128 research outputs found
Metabolic and physiological responses of shiraz and cabernet sauvignon (Vitis vinifera L.) to near optimal temperatures of 25 and 35 °C
No full textShiraz and Cabernet Sauvignon (Cs) grapevines were grown at near optimal temperatures (25 or 35 °C). Gas exchange, fluorescence, metabolic profiling and correlation based network analysis were used to characterize leaf physiology. When grown at 25 °C, the growth rate and photosynthesis of both cultivars were similar. At 35 °C Shiraz showed increased respiration, non-photochemical quenching and reductions of photosynthesis and growth. In contrast, Cs maintained relatively stable photosynthetic activity and growth regardless of the condition. In both cultivars, growth at 35 °C resulted in accumulations of secondary sugars (raffinose, fucose and ribulose) and reduction of primary sugars concentration (glucose, fructose and sucrose), more noticeably in Shiraz than Cs. In spite of similar patterns of metabolic changes in response to growth at 35 °C, significant differences in important leaf antioxidants and antioxidant precursors (DHA/ascorbate, quinates, cathechins) characterized the cultivar response. Correlation analysis reinforced Shiraz sensitivity to the 35 °C, showing higher number of newly formed edges at 35 °C and higher modularity in Shiraz as compared to Cs. The results suggest that the optimal growth temperatures of grapevines are cultivar dependent, and allow a first insight into the variability of the metabolic responses of grapevines under varied temperatures
The variability in the xylem architecture of grapevine petiole and its contribution to hydraulic differences
No full textGrapevine cultivars possess large variability in their response to water availability, and are therefore considered as a good model to study plant hydraulic adjustments. The current research compared the petiole anatomy of two grapevine (Vitis vinifera L.) cultivars, Shiraz and Cabernet Sauvignon, in respect to hydraulic properties. Hydraulic differences between the cultivar petioles were tested over 3 years (2011–2013). Anatomical differences, hydraulic conductivity and embolism were tested under terminal drought conditions. Additionally, xylem differentiation under well watered (WW) and water deficit (WD) conditions was compared. Shiraz was shown to possess larger xylem vessels that resulted in a significantly higher theoretical specific hydraulic conductivity (Kts), leaf hydraulic conductivity (Kleaf) and maximal petiole hydraulic conductivity (Kpetiole). Under WD, smaller vessels were developed, more noticeably in Shiraz. Results confirmed a link between petiole hydraulic architecture and hydraulic behaviour, providing a simple mechanistic explanation for the higher transpiration rates commonly measured in Shiraz. Smaller xylem vessels in Cabernet Sauvignon could imply on its adaptation to WD, and explains its better performances under such conditions
Cultivar specific metabolic changes in grapevines berry skins in relation to deficit irrigation and hydraulic behavior
No full textDeficit irrigation techniques are widely used in commercial vineyards. Nevertheless, varieties respond differently to water availability, prompting the need to elucidate the physiological and molecular mechanisms involved in the interactions between genotypes and their environment.
In the present study, the variability in berry metabolism under deficit irrigation was investigated in the field on Shiraz and Cabernet Sauvignon (CS), known for their hydraulic variability. Berry skin metabolite profiling of the two cultivars was performed by parallel GC–MS and LC-MS at four development stages.
Under similar irrigation, the cultivars differed in stomata regulation. In response to water deficit, CS exhibited lessened loss in berry weight and milder metabolic alteration of berry-skin primary metabolites, as compared with Shiraz. The metabolic stress responses were shown to depend on berry phenology. Characteristic metabolic changes included a decrease in amino acids and TCA cycle intermediates from veraison onward. In contrast, water deficit induced the accumulation of stress-related metabolites such as: proline, beta-alanine, raffinose, nicotinate and ascorbate, to a greater extent in Shiraz. Polyphenol metabolism in response to water stress also underwent significant changes, unique to each cultivar.
