Conservação pós-colheita em condição ambiente de híbridos de tomate tipo salada.

O objetivo deste trabalho foi avaliar as modificações fisico-quimicas e a qualidade pós-colheita de dois hibridos de tomate tipo salada, colhidos no estádio de maturação verde e mantidos numa temperatura simulando condição ambiente de transporte e comercialização dos frutos.Suplemento. Trabalho apresentado no 52. Congresso Brasileiro de Olericultura, Salvador, 2012

Maturação de maçãs "Brookfield" em função da forma de aplicação de aminoetoxivinilglicina.

RESUMO Este trabalho teve como objetivo avaliar o efeito da aplicação pré-colheita do aminoetoxivinilglicina (AVG), em dose única e parcelada, sobre a maturação de maçãs ?Brookfield?, cultivada sob tela antigranizo. O experimento foi conduzido em pomar comercial, no município de Vacaria/RS (50°42' W; 28°33' S; 955 m de altitude), nas safras 2014/15 e 2015/16. Foram avaliados os seguintes tratamentos: Controle; AVG em dose única (125 mg L-1); AVG parcelado (62,5 mg L-1 + 62,5 mg L1 ), combinados com três datas de colheita [colheitas 1 (colheita comercial), 2 e 3 (sete e 14 dias após a primeira colheita, respectivamente)]. O AVG em dose única foi aplicado aos 30 dias antes da colheita comercial (DAC) e o AVG parcelado foi aplicado aos 30 e 20 DAC. Foram avaliados os seguintes atributos: taxas respiratória (ηmol de CO2 kg-1 s-1) e de produção de etileno (pmol C2H4 kg-1 s-1), índice iodo-amido (1-5), firmeza de polpa (N), sólidos solúveis (SS; °Brix), acidez titulável (AT; % ácido málico), cor da epiderme (hº; regiões mais e menos vermelha) e índice de cor vermelha (ICV). O delineamento utilizado foi em blocos casualizados, com quatro repetições, compostas por 20 frutos cada. O uso do AVG, independentemente da forma de aplicação, manteve menor o índice iodo?amido, o teor de SS e reduziu o grau de amarelecimento da epiderme dos frutos, além de manter maior firmeza de polpa e AT de maçãs ?Brookfield?. A aplicação de AVG (125 mg L-1) reduz a cor vermelha dos frutos, porém a aplicação parcelada não reduziu esse atributo na safra 2014/2015, enquanto que na safra 2015/2016 ocorreu redução, porém em menor intensidade do que a aplicação de AVG em dose única (125 mg L-1). Conclui-se que a aplicação pré-colheita de AVG dose única (125 mg L-1) ou parcelada (62,5 mg L-1 + 62,5 mg L-1) retarda a maturação e a aplicação parcelada apresenta menor comprometimento da cor vermelha da epiderme de maçãs ?Brookfield? cultivada sob tela antigranizo. Palavras-chave: Malus domestica Borkh., qualidade físico-química, AVG

Patterns of wood carbon dioxide efflux across a 2,000-m elevation transect in an Andean moist forest

During a 1-year measurement period, we recorded the CO2 efflux from stems (RS) and coarse woody roots (RR) of 13–20 common tree species at three study sites at 1,050, 1,890 and 3,050 m a.s.l. in an Andean moist forest. The objective of this work was to study elevation changes of woody tissue CO2 efflux and the relationship to climate variation, site characteristics and growth. Furthermore, we aim to provide insights into important respiration–productivity relationships of a little studied tropical vegetation type. We expected RS and RR to vary with dry and humid season conditions. We further expected RS to vary more than RR due to a more stable soil than air temperature regime. Seasonal variation in woody tissue CO2 efflux was indeed mainly attributable to stems. At the same time, temperature played only a small role in triggering variations in RS. At stand level, the ratio of C release (g C m−2 ground area year−1) between stems and roots varied from 4:1 at 1,050 m to 1:1 at 3,050 m, indicating the increasing prevalence of root activity at high elevations. The fraction of growth respiration from total respiration varied between 10 (3,050 m) and 14% (1,050 m) for stems and between 5 (1,050 m) and 30% (3,050 m) for roots. Our results show that respiratory activity and hence productivity is not driven by low temperatures towards higher elevations in this tropical montane forest. We suggest that future studies should examine the limitation of carbohydrate supply from leaves as a driver for the changes in respiratory activity with elevation

Fine root dynamics across pantropical rainforest ecosystems

Fine roots constitute a significant component of the net primary productivity (NPP) of forest ecosystems but are much less studied than above-ground NPP. Comparisons across sites and regions are also hampered by inconsistent methodologies, especially in tropical areas. Here, we present a novel dataset of fine root biomass, productivity, residence time, and allocation in tropical old-growth rainforest sites worldwide, measured using consistent methods, and examine how these variables are related to consistently determined soil and climatic characteristics. Our pantropical dataset spans intensive monitoring plots in lowland (wet, semi-deciduous, deciduous) and montane tropical forests in South America, Africa, and Southeast Asia (n=47). Large spatial variation in fine root dynamics was observed across montane and lowland forest types. In lowland forests, we found a strong positive linear relationship between fine root productivity and sand content, this relationship was even stronger when we considered the fractional allocation of total NPP to fine roots, demonstrating that understanding allocation adds explanatory power to understanding fine root productivity and total NPP. Fine root residence time was a function of multiple factors: soil sand content, soil pH, and maximum water deficit, with longest residence times in acidic, sandy, and water-stressed soils. In tropical montane forests, on the other hand, a different set of relationships prevailed, highlighting the very different nature of montane and lowland forest biomes. Root productivity was a strong positive linear function of mean annual temperature, root residence time was a strong positive function of soil nitrogen content in montane forests, and lastly decreasing soil P content increased allocation of productivity to fine roots. In contrast to the lowlands, environmental conditions were a better predictor for fine root productivity than for fractional allocation of total NPP to fine roots, suggesting that root productivity is a particularly strong driver of NPP allocation in tropical mountain regions.Output Status: Forthcoming/Available Online Additional co-authors: Christopher E. Doughty, Imma Oliveras, Darcy F. Galiano Cabrera, Liliana Durand Baca, Filio Farfán Amézquita, Javier E. Silva Espejo, Antonio C.L. da Costa, Erick Oblitas Mendoza, Carlos Alberto Quesada, Fidele Evouna Ondo, Josué Edzang Ndong, Vianet Mihindou, Natacha N’ssi Bengone, Forzia Ibrahim, Shalom D. Addo-Danso, Akwasi Duah-Gyamfi, Gloria Djaney Djagbletey, Kennedy Owusu-Afriyie, Lucy Amissah, Armel T. Mbou, Toby R. Marthews, Daniel B. Metcalfe, Luiz E.O. Aragão, Ben H. Marimon-Junior, Beatriz S. Marimon, Noreen Majalap, Stephen Adu-Bredu, Miles Silman, Robert M. Ewers, Patrick Meir, Yadvinder Malh