Home About us Contact
|
Home About us Contact | ||
|
|
||
Dry Matter Content (dry + matter_content)
Selected AbstractsDoes timing of daily feeding affect growth rates of juvenile three-spined sticklebacks, Gasterosteus aculeatus L?ECOLOGY OF FRESHWATER FISH, Issue 3 2001M. Ali Abstract , To assess the consequences of unpredictability in the availability of food, this study measured the effect of timing of the daily feeding on food consumption and growth rates of juvenile Gasterosteus aculeatus. The experiment lasted 21 days at 14 °C and a photoperiod of 10 hours of light and 14 hours of dark. Fish were housed individually and allocated at random to three treatments. The mean initial weight of fish was 0.402 g. Group 1 were fed live enchytraeid worms for 2 h after lights came on ("morning"), group 2 was offered food for 2 h randomly at any time of the day ("random") during the light period and group 3 received food for 2 h before the lights went off ("evening"). There was no significant effect of timing of feeding on mean daily food consumption, which was 0.052 g day,1. Daily consumption on the random schedule was more irregular than on the two fixed schedules. Timing of feeding had no significant effect on mean specific growth rate (G) (2.42% day,1), gross growth efficiency (23.3%), white muscle RNA:DNA ratio (5.6), carcase lipid content (31.7% dry wt) and carcase dry matter content (27.4% wet wt). Thus, a lack of predictability in the availability of food during the light period of the day did not impose a detectable cost on the growth performance of the stickleback., [source] Palatability of macrophytes to the invasive freshwater snail Pomacea canaliculata: differential effects of multiple plant traitsFRESHWATER BIOLOGY, Issue 10 2010PAK KI WONG Summary 1.,By selective grazing, invasive grazers can alter macrophyte-herbivore relationships in shallow freshwater bodies. Evaluating the palatability of macrophytes and understanding the determinants of plant palatability can help predict grazing impact. In no-choice feeding assays, we tested the palatability of 21 species of freshwater macrophytes to the invasive freshwater apple snail Pomacea canaliculata. 2.,Daily feeding rate varied greatly with plant species, ranging from 1.1 to 22% of snail body mass. We assessed six plant properties and examined their correlation with feeding rate. Total nitrogen content was positively related, and C:N ratio and dry matter content (DMC) negatively related, to snail feeding rate. There was no significant correlation between snail feeding rate and plant phenolic content, but the feeding rate on Myriophyllum aquaticum (the plant with the highest phenolic content) was very low. 3.,We repeated the feeding assays for 15 species that were not palatable as fresh leaves with reconstituted plant tissues formed by mixing ground up dried leaves with agar. The feeding rate still differed greatly among macrophyte species. Phragmites australis and Vallisneria natans (two species with the highest DMC) were eaten much more as reconstituted plant than as fresh leaves, indicating that structure (i.e. DMC) may be important in their defence against snail herbivory. For two plants (M. aquaticum and Alternanthera philoxeroides) that had moderate amounts of nitrogen/phosphorus but were consumed very little as fresh and reconstituted tissues, we incorporated their extracts into a palatable agar-based food. The extracts from both species greatly reduced snail feeding rate, indicating the presence of chemical defences in these two species. 4.,These results indicated that feeding was affected by several plant traits. The snail favoured plants with a high nitrogen content and avoided plants with a high DMC. Only a few plants possessed chemical feeding deterrents that were effective against this snail. Given the invasive spread of P. canaliculata in Asia, ecologists and managers should consider plant palatability when selecting plants for use in wetland restoration and when predicting the impact of further invasion by this species. [source] A multi-trait test of the leaf-height-seed plant strategy scheme with 133 species from a pine forest floraFUNCTIONAL ECOLOGY, Issue 3 2010Daniel C. Laughlin Summary 1.,Westoby's [Plant and Soil (1998), 199, 213] Leaf-Height-Seed (LHS) plant strategy scheme quantifies the strategy of a plant based on its location in a three-dimensional space defined by three functional traits: specific leaf area (SLA), height, and seed mass. This scheme is based on aboveground traits and may neglect strategies of belowground resource capture if root functioning is not mirrored in any of the axes. How then do fine roots fit into the LHS scheme? 2.,We measured 10 functional traits on 133 plant species in a ponderosa pine forest in northern Arizona, USA. This data set was used to evaluate how well the LHS scheme accounts for the variation in above and belowground traits. 