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Eric Bauce - One of the best experts on this subject based on the ideXlab platform.
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Is Feeding Behaviour on Foliage Affected by lab-Rearing on Artificial Diet?
Journal of Insect Behavior, 2015Co-Authors: Darragh Ennis, Eric Bauce, B. J. Mader, K. Burnside, Emma DesplandAbstract:Eastern spruce budworm, Choristoneura fumiferana, larvae were reared on white spruce (Picea glauca) Foliage and/or an agar based artificial diet medium for different proportions of their development: fed Foliage throughout, fed diet until the 4th instar then Foliage for two instars, fed diet until the 6th instar then Foliage for 24 h and fed diet only. The insects were then observed feeding on white spruce needles. First, insects reared exclusively on artificial diet exhibited a longer latency to initiate feeding than insects with some prior exposure to Foliage. Second, artificial diet-reared insects and those pretreated on Foliage for only a few hours had significantly longer meals but lower food consumption than those reared exclusively on Foliage or pretreated on Foliage for two instars, suggesting that artificial diet-reared insects ingest Foliage more slowly during a meal. Third, caterpillars pretreated on Foliage for several days, like their diet-reared and short exposure counterparts, had longer intermeal intervals than Foliage-reared caterpillars. Finally, subsequent measurements showed that diet-reared budworm have smaller head capsules than Foliage-reared insects. These findings show that prior experience influences a folivore’s behaviour on a given food, that insects reared on artificial diet do not develop the same ability to feed on plants as do Foliage-reared insects and that different mechanisms of acclimation to a food operate at different time scales.
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taste receptor activity and feeding behaviour reveal mechanisms of white spruce natural resistance to eastern spruce budworm choristoneura fumiferana
Physiological Entomology, 2011Co-Authors: Emma Despland, Maria T Gundersen, Simon P Daoust, Brian J Mader, Nathalie Delvas, P J Albert, Eric BauceAbstract:The pattern of feeding of Eastern spruce budworm Choristoneura fumiferana (Clem.) (Lepidoptera, Tortricidae) is compared on Foliage from white spruce Picea glauca (Moench) Voss. (Pinaceae) trees previously determined to be susceptible and resistant to defoliation by budworm. No differences are observed in electrophysiological responses from taste sensilla to aqueous extracts of the two Foliage types, nor is there a preference for either extract type in a choice test. Acetone extracts from the two Foliage types are both preferred to a control sucrose solution, although neither elicits a preference relative to the other. These results suggest that there is no difference in phagostimulatory power of internal leaf contents of the two Foliage types. Longer-term observation of feeding behaviour in a no-choice situation shows no difference in meal duration, confirming the lack of difference in phagostimulatory power. However, on average, intermeal intervals are twice as long on the resistant Foliage, leading to an overall lower food consumption during the assay. This result suggests an anti-digestive or toxic effect of the resistant Foliage that slows behaviour and limits food intake. Previous research has shown that waxes of the resistant Foliage deter initiation of feeding by the spruce budworm and that this Foliage contains higher levels of tannins and monoterpenes. The data suggest that the resistant Foliage contains a post-ingestive second line of defence against the spruce budworm.