Results suggest a link between the vine hydraulics and water-deficit driven changes in the berry skin metabolism, with significant consequences on the metabolic composition of the fruit
Evaporative demand determines the relative transpirational sensitivity of deficit-irrigated grapevines
No full textA common irrigation strategy is to replenish the soil water reservoir according to evapotranspiration (ET). However, the ET from plants under deficit irrigation is not well explored and is normally assumed to be a constant fraction of their respective well-watered condition. In the current experiment, we hypothesized that the ratio between the ET of well-watered (WW) and water deficit (WD) grapevines is not constant but depends on the reference ET (ETO). The hypothesis was tested using lysimeters over two consecutive seasons to measure the ET of WD grapevines (Vitis vinifera L.) that were irrigated at 35 % of a second set of lysimeters with WW vines. The WD treatment started at veraison and resulted in a quick depletion of the soil water reservoir; thereafter a relatively stable soil water content (θ) and crop coefficient (KC) were measured. The ET of the WD vines was 20–75 % lower than that of the WW vines, depending on the reference evapotranspiration (ETO). Under high ETO, the difference between the treatments was much larger than under low ETO. The dynamic ratio between the ET of the treatments demonstrates the difficulty in predicting the ET of WD plants and suggests that irrigation according to a constant fraction from a WW plant might result in either excessive or insufficient irrigation amounts. The high correlation between instantaneous stomatal conductance (gs) measurements and KC emphasizes the advantage of utilizing gs to improve current irrigation models
Grape Metabolic Response to Postveraison Water Deficit Is Affected by Interseason Weather Variability
No full textPostveraison water deficit is a common strategy implemented to improve fruit composition in many wine-growing regions. However, contrasting results are often reported on fruit size and composition, a challenge for generalizing the positive impact of this technique. Our research investigated the effect of water deficit (WD) imposed at veraison on Merlot grapevines, during two experimental seasons (2014–2015). In both years WD resulted in reduced carbon assimilation rates and leaf shedding. However, the treatment effect on the analyzed berry parameters varied between seasons. Modification of skin metabolites was more evident in 2015 than in 2014, despite the similar soil water content and water stress physiological parameters (gas exchange, water potential) recorded in the two experimental years. Higher solar radiation and air temperature in 2015 than in 2014 hint for the involvement of atmospheric parameters in fulfilling the potential effect of WD. Our results suggest that the interaction between water availability and weather conditions plays a crucial role in modulating the grape berry composition
The Response of Ethiopian Grain Markets to Liberalization
No full textThe objective of this paper is to determine how liberalization of Ethiopia’s grain marketing system in March 1990 has affected the level and volatility of wholesale prices and price spreads between major regional cereal markets. The paper also identifies issues and problems needing attention to guide future policy decisions with the aim of reducing costs in the food system and thereby promoting the welfare of grain producers and consumers in Ethiopia.food security, food policy, Ethiopia, grain markets, International Relations/Trade, Marketing, Q18,
L.) berries subjected to post-harvest withering
No full textThe grape berry withering process is often seen as a means to concentrate the constituents of the berry via water
removal, however, recent molecular studies have indicated that the reprogramming of biosynthetic pathways that
impart the unique aroma and flavour of the final wine also occur. Metabolic analysis was performed using GC-MS and
LC-MS on Corvina berry dehydrated for up to 108 days. The temporal pattern of metabolic changes and time-series
relationship between various classes of metabolites were investigated on berries sampled at 23-time points. Principal
component analysis of both GC-MS and LC-MS datasets revealed three distinct phases of post-harvest withering;
early (day 0–28), mid (day 35–66) and late (day 69–108) stages. Stress-associated amino acids such as proline,
serine, ethanolamine, and leucine accumulated significantly during the mid and late stages of the drying process
while phosphorylated glucose and fructose, sucrose, kestose and resveratrol increased massively across time. Unlike
most of the identified metabolites, low molecular weight flavanols exhibited a consistent pattern of decline during the