3.,The three most important plant strategies were composed of multiple correlated traits, but SLA, seed mass, and height loaded on separate principle components. The first axis reflected the widely observed ,leaf economics spectrum'. Species at the high end of this spectrum had high SLA, high leaf and fine root nitrogen (N) concentration, and low leaf dry matter content. The second axis reflected variation in seed mass and fine root morphology. Plants at the positive end of this spectrum were plants with large seeds and low specific root length (SRL). The third axis reflected variation in height and phenology. Plants at the positive end of this spectrum were tall species that flower late in the growing season. 4.,Leaf N concentration was positively correlated with fine root N concentration. SRL was weakly positively correlated with SLA. SRL was not correlated with fine root N concentration. Leaf litter decomposition rate was positively correlated with the leaf economics spectrum and was negatively correlated with the height and phenology spectrum. 5.,Leaf traits, seed mass, and height appear to be integrating properties of species that reflect much of the variation in plant function, including root function. Fine root N concentration was positively mirrored by the leaf economics spectrum, and SRL was inversely mirrored by seed mass. The leaf and height axes play a role in controlling leaf litter decomposability, indicating that these strategy axes have important consequences for ecosystem functioning. [source] Relationship between post-fire regeneration and leaf economics spectrum in Mediterranean woody speciesFUNCTIONAL ECOLOGY, Issue 1 2009S. Saura-Mas Summary 1Recent work has identified global-scale relationships between key leaf traits (leaf economics spectrum). However, it is important to determine whether this approach can be applied at local scale with smaller subsets of species facing similar environments. Since fire is a key process in Mediterranean shrubland dynamics we analyze whether fire-related life-history traits influence the pattern of correlation between the leaf economic spectrum and leaf moisture traits. 2Using structural equation modelling and exploratory path analysis, we developed alternative models to test how interspecific leaf traits are related to the seasonal variation of water content (leaves and shoots) and to the type of post-fire regeneration of Mediterranean woody species. 3This study demonstrates that for these species seasonal variation in water content and fuel moisture would be better predicted by the presence or absence of a trait describing post-fire seedling establishment than by the leaf economic spectrum traits. However, leaf dry matter content (LDMC) is influenced by both the leaf economic spectrum and the post-fire regenerative type. 4Seeder species (those that recruit via seeds immediately after fire) present lower LDMC and higher relative seasonal variation of relative water content (RWCrsv) than non-seeders. We hypothesize that since seeder species mostly evolved under the Mediterranean climate, they developed a particular strategy of drought tolerance (without causing an effect to the relation between the volume occupied by cytoplasm relative to the volume occupied by cell walls), which is the cause of the observed relation between LDMC and RWCrsv. 5This study suggests that the leaves of Mediterranean woody species would follow the general leaf economics spectrum (Wright et al. 2004) but that specific selective forces, such as disturbance regime, acting at regional scale also play a relevant role to explain leaf traits related to water content. [source] Leaf dry matter content as an integrative expression of plant palatability: the case of freshwater macrophytesFUNCTIONAL ECOLOGY, Issue 1 2003A. Elger Summary 1We examined the possibility of using the dry matter content (DMC) of macrophytes (the ratio of dry mass to wet mass) as an integrative variable to predict their palatability to generalist invertebrate grazers. 2We assessed the palatability of 20 macrophyte species, using the snail Lymnaea stagnalis (L.) in non-choice feeding experiments. Three of the species were studied at two different dates in the year, at two or four sites. 3The average dry mass consumed by L. stagnalis ranged widely between species, and was negatively correlated to plant DMC. At the intraspecific level, the dry mass consumed varied over time but was not related to site location. Again, the dry mass consumed was negatively correlated to plant DMC. 4The DMC of the macrophytes studied explained about 30% of interspecific variability, and >80% of seasonal variability, in snail consumption rate. Therefore this trait could be used as a shortcut to predict variations in macrophyte palatability, especially at the intraspecific level. At the interspecific level, the relationship between DMC and palatability might be weakened by the presence in some plants of low molecular weight chemical deterrents. [source] Silage quality when Moringa oleifera is ensiled in mixtures with Elephant grass, sugar cane and molassesGRASS & FORAGE SCIENCE, Issue 4 