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Advantages of a mixed diet: feeding on several foliar age classes increases the performance of a specialist insect herbivore
Oecologia, 2003Co-Authors: Gaétan Moreau, Dan T. Quiring, Eldon S. Eveleigh, Eric BauceAbstract:Two field studies were carried out to determine the influence of Abies balsamea Foliage age on the preference and performance of larvae of Neodiprion abietis , a specialist Diprionid sawfly. Preference was determined by examining N. abietis defoliation on all age classes of Foliage. Performance was estimated using larval survival, cocoon weights and the percentage of adults that were females. Neodiprion abietis preference for, and performance on, current-year Foliage was very low, peaked on 2 or 3-year-old Foliage, and declined on older Foliage. Thus, sawfly feeding preference was adaptive. However, survival and cocoon weight were highest when sawflies were allowed to feed on all age classes of Foliage, demonstrating that an insect specialist may perform better when feeding on several age classes of Foliage from a single host plant species. These results indicate that either different larval instars have different nutritional requirements, or that food mixing provides the best diet, permitting the herbivore to obtain needed nutrients while avoiding ingestion of toxic doses of secondary metabolites. In addition, our results suggest that limited availability of varied Foliage has more negative consequences for N. abietis females than for males, as the percentage of survivors that were females decreased when juvenile mortality was high. Our results emphasize the importance of considering non-linear changes in foliar quality as leaves age on herbivore preference and performance, and demonstrate how a herbivore can use this variability to maximize its fitness.
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Impact of balsam fir flowering on pollen and Foliage biochemistry in relation to spruce budworm growth, development and food utilization
Entomologia Experimentalis et Applicata, 1997Co-Authors: Nathalie Carisey, Eric BauceAbstract:The impact of balsam fir (Abies balsamea (L.) Miller) flowering on nutritional and allelochemical quality of pollen, current-year and one-year-old Foliage is studied in relation to spruce budworm (Choristoneura fumiferana Clem.) (Lepidoptera: Tortricidae) growth, development and utilization of food and nitrogen. In the laboratory, using fresh food from the field, we simulated conditions of low larval population density, in which there is no current-year Foliage depletion during the spruce budworm feeding period. Similarly, we simulated conditions of high larval population density when current-year Foliage depletion occurs. Because of the high nutritive value of pollen (high amounts of amino acids and minerals, especially nitrogen; low monoterpene content), insects from flowering trees reached the fifth instar five days earlier than those from non-flowering trees, and had heavier dry- and nitrogen-weights at the beginning of the fifth instar. At budbreak, switching from pollen to current-year Foliage negatively affected conversion efficiencies and digestibilities of food and nitrogen (AD; ADN; ECDN; ECI; ECIN). The switch from pollen to new Foliage had a detrimental impact on fifth-instar survival and on newly-moulted sixth-instar dry- and nitrogen-weights. Moreover, during the fifth instar, balsam fir flowering reduced the nutritive value of current-year Foliage, which in turn, might have contributed to the reduced larval growth. Nevertheless, during the sixth instar, balsam fir flowering affected the biochemistry of current-year Foliage in ways that enabled larvae to compensate for their low fifth-instar biological performance; larvae also managed to reach pupal dry weight similar to larvae reared on non-flowering trees. Current-year Foliage from flowering trees contained less nitrogen, total soluble sugars and total monoterpenes. Those foliar characteristics enabled larvae to increase food and nitrogen consumption rates (RCR; RNCR), because of lower repellency and/or post-ingestional feedback from monoterpenes. As for current-year Foliage, balsam fir flowering reduced nitrogen, total soluble sugar and total monoterpene contents in one-year-old Foliage during the sixth-instar feeding period. These characteristics enabled sixth-instar larvae, fed on old Foliage from flowering trees, to have high relative food and nitrogen consumption rates (RCR; RNCR). Larvae were also able to reach higher relative growth rates (RGR) and relative nitrogen accumulation rates (RNAR) compared to larvae reared on one-year-old Foliage from non-flowering trees. Finally, larvae on flowering trees had pupal dry weight similar to those from non-flowering trees, but reached the adult stage nine days earlier. Regardless the Foliage type consumed by spruce budworm larvae during the sixth instar, pollen consumption during early larval stages reduced total development time, and thus exposure time to natural enemies. This phenomenon might increase larval survival. Balsam fir flowering changed the biochemistry of one-year-old and current-year Foliages, but did not affect pupal dry weights of larvae reared on flowering trees compared to those reared on non-flowering trees. Thus, at low population density, spruce budworm populations in balsam fir flowering stands might be favoured over those in balsam fir non-flowering stands. In addition, when larvae consumed one-year-old Foliage during the entire sixth instar, those on flowering trees are probably favoured over those on non-flowering trees. However, because flowering trees produce less new Foliage than non-flowering trees, current-year Foliage depletion may occur earlier on flowering trees than on non-flowering trees. Thus, at similar larval population density, larvae on flowering trees might have to feed on one-year-old Foliage earlier than those on non-flowering trees. In that case, spruce budworm populations on non-flowering stands would be favoured over those on flowering stands.
