Soy is one of the main cultivated species in the world with great economic expression and high impact on Brazilian agribusiness. The productive potential is expressed due to the genetic constitution of the cultivar and the environment in which it is exposed. The market demands for bean production require the ideal handling of the culture in order to optimize the yield potential of the plant. In this context, the handling of the culture is essential to achieve success when cultivating soy. Plant population influences the agronomic characters and consequently in the grain yield. Thus, this factor needs particular studies for each cultivar. The objective in this study was evaluating the influence of the plant population on the productive potential and agronomic characters in soy, in Uberlandia, Minas Gerais. The experiment was performed in Capim Branco Farm, which belongs to the Federal University of Uberlandia. The study was composed by 15 treatments in a 3x5 factorial scheme, constituted by three cultivars (UFUS 7415, UFUS 7401 and UFUS 6901) and five plant populations (200, 240, 280, 320 and 360 thousand plants ha-1). It was adopted the experimental outlining of randomized complete blocks, with five repetitions. The evaluated characters were: number of days to flowering and maturity (NDF and NDM), plant height at flowering and maturity (APF and APM), number of nodes at flowering and maturity (NNF and NNM), insertion height for the first pod (APV), total number of pods (NVT), thousand grain weight (P1000G) and productivity (PROD). It was noted that plant population didn’t interfere in the soy cycle, number of nodes and thousand grain weight. The cultivars UFUS 6901, UFUS 7415 and UFUS 7401 presented better yields in populations of 240, 280 and 320 thousand plants ha-1 respectively.

Allelopathy involves the release of compounds into the environment that affects the growth and development of other organisms. This phenomenon may lead to the production of compounds less harmful to the environment than traditional herbicides used in weed control. In plants, terpenes have been identified as components of allelochemicals and are synthesized by enzymes named as geranylgeranyl diphosphate synthases (GGPPS). There are about 12 GGPPS genes in Arabidopsis, among which is GGR. This work aims to study the association between the expression levels of GGR and the allelopathic response of sesame seedlings to Arabidopsis leaf extracts. Hence, the GGR gene was inserted into Arabidopsis with the purpose to investigate the allelopathic effects of GGR expression levels on sesame seedlings. GGR expression levels were quantified by RT-PCR in both transgenic and non-transgenic [wild-type (WT)] lines. It has been observed that both wild-type and GGR expressing transgenic lines inhibited the growth of sesame seedlings. However, it is noteworthy that the phytotoxicity of extracts from GGR lines were greater than WT extracts. RT-PCR analysis of GGR expression revealed that WT plants had higher levels of GGR expression than GGR transgenic lines, which suggests that a homologous-dependent gene silencing (HDGS) occurred in GGR lines. GGR is part of an enzyme complex that works as a hub that determines the types of terpenes produced in Arabidopsis chloroplasts. The present data indicates that decreases in GGR expression may have favoured the production of terpenes with stronger allelopathic capacity in Arabidopsis leaves.

A Deus, por ser a luz do meu caminho. Aos meus pais, Flávio e Vera, pelo incentivo e apoio nessa jornada. Ao meu irmão, João Paulo, pela amizade, dedicação e ajuda durante suas férias. Ao meu namorado, João Pedro, pelo amor, companheirismo, incentivo e compreensão desde o início. À minha amiga, Fernanda, pela amizade, companheirismo e ajuda durante as aulas e condução do experimento e pelos momentos de descontração, o melhor presente que a UFU me deu. À minha amiga, Marlize, pela amizade, conselhos e pelas longas conversas no café da tarde. À professora Dr.ª Ana Paula, pela confiança, orientação, dedicação e pelos conhecimentos transmitidos, por ser um exemplo de mulher e profissional. Ao professor Dr. Osvaldo, pela oportunidade de participar do Programa de Melhoramento de Soja da UFU. Aos estagiários do Programa de Melhoramento de Soja da UFU, pela ajuda e suporte nas atividades experimentais, e pela descontração durante os sábados de trabalho, em especial ao Thiago, Arthur, Diego e Gustavo. Aos colegas da pós-graduação,