2009B. Mendieta-Araica Abstract Fourteen different silages were prepared using mixtures of Moringa (Moringa oleifera), Elephant grass (Pennisetum purpureum cv Taiwan) or sugar cane (Saccharum officinarum). Molasses from sugar cane was used in the amounts of either 10 or 50 g kg,1 fresh matter (FM) in treatments without sugar cane. A completely randomized design with three replicates of each treatment was used. The silages were prepared in 1800 mL micro silos and opened after 120 d. The presence of Moringa and Elephant grass in the silage changed the pH by ,0·8 and +0·7, respectively (P < 0·001), indicating a favourable effect of Moringa on silage pH. Overall differences were found among treatments for dry matter content, crude protein and acetic acid concentrations, weight loss, CO2 production and silage pH after spoilage (P < 0·001). Weight loss was proportionately 0·034 and 0·014 in silages with and without sugar cane respectively (P < 0·001). Overall, differences (P < 0·05) were also found for neutral-detergent fibre and lactic acid concentrations, lactic acid bacteria counts, clostridial counts and time to spoilage of the silages. Treatments containing Moringa had higher lactic acid concentrations (+16 g kg,1 DM; P < 0·01) compared to treatments without but the presence of Moringa decreased time to spoilage by 67 h (P < 0·05). No differences were found in propionic acid concentration or fungal growth of the silages. It is concluded that Moringa can be used as a component of high quality silages which also contain high concentrations of crude protein. [source] Monitoring the fermentation of the traditional Bulgarian beverage bozaINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2001Velitchka Gotcheva Summary For many centuries fermented foods have been produced and consumed world-wide as they are of such great importance for human nutrition. Fermentation helps to preserve the food, provides a wide variety of textures and flavours and significantly improves the nutritional properties of the raw materials used. In this work we tested the hypothesis that the fermentation process of the Bulgarian cereal-based traditional beverage boza was similar to other cereal-based fermentations. Boza was prepared both from whole-wheat grains and flour, and the effect of the raw material on product quality was studied. The main microorganisms responsible for boza fermentation, yeasts and lactobacilli, were identified and some physical and biochemical changes were monitored during the first 48 h of fermentation. A significant increase in glucose content was observed, while pH, viscosity, free amino nitrogen content and dry matter decreased during the fermentation. The use of wheat flour resulted in a product with higher viscosity and dry matter content when compared to that produced from whole-wheat grains. The effect of temperature on fermentation rate was also tested. [source] ,-Oxidation capacity in liver increases during parr-smolt transformation of Atlantic salmon fed vegetable oil and fish oilJOURNAL OF FISH BIOLOGY, Issue 2 2006I. Stubhaug Atlantic salmon Salmo salar were fed diets containing 100% fish oil (FO; capelin oil) or 100% vegetable oil (VO) from start of feeding until the fish reached the size of 2·5 kg. Samples were taken during the period of the parr-smolt transformation (October 2002 to February 2003). The VO diet consisted of a blend of 55% rapeseed oil, 30% palm oil and 15% linseed oil to maintain the sum of saturated, monounsaturated and polyunsaturated fatty acids between the two diets, although with differences in the individual chain length of fatty acids. Na+/K+ -ATPase activity in the gills, total ,-oxidation capacity in muscles and liver and total lipid, glycogen and dry matter content in the muscles were measured during the parr-smolt transformation and after seawater transfer. Na+/K+ -ATPase activity in gills increased prior to seawater transfer, showing an adaptation for seawater survival. Major changes in the lipid and glycogen content in the fillet and in ,-oxidation capacity were found in the tissues measured. ,-oxidation capacity increased significantly in liver and decreased in red muscle, prior to seawater transfer, giving liver an important role in energy production during this period. Results also indicated that feeding Atlantic salmon a diet where 100% of FO was replaced with VO did not have any negative effects on lipid metabolism during parr-smolt transformation. [source] Preliminary study on the use of near-infrared reflectance spectroscopy to assess nitrogen content of undried wheat plantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2007Alejandro Morón Abstract Near-infrared reflectance (NIR) spectroscopy combined with chemometrics was used to assess nitrogen (N) and dry matter content (DM) and chlorophyll in whole-wheat plant (Triticum aestivum L). Whole-wheat plant samples (n = 245) were analysed by reference method and by visible and NIR spectroscopy, in fresh (n = 182) and dry (n = 63) presentations, respectively. Calibration