Douglas G. Sprugel - One of the best experts on this subject based on the ideXlab platform.
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The effects of light acclimation during and after Foliage expansion on photosynthesis ofAbies amabilis Foliage within the canopy.
Oecologia, 1996Co-Authors: J. Renée Brooks, Douglas G. Sprugel, Thomas M HinckleyAbstract:Variation in the photosynthetic function ofAbies amabilis Foliage within a canopy was examined and related to three different processes that affect Foliage function: Foliage aging, sun-shade acclimation that occurred while Foliage was expanding, and reacclimation after expansion was complete. Foliage produced in the sun had higher photosynthesis at light saturation (A max, μmol·m-2·s-1), dark respiration (μmol·m-2·s-1), nitrogen content (g·m-2), chlorophyll content (g·m-2), and chlorophylla:b ratio, and a lower chlorophyll to nitrogen ratio (chl:N), than Foliage produced in the shade. As sun Foliage becomes shaded, it becomes physiologically similar to shade Foliage, even though it still retains a sun morphology. Shaded sun Foliage exhibited lowerA max, dark respiration, nitrogen content, and chlorophylla:b ratio, and a higher chl:N ratio than sun Foliage of the same age remaining in the open. However, shaded sun Foliage had a higher chlorophyll content than sun Foliage remaining in the open, even though true shade Foliage had a lower chlorophyll content than sun Foliage. This anomaly arises because as sun Foliage becomes shaded, it retains a higher nitrogen content than shade Foliage in a similar light environment, but the two forms have similar chl:N ratios. Within the canopy, most physiological indicators were more strongly correlated with the current light environment than with Foliage age or leaf thickness, with the exception of chlorophyll content.A max decreased significantly with both decreasing current light environment of the Foliage and increasing Foliage age. The same trend with current light and age was found for the chlorophylla:b ratio. Foliage nitrogen content also decreased with a decrease in current light environment, but no distinct pattern was found with Foliage age. Leaf thickness was also important for predicting leaf nitrogen content: thicker leaves had more nitrogen than thinner leaves regardless of light environment or age. The chl:N ratio had a strong negative correlation with the current light environment, and, as with nitrogen content, no distinct pattern was found with Foliage age. Chlorophyll content of the Foliage was not well correlated with any of the three predictor variables: current light environment, Foliage age or leaf thickness. On the other hand, chlorophyll content was positively correlated with the amount of nitrogen in a leaf, and once nitrogen was considered, the current light environment was also highly significant in explaining the variation in chlorophyll content. It has been suggested that the redistribution of nitrogen both within and between leaves is a mechanism for photosynthetic acclimation to the current light environment. Within theseA. amabilis canopies, both leaf nitrogen and the chl:N ratio were strongly correlated with the current light environment, but only weakly with leaf age, supporting the idea that changing light is the driving force for the redistribution of nitrogen both within and between leaves. Thus, our results support previous theories on nitrogen distribution and partitioning. However,A max was significantly affected by both Foliage age and the current light environment, indicating that changes in light alone are not enough to explain changes inA max with time.
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acclimation responses of mature abies amabilis sun Foliage to shading
Oecologia, 1994Co-Authors: J R Brooks, Thomas M Hinckley, Douglas G. SprugelAbstract:This paper addresses two main questions. First, can evergreen Foliage that has been structurally determined as sun Foliage acclimate physiologically when it is shaded? Second, is this acclimation independent of the Foliage ageing process and source-sink relations? To investigate these questions, a shading and debudding experiment was established using paired branches on opengrown Abies amabilis trees. For each tree, one branch was either shaded, debudded, or both, from before budbreak until the end of summer, while the other branch functioned as a control. Foliage samples were measured both prior to and during treatment for photosynthesis at light saturation (Amax), dark respiration, nitrogen content, chlorophyll content, chlorophyll-to-nitrogen ratio and chlorophyll a:b ratio. All age classes of Foliage responded similarly during the treatment, although pre-treatment values differed between age classes. Within 1 month after the treatment began, Amax was lower in shaded Foliage and remained lower throughout the treatment period. For debudded branches, Amax was lower than the controls only during active shoot elongation. At the end of the treatments in September, Amax in shade-treated sun Foliage matched the rates in the true shade-formed Foliage, but nitrogen remained significantly higher. By 1.5 months after treatment, chlorophyll content in shaded Foliage was higher than in controls, and the chlorophyll a:b ratio was lower for the shaded Foliage. On debudded branches, chlorophyll content and chlorophyll a:b ratio were similar to the values in control samples. Shading lowered the rate of nitrogen accumulation within a branch, while removing debudding decreased the amount of sequestered N that was exported from the older Foliage to supply new growth. By September, chlorophyll content in shade-treated Foliage was higher than that in the control sun Foliage or in true shade Foliage. The chlorophyll increase as a result of shading was unexpected. However, the chlorophyll-to-nitrogen ratio was identical for the shade-treated sun Foliage and the true shade Foliage while being significantly lower than the control sun Foliage. It appears that acclimation to shading in mature Foliage involves a reallocation of nitrogen within the leaf into thylakoid proteins. A redistribution of resources (nitrogen) among leaves is secondary and appears to function on a slower time scale than reallocation within the leaf. Thus, A. amabilis Foliage that is structurally determined as sun Foliage can acclimate to shade within a few months; this process is most likely independent of ageing and is only slightly affected by source-sink relations within a branch.
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Foliage dark respiration in abies amabilis dougl forbes variation within the canopy
Tree Physiology, 1991Co-Authors: J R Brooks, E D Ford, Thomas M Hinckley, Douglas G. SprugelAbstract:: Dark respiration of Foliage was measured in a 30-year-old stand of Abies amabilis in western Washington from June to November. Both laboratory and field measurements were used to study the effect of environmental and tree variables on respiration. Foliage respiration rates were most strongly influenced by needle temperature. After accounting for leaf temperature differences, Foliage respiration decreased with depth in the canopy for all age classes of Foliage. Respiration differences attributed to location within the canopy were greatest early in the growing season, but were still significant in November. Younger Foliage respired more than older Foliage in the upper canopy, but not in the lower canopy. Respiration differences due to Foliage age were highly significant in the early growing season, but were not detectable by mid-October.
J R Brooks - One of the best experts on this subject based on the ideXlab platform.
