades básicas cuyas dimensiones se combinaron en 14 formas de parcela. Se utilizaron los métodos de información relativa y curvatura máxima modificada para obtener la mejor forma y el tamaño de parcela más apropiado, respecti vamente, para la evaluación experimental con frijol común. Considerando que la parcela óptima debería permitir una evaluación eficiente de todas las características evaluadas, el tamaño de parcela apropiado fue de cinco UB (25 plantas) en el formato de cinco filas x una UB por fila.

Abstract The objective was to estimate the optimal plot size for field experiments with the common bean (Phaseolus vulgaris L.) using the modified maximum curvature method. A uniformity trial was carried out with the cultivar BRSFC-402 sown at a spacing of 0.5 m between plant rows and 10 plants per meter within the row. Final bean stand, mean number of pods per plant, mean number of grain per pod, mean 100-grain weight, and grain yield were evaluated. Measurement were taken from 20 central rows measuring 20 m in length, totaling 4,000 plants on an area of 200 m2. A basic unit (0.5 m2) was a row containing 10 plants. Four hundred basic units were combined to form 14 plot shapes. The methods relative information and modified maximum curvature were used to define the optimal shape and size of plots, respectively, for experimental evaluation with the common bean. As the plot should be suitable for efficient evaluation of all evaluated characteristics, the optimal plot size consisted of five basic units (25 plants) and was shaped as five rows x one basic unit per row.

Resumen El objetivo de este estudio fue evaluar la capacidad competitiva de los híbridos de canola (Brassica napus var. oleifera) en competencia con la avena negra (Avena strigosa), en un ambiente subtropical. Los experimentos se llevaron a cabo en un invernadero donde los híbridos de canola Hyola 61, Hyola 76, Hyola 433 y Hyola 571 fueron probadas individualmente por su habilidad competitiva contra la avena negra. Se cambió la proporción de plantas (100%: 0%; 75%: 25%; 50%: 50%; 25%: 75% y 0%: 100%) manteniendo constante la población total de plantas (20 plantas parcela -1). Se evaluaron el área foliar (AF: m2 m-2) y la materia seca (DM: g m-2) además de la tasa de fotosíntesis (A: μmol m-2 s-1), la concentración interna de CO2 (Ci: μmol mol-1) y la tasa de transpiración (E: mol H2O m-2 s-1) se evaluaron utilizando un analizador de gases en el infrarrojo (IRGA) 55 días después de la emergencia. Se registró una intensa competencia entre la canola y la avena negra. La capacidad competitiva de los híbridos de canola fue distinta; Hyola 571 se desempeñó mejor que los otros, siendo una opción para mantener altos niveles de rendimiento en condiciones competitivas con avena negra. Elegir híbridos más competitivos como el Hyola 571 ayuda a mantener altos niveles de rendimiento de canola en áreas infestadas con avena negra.

Abstract The objective of this study was to assess the competitive ability of canola (Brassica napus var. oleifera) hybrids in competition with black oat (Avena strigosa) in a subtropical environment. The experiments were conducted in a greenhouse where canola hybrids ‘Hyola 61,’ ‘Hyola 76,’ ‘Hyola 433,’ and ‘Hyola 571’ were tested individually for their competitive performance with black oat. The plant proportion between black oat and the canola hybrid was changed (100%:0%; 75%:25%; 50%:50%; 25%:75%; and 0%:100%) while keeping the total population of plants constant (20 plants plot-1). Photosynthesis rate (μmol m-2 s-1), internal CO2 concentration (μmol mol-1), and transpiration rate (mol H2O m-2 s-1) were assessed using an infrared gas analyzer 55 days after emergence. Leaf area (m2 m-2) and dry matter (g m-2) were also assessed on the same day. The data set was analyzed by the replacement series method for competition studies. There was evidence of intense competition between canola and black oat, independent of plant proportion. The competitive ability of canola was distinct among hybrids; Hyola 571 performed better than the others in the competition against black oat. Choosing the most competitive hybrid, such as Hyola 571, helps maintain high canola grain yield levels in areas infested with black oat.