equations were developed using partial least squares (PLS) and validated using full cross-validation (leave-one-out method). Coefficient of determination in calibration (R2CAL) and the standard error of cross-validation (SECV) for N content in fresh sample presentation, after second derivative, were 0.89 (SECV: 0.64%), 0.86 (SECV: 0.66%) and 0.82 (SECV: 0.74%) using the visible + NIR, NIR and visible wavelength regions, respectively. Dry sample presentation gave better R2CAL and SECV for N compared with fresh presentation (R2CAL > 0.90, SECV < 0.20%) using visible + NIR. The results demonstrated that NIR is a suitable method to assess N concentration in wheat plant using fresh samples (unground and undried). Copyright © 2006 Society of Chemical Industry [source] Effects of cultivar, root weight, storage and boiling on carbohydrate content in carrots (Daucus carota L)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2005E Margareta G-L Nyman Abstract The effects of cultivar (n = 4), root weight (n = 4), storage (5 months) and boiling (7 min) and their interactions on the content of dry matter and carbohydrates were studied and ranked in carrots. Boiling had the greatest effect and had an influence on all variables except the ratio between sucrose and the monosaccharides glucose and fructose. The choice of cultivar was also of great importance as regards glucose, fructose and sucrose content, while dietary fibre and dry matter were much less affected, or even unaffected, by this factor. Root weight and storage were consistently of less significance than boiling and cultivar. Thus dietary fibre solubility, fructose content and the ratio between sucrose and the monosaccharides glucose and fructose were independent of the root weight, while storage had no impact on the dry matter content. After storage the cultivar Lonto had lost more dry matter than the other cultivars (10% versus mean 1% for the others, P = 0.009) and the sugar ratio between sucrose and the monosaccharides glucose and fructose had increased in the cultivar Amarant, while it decreased in the other cultivars (P < 0.001). Furthermore, Amarant had a lower loss of sugars (35%) following boiling than the other cultivars (mean 39%, P = 0.002). Storage and boiling interacted concerning soluble and insoluble dietary fibre, fibre solubility and glucose content. It is concluded that the various factors (especially boiling and cultivar) gave rise to such differences in carbohydrate content and composition that they might be of nutritional importance. The results may thus provide a basis for selecting raw material when studying possible health effects of carrots. Copyright © 2004 Society of Chemical Industry [source] Correlated changes in skeletal muscle connective tissue and flesh texture during starvation and re-feeding in brown trout (Salmo trutta) reared in seawaterJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2004Jérôme Bugeon Abstract Quantitative and qualitative changes to muscle and collagen were analysed following starvation and re-feeding of brown trout (Salmo trutta) reared in seawater. Fish were submitted to starvation for 2 months followed by re-feeding for 1 month and compared with a control group continuously fed. Classical effects of starvation on growth and morphometrics traits were observed with only a partial recovery of these parameters after 1 month of re-feeding. Muscle composition of starved fish was significantly affected (lower dry matter content and higher post-mortem pH) compared with control fish and was partially recovered in re-fed fish compared with continuously fed fish. Muscle structure and composition were affected with thinner muscle fibre and higher connective tissue content for the starved fish but similar thickness of myosepta compared with the control group. No difference was observed after 1 month of re-feeding. Characteristics of the connective tissue were significantly affected by starvation (more high weight molecular collagen form, higher thermal stability of skin collagen). These differences remained significant after the re-feeding period. Starved fish showed also higher mechanical resistance of the raw flesh compared with the control group, but no difference in rheological measurements was observed after 1 month of re-feeding. The changes in texture and their relationships with muscle composition, muscle structure and collagen characteristics are discussed. Copyright © 2004 Society of Chemical Industry [source] A community-level test of the leaf-height-seed ecology strategy scheme in relation to grazing conditionsJOURNAL OF VEGETATION SCIENCE, Issue 3 2009Carly Golodets Abstract Question: Is the assumption of trait independence implied in Westoby's (1998) leaf-height-seed (LHS) ecology strategy scheme upheld in a Mediterranean grazing system dominated by annuals? Is the LHS approach applicable at the community level? Location: Northern Israel. Methods: LHS traits (specific leaf area [SLA], plant height and seed mass), and additional