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acclimation responses of mature abies amabilis sun Foliage to shading
Oecologia, 1994Co-Authors: J R Brooks, Thomas M Hinckley, Douglas G. SprugelAbstract:This paper addresses two main questions. First, can evergreen Foliage that has been structurally determined as sun Foliage acclimate physiologically when it is shaded? Second, is this acclimation independent of the Foliage ageing process and source-sink relations? To investigate these questions, a shading and debudding experiment was established using paired branches on opengrown Abies amabilis trees. For each tree, one branch was either shaded, debudded, or both, from before budbreak until the end of summer, while the other branch functioned as a control. Foliage samples were measured both prior to and during treatment for photosynthesis at light saturation (Amax), dark respiration, nitrogen content, chlorophyll content, chlorophyll-to-nitrogen ratio and chlorophyll a:b ratio. All age classes of Foliage responded similarly during the treatment, although pre-treatment values differed between age classes. Within 1 month after the treatment began, Amax was lower in shaded Foliage and remained lower throughout the treatment period. For debudded branches, Amax was lower than the controls only during active shoot elongation. At the end of the treatments in September, Amax in shade-treated sun Foliage matched the rates in the true shade-formed Foliage, but nitrogen remained significantly higher. By 1.5 months after treatment, chlorophyll content in shaded Foliage was higher than in controls, and the chlorophyll a:b ratio was lower for the shaded Foliage. On debudded branches, chlorophyll content and chlorophyll a:b ratio were similar to the values in control samples. Shading lowered the rate of nitrogen accumulation within a branch, while removing debudding decreased the amount of sequestered N that was exported from the older Foliage to supply new growth. By September, chlorophyll content in shade-treated Foliage was higher than that in the control sun Foliage or in true shade Foliage. The chlorophyll increase as a result of shading was unexpected. However, the chlorophyll-to-nitrogen ratio was identical for the shade-treated sun Foliage and the true shade Foliage while being significantly lower than the control sun Foliage. It appears that acclimation to shading in mature Foliage involves a reallocation of nitrogen within the leaf into thylakoid proteins. A redistribution of resources (nitrogen) among leaves is secondary and appears to function on a slower time scale than reallocation within the leaf. Thus, A. amabilis Foliage that is structurally determined as sun Foliage can acclimate to shade within a few months; this process is most likely independent of ageing and is only slightly affected by source-sink relations within a branch.
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Foliage dark respiration in abies amabilis dougl forbes variation within the canopy
Tree Physiology, 1991Co-Authors: J R Brooks, E D Ford, Thomas M Hinckley, Douglas G. SprugelAbstract:: Dark respiration of Foliage was measured in a 30-year-old stand of Abies amabilis in western Washington from June to November. Both laboratory and field measurements were used to study the effect of environmental and tree variables on respiration. Foliage respiration rates were most strongly influenced by needle temperature. After accounting for leaf temperature differences, Foliage respiration decreased with depth in the canopy for all age classes of Foliage. Respiration differences attributed to location within the canopy were greatest early in the growing season, but were still significant in November. Younger Foliage respired more than older Foliage in the upper canopy, but not in the lower canopy. Respiration differences due to Foliage age were highly significant in the early growing season, but were not detectable by mid-October.
Nurmardhiyyah Azizuddin - One of the best experts on this subject based on the ideXlab platform.
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A comparative study on Foliage and peels of Hylocereus undatus (white dragon fruit) regarding their antioxidant activity and phenolic content
Heliyon, 2019Co-Authors: Ayub Md Som, Norizan Ahmat, Hairul A. A. Hamid, Nurmardhiyyah AzizuddinAbstract:Abstract Hylocereus undatus Foliage is believed to contain antioxidants similar to its peel. Numerous studies have been conducted to determine the total phenolic content (TPC) and antioxidant activity on the Hylocereus undatus pulps and peels; however, similar studies on its Foliage have yet to be investigated. In this study, Hylocereus undatus Foliage and peels were extracted using two different solvents namely; chloroform and methanol through Folin-Ciocalteu method and Diphenyl-1-Ipicrylhydrazyl (DPPH) free radical scavenging assay for TPC and antioxidant activity, respectively. As for TPC, results revealed that the peels gave higher TPC in both methanol (48.15 mg GAE/100g extract) and chloroform (18.89 mg GAE/100g extract) extractions than Foliage (30.3 mg GAE/100g extract and 5.92 mg GAE/100g extract, respectively). However, when a comparison was made between Foliage and peels in terms of its scavenging effects in DPPH assay, the peels contained more antioxidants (18.71%) than Foliage (38.3%) in the chloroform solvent extracts. This study shows that Hylocereus undatus Foliage has a similar antioxidant activity as its peels and is potentially a natural antioxidant in food applications.
