ABSTRACT The aims of this study were: to assess the genetic relationship of supersweet corn populations; and to establish the heterotic pattern of 49 supersweet (sh2) corn inbreds on F2S5 generation based on molecular marker data and specific combining ability. Forty-nine inbreds were evaluated using 20 SSR molecular markers, which were allocated into heterotic groups according to the discriminant principal component analysis. Twelve inbreds were crossed in a complete diallel scheme. The 81 entries (hybrids developed, parental lines and three commercial checks) were evaluated in a triple partial balanced lattice design (9 × 9) during the growing seasons of 2016/2017 and 2017. The general combining ability (GCA) and specific combining ability (SCA) were estimated. The SCA values were used to set the heterotic patterns of the parental lines as well. Commercial yield without husk (CYWH) and ear length (EL) were more informative to set the heterotic groups. Additive and non-additive effects were important on the genetic control of the evaluated traits. However, for five of the six traits, the non-additive/dominance genetic effects showed to be more important in both environments. In fact, the hybrids developed among tropical by temperate germplasm had better performance than those ones developed within the temperate germplasm itself. SSR based-genetic distance demonstrate to be a reliable predictor as significant correlation was obtained between genetic distance with hybrid performance (for length of ears, ear height and CYWH) and SCA for all observed traits. The non-additive genetic effect that predominantly controlled all traits was the feasible explanation for the good prediction.

ABSTRACT Castor bean is a very important crop, however, in Brazil it still has relatively low productivity, 0.47 Mg ha-1 as a mean. Besides that the Country has significant castor oil demand and depends on international commerce to complement its production. The solution of these problems goes through the development of genotypes highly productive and adapted to the producing regions. So, the objective of this research was to evaluate the productive potential and selection of castor progenies of the cultivar FCA-PB, resulting from three types of pollination, in two crops and in two localities of the State of São Paulo. Grain productivity was evaluated, and some genetic parameters were estimated. In relation to the 2005/2006 crop, the progeny 49 cultivated in the locality of São Manuel produced 4170.66 kg ha-1 of grains. The highest heritability coefficients were observed in the 2005/2006 crop in the locality of Araçatuba. Progenies 1, 5, 6, 8, 15, 18, 19, 21, 27, 31, 35, 36, 38, 45, 49, 55, 56 and 58 were selected. Genotype interaction with the location indicated productive materials and adapted to the state of São Paulo.

RESUMO Redução no ciclo e uniformidade na maturação de frutos são características desejadas para a colheita mecanizada da cultura da mamona. O objetivo do presente trabalho foi estudar o efeito da limitação do crescimento secundário sobre o crescimento e os parâmetros produtivos da mamona. O experimento de campo foi conduzido entre fevereiro e maio de 2012, em delineamento experimental de blocos casualizados e esquema fatorial 2x2, com quatro repetições. Dois híbridos de mamona (Híbrido 12 e Híbrido 18) foram cultivados em duas formas de condução: (i) plantas sem nenhuma limitação ao crescimento e (ii) plantas com limitação do crescimento secundário do caule (poda e desbaste). A limitação do crescimento secundário das plantas resultou em maior partição de assimilados para o racemo primário das plantas, promovendo maior número e massa de grãos. Como resultado, plantas com apenas o racemo primário apresentaram produtividade de grãos equivalente a plantas que cresceram sem limitações. A produtividade de óleo em plantas com apenas o racemo primário foi equivalente a plantas testemunha para o Híbrido 12 e superiores para o Híbrido 18, com a vantagem da obtenção de plantas com maturação uniforme.

ABSTRACT Cycle reduction and uniform fruit maturation are desired characteristics for a mechanical harvest of castor bean crop. The objective of this research was to study the effect of secondary growth limitation on growth and production parameters of castor bean plants. A field experiment was conducted between February and May 2012 in a randomized block design in a factorial scheme 2 × 2, with four replications. Two castor bean hybrids (Hybrid 12 and Hybrid 18) were grown in two cultivation systems: (i) plants without growth limitation and (ii) plants with secondary stem growth limitation (thinning with pruning). Removal of secondary stems resulted in higher partitioning of assimilates to the primary raceme, promoting higher number and dry weight of grains. As a result, plants with only the primary raceme presented grain yield equivalent to plants without growth limitation. Oil yield of plants with only the primary raceme was equivalent to the control for the Hybrid 12 and higher for the Hybrid 18, with advantage of uniform maturation for these plants.