leaf traits (leaf dry matter content [LDMC], leaf area, and leaf content of nitrogen [LNC], carbon [LCC], and phosphorus [LPC]), were analyzed at the species and community levels. Treatments included manipulations of grazing intensity (moderate and heavy) and protection from grazing. We focused on species comprising 80% of biomass over all treatments, assuming that these species drive trait relationships and ecosystem processes. Results: At the species level, SLA and seed mass were negatively correlated, and plant height was positively correlated to LCC. SLA, seed mass, and LPC increased with protection from grazing. At the community level, redundancy analysis revealed one principal gradient of variation: SLA, correlated to grazing, versus seed mass and plant height, associated with protection from grazing. We divided community functional parameters into two groups according to grazing response: (1) plant height, seed mass, LDMC, and LCC, associated with protection from grazing, and (2) SLA, associated with grazing. Conclusions: The assumption of independence between LHS traits was not upheld at the species level in this Mediterranean grazing system. At the community level, the LHS approach captured most of the variation associated with protection from grazing, reflecting changes in dominance within the plant community. [source] Leaf dry matter content and lateral spread predict response to land use change for six subalpine grassland speciesJOURNAL OF VEGETATION SCIENCE, Issue 2 2007Nicolas Gross Abstract Question: Land-use change has a major impact on terrestrial plant communities by affecting fertility and disturbance. We test how particular combinations of plant functional traits can predict species responses to these factors and their abundance in the field by examining whether trade-offs at the trait level (fundamental trade-offs) are linked to trade-offs at the response level (secondary trade-offs). Location: Central French Alps. Methods: We conducted a pot experiment in which we characterized plant trait syndromes by measuring whole plant and leaf traits for six dominant species, originating from contrasting subalpine grassland types. We characterized their response to nutrient availability, shading and clipping. We quantified factors linked with different land usage in the field to test the relevance of our experimental treatments. Results: We showed that land management affected nutrient concentration in soil, light availability and disturbance intensity. We identified particular suites of traits linked to plant stature and leaf structure which were associated with species responses to these environmental factors. Leaf dry matter content separates fast and slow growing species. Height and lateral spread separated tolerant and intolerant species to shade and clipping. Discussion and Conclusion: Two fundamental trade-offs based on stature traits and leaf traits were linked to two secondary trade-offs based on response to fertilization shade and mowing. Based on these trade-offs, we discuss four different species strategies which could explain and predict species distributions and traits syndrome at community scale under different land-uses in subalpine grasslands. [source] Variation in leaf traits through seasons and N-availability levels and its consequences for ranking grassland speciesJOURNAL OF VEGETATION SCIENCE, Issue 4 2005Raouda Al Haj Khaled Abstract Question: Are leaf dry matter content, specific leaf area and leaf life span relevant plant traits to discriminate the fertility gradient in species-rich natural grasslands? In other words, is species ranking conserved when nitrogen availability or growing periods change? Location: Toulouse Research Centre, France; 150 m a.s.l. Methods: Fifteen grasses and nine dicotyledons were sown in pure stands in a random block design with three replicates. Each species was cultivated at two levels of nitrogen supply, limiting and non-limiting for growth, with three replications per nitrogen level. Leaf traits were measured across both levels of nitrogen supply and growing periods over the year. Results: Leaf dry matter content values separated the species into three life-form classes (grasses, rosette forbs and upright forbs, P < 0.001). This was not the case for specific leaf area and leaf life span. The three leaf traits were variable across growing periods and nitrogen levels, but the ranking of species was conserved over N-levels and growth periods. Furthermore leaf dry matter content was always less variable than the other leaf traits. Conclusion: We conclude that leaf dry matter content measured only on grasses could be used as an indicator to describe the N-richness of the habitat where native herbaceous vegetation develops. [source] Plant traits and functional types in response to reduced disturbance in a semi-natural grasslandJOURNAL OF VEGETATION SCIENCE, Issue 2 2005F. Louault Abstract. Question: How do functional types respond to contrasting levels of herbage use in temperate and fertile