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Percentage Loss (percentage + loss)
Selected AbstractsConsistency of resistance to attack by the green spruce aphid (Elatobium abietinum Walker) in different ontogenetic stages of Sitka spruceAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2003S. Harding Abstract 1,The susceptibility of different genotypes of 29-year-old Sitka spruce to damage by the green spruce aphid, Elatobium abietinum, was investigated in a progeny trial where aphid damage on individual trees had previously been assessed twice in an earlier stage of ontogenetic development. The progeny trial comprised 14 open-pollinated families originating from a clonal seed orchard that had been established using mature spruce trees selected for aphid resistance. 2,Previous investigations had demonstrated that resistance was inherited by the offspring, and that differences in resistance between progenies of the individual orchard clones were highly significant. 3,Susceptibility to aphid attack was recorded as the percentage loss of previous year's needles. Differences in susceptibility recorded between the juvenile trees were found to persist after the trees had developed into the closed-canopy, sexually reproducing stage. Needle loss of the families was significantly less than that of the reference population of Sitka spruce. 4,Hybrids between Sitka spruce and white spruce were defoliated more heavily than pure Sitka spruce, and the difference increased with age. 5,Family heritability of resistance was estimated as 0.60 compared to 0.73 when the trees were assessed in the juvenile stage. The genetic correlation based on family means between damage in the juvenile and sexually reproducing stand was high (0.83), indicating a high consistency of resistance to the aphid over years and ontogenetic stages. 6,A skewed distribution of defoliation indicated that major genes are involved in the expression of resistance, and that the genetics behind resistance has a nonadditive component. [source] Freeze,thaw-induced embolism in Pinus contorta: centrifuge experiments validate the ,thaw-expansion hypothesis' but conflict with ultrasonic emission dataNEW PHYTOLOGIST, Issue 4 2010Stefan Mayr Summary ,The ,thaw-expansion hypothesis' postulates that xylem embolism is caused by the formation of gas bubbles on freezing and their expansion on thawing. We evaluated the hypothesis using centrifuge experiments and ultrasonic emission monitoring in Pinus contorta. ,Stem samples were exposed to freeze,thaw cycles at varying xylem pressure (P) in a centrifuge before the percentage loss of hydraulic conductivity (PLC) was measured. Ultrasonic acoustic emissions were registered on samples exposed to freeze,thaw cycles in a temperature chamber. ,Freeze,thaw exposure of samples spun at ,3 MPa induced a PLC of 32% (one frost cycle) and 50% (two cycles). An increase in P to ,0.5 MPa during freezing had no PLC effect, whereas increased P during thaw lowered PLC to 7%. Ultrasonic acoustic emissions were observed during freezing and thawing at ,3 MPa, but not in air-dried or water-saturated samples. A decrease in minimum temperature caused additional ultrasonic acoustic emissions, but had no effect on PLC. ,The centrifuge experiments indicate that the ,thaw-expansion hypothesis' correctly describes the embolization process. Possible explanations for the increase in PLC on repeated frost cycles and for the ultrasonic acoustic emissions observed during freezing and with decreasing ice temperature are discussed. [source] New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L.PLANT CELL & ENVIRONMENT, Issue 8 2004S. SALLEO ABSTRACT Xylem recovery from embolism was studied in Laurus nobilis L. stems that were induced to cavitate by combining negative xylem pressure potentials (PX = ,1.1 MPa) with positive air pressures (PC) applied using a pressure collar. Xylem refilling was measured by recording the percentage loss of hydraulic conductance (PLC) with respect to the maximum 2 min, 20 min and 15 h after pressure release. Sodium orthovanadate (an inhibitor of many ATP-ases) strongly inhibited xylem refilling while fusicoccin (a stimulator of the plasma membrane H+ -ATPase) promoted complete embolism reversal. So, the refilling process was interpreted to result from energy-dependent mechanisms. Stem girdling induced progressively larger inhibition to refilling the nearer to the embolized stem segment phloem was removed. The starch content of wood parenchyma was estimated as percentages of ray and vasicentric cells with high starch content with respect to the total, before and after stem embolism was induced. A closely linear positive relationship was found to exist between recovery from PLC and starch hydrolysis. This, was especially evident in vasicentric cells. A mechanism for xylem refilling based upon starch to sugar conversion and transport into embolized conduits, assisted by phloem pressure-driven radial mass flow is proposed. [source] The Effect of Hurricane Iris on the Food Supply of Black Howlers (Alouatta pigra) in Southern Belize1BIOTROPICA, Issue 1 2005Mary S. M. Pavelka ABSTRACT Hurricanes frequently affect the forests of South and Central America; however, few studies have quantified their effects to forest structure, especially when concentrating on the food supply of an animal population. Hurricane Iris made landfall in Southern Belize on 8 October 2001, severely damaging a 52 hectare site where the behavioral ecology of a population of Central American Black Howlers (Alouatta pigra) had been under study for 2.5 yr. The hurricane resulted in a mortality rate of 35 percent for major food trees, which was primarily attributed to uprooting, snapping, and major delimbing. This damage accounted for 97 percent of the food tree loss between the two sample periods. Tree species differences were found in both the percentage loss and category