RESUMO Objetivou-se avaliar durante três ciclos de produção a exportação de nutrientes, o balanço nutricional e a taxa de recuperação de macronutrientes pela palma forrageira‘Gigante sob doses e fontes de adubação, e arranjos de disposição de plantas na área. Os 72 tratamentos foram dispostos em esquema de parcelas sub-subdivididas em delineamento em blocos casualizados com três repetições, sendo duas configurações nas parcelas (fileira tripla e quadrupla); três espaçamentos nas subparcelas (3,00 x 1,00 x 0,25 m; 3,00 x 1,00 x 0,16 m e 3,00 x 1,00 x 0,125 m); e 12 tipos de adubação nas sub-subparcelas (com fontes orgânica, organomineral e mineral). Os maiores aportes de nutrientes proporcionam maiores exportações, independentemente da fonte. A ordem de exportação de nutrientes foi K > Ca > N > Mg > S > P para as adubações mineral, orgânica com 30 Mg ha-1 ano-1 e organomineral com 30 e 60 Mg ha-1 ano-1 adicionada de N-P-K e P-K, enquanto nas adubações orgânicas com 60 e 90 Mg ha-1 ano-1 e organomineral com 90 Mg ha-1 ano-1 mais 600 kg ha-1 de K2O, a ordem de exportação altera para K > Ca > N > Mg > P > S. O balanço de nutrientes apos três ciclos foi positivo para N, P e S, como também para K nas adubações mineral com 600 kg ha-1 de K2O e organomineral com 30, 60 e 90 Mg ha-1 ano-1 de esterco bovino adicionado de 600 kg ha-1 de K2O. Porém, negativo para Ca e Mg em todas as adubações. As maiores taxas de recuperação de K e as menores de N ocorrem nas adubações orgânicas.

ABSTRACT The objective of this study was to evaluate nutrient export, nutritional balance and macronutrient recovery rate in ‘Gigante cactus pear under different fertilization doses, spacings and configurations during three production cycles. The 72 treatments were arranged in a randomized block design with three repetitions, two configurations in the plots (triple and quadruple row), three spacings in the subplots (3.00 x 1.00 x 0.25 m; 3.00 x 1.00 x 0.16 m and 3.00 x 1.00 x 0.125 m); and 12 types of fertilization in the sub-subplots (with organic, organomineral and mineral sources). Exports of nutrients are higher under fertilizers with higher nutrient supplies, regardless of source. The order of export was K > Ca > N > Mg > S > P for mineral fertilization, organic fertilization with 30 Mg ha-1 year-1 and organomineral fertilization with 30 and 60 Mg ha-1 year-1 plus NPK and PK, and it changed to K > Ca > N > Mg > P > S under organic fertilization with 60 and 90 Mg ha-1 year-1 and organomineral fertilization with 90 Mg ha-1 year-1 plus K. The nutrient balance after three production cycles was positive for N, P and S, negative for Ca and Mg in all fertilizations, and positive for K under mineral fertilization with 600 kg ha-1 of K2O and organomineral fertilization with 30, 60 and 90 Mg ha-1 year-1 plus 600 kg ha-1 of K2O. The highest recovery rates of K and the lowest recovery rates of N occur under organic fertilization.

RESUMO Alternativas que possibilitem a melhoria da retenção de água no solo devem ser buscadas visando maior aproveitamento de água por plantas cultivadas. Objetivou-se avaliar o efeito de doses de resina vegetal natural e estratégias de irrigação nas culturas do algodão (ciclo intermediário) e rabanete (ciclo curto). Foram desenvolvidos dois experimentos, em fatorial 5 x 5, em delineamento inteiramente casualizado, com três repetições e cinco doses de resina vegetal (0; 0,67; 1,33; 2,00; e 2,67 g planta-1), cinco tensões de água no solo (15; 30; 45; 60; e 75 kPa) para o algodoeiro e cinco reposições de água (40; 60; 80; 100; e 120 % da ETc) para o rabanete. Aos 93 dias após a semeadura (DAS), foram avaliados a altura, diâmetro de caule e número de folhas do algodoeiro. Aos 30 DAS, foram medidos a altura, diâmetro de raiz e número de folhas do rabanete, bem como quantificada a matéria seca da parte aérea e das raízes de ambas as culturas. A resina vegetal reduz a suscetibilidade da cultura ao déficit hídrico, com a dose máxima de 2,7 g planta-1 sendo recomendada para se obter melhor desenvolvimento das plantas. A resina aumenta a eficiência do uso de água nas culturas de algodão e rabanete, correspondendo a até 0,68 g L-1 e 69,6 g L-1, respectivamente.

ABSTRACT The search for alternatives that enable the improvement of the soil water retention capacity should focus on a better water use by cultivated plants. This study aimed to evaluate the effect of natural tree resin rates and irrigation levels on the cotton (intermediate cycle) and wild radish (short cycle) crops. Two experiments were conducted in a completely randomized design, in a 5 × 5 factorial arrangement, with three replications and five tree resin rates (0, 0.67, 1.33, 2.00 and 2.67 g plant-1), five soil water tensions (15, 30, 45, 60 and 75 kPa) for cotton plants and five irrigation water levels (40, 60, 80, 100 and 120 % of the ETc) for wild radish plants. The plant height, stem diameter and number of leaves were evaluated at 93 days after sowing (DAS) for the cotton plants; while the plant height, root diameter and number of leaves were evaluated at 30 DAS for the wild radish plants, as well as quantified the shoot and root dry weights of both plant species. The application of tree resin reduces the susceptibility of the crop to water deficit, being 2.7 g plant-1 the highest recommended rate to improve the plant development. The use of tree resin increases the water-use efficiency in cotton and wild radish crops in up to 0.68 g L-1 and 69.6 g L-1, respectively.