grasslands? Location: Central France (3°1'E, 45°43'N), 870 m a.s.l. Methods: Community structure and the traits of dominant plant species were evaluated after 12 years of contrasted grazing and mowing regimes in a grazing trial, comparing three levels of herbage use (high, medium and low). Results and Conclusions: Of 22 measured traits (including leaf traits, shoot morphology and composition, phenology), seven were significantly affected by the herbage use treatment. A decline in herbage use reduced individual leaf mass, specific leaf area and shoot digestibility, but increased leaf C and dry matter contents. Plants were taller, produced larger seeds and flowered later under low than high herbage use. Nine plant functional response types were identified by multivariate optimization analysis; they were based on four optimal traits: leaf dry matter content, individual leaf area, mature plant height and time of flowering. In the high-use plots, two short and early flowering types were co-dominant, one competitive, grazing-tolerant and moderately grazing-avoiding, and one grazing-avoiding but not -tolerant. Low-use plots were dominated by one type, neither hardly grazing-avoiding nor grazing-tolerant, but strongly competitive for light. [source] Suboptimal temperature favors reserve formation in biennial carrot (Daucus carota) plantsPHYSIOLOGIA PLANTARUM, Issue 1 2009María V. González In response to suboptimal temperatures, temperate annual plants often increase root:shoot ratios, build-up carbohydrates and display typical morphological and anatomical changes. We know less about the responses of biennials such as carrot. As a model plant, carrot has the additional feature of two functionally and morphologically distinct root parts: the taproot, which stores carbohydrate and other compounds, and the fibrous root system involved in acquisition of water and nutrients. Here, we analyze the effects of temperature (12 vs 25°C) on growth, carbohydrate accumulation and whole-plant morphology in two carrot cultivars. Our working hypothesis is that suboptimal temperature favors active formation of reserve structures, rather than passive accumulation of storage carbohydrates. In comparison with plants grown at 25°C, plants grown at 12°C had: (1) higher fibrous root:shoot ratio (13%) , (2) thicker (10,15%) and smaller (up to two- to three-fold) leaves, (3) lower leaf cuticular permeance (two- to four-fold), (4) higher taproot:shoot ratio (two-fold), (5) higher phloem:xylem ratios in taproot (two- to six-fold), (6) unchanged percentage dry matter content (%DMC) in leaves, petioles or fibrous roots and (7) higher %DMC in taproot (20%). However, %DMC of individual taproot tissues (phloem and xylem) was unaffected by temperatures and was consistently higher in the phloem (up to 30%). Therefore, the higher %DMC of whole taproots at 12°C was attributed solely to the increased development of phloem tissue. Carrot, therefore, shares many of the most conspicuous elements of temperate plant responses to low temperatures. Consistently with our hypothesis, however, carrots grown at suboptimal temperature promoted reserve structures, rather than the increase in carbohydrate concentration typical of most temperate annual species and woody perennials. [source] Trends in genetic variance components during 30 years of hybrid maize breeding at the University of HohenheimPLANT BREEDING, Issue 5 2008S. Fischer Abstract The ratio of variance due to specific vs. general combining ability (GCA) (,2SCA:,2GCA) is of central importance for predicting hybrid performance from GCA effects. The objectives of our study were to (1) analyse the changes in estimates of ,2GCA, ,2SCA and their ratio during 30 years of hybrid maize breeding and (2) compare the observed trends in genetic variances with those expected under a simple genetic model. We analysed multilocation yield trials based on the North Carolina Design II conducted in the maize breeding programme of the University of Hohenheim from 1975 to 2004 for grain yield (GY) and dry matter content (DMC). GY showed a significant (P < 0.05) annual increase of 0.17 Mg/ha, but no linear trend was found for DMC. Since the beginning of hybrid breeding at the University of Hohenheim, the sum of estimates of ,2GCA of the flint and dent heterotic groups were higher than the estimates of their ,2SCA. This predominance did not change with ongoing inter-population improvement. Consequently, superior hybrids can be identified and selected mainly based on their prediction from GCA effects. [source] Inheritance of useful traits in cassava grown in subhumid conditionsPLANT BREEDING, Issue 2 2006N. T. Cach Abstract A diallel study among nine parental clones of cassava was conducted in the subhumid environment on the northern coast of Colombia. Analysis of variance suggested significant effects for the six variables analysed: fresh-root yield, harvest index, root dry matter content, height of first branching, reaction to thrips and plant-type scores. General and