RESUMO A cultura da mamona possui grande potencial para o cultivo em condições brasileiras, contudo, deve-se buscar métodos cada vez mais eficientes de manejo da cultura, a fim de atingir altas produtividades e introduzir de modo definitivo a cultura no sistema agrícola nacional. O objetivo do presente estudo foi avaliar as características agronômicas e a produtividade da mamoneira em função do método de condução de plantas e da densidade de cultivo. O estudo foi conduzido em condições de campo no ano agrícola de 2010, utilizando a cultivar IAC 2028, em delineamento experimental de blocos casualizados em esquema fatorial 2x3 com quatro repetições. O primeiro fator foi composto por duas densidades de semeadura (26666 e 111111 plantas ha-1), enquanto o segundo fator foi composto por três métodos de condução de plantas (testemunha, poda parcial e poda+desbrota). Ao final do desenvolvimento da cultura, foram determinadas as características agronômicas das plantas, os componentes da produção e a produtividade. A poda + desbrota proporcionou melhoria dos caracteres agronômicos, sem afetar a produtividade e reduziu o ciclo da cultura em até 30 dias. Este comportamento, aliado à maturação uniforme, pode proporcionar a colheita mecanizada da cultura, além de proporcionar o cultivo da mamoneira em janelas de cultivo na safrinha, sem prejudicar a implantação da safra seguinte. O cultivo adensado de plantas de mamona limitou a emissão de ramos produtivos secundários sem afetar a produtividade, revelando elevada plasticidade fenotípica no desenvolvimento da cultura.

ABSTRACT The castor bean shows great potential for cultivation under the conditions found in Brazil, however, in order to achieve high productivity and introduce the crop into the Brazilian agricultural system, ever more efficient methods of crop management should be developed. The aim of this study was to evaluate the agronomic characteristics and productivity of the castor bean for the method of cultivation and planting density. The study was carried out under field conditions during the 2010 crop year, using the IAC 2028 cultivar. An experimental design of randomised blocks was employed in a 2 x 3 factorial, with four replications. The first factor comprised two planting densities (26,666 and 111,111 plants ha-1), while the second factor consisted of three methods of cultivation (control, partial pruning and thinning with pruning). At the end of crop development, the agronomic characteristics of the plants, yield components and productivity were determined. Pruning with thinning resulted in an improvement in the agronomic characteristics without affecting productivity, and reduced the crop cycle by 30 days. This behaviour, together with uniform maturation, may contribute to the mechanical harvesting of the crop, as well as allowing cultivation of the castor bean in the off-season without affecting the following harvest. Dense cultivation of the castor bean limited the appearance of secondary productive branches without affecting productivity, demonstrating a high phenotypic plasticity in crop development.

Para maximizar a produtividade de grãos de genótipos de mamona (Ricinus communis L.) de porte baixo, devem ser definidos a população e o arranjo de plantas mais adequados a cada época de cultivo. Foi conduzido um experimento no outono-inverno dos anos de 2008 e 2009, em Botucatu-SP, para avaliar os efeitos do espaçamento entre fileiras (0,45; 0,60; 0,75 e 0,90 m) e da população de plantas (25.000, 40.000, 55.000 e 70.000 plantas ha-1) sobre as características agronômicas, componentes da produção, produtividade de grãos e de óleo do genótipo FCA-PB. Elevada densidade de plantas provocou redução na sobrevivência das mesmas e aumentou a altura de inserção do primeiro racemo, especialmente no ano com maior disponibilidade hídrica. O diâmetro do caule, o número de racemos por planta e de sementes por racemo foram reduzidos com o aumento da densidade de plantas. As produtividades de grãos e de óleo foram pouco influenciadas pela população de plantas e espaçamento entre fileiras, pois a mamoneira compensa um baixa população de plantas, com um elevado número de racemos e grãos por planta. A máxima produtividade de grãos foi obtida com o espaçamento entre fileiras estimado de 0,64 m e 50.107 plantas ha-1 (ou seja, 3,2 plantas m-1).