withering period. Our network analysis revealed that increased metabolic network connectivity occurred during the
middle stage of withering, thus reflecting more coordinated metabolite changes while reduced network connectivity
at early and late stages indicates minimal metabolite perturbation during these stages. The current prolonged berry
withering experiment revealed the timing of metabolite interconversions in the central metabolism and provided
critical clues that link the concentration effect, protein degradation, and the onset of stress-like conditions in drying
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Swift metabolite changes and leaf shedding are milestones in the acclimation process of grapevine under prolonged water stress
No full textFigure S1. Number of significantly altered metabolites under water stress identified using GC-MS (primary metabolites) and LC-MS (secondary metabolites) during the course of the experiment. (PPTX 38 kb
Metabolite and transcript profiling of berry skin during fruit development elucidates differential regulation between Cabernet Sauvignon and Shiraz cultivars at branching points in the polyphenol pathway
No full textGrapevine berries undergo complex biochemical changes during fruit maturation, many of which are dependent upon the variety and its environment. In order to elucidate the varietal dependent developmental regulation of primary and specialized metabolism, berry skins of Cabernet Sauvignon and Shiraz were subjected to GC-MS and LC-MS based metabolite profiling from pre-veraison to harvest. The generated dataset was augmented with RNAseq-transcript profiling. The analysis of the metabolite data revealed similar developmental patterns of change in primary metabolites between the two cultivars. In contrast, quite distinct pattern of change was apparent in specialized metabolites towards maturation, suggesting a varietal-dependent metabolic regulation, Transcript profiling revealed coordinated increased transcript abundance for genes encoding enzymes of committing steps in the phenylpropanoid pathway. The anthocyanin metabolite profile showed F3'5'H-mediated delphinidin-type anthocyanin enrichment in both varieties toward maturation, consistent with the transcript data, indicating that the F3’5’H-governed branching step dominates the anthocyanin profile at late berry development. The comparative metabolite profiles and RNAseq analysis of two physiologically different dark-skinned grape varieties revealed the underlying commonalities and cultivar-specificities of berry metabolism and its regulation. Enhanced stress related metabolism, e.g. trehalose, stilbene and ABA in Shiraz berry-skin corroborate its relatively higher susceptibility to environmental cue
Characteristics of Squatter Houses in Burayu Town Adjoining Addis Ababa, Capital City of Ethiopia
No full textExpansion of squatter settlements and burgeoning of slum are among the challenges being posed by rapid rate of urbanization especially in developing countries like Ethiopia. Burayu town is one of the fastest growing towns in Oromia National Regional State of Ethiopia. The town is located about 15 kilometers from the center of Addis Ababa metropolis, the capital of Ethiopia. The population of Burayu town was 4,138 in 1984; 10,027 in 1994; 63,873 in 2007 (Census) and has grown to 150,000 in 2014 (estimated), showing that the population of the town has increased by more than 36 folds within the past 20 years. The town is characterized by many land related problems like proliferation of squatter settlements, expansion of slums and other illegal land developments. This article tries to identify characteristics of squatter houses in Burayu town in relation to location of the houses in environmentally sensitive areas, construction materials of the houses and accessibility of the houses to public utility services and facilities. By random purposive sampling method, 246 squatter households were selected from different social segments of the squatter households in the town and quantitative data and qualitative information were collected from primary as well as secondary sources and analyzed. The finding indicates that the characteristics of squatter houses in Burayu town are not different from characteristics of other houses which are developed in legal manner in the town. But, 58.1 per cent of the squatter houses are located in environmentally sensitive areas which are prohibited by the Structure Plan Preparation Manual prepared by Ethiopian Ministry of Urban Development and Construction, 2012. The common characteristic is the lack of ownership of the residential land on which the squatter houses have been built. Key Words: Squatter and squatter house
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