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1.
J Plant Res ; 137(1): 49-64, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37962735

RESUMEN

Species in dry environments may adjust their anatomical and physiological behaviors by adopting safer or more efficient strategies. Thus, species distributed across a water availability gradient may possess different phenotypes depending on the specific environmental conditions to which they are subjected. Leaf and vascular tissues are plastic and may vary strongly in response to environmental changes affecting an individual's survival and species distribution. To identify whether and how legumes leaves vary across a water availability gradient in a seasonally dry tropical forest, we quantified leaf construction costs and performed an anatomical study on the leaves of seven legume species. We evaluated seven species, which were divided into three categories of rainfall preference: wet species, which are more abundant in wetter areas; indifferent species, which are more abundant and occur indistinctly under both rainfall conditions; and dry species, which are more abundant in dryer areas. We observed two different patterns based on rainfall preference categories. Contrary to our expectations, wet and indifferent species changed traits in the sense of security when occupying lower rainfall areas, whereas dry species changed some traits when more water was available, such as increasing cuticle and spongy parenchyma thickness, or producing smaller and more numerous stomata. Trischidium molle, the most plastic and wet species, exhibited a similar strategy to the dry species. Our results corroborate the risks to vegetation under future climate change scenarios as stressed species and populations may not endure even more severe conditions.


Asunto(s)
Árboles , Agua , Árboles/fisiología , Sequías , Clima Tropical , Bosques , Hojas de la Planta/fisiología
2.
Tree Physiol ; 44(1)2024 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-38102768

RESUMEN

Leaf nutrient resorption and drought resistance are crucial for the growth and survival of plants. However, our understanding of the relationships between leaf nutrient resorption and plant drought resistance is still limited. In this study, we investigated the nitrogen and phosphorus resorption efficiencies (NRE and PRE), leaf structural traits, leaf osmotic potential at full hydration (Ψosm), xylem water potential at 50% loss of xylem-specific hydraulic conductivity (P50) and seasonal minimum water potential (Ψmin) for 18 shrub and tree species in a semiarid savanna ecosystem, in Southwest China. Our results showed that NRE and PRE exhibited trade-off against drought resistance traits (Ψosm and P50) across woody species. Moreover, this relationship was modulated by leaf structural investment. Species with low structural investment (e.g., leaf mass per area, leaf dry mass content and leaf construction cost [LCC]) tend to have high NRE and PRE, while those with high LCCs show high drought resistance, showing more negative Ψosm and P50.These results indicate that species with a lower leaf structural investment may have a greater need to recycle their nutrients, thus exhibiting higher nutrient resorption efficiencies, and vice versa. In conclusion, nutrient resorption efficiency may be a crucial adaptation strategy for coexisting plants in semiarid ecosystems, highlighting the importance of understanding the complex relationships between nutrient cycling and plant survival strategies.


Asunto(s)
Ecosistema , Pradera , Resistencia a la Sequía , Nitrógeno/análisis , Fósforo/análisis , Plantas , Árboles , China , Agua , Hojas de la Planta/química
3.
Math Biosci Eng ; 20(8): 15044-15074, 2023 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-37679171

RESUMEN

Predicting construction costs often involