Academic literature on the topic 'Calorespirometric ratio'

`Lovell' peach seeds were stratified for 0 to 13 weeks at 4C under moist conditions. Heat of metabolism and CO2 evolution, measured by Differential Scanning Calorimetry, increased with stratification time. The calorespirometric ratio increased between 0 and 6 weeks and then remained constant until 13 weeks. Germination percentages paralleled this ratio and reached 80% only after 6 weeks of stratification. After radicle emergence, seedlings from different stratification treatments were grown for 3 weeks. Increasing stratification time resulted in taller seedling growth. Calorimetrically measured CO2, evolution and the calorespirometric ratio of the apex (one cm) of the seedling increased with longer stratification time. Contrary to the observations of the seeds, metabolic heat rates decreased as stratification time increased. Yet, seedling sustained higher growth rates. These data suggest that the stratification treatment resulted in an improvement in metabolic efficiency.

This study describes a calorespirometric method for determining the coefficients of the correlation of specific respiration and growth rates. To validate the calorespirometric method, coefficients obtained from calorespirometric data are compared with coefficients obtained from mass and elongation growth rates measured at three temperatures on oat (Avena sativa L.) shoots. Calorespirometric measurements were also made on leaf tissue of varying age from Verbascum thapsus L., Convolvulus arvensis L., and Helianthus tuberosus Nutt. Measurements on A. sativa, C. arvensis and H. tuberosus at several temperatures show maintenance coefficients generally increase with temperature, but, in disagreement with accepted theory, growth coefficients for C. arvensis and A. sativa vary with temperature. A comparison of rates expressed as intensive and extensive quantities showed that the decline in specific respiration and growth rates with age is caused by dilution-by-growth, not down-regulation of respiration rate by reduced demand. The ratio of heat rate to CO2 rate increases with leaf age, and, for fully mature leaves, exceeds the maximum possible value for carbohydrates. This shows that the catabolic substrate may vary with leaf age in immature leaves and cannot be assumed to consist only of carbohydrates in mature leaves. Dilution-by-growth, substrate variation, and inseparability of the variables in the growth-maintenance model all complicate physiological interpretation of the slope and intercept of plots of specific respiration rates v. specific growth rates.

The increasing respiration of breaking `Pinot Noir' buds was measured by Differential Scanning Calorimetry. Bud development was classified into ecodormant, initial swelling, fully swollen, and breaking buds. Metabolic and CO2 evolution heat rates increased as the buds developed. Activation energy decreased steadily as development proceeded, which implied that less energy was required for metabolism to continue at later bud stages. A decrease in metabolic efficiency noted by a low calorespirometric ratio was observed during the transition from ecodormant to the initial swelling stage. From the second stage on, metabolic efficiency increased. The responsive nature of grape buds to warm temperatures was explained by increasing Q10 (10-20C) values from 2.8 to 3.8, 3.2, and 3.6 for the four developmental stages described above.

Growth of sand-cultured Eucalyptus camaldulensis Dehnh. (river red gum) seedlings from six wide-ranging provenances was reduced in the presence of 150 mM NaCl, a high pH of 9.5, and combined NaCl and high pH, compared with no applied NaCl and neutral pH. Effects of these stress conditions on respiration rates and substrate carbon conversion efficiencies of rapidly-expanding leaf tissue were measured with calorespirometric techniques. Growth rates were calculated from respiration parameters. Respiration rate, measured as metabolic heat production rate (q), showed no consistent trend with either NaCl or high pH, whereas the rate measured as CO2 production rate (R CO2) was generally lower with both treatments. The ratio of heat lost per mole of CO2 produced [q/(R CO2)] was consistently increased by both stresses. Stress causes a larger fraction of metabolic energy produced by aerobic metabolism to be lost as heat, relative to non-stressed controls. Consequently, a larger fraction of photosynthetic product in stressed seedlings must be metabolized to CO2 per mole of C incorporated into biomass. Our results indicate that 0.42 mol substrate C is converted to CO2 per mole C incorporated into biomass for control plants, compared with 0.96 mol for plants treated with combined NaCl and high pH. Respiratory responses to treatment varied with provenance. Specific growth rates, calculated from repiratory parameters (q and RCO2) of stressed E. camaldulensis seedlings, generally paralleled experimentally-determined reduced growth (dry weight) of these seedlings. Thus, measurements of leaf respiration allow calculation of growth inhibition caused by NaCl and high pH stress. However, we could not discriminate among provenances in this experiment with only one level of NaCl and pH.

