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1

The influence of disturbance type on precipitation − use efficiency at functional group and species scales in an arid habitat

100%
Busso C. A., Montenegro O. A., Torres Y. A., Giorgetti H. D., Rodriguez G. D.
Polish Journal of Ecology
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2016
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tom 64
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nr 2
We used long-term datasets (1984–1992) to contrast precipitation-use efficiency estimates between various disturbance kinds at a functional group and/or a species scale. Effects of varying amounts of precipitation and plant cover on PUE were also examined. Field studies were conducted at northeastern, arid Patagonia, Argentina (40°39′49″S, 62°53′6.4″W). Within each management kind, biomass was sampled in 0.5 × 0.5m permanent plots (n = 30) over 9 years after defoliation at 5 cm stubble at the end of each growing season, and it was separated into species. Biomass sampling allowed determination of annual net primary production. Thereafter, species were grouped into each of three functional groups. Precipitation-use efficiency (PUE) was calculated as the total dry matter produced per unit surface area on any given year divided by the total rainfall in that year. Plant cover on 20 out of those 30 plots was determined to study the relationship between plant cover and PUE. The contribution of cool-season perennial grasses to total PUE was higher (P <0.05) than that found for the other two functional groups in all management kinds and years. PUE was similar (P> 0.05) in wet than dry years, and it was greater (P <0.05) or similar (P> 0.05), but not lower, on the more than less competitive perennial grass species in all management kinds. The relationship between plant cover and PUE was positive, linear (P <0.0000) and management-kind dependent.
2
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Antioxidant response in natural senescence of Sempervivum tectorum L. leaves

80%
Glusac J., Veljovic-Jovanovic S., Kukavica B.
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
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2013
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tom 94
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nr 2
3
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Changes in ion (K, Ca and Na) regulation, antioxidant enzyme activity and photosynthetic pigment content in melon genotypes subjected to salt stress - a mixture modeling analysis

80%
Erdinc C.
Acta Scientiarum Polonorum. Hortorum Cultus
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2018
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tom 17
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nr 1
The present study aimed to identify the response of melon accessions and cultivars to salt stress in terms of ion exchange, enzyme activity, lipid peroxidation and photosynthetic pigment contents by mixture modelling. In mixture modeling, it is expected that the data set demonstrates a heterogeneous structure. This heterogeneity is characterized as unobservable heterogeneity. The data set’s heterogeneity produces severe deviations in the parameter assessments and the standard deviations. Heterogeneity is overcome when the data set separates itself into homogeneous sub-populations. Mixture modeling was performed using the Mclust mixture cluster program of the statistical software package R 5.2.3. Sub-populations were constructed by evaluating genotypes according to studied traits and correlation analysis was performed using the SPSS software package. The seedlings of 13 melon genotypes were harvested two weeks after salt application (0 mM or 50 mM NaCl) when symptoms of salt stress were observed. Nutrient contents and ratios (K, Ca, Na, K : Na and Ca : Na); superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities malondialdehyde (MDA) chlorophyll a, chlorophyll b, total chlorophyll and carotenoid contents were measured. Mixture modeling and correlation analysis were used in evaluating the experimental data sets. Differences in responses to salt application were observed among genotypes. While all genotypes exhibited negative responses in terms of K : Na ratio, which is an important parameter of salt tolerance, the smallest decreases in K : Na ratios were observed in the YYU-11 (–57.09%) and YYU-4 (–58.78%) genotypes, indicating them to be the most tolerant to salt stress. In general, enzyme activity decreased in response to salt application, although the responses varied among genotypes, especially with regard to CAT and APX activity. The YYU-29 genotype was notable as the genotype with the highest K : Na ratio (1.79) as well as the smallest change in MDA content under salt stress.
4

Anatomical and chemical adaptation of Spartium junceum L. in arid habitat

80%
Bezic N., Dunkic V., Radonic A.
Acta Biologica Cracoviensia. Series Botanica
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2003
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tom 45
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nr 2
A number of anatomical adaptations to an arid habitat can be noted in the microscopic structure of Spartium junceum L. vegetative organs. The xerophytic adaptation of the leaf is seen in its short life and the transformation of its inner structure, with palisade parenchyma dominating. The top part of the stem has taken over the leaf function, while sclerenchyma fiber and conductive elements occupy most of its secondary units. A peculiar feature of the primary structure of the root is its incompletely developed endodermis, and the secondary structure points to its storage and mechanical roles. GC/MS analyses of the essential oils showed that they consist mainly of monoterpene hydrocarbons with α-thujene as the main compound. The essential oils also play a xeromorphic role in this plant species.
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