of damage to food trees. Trees of different heights also experienced different percentage loss and levels of damage; subcanopy and emergent trees experienced higher loss than canopy trees, and subcanopy trees were frequently uprooted. This was partially attributed to a lack of buttressing on these subcanopy trees. Buttressing was found to decrease the frequency of uprooting. Tree size was the only factor that did not influence either damage or death. Trees from which fruit were eaten by black howlers died more than twice as often as did trees eaten for leaves. [source] Effect of Substrate Temperature on the Plasma Polymerization of Poly(methyl methacrylate),CHEMICAL VAPOR DEPOSITION, Issue 1 2006B. Casserly Abstract Low-power, plasma-enhanced (PE)CVD together with polymerization of methyl methacrylate (MMA) can be used to deposit thin films of poly(methyl methacrylate) (PMMA) with,minimal loss of functional groups, as shown by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Raman spectrometry (RS). Retention of functional groups decreases with increased substrate temperature, corresponding to decreased deposition rates. From XPS data, the calculated percentage loss of functional groups ranges from 0.9,% to 43.4,%, changing as a function of deposition conditions. RS confirms the presence of C=C bonds in the polymer backbone as a result of scission of the ester group from MMA. The thermal properties of PECVD-produced films from MMA can be tailored by varying the substrate temperature. Onset of thermal decomposition increases with increased substrate temperature by eliminating thermally labile peroxide linkages in the polymer backbone, and by crosslinking that occurs at radical sites generated via scission of functional group bonds. The post-anneal thicknesses of the remaining polymer is of the order of 4,nm or less, indicating that low-power PECVD of PMMA is a viable candidate to act as a sacrificial material for air-gap fabrication. [source] Peroxidase activity, chlorophylls and antioxidant profile of two leaf vegetables (Solanum nigrum L. and Amaranthus cruentus L.) under six pretreatment methods before cookingINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2008Odunayo Clement Adebooye Summary The study evaluated the effects of six pretreatment methods before cooking on the peroxidase activity, chlorophyll and antioxidant profile of Amaranthus cruentus L. and Solanum nigrum L. The six pretreatments methods used were chopped only (raw sample) (coded M1); chopped and dried at 50 °C for 5 h (coded M2); chopped and squeezed in water (at room temperature) (coded M3); chopped and soaked in warm water (approximately 60 °C), then cooled and squeezed (coded M4); chopped and soaked in salt-treated water (approximately 20 g NaCl per litre of water) for 15 min, then squeezed (coded M5) and chopped and soaked in boiling water (100 °C), then cooled and squeezed (coded M6). The main effect of vegetable type and the main effect of pretreatment methods have significant effects (P 0.05) on the parameters measured, while the interaction of vegetable type and pretreatment methods have no significant effect on the parameters measured. Statistical analyses (P 0.05) showed that chlorophyll a and b occur in ratio 3:1 in the two vegetables, irrespective of the pretreatment imposed. Peroxidase activity test showed that A. cruentus, irrespective of the pretreatment imposed showed, no peroxidase activity, while S. nigrum showed high peroxidase activity for all the pretreatments except for M6. Results showed that there was a significantly (P 0.05) higher content of carotenoids in A. cruentus when compared with S. nigrum, while the total phenolics, total flavonoids and total tannins contents were higher in S. nigrum when compared with A. cruentus, irrespective of the pretreatment method used. For the two vegetables, the percentage losses in total carotenoids, phenolics, flavonoids and total tannins at M6 when compared with M1 were 53.3,60.5%, 55.6,57.1%, 62.4,63.6% and 66.1,73.5%, respectively. There was a sharp drop in the carotenoids, phenolics, flavonoids and tannins contents of the two vegetables at M4 and M6, with both treatments having closely similar values for each parameter. [source] Effect of drying and storage on the degradation of total carotenoids in orange-fleshed sweetpotato cultivarsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2010Aurélie Bechoff Abstract BACKGROUND: Orange-fleshed sweetpotato (OFSP) can be used to tackle vitamin A deficiency, a major public health problem in most developing countries. In East Africa, common ways of using sweetpotato include drying and subsequent storage. The aim of the study was to investigate the impact of drying and storage on the total carotenoid retention (as an estimate of provitamin A retention) from OFSP. RESULTS: Losses of total carotenoid during drying were generally low (15% or less). Total carotenoid retention in OFSP was not dependent on the type of dryer (solar or sun). Sweetpotato cultivar (Ejumula, Kakamega, SPK004/1, SPK004/1/1, SPK004/6 or SPK004/6/6) had a significant effect on retention in drying (P < 0.05). High percentage losses of total carotenoids were, however, correlated with high moisture content and high carotenoid content in fresh sweetpotato roots. After 4 months' storage at room temperature in Uganda, losses of total carotenoid in dried sweetpotato chips were high (about 70%) and this was not dependent on the use of opaque or transparent packaging. CONCLUSION: Losses of carotenoids during storage were considered to be more of a nutritional constraint to the utilisation of dried sweetpotato than losses occurring during drying. The relationship between characteristics of the cultivars and losses of carotenoids during drying should be taken into account in selection of cultivars for processing. Copyright © 2009 Society of Chemical Industry [source] | |||||||||||||