At present, soils face great threats. Consequences of human activities, such as climate change, acidification and contamination result in decreased soil health. This is a threat to human health and well-being, since our society is dependent on soil ecosystem services. The soil ecosystems provide resources, such as food and fresh water, regulate the climate and play key parts in important life supporting biological processes, e.g. cycling of carbon and nutrients. Due to increased awareness of the threats that soils face, and its importance to humans, soil quality monitoring has recently received increased attention. Microorganisms run most biological processes in the soil, such as decomposition of organic material and nutrient cycling. Thus, microbial activity and diversity are considered useful biological indicators for soil quality monitoring. These biological properties can be examined using different methods. The aim of the project was to evaluate the potential of multiple substrate-induced respiration (MSIR), using the MicroRespTM system, and isothermal calorimetry for determining microbial activity and diversity in soils contaminated with copper (Cu) and polycyclic aromatic hydrocarbons (PAH). Thereby, the methods’ applicability in risk assessment of contaminated soil could be decided. MSIR is considered appropriate for determining microbial activity and functional diversity, while isothermal calorimetry has not been tested as much in this area. The calorespirometric ratio (produced heat per unit CO2) was calculated to evaluate potential relationships between heat and CO2 at different contamination levels. Although there was some variation between the methods, Cu had a clear effect on both microbial activity and functional diversity. Both methods were thus considered applicable in risk assessment of soil contaminated with Cu. The impact of PAH appeared to be more complex, the effects on microbial activity varied and PAH had little significant effect on functional diversity. Neither of the methods were therefore considered applicable for assessment of soil contaminated with PAH. The calorespirometric ratio did not provide useful results, and cannot be recommended for risk assessment purposes at present.
I dagsläget utsätts marken för stora hot. Följder av mänsklig aktivitet, så som klimatförändringar, försurning och förorening försämrar markens kvalitet. Detta är ett hot mot människors hälsa och välmående, eftersom vårt samhälle är beroende av markens ekosystemtjänster. Markens ekosystem förser oss med exempelvis mat och rent vatten, reglerar klimatet, och har nyckelroller i viktiga biologiska processer, exempelvis cirkulering av kol och näringsämnen. På grund av ökad medvetenhet om hoten mot marken samt dess betydelse för människan, har kontroll av markens kvalitet börjat få ökad uppmärksamhet. Mikroorganismer sköter de flesta biologiska processer som sker i marken, så som nedbrytning av organiskt material och cirkulering av näringsämnen. Därmed anses mikrobiell aktivitet och diversitet vara lämpliga biologiska indikatorer vid kontroll av markens kvalitet. Dessa biologiska egenskaper kan mätas med flera olika metoder. Syftet med projektet var att utvärdera potentialen i att använda multipla substrat-inducerad respiration (MSIR), genom att använda systemet MicroRespTM, samt isotermisk kalorimetri för att mäta mikrobiell aktivitet och funktionell diversitet i mark förorenad med koppar (Cu) och polycykliska aromatiska kolväten (PAH). Därmed kunde metodernas tillämplighet i riskbedömning av förorenad mark bestämmas. MSIR anses vara en lämplig metod i syfte att undersöka mikrobiell aktivitet och funktionell diversitet, medan isotermisk kalorimetri inte är lika beprövat. Kvoten mellan värmeproduktion och respirerad CO2, the calorespirometric ratio, beräknades för att utvärdera eventuella samband mellan värmeproduktion och respiration vid olika föroreningskoncentrationer. Trots att det förekom viss variation mellan metoderna, hade Cu en tydlig effekt på både mikrobiell aktivitet och funktionell diversitet. Båda metoder ansågs därför vara tillämpbara i riskbedömning av Cu-förorenad jord. PAH hade varierande effekt på mikrobiell aktivitet och liten signifikant effekt på funktionell diversitet. Ingen av metoderna ansågs därför tillämpbar i riskbedömning av jord förorenad med PAH. The calorespirometric ratio tillhandahöll ej användbara resultat, och kunde därmed inte rekommenderas i riskbedömningssyfte.