Additive and Non-Additive Effects on the Control of Key Agronomic Traits in Popcorn Lines under Contrasting Phosphorus Conditions.

Phosphorus is a non-renewable natural resource that will run out of reserves in the upcoming decades, making it essential to understanding the inheritance of nutrient use efficiency for selecting superior genotypes. This study investigated the additive and non-additive effects of commercially relevant traits for the popcorn crop (grain yield-GY, popping expansion-PE, and expanded popcorn volume per hectare-PV) in different conditions of phosphorus (P) availability in two locations in Rio de Janeiro State, Brazil. Six S7 lines previously selected for P use-L59, L70, and P7, efficient and responsive; and L54, L75, and L80, inefficient and non-responsive-were used as testers in crosses with 15 progenies from the fifth cycle of intrapopulation recurrent selection of UENF-14, with adaptation to the North and Northwest regions of Rio de Janeiro State. Using the Griffing diallel analysis, P use efficiency was predominantly additive in the expression of PE, and non-additive effects were prominent for GY and PV. For obtaining genotypes that are efficient for phosphorus use, it is recommended that heterosis with parents that provide additive gene accumulation for PE be explored.

Mitochondrial proteomics reveals new insights into embryogenic competence acquisition in Carica papaya L. callus.

Understanding the mechanisms that endow a somatic cell with the ability to differentiate into a somatic embryo, which could result in numerous biotechnological applications, is still a challenge. The objective of this work was to identify some of the molecular and physiological mechanisms responsible for the acquisition of embryogenic competence during somatic embryogenesis in Carica papaya L. We performed a broad characterization of embryogenic (EC) and nonembryogenic calli (NEC) of using global and mitochondrial proteomic approaches, histomorphology, histochemistry, respiratory activity, and endogenous hormonal and hydrogen peroxide (H2O2) contents. EC and NEC presented remarkable differences in anatomical and histochemical characteristics, with EC showing a higher reactivity for the presence of proteins and neutral polysaccharides. Our results demonstrate that mitochondrial metabolism affects the embryogenic competence of C. papaya callus. The EC presented higher participation of alternative oxidase (AOX) enzymes, higher total cell respiration and presented a stronger accumulation of mitochondrial stress response proteins. Differential accumulation of auxin-responsive Gretchen Hagen 3 (GH3) family proteins in EC was related to a decrease in the content of free 2,4-dichlorophenoxyacetic acid (2,4-D). EC also showed higher endogenous H2O2 contents. H2O2 is a promising molecule for further investigation in differentiation protocols for C. papaya somatic embryos. SIGNIFICANCE: To further advance the understanding of somatic embryogenesis, we performed a broad characterization of embryogenic and nonembryogenic callus, through global and mitochondrial proteomic approaches, histomorphology, histochemistry, respiratory activity, and endogenous hormonal and hydrogen peroxide contents. Based on these results, we propose a working model for the competence of papaya callus. This model suggests that GH3 proteins play an important role in the regulation of auxins. In addition, embryogenic callus showed a greater abundance of stress response proteins and folding proteins. Embryogenic callus respiration occurs predominantly via AOX, and the inhibition of its activity is capable of inhibiting callus differentiation. Although the embryogenic callus presented greater total respiration and a greater abundance of oxidative phosphorylation proteins, they had less COX participation and less coupling efficiency, indicating less ATP production.

Structural and ecophysiological alterations of the water hyacinth [Eichhornia crassipes (Mart.) Solms] due to anthropogenic stress in Brazilian rivers

In this work, the structural and ecophysiological alterations (chlorophyll a fluorescence and photosynthetic pigments), and quantification of Cr, Pb and Zn in the leaf limb, petiole and younger and older roots of water hyacinth from the lower, medium and upper Paraíba do Sul river (PSR) and Imbé river were evaluated. The plants from the medium and upper PSR (more industrialized and populated regions) exhibited lower turgid cell in the root cortex, less root hairs and leaf epidermis, chloroplasts with plastoglobules and increased stroma volume. Higher concentrations of metals were observed in the younger and older roots from the medium PSR plants. The results suggested that the plants from more anthropized regions were able to maintain the maximum quantum yield (Fv/Fm) which was a result from the metabolic fitting, increasing the non-photochemical quenching, reducing total chlorophyll/carotenoids and leading to the structural modifications.

Mancha fisiologica e produtividade do mamão Tainung 01: efeito da lâmina de irrigação e cobertura do solo / Skin freckles and yield components of papaya Tainung 01: effect of irrigation depths and soil coverings

Nesse experimento avaliou-se o efeito de diferentes lâminas de irrigação e coberturas do solo, sobre a incidência da mancha fisiológica do mamão e aspectos de produção do mamão cv. Tainung 01, no período de dezembro de 2003 a novembro de 2004. Utilizou-se delineamento em blocos casualizados em esquema fatorial. Quando as interações foram significativas desdobraram-se as mesmas e efetuaram-se as comparações das médias, via Teste Tukey. Os resultados encontrados demonstram uma alta correlação entre os fatores estudados e a época de colheita. Com relação à mancha fisiológica do mamoeiro confirmou-se o aspecto sazonal de incidência, sendo que, a cv. Tainung 01 apresentou a maior incidência do distúrbio, nos meses de setembro e outubro. Com relação às coberturas de solo, a cobertura morta se mostrou promissora para as variáveis de produção, ao contrário da cobertura verde com a leguminosa Arachis pintoi, pois a mesma competiu com o mamoeiro acarretando, assim, redução na produtividade.