specific combining ability effects and their interaction with the environment were significant for most of the variables as well. Results suggested that dominance plays a particularly important role in the cases of fresh-root yield and harvest index but had relatively little importance in the reaction to thrips, dry matter content or height of first branching. Specific breeding approaches are suggested for these traits, depending on the relative importance of additive or non-additive effects in their inheritance. The correlations among different traits were also analysed and in several cases their magnitude reached statistical and biological significance. [source] Yield and cooking qualities of somaclonal variants of cv. Russet Burbank selected for resistance to common scab disease of potatoANNALS OF APPLIED BIOLOGY, Issue 2 2010C.R. Wilson We previously obtained somaclonal variants of the important French fry processing cultivar Russet Burbank with significantly enhanced resistance to common scab disease. In this study we have shown the commercial merit of a proportion of these variants through comparison of relative yield and tuber quality with the parent cultivar Russet Burbank. Whilst we showed a weak negative correlation between tuber yield (as assessed by weight of tubers per plant) and relative disease resistance within selected variants, we identified several with equivalent yields to the parent cultivar. Furthermore, two disease-resistant variants (TC-RB8 and NZ-24B) consistently yielded more tuber mass than the parent. The majority of our Russet Burbank variants showed equivalent tuber quality characteristics (occurrence of defects, tuber specific gravity and dry matter content, and flesh colour) and cooking qualities (fry colour and presence of dark end defects) to the parent cultivar. Independent testing by a commercial French fry processor confirmed these quality characteristics. We present data demonstrating that highly common scab disease-resistant somaclonal variants of Russet Burbank have commercially acceptable tuber yield and quality characteristics, comparable to the industry standard and parent Russet Burbank cultivar. We also demonstrate the value of in vitro cell selection techniques for potato cultivar improvement. [source] The IBUS Process , Lignocellulosic Bioethanol Close to a Commercial RealityCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2008J. Larsen Abstract Integrated Biomass Utilization System (IBUS) is a new process for converting lignocellulosic waste biomass to bioethanol. Inbicon A/S has developed the IBUS process in a large-scale process development unit. This plant features new continuous and energy-efficient technology developed for pretreatment and liquefaction of lignocellulosic biomass and has now been operated and optimized for four years with promising results. In the IBUS process, biomass is converted using steam and enzymes only. The process is energy efficient due to very high dry matter content in all process steps and by integration with a power plant. Cellulose is converted to bioethanol and lignin to a high-quality solid biofuel which supply the process energy as well as a surplus of heat and power. Hemicellulose is used as feed molasses but in the future it could also be used for additional ethanol production or other valuable products. Feasibility studies of the IBUS process show that the production price for lignocellulosic bioethanol is close to the world market price for fuel ethanol. There is still room for optimization , and lignocellulosic bioethanol is most likely a commercial alternative to fossil transport fuels before 2012. [source] Influence of growth stage and postharvest storage on ascorbic acid and carotenoid content and visual quality of baby spinach (Spinacia oleracea L.)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2006Sara ÅM Bergquist Abstract To investigate the variations in quality with growth stage and postharvest storage, spinach was sown on three occasions. For each occasion, the spinach was harvested at three growth stages at 6-day intervals. The second stage corresponded to a growth period used for baby spinach by commercial growers. After harvest, the leaves were stored in polypropylene bags at 2 °C or 10 °C. The highest ascorbic acid content in fresh material was found at stage I. During storage, the ascorbic acid content decreased considerably and the dehydroascorbic acid/vitamin C ratio increased. Storage at 2 °C gave a smaller reduction in ascorbic acid content than storage at 10 °C. Total carotenoid content increased or remained stable during storage. Lutein was the major carotenoid, making up about 39% of the total carotenoid content, followed by violaxanthin, ,-carotene and neoxanthin. Visual quality decreased during storage in most cases, and was correlated to initial ascorbic acid and dry matter contents. The initial AA content might therefore be used as a parameter for predicting the shelf-life of baby spinach. The results also indicate that by harvesting