Abstract Thus, the objective of the research was to evaluate the initial growth and development of seedlings under Platymiscium floribundum at different levels of luminosity. The experimental design was completely randomized in a 4 x 10 factorial scheme (four levels of shade: full sun, 50%, 65% and 80% with ten replications per treatment. The height, number of leaves was evaluated monthly. At the end of the experiment at 180 days, leaf dry matter, stems, roots, and dry matter. In addition, measurements were made of the variables related to gas exchange and plant anatomy of leaves. The results obtained were observed higher growth and developed satisfactorily at full sun), without presenting morphological changes. For the gas exchange did not differ statistically. It is concluded that the initial growth of P. floribundum seedlings was superior in the light level in full sun, providing favorable conditions for their development.

Resumo: A microbiolização de sementes é uma alternativa na substituição dos defensivos químicos para o tratamento de sementes na agricultura orgânica. Assim, objetivou-se avaliar o crescimento inicial e o controle de fungos associados a sementes de algodoeiro orgânico, através da microbiolização de sementes com Trichoderma sp. e Saccharomyces cerevisiae. Sementes certificadas da cultivar Aroeira, cujo línter havia sido removido com ácido sulfúrico, foram analisadas em delineamento inteiramente casualizado em arranjo fatorial de 5 x 2 + 1, com cinco concentrações (0; 0,5; 1,0; 1,5 e 2,0), dois agentes biocontroladores (Trichoderma sp. e S. cerevisiae) e o fungicida como tratamento adicional (Captan®). Os testes de sanidade, germinação e emergência das sementes foram avaliados para confirmar as hipóteses. A microbiolização das sementes é eficiente na redução da incidência de fungos e no crescimento inicial de plântulas de algodoeiro orgânico cv. Aroeira. Os agentes biocontroladores avaliados são superiores ao tratamento químico no crescimento inicial de plântulas. Trichoderma sp. é o agente mais eficaz, proporcionando alto crescimento inicial de plântulas e redução significativa da incidência de fungos.

Abstract: Seed microbiolization is an alternative to chemical pesticides for seed treatment in organic agriculture. Thus, this study aimed at evaluating the initial growth and control of fungi associated with organic cotton seeds, through seed microbiolization with Trichoderma sp. and Saccharomyces cerevisiae. Certified cotton seeds (cultivar Aroeira), whose linter was removed with sulfuric acid, were analyzed in a completely randomized design in a 5 x 2 + 1 factorial scheme, corresponding to five concentrations (0, 0.5, 1.0, 1.5, and 2.0), two biocontrol agents (Trichoderma sp. and S. cerevisiae), and an additional treatment composed of a fungicide (Captan®). Seed health, germination, and emergence tests were conducted to confirm the hypotheses. The microbiolization of seeds is efficient in reducing both incidence and initial growth of fungi in organic cotton cv. Aroeira. The appraised biocontrol agents proved to be superior to the chemical treatment regarding the initial seedling growth. Trichoderma sp. is the most effective agent and provides a high initial seedling growth and a significant reduction in fungal incidence.