In this experiment one evaluated the effect of different irrigation dosages and soil coverings in skin freckles aspects in yield components of the papaya cv. Tainung 01 in the period from December 2003 to November 2004. It was used a randomized complete block design, with a three replications, in a factorial scheme. When the interactions were significant the analysis was partitioned and the means were compared by the Tukey Test for each factor. The results found demonstrated high correlation between the variable studied and the harvest season. With relation to the skin freckles the seasonal aspect of incidence was confirmed, showing that for cv. Tainung 01 the major incidence of the disturbance was verified in September and October. With relation to the soil coverings, the mulching showed promising for the variables in yield, in contrast of the green covering with the leguminosae Arachis pintoi, because the last one competed with the papaya trees causing reduction in the yield components.

Lâminas de irrigação e coberturas do solo sobre a incidência da mancha fisiológica e produtividade do mamão "Golden" / Irrigation dosages and soil coverings in the incidence of skin freckles and yield components of papaya 'Golden'

Nesse experimento, avaliou-se o efeito de diferentes lâminas de irrigação e coberturas do solo sobre aspectos qualitativos e de produção do mamão cv. "Golden" no período de dezembro de 2003 a novembro de 2004. Utilizou-se delineamento em blocos casualizados, com três repetições, em esquema fatorial. Os resultados encontrados demonstram uma alta correlação entre a época de colheita com a incidência da mancha fisiológica e as variáveis de produção. Com relação à mancha fisiológica do mamão (MFM), confirmou-se o aspecto sazonal de incidência, sendo que a cv. "Golden" apresentou a maior incidência do distúrbio no mês de setembro. Com relação às coberturas de solo, a cobertura morta se mostrou promissora para os fatores em estudo, ao contrário da cobertura verde com a leguminosa Arachis pintoe, pois a mesma, provavelmente, competiu por água e nutrientes com o mamoeiro, acarretando, assim, redução na sua produtividade.

In this experiment the effect of different irrigation rates and soil coverings on qualitative aspects as well as yield components of the papaya cv. 'Golden' during the period December 2003 to November 2004 were evaluated. A randomized complete block design was used with three replications in a factorial scheme. The results demonstrate high correlation involving the factors harvest season, incidence of skin freckles and yield components. With relation to skin freckles a seasonal incidence was confirmed, showing that for cv. 'Golden', the major incidence of the disturbance was verified in September. The mulching treatment was promising for the factors studied, in contrast to the green covering using the leguminosae Arachis pintoe, due to competition with the papaya trees for water and nutrients, causing a reduction in the yield components.

Época de colheita e período de repouso dos frutos de mamão ( Carica papaya L. ) cv Golden na qualidade fisiológica das sementes / Haverst periods and storage of papaya fruit cv Golden in the seeds physiology quality

Este trabalho teve como objetivo verificar a influência da época de colheita e do período de repouso dos frutos na qualidade fisiológica de sementes de mamão. Os frutos, produzidos no inverno e no verão, da cv Golden, no estádio dois de maturação, foram colhidos e mantidos em câmara a 25ºC por 12 dias. Após a extração e lavagem das sementes, determinou-se a umidade e matéria seca das mesmas. A secagem foi realizada em estufa com circulação de ar a 30ºC, até atingirem 8 a 10 por cento de umidade. A germinação e o vigor (primeira contagem de germinação) foram avaliados aos 0, 2, 4, 6, 8, 10 e 12 dias de repouso dos frutos, imediatamente, após a extração das sementes e 30 dias após armazenamento a 15ºC. O delineamento experimental foi inteiramente casualizado, com quatro repetições. Os tratamentos resultaram da combinação de duas épocas de colheita dos frutos (janeiro e setembro), em oito período de repouso dos frutos (0, 2, 4, 6, 8, 10 e 12 dias) avaliados em dois períodos de armazenamento das sementes (0 e 30 dias). Houve variação na umidade e matéria seca das sementes durante o repouso e a época de colheita dos frutos. O maior vigor das sementes ocorreu em torno de 12 dias de repouso dos frutos, independente do armazenamento das sementes. O período de repouso dos frutos contribuiu para um aumento na germinação das sementes; para frutos colhidos em janeiro, a máxima germinação sementes foi evidenciada em período de repouso inferior (9 a 12 dias) aos dos frutos colhidos em setembro (13 dias). Em geral, o armazenamento das sementes proporcionou aumento da germinação das mesmas.