baby spinach a few days earlier than the current commercial stage of harvest the postharvest visual quality and nutritional quality may be improved. Copyright © 2005 Society of Chemical Industry [source] Cassava root yields and culinary qualities as affected by harvest age and test environmentJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2003Jacob M Ngeve Abstract Five cassava genotypes were grown at five contrasting sites in Cameroon, and their roots were harvested 6, 8, 10, 12, 14 and 16 months after planting, to determine the effects of growing environment and harvest age on storage root yields and culinary qualities. The highest root yields were obtained at Ekona (26.3,t,ha,1), whereas the highest root counts were recorded at Bertoua (33 roots per 10,m2). Root yields were lowest (2.9,t,ha,1) when roots were harvested at 6 months, but continued to bulk up to 18.5,t,ha,1 at 16 months. The greatest root increase (9.3,t,ha,1) was observed between 8 and 12 months. Improved and local varieties had comparable dry matter contents (39%). All clones cooked when harvested at 6 and 8 months; thereafter, improved clones did not cook, and cooking duration continued to increase even for the local variety, accounting for the difficulty seen in disseminating these newly developed clones to growers. Cooking durations of roots were longer at Nkolbisson, Bertoua and Ebolowa than at Ekona and Yoke. Soil carbon content was negatively correlated (r,=,,0.999***) with mealiness but not with cooking duration. Cooking quality appears to be under genetic and environmental control. Further studies to elucidate the role of the environment on cookability should concentrate on duration of the rainy and dry seasons, soil physical and chemical properties, and starch chemistry of the genotypes. Suggestions for further research are discussed. © 2003 Society of Chemical Industry [source] Effects of Dietary Lipids on Growth and Feed Utilization of Jade Perch, Scortum barcooJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2009Li Ping Song To examine the effects of dietary lipids on the growth and feed utilization of jade perch juveniles, Scortum barcoo, diets containing 36.3% crude protein supplemented with increasing lipid levels (6, 9, 12, and 15% of the dry matter) were used to feed triplicate groups of 30 fish for 60 d. At the end of the experiment, more than 95% fish survived well from all diet groups (P > 0.05). Measurements on the weight gains and the daily specific growth rates indicated that fish fed with diets of 12 and 15% lipids exhibited higher growth rates (P < 0.05); evaluations for the feed conversion ratio and the protein efficiency ratio indicated that fish fed with 12 and 15% lipid diets used their feed and dietary proteins more efficiently (P < 0.05). The muscle lipid and dry matter contents increased dramatically in fish fed with higher dietary lipid levels (P < 0.05). The highest lipid contents were obtained from fish in the 15% lipid diet group and the highest amount of dry matters from the 12% lipid diet group. On the other hand, protein contents in fish muscles declined with increasing dietary lipid levels (P < 0.05), and the lowest values were shown in the 15% lipid diet group. Ash contents showed no significant differences from muscles of fish fed with four different diets (P > 0.05). Together, increasing lipid levels in fish diets was effective to improve fish growth, feed efficiency, and protein utilization. [source] Plant traits and functional types in response to reduced disturbance in a semi-natural grasslandJOURNAL OF VEGETATION SCIENCE, Issue 2 2005F. Louault Abstract. Question: How do functional types respond to contrasting levels of herbage use in temperate and fertile grasslands? Location: Central France (3°1'E, 45°43'N), 870 m a.s.l. Methods: Community structure and the traits of dominant plant species were evaluated after 12 years of contrasted grazing and mowing regimes in a grazing trial, comparing three levels of herbage use (high, medium and low). Results and Conclusions: Of 22 measured traits (including leaf traits, shoot morphology and composition, phenology), seven were significantly affected by the herbage use treatment. A decline in herbage use reduced individual leaf mass, specific leaf area and shoot digestibility, but increased leaf C and dry matter contents. Plants were taller, produced larger seeds and flowered later under low than high herbage use. Nine plant functional response types were identified by multivariate optimization analysis; they were based on four optimal traits: leaf dry matter content, individual leaf area, mature plant height and time of flowering. In the high-use plots, two short and early flowering types were co-dominant, one competitive, grazing-tolerant and moderately grazing-avoiding, and one grazing-avoiding but not -tolerant. Low-use plots were dominated by one type, neither hardly grazing-avoiding nor grazing-tolerant, but strongly competitive for light. [source] | ||||||||||||||||||||||||||||