Gas exchange and water relations responses to drought of fast- and slow-growing black spruce families

1997 ◽  
Vol 75 (10) ◽  
pp. 1700-1706 ◽  
Author(s):  
Weixing Tan ◽  
Terence J. Blake
Keyword(s):  
Growth Rate ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Soil Water ◽  
Water Relations ◽  
Picea Mariana ◽  
Black Spruce ◽  
Turgor Pressure ◽  
Fast Growing ◽  
Slow Growing

To determine how different mechanisms of drought tolerance contribute to growth rate under drought, this study compared four full-sib black spruce (Picea mariana (Mill.) B.S.P.) families which differed in growth rate when soil water became limiting, stomatal conductance, photosynthesis, and water relations responses to drought. Repeated drought cycles were imposed by withholding soil water in a nursery and physiological responses were measured near the end of the first and third cycle. The most vigorous family under drought had greater osmotic adjustment and maintained higher rates of net photosynthesis during the first cycle of drought and resumed higher rates of photosynthesis sooner upon stress relief, compared with two slow-growing families. Pressure–volume analysis of drought-stressed shoot tissues indicated that the fast-growing family exhibited a larger degree of elastic enhancement (i.e., decrease in bulk modulus of elasticity), which would explain its higher turgor pressure, compared with the two less vigorous families. However, family differences in gas exchange and water relations largely diminished when seedlings were exposed to repeated cycles of drought. Therefore, fast-growing black spruce families under drought may gain selective growth advantage by a better ability to tolerate, rather than postpone, momentary dehydration. Short-term screening trials could be used to detect drought tolerant genotypes in black spruce. Key words: drought, family variation, photosynthesis, Picea mariana, stomatal conductance, water relations.

Diurnal and seasonal variations in gas exchange and water relations of lowland and upland black spruce ecotypes

1995 ◽  
Vol 73 (5) ◽  
pp. 716-722 ◽  
Author(s):  
Abdenbi Zine El Abidine ◽  
James D. Stewart ◽  
André P. Plamondon ◽  
Pierre Y. Bernier
Keyword(s):  
Gas Exchange ◽  
Environmental Factors ◽  
Water Relations ◽  
Picea Mariana ◽  
Black Spruce ◽  
Net Photosynthesis ◽  
Atmospheric Conditions ◽  
Mature Trees ◽  
Ecotypic Differentiation ◽  
Seasonal Responses

Gas exchange and water relations were measured on seedlings from two pairs of upland and lowland black spruce (Picea mariana (Mill.) BSP) populations. The seedlings were planted under natural atmospheric conditions in exterior sand beds. Measurements were carried out on eight separate days during the summer of 1992. Diurnal and seasonal responses of gas exchange and water relations parameters to natural changes in environmental factors were analyzed for possible ecotypic differences. Differences were found among the four populations and within one of the two upland–lowland pairs. However, no differences could be linked significantly to an upland–lowland ecotypic differentiation. The physiological responses are discussed with respect to diurnal and seasonal changes in environmental factors and to similarities with results from an earlier experiment involving mature trees from the same four populations. Key words: Picea mariana, water stress, net photosynthesis, stomatal conductance.

The Translocation of 14C-photoassimilate in Single Tree Progeny of White Spruce (Piceaglauca (Moench) Voss)

1973 ◽  
Vol 3 (2) ◽  
pp. 315-318 ◽  
Author(s):  
D. J. Ursino
Keyword(s):  
Growth Rate ◽  
White Spruce ◽  
Shoot Height ◽  
Fast Growing ◽  
Single Tree ◽  
Slow Growing

Young trees from seedlots representing single tree progeny of white spruce and assessed as either fast- or slow-growing on the basis of shoot height, were allowed to photoassimilate 14CO2 and either 24 or 48 h later, the magnitude and distribution of 14C were determined. In comparison to the slow-growing plants 48 h after 14CO2 photoassimilation, the fast-growing spruce retained a higher percentage of the assimilated 14C and translocated less to the root. Differences in growth rate between the seedlots did not affect the partitioning of 14C between the 80% ethanol-soluble and -insoluble fractions.

Effect of protozoan predation on relative abundance of fast- and slow-growing bacteria

1989 ◽  
Vol 35 (5) ◽  
pp. 578-582 ◽  
Author(s):  
James L. Sinclair ◽  
Martin Alexander
Keyword(s):  
Growth Rate ◽  
Bacterial Community ◽  
Relative Abundance ◽  
Growth Rates ◽  
Bacterial Species ◽  
Test Species ◽  
Fast Growing ◽  
Population Sizes ◽  
Slow Growing ◽  
Fast Growing Species

The survival of six bacterial species that had different growth rates was tested in raw sewage and sewage that was rendered free of protozoa. When test bacteria were added to protozoa-free sewage at densities of approximately 105 to 106 cells/mL, five of the six species did not decline below 105 cells/mL. If protozoa were present, the population sizes of all test species were markedly reduced, but bacterial species able to grow faster in artificial media had the larger number of survivors. When the same bacteria were inoculated into protozoa-free sewage at densities of less than 103 cells/mL, only the three species able to grow quickly in artificial media increased in abundance. When the six species were inoculated at the same densities into sewage containing protozoa, the three slow-growing species were rapidly eliminated, and two of the three fast-growing species survived in detectable numbers. We suggest that in environments with intense protozoan predation, protozoa may alter the composition of the bacterial community by eliminating slow-growing bacteria.Key words: growth rate, predation, protozoa, sewage.

scholarly journals Breast meat quality of chickens with divergent growth rates and its relation to growth curve parameters

2017 ◽  
Vol 60 (4) ◽  
pp. 427-437 ◽  
Author(s):  
Philipp C. Muth ◽  
Anne Valle Zárate
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Meat Quality ◽  
Growth Curve ◽  
Growth Rates ◽  
Cooking Loss ◽  
Growth Potential ◽  
Breast Meat ◽  
Fast Growing ◽  
Slow Growing

Abstract. The effects of the increase of body weight of contemporary broilers during growth on functional meat quality and color characteristics of the chicken breast muscle are controversially debated. Therefore, male chickens (n = 264) of a fast-growing commercial broiler (Ross 308) and two slow-growing experimental meat-type chicken lines were compared at equal age and at similar body weight in order to investigate the effect of growth rate on selected functional breast meat traits and meat color. Additionally, the breast meat characteristics of birds with different growth profiles were compared within lines. When the body weight of commercial broilers reached about 40 to 60 % of their growth potential, they exhibited particularly high ultimate pH values compared with slow-growing lines. The ability of the meat of fast-growing broilers to retain water during cooking was impaired (5 to 16 percentage points increased cooking loss compared to slow-growing lines), which, in contrast to pH, was only marginally affected by body weight and/or age at slaughter. No unfavorable correlations of breast meat quality traits with the growth profile, represented by growth curve parameters derived from the Gompertz–Laird equation, were detected within any of the investigated chicken lines. It is noteworthy that the associations of ultimate pH and cooking loss with maximum growth speed indicate a non-linear relationship. Thus, some of the functional characteristics of breast meat of the fast-growing broiler resembled the white-striping defect described for poultry meat, but the hypothesis that selection on increased growth rates is detrimental for meat quality per se could not be confirmed. In fact, an elevated growth potential in particular, i.e., body weight at maturity, could have some beneficial effects for the water-holding capacity of breast meat, regardless of the genotypic growth rate.

scholarly journals Analysis of the fecal microbiota of fast- and slow-growing rainbow trout (Oncorhynchus mykiss)

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Pratima Chapagain ◽  
Brock Arivett ◽  
Beth M. Cleveland ◽  
Donald M. Walker ◽  
Mohamed Salem
Keyword(s):  
Growth Rate ◽  
Gut Microbiota ◽  
Dna Extraction ◽  
Significant Variation ◽  
Extraction Methods ◽  
Fish Growth ◽  
Indicator Taxa ◽  
Fast Growing ◽  
Dna Extraction Methods ◽  
Slow Growing

Abstract Background Diverse microbial communities colonizing the intestine of fish contribute to their growth, digestion, nutrition, and immune function. We hypothesized that fecal samples representing the gut microbiota of rainbow trout could be associated with differential growth rates observed in fish breeding programs. If true, harnessing the functionality of this microbiota can improve the profitability of aquaculture. The first objective of this study was to test this hypothesis if gut microbiota is associated with fish growth rate (body weight). Four full-sibling families were stocked in the same tank and fed an identical diet. Two fast-growing and two slow-growing fish were selected from each family for 16S rRNA microbiota profiling. Microbiota diversity varies with different DNA extraction methods. The second objective of this study was to compare the effects of five commonly used DNA extraction methods on the microbiota profiling and to determine the most appropriate extraction method for this study. These methods were Promega-Maxwell, Phenol-chloroform, MO-BIO, Qiagen-Blood/Tissue, and Qiagen-Stool. Methods were compared according to DNA integrity, cost, feasibility and inter-sample variation based on non-metric multidimensional scaling ordination (nMDS) clusters. Results Differences in DNA extraction methods resulted in significant variation in the identification of bacteria that compose the gut microbiota. Promega-Maxwell had the lowest inter-sample variation and was therefore used for the subsequent analyses. Beta diversity of the bacterial communities showed significant variation between breeding families but not between the fast- and slow-growing fish. However, an indicator analysis determined that cellulose, amylose degrading and amino acid fermenting bacteria (Clostridium, Leptotrichia, and Peptostreptococcus) are indicator taxa of the fast-growing fish. In contrary, pathogenic bacteria (Corynebacterium and Paeniclostridium) were identified as indicator taxa for the slow-growing fish. Conclusion DNA extraction methodology should be carefully considered for accurate profiling of the gut microbiota. Although the microbiota was not significantly different between the fast- and slow-growing fish groups, some bacterial taxa with functional implications were indicative of fish growth rate. Further studies are warranted to explore how bacteria are transmitted and potential usage of the indicator bacteria of fast-growing fish for development of probiotics that may improve fish health and growth.

Aphid fitness on 13 grass species: a test of plant defence theory

2000 ◽  
Vol 77 (12) ◽  
pp. 1783-1789 ◽  
Author(s):  
Lauchlan H Fraser ◽  
J Philip Grime
Keyword(s):  
Growth Rate ◽  
Aboveground Biomass ◽  
Plant Defence ◽  
Grass Species ◽  
Fast Growing ◽  
Grain Aphid ◽  
Growth Rate Hypothesis ◽  
Aphid Feeding ◽  
Grass Growth ◽  
Slow Growing

The growth rate hypothesis, which states that fast-growing plants support more herbivores than slow-growing plants, was tested with 12 native and 1 naturalized British grasses using the grain aphid (Sitobion avenae). Five aphids were enclosed with grasses for two weeks in a growth chamber. After 2 weeks, fast-growing plants had 38 aphids, whilst slow-growing plants had 6, which supports the growth-rate hypothesis. When aphid numbers were analysed on plants according to "CSR" theory (Grime 1977, 1979), ruderals (R) had 54, competitors (C) had 18, and stress tolerators (S) had 6. This supports the predictions of CSR theory. Furthermore, aphid numbers increased significantly with grass growth rates and a mollusc palatability index, although this largely resulted from a single outlier, Poa annua. Aphid number was not affected by hairs on grasses. Finally, the effect of aphid feeding on grasses was tested. Generally, the greatest change in total and aboveground biomass of the grasses was found in the ruderals, whilst stress tolerators had the least amount of change.

Water relations of temperate mistletoes on various hosts

2002 ◽  
Vol 29 (1) ◽  
pp. 89 ◽  
Author(s):  
Graham L. Strong ◽  
Peter Bannister
Keyword(s):  
New Zealand ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Relations ◽  
Daily Minimum ◽  
Relative Water ◽  
Artificial Shading ◽  
Osmotic Potentials ◽  
Moduli Of Elasticity ◽  
Water Contents

The daily field water relations and gas exchange of the temperate mistletoes Ileostylus micranthus (Hook.f.) Tiegh. and Tupeia antarctica Cham. et Schlecht. on various hosts were examined seasonally in Dunedin, New Zealand during 1996–1998. Mistletoes commonly have higher transpiration rates (E) than their hosts, and this is generally cited as the reason why mistletoes develop lower water potentials (ψ) than their hosts. The mistletoe-host pairs that we examined showed no significant overall differences in E and stomatal conductance (g), and we used them to test the hypothesis that lowered ψ in mistletoes result from higher E. Despite the lack of differences in E and g, osmotic potentials, predawn and daily minimum ψ (ψmin) were significantly more negative in mistletoes, although differences between host and mistletoe ψ were less on hosts with low osmotic potentials and ψ. Mistletoes maintained lower ψ than their hosts both when unshaded and under artificial shading, had lower ψ than hosts at equal E, but had shoot hydraulic resistances similar to that of their hosts. E and ψ of hosts and mistletoes tended to be coordinated only in summer, when hosts were most water-stressed. Mistletoes maintained higher relative water contents at turgor loss, symplastic water contents, and bulk moduli of elasticity (ε) than their hosts. We conclude that the lower ψ in these temperate mistletoes are a consequence of greater mistletoe E only when host ψ are low, but are otherwise maintained by greater succulence and higher ε than in their hosts.

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