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A comparative study on Foliage and peels of Hylocereus undatus (white dragon fruit) regarding their antioxidant activity and phenolic content
Elsevier, 2019Co-Authors: Ayub Md Som, Norizan Ahmat, Hairul A. A. Hamid, Nurmardhiyyah AzizuddinAbstract:Hylocereus undatus Foliage is believed to contain antioxidants similar to its peel. Numerous studies have been conducted to determine the total phenolic content (TPC) and antioxidant activity on the Hylocereus undatus pulps and peels; however, similar studies on its Foliage have yet to be investigated. In this study, Hylocereus undatus Foliage and peels were extracted using two different solvents namely; chloroform and methanol through Folin-Ciocalteu method and Diphenyl-1-Ipicrylhydrazyl (DPPH) free radical scavenging assay for TPC and antioxidant activity, respectively. As for TPC, results revealed that the peels gave higher TPC in both methanol (48.15 mg GAE/100g extract) and chloroform (18.89 mg GAE/100g extract) extractions than Foliage (30.3 mg GAE/100g extract and 5.92 mg GAE/100g extract, respectively). However, when a comparison was made between Foliage and peels in terms of its scavenging effects in DPPH assay, the peels contained more antioxidants (18.71%) than Foliage (38.3%) in the chloroform solvent extracts. This study shows that Hylocereus undatus Foliage has a similar antioxidant activity as its peels and is potentially a natural antioxidant in food applications. Keywords: Food science, Food analysi
Thomas M Hinckley - One of the best experts on this subject based on the ideXlab platform.
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The effects of light acclimation during and after Foliage expansion on photosynthesis ofAbies amabilis Foliage within the canopy.
Oecologia, 1996Co-Authors: J. Renée Brooks, Douglas G. Sprugel, Thomas M HinckleyAbstract:Variation in the photosynthetic function ofAbies amabilis Foliage within a canopy was examined and related to three different processes that affect Foliage function: Foliage aging, sun-shade acclimation that occurred while Foliage was expanding, and reacclimation after expansion was complete. Foliage produced in the sun had higher photosynthesis at light saturation (A max, μmol·m-2·s-1), dark respiration (μmol·m-2·s-1), nitrogen content (g·m-2), chlorophyll content (g·m-2), and chlorophylla:b ratio, and a lower chlorophyll to nitrogen ratio (chl:N), than Foliage produced in the shade. As sun Foliage becomes shaded, it becomes physiologically similar to shade Foliage, even though it still retains a sun morphology. Shaded sun Foliage exhibited lowerA max, dark respiration, nitrogen content, and chlorophylla:b ratio, and a higher chl:N ratio than sun Foliage of the same age remaining in the open. However, shaded sun Foliage had a higher chlorophyll content than sun Foliage remaining in the open, even though true shade Foliage had a lower chlorophyll content than sun Foliage. This anomaly arises because as sun Foliage becomes shaded, it retains a higher nitrogen content than shade Foliage in a similar light environment, but the two forms have similar chl:N ratios. Within the canopy, most physiological indicators were more strongly correlated with the current light environment than with Foliage age or leaf thickness, with the exception of chlorophyll content.A max decreased significantly with both decreasing current light environment of the Foliage and increasing Foliage age. The same trend with current light and age was found for the chlorophylla:b ratio. Foliage nitrogen content also decreased with a decrease in current light environment, but no distinct pattern was found with Foliage age. Leaf thickness was also important for predicting leaf nitrogen content: thicker leaves had more nitrogen than thinner leaves regardless of light environment or age. The chl:N ratio had a strong negative correlation with the current light environment, and, as with nitrogen content, no distinct pattern was found with Foliage age. Chlorophyll content of the Foliage was not well correlated with any of the three predictor variables: current light environment, Foliage age or leaf thickness. On the other hand, chlorophyll content was positively correlated with the amount of nitrogen in a leaf, and once nitrogen was considered, the current light environment was also highly significant in explaining the variation in chlorophyll content. It has been suggested that the redistribution of nitrogen both within and between leaves is a mechanism for photosynthetic acclimation to the current light environment. Within theseA. amabilis canopies, both leaf nitrogen and the chl:N ratio were strongly correlated with the current light environment, but only weakly with leaf age, supporting the idea that changing light is the driving force for the redistribution of nitrogen both within and between leaves. Thus, our results support previous theories on nitrogen distribution and partitioning. However,A max was significantly affected by both Foliage age and the current light environment, indicating that changes in light alone are not enough to explain changes inA max with time.
