No abstract

Gonçalves de Lima e Roseli Aparecida Leandro, pelos ensinamentos e amizade. Ao departamento de Ciências exatas da ESALQ-USP, por proporcionar formação de qualidade, com excelente estrutura física e corpo docentes. Ao Prof • Geraldo Veríssimo de Souza Barbosa, por ter me guiado nos primeiros passos dessa longa caminhada, pelo exemplo de pessoa e profissionalismo, por todo carinho, incentivo e conhecimento compartilhado, com certeza, o seu apoio e orientação foram fundamentais para escolha da minha formação profissional.

RESUMOO presente trabalho objetivou estudar métodos alternativos de controle de Pyricularia grisea, em sementes de trigo, uma das principais fontes de inóculo da brusone. Após ensaios preliminares para avaliação do efeito dos produtos, em diferentes concentrações, tempos e temperaturas de imersão sobre a germinação das sementes, os tratamentos hipoclorito de sódio (2%; pH 11,5; 50°C; 10 min) e (2%; pH 11,5; 50°C; 10 min) e água quente (55°C/5min) foram selecionados para estudar sua eficiência no controle de P. grisea e transmissão do patógeno para plântula. O delineamento estatístico constou de 400 sementes em 4 repetições em blocos ao acaso. A incidência do fungo foi examinada do 2º. ao 4º. dia através do "blotter test" a 22ºC com fotoperíodo de 12h, a germinação das sementes foi avaliada aos 7 dias através da observação visual da emissão do tubo germinativo e a transmissão aos 7 e 14 dias pela identificação de conídios de P. grisea das lesões necróticas que surgiram em qualquer tecido da parte aérea. Dados do presente estudo revelaram que o tratamento hipoclorito de sódio (pH 11,5/50ºC/ 10min) foi eficiente no controle de P. grisea em sementes de trigo pois reduziu a incidência inicial de 57,7% para 2,25%, mas reduzindo significativamente a germinação para 46%. O tratamento hipoclorito de sódio reduziu a transmissão do patógeno para plântulas de 39,7 para 0,5%. Palavras-chave: Magnaporthe grisea, Triticum aestivum, brusone, controle alternativo, sementes ABSTRACT Efficiency of alternative treatments in the control of Pyricularia grisea in wheat seedsThe present study aimed to examine alternative methods of control of Pyricularia grisea in wheat seeds, one primary source of blast disease. The treatments sodium hypochlorite (2%; pH11,5; 50C; 10min) and hot water (55°C/5min) were selected after preliminary trials that examined the effect on germination of several reagents, at different concentrations, temperatures and period of submersion. Their efficiency in controlling P. grisea in wheat seeds and its transmission to seedlings was studied in seed lots of 400 in four replications in a randomized block design. The fungal incidence was analyzed through blotter test employing 22ºC and photoperiod of 12 h from the second to fourth day, seed germination at the seventh day through visual emergence of germ tube and transmission to seedlings at the seventh and 14 th days through identification of P. grisea conidia from necrotic lesions of any aerial tissues. The present data revealed that sodium hypochlorite (pH 11.5/50ºC/10min) was effective in controlling P. grisea in wheat seeds because it decreased the initial incidence from 57.7% to 2.25% but with deleterious effect on germination. This treatment reduced the fungal transmission to seedlings from 39.7 to 0.5%.

In sugarcane (Saccharum spp) breeding, despite the potential use of reciprocal recurrent selection (RRS) to explore both nonadditive and additive effects for economic value traits, to date, no publications have targeted obtaining heterotic groups to support this selection strategy. The aim of this study was to (a) to identify sugarcane gene pools to effectively explore nonadditive and additive genetic effects via reciprocal recurrent selection, (b) estimate genetic parameters, and (c) select parents and cross combinations. Seventy-nine sugarcane families were obtained from crossing 38 parents in a crossing scheme known as disconnected factorial design. The families were evaluated in randomized complete block design with five replicates. The statistical genetic analysis was performed with linear mixed models through restricted maximum likelihood/best linear unbiased predictor. The results revealed that nonadditive effects were predominant in explaining genetic variation for cane yield (t ha −1), pol yield (t ha −1), and fiber yield (t ha −1). For brix, fiber and corrected Pol (PCC) traits, additive effects were predominant. Estimates of specific combining ability and pedigree information allowed the establishment of gene pools for systematic heterosis exploitation through RRS breeding efforts. The prediction of the additive genetic values of parents for selection based on the progeny's behavior obtained via disconnected factorial design is an alternative that should be used in sugarcane breeding programs.

Sugarcane cultivar RB0442 has a high yield, late maturation and good drought tolerance. It is recommended for planting in restrictive environments, mainly with water-deficient soils, and is resistant to the major sugarcane diseases of the Northeastern region of Brazil.