Plant population and arrangement should be properly designed to maximize the seed yield of short-height genotypes of castor (Ricinus communis L.) in each cropping season. Experiments were performed in the in the fall-winter cropping season of 2008 and 2009 in Botucatu, State of São Paulo, Brazil, to evaluate the effects of row spacing (0.45, 0.60, 0.75, and 0.90 m) and plant population (25,000, 40,000, 55,000, and 70,000 plants ha-1) on agronomical traits, yield components, seed yield, and oil yield of the genotype FCA-PB. A high plant density caused a reduction in plant survival and increased the first raceme insertion height, particularly in the year with the higher rainfall. The basal stem diameter, number of racemes per plant, and seeds per raceme were reduced by increasing the plant density. However, the seed and oil yields were minimally influenced by plant population density and row spacing because the castor plant compensated for a low plant population with a high number of racemes and seeds. The maximum seed yield was achieved with an estimated 0.64 m of row spacing and 50,107 plants ha-1 (i.e., 3.2 plants m-1).

A mamoneira (Ricinus communis L.) é uma espécie oleaginosa tropical, sendo o óleo extraído de suas sementes um dos mais versáteis da natureza e com inúmeras aplicações industriais. Embora ainda seja uma espécie rústica, ela está sujeita a diversas doenças, dentre elas o mofo-cinzento, causada pelo fungo Amphobotrys ricini. O melhoramento genético seria a melhor alternativa para o controle da doença, mas demanda tempo para se obter cultivares resistentes. Dessa maneira, o uso de métodos de controle baseado em métodos químicos, alternativos ou biológicos mostra-se viável no curto prazo. O objetivo do trabalho foi estudar a eficiência do controle do mofo-cinzento, na cultura da mamoneira, utilizando-se de métodos químico, alternativo e biológico. Assim, procurou-se avaliar, tanto in vitro, quanto in vivo a eficiência de controle do patógenos utilizando-se de fungicidas, óleos essenciais e agentes de controle biológico. Quanto a inibição do crescimento micelial do patógeno in vitro os melhores tratamentos com os óleos essenciais foram os com a base de Cymbopogon martini e Cynnamomum zeylanicum, nas cinco concentrações testadas. Em ambos os óleos, o diâmetro médio das colônias ficou em 0,7 cm contra a média de 4,79 cm da testemunha. Com os fungicidas, nas quatro concentrações testadas, os mais eficientes foram os ingredientes ativos tiofanato metílico, carbendazim, tebuconazole e iprodione. O ED50 destes fungicidas ficou < 1uL/L, atestando 100% de inibição do crescimento micelial em todas as concentrações. Quanto à inibição da germinação dos conídios de A. ricini, os fungicidas tebuconazole e clorotalonil foram os melhores em todas as concentrações testadas, sendo a média dos conídios germinados destes fungicidas de 0,0 e 0,15%, respectivamente, contra 100% da testemunha. No campo, o tratamento com o fungicida iprodione foi o melhor quanto ao controle da doença quando comparados com os tratamentos biológico e alternativo. Em condições de campo, a severidade média da doença com o tratamento com iprodione foi de 15,76% contra 95,81% na testemunha inoculada.

The castor bean (Ricinus communis L.) is a tropical oilseed species, and the oil extracted from its seeds is one of the most versatile oils in the nature, showing various industrial uses. Even though it is a rustic species, the castor bean is subjected to several diseases such as the gray mold, caused by the fungus Amphobotrys ricini. Genetic breeding would be the best alternative for the disease control, but a long time is required to obtain resistant cultivars. Thus, the use of control strategies based on chemical, alternative or biological methods shows viable in the short term. The aim of this study was to investigate gray mold control efficiency, in castor bean crop, using chemical, alternative and biological methods. The pathogen control efficiency was evaluated both in vitro and in vivo using fungicides, essential oils and biological control agents. As regards the in vitro inhibition of the pathogen mycelial growth, the best treatments with essential oils were those based on C. martini and C. zeylanicum at all five tested concentrations. For both oils, the average diameter of colonies was 0.7 cm against 4.79 cm for the control treatment. For the fungicides, at all four tested levels, the most efficient active ingredients were methyl tiophanate, carbendazim, tebuconazole and iprodione. The ED50 of these fungicides was <1uL/L, yielding 100% mycelial growth inhibition at all concentrations. As to the inhibition of A. ricini conidium germination, the fungicides tebuconazole and chlorotanolyl were the best at all tested concentrations, and the average of germinated conidia with these fungicides was 0.0 and 0.15%, respectively, against 100% for the control treatment. In the field, treatment with the fungicide iprodione was the best for the disease control when compared to biological and alternative treatments. Under field conditions, the average disease severity for the treatment with iprodione was 15.76% against 95.81% for the inoculated control.