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acclimation responses of mature abies amabilis sun Foliage to shading
Oecologia, 1994Co-Authors: J R Brooks, Thomas M Hinckley, Douglas G. SprugelAbstract:This paper addresses two main questions. First, can evergreen Foliage that has been structurally determined as sun Foliage acclimate physiologically when it is shaded? Second, is this acclimation independent of the Foliage ageing process and source-sink relations? To investigate these questions, a shading and debudding experiment was established using paired branches on opengrown Abies amabilis trees. For each tree, one branch was either shaded, debudded, or both, from before budbreak until the end of summer, while the other branch functioned as a control. Foliage samples were measured both prior to and during treatment for photosynthesis at light saturation (Amax), dark respiration, nitrogen content, chlorophyll content, chlorophyll-to-nitrogen ratio and chlorophyll a:b ratio. All age classes of Foliage responded similarly during the treatment, although pre-treatment values differed between age classes. Within 1 month after the treatment began, Amax was lower in shaded Foliage and remained lower throughout the treatment period. For debudded branches, Amax was lower than the controls only during active shoot elongation. At the end of the treatments in September, Amax in shade-treated sun Foliage matched the rates in the true shade-formed Foliage, but nitrogen remained significantly higher. By 1.5 months after treatment, chlorophyll content in shaded Foliage was higher than in controls, and the chlorophyll a:b ratio was lower for the shaded Foliage. On debudded branches, chlorophyll content and chlorophyll a:b ratio were similar to the values in control samples. Shading lowered the rate of nitrogen accumulation within a branch, while removing debudding decreased the amount of sequestered N that was exported from the older Foliage to supply new growth. By September, chlorophyll content in shade-treated Foliage was higher than that in the control sun Foliage or in true shade Foliage. The chlorophyll increase as a result of shading was unexpected. However, the chlorophyll-to-nitrogen ratio was identical for the shade-treated sun Foliage and the true shade Foliage while being significantly lower than the control sun Foliage. It appears that acclimation to shading in mature Foliage involves a reallocation of nitrogen within the leaf into thylakoid proteins. A redistribution of resources (nitrogen) among leaves is secondary and appears to function on a slower time scale than reallocation within the leaf. Thus, A. amabilis Foliage that is structurally determined as sun Foliage can acclimate to shade within a few months; this process is most likely independent of ageing and is only slightly affected by source-sink relations within a branch.
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Foliage dark respiration in abies amabilis dougl forbes variation within the canopy
Tree Physiology, 1991Co-Authors: J R Brooks, E D Ford, Thomas M Hinckley, Douglas G. SprugelAbstract:: Dark respiration of Foliage was measured in a 30-year-old stand of Abies amabilis in western Washington from June to November. Both laboratory and field measurements were used to study the effect of environmental and tree variables on respiration. Foliage respiration rates were most strongly influenced by needle temperature. After accounting for leaf temperature differences, Foliage respiration decreased with depth in the canopy for all age classes of Foliage. Respiration differences attributed to location within the canopy were greatest early in the growing season, but were still significant in November. Younger Foliage respired more than older Foliage in the upper canopy, but not in the lower canopy. Respiration differences due to Foliage age were highly significant in the early growing season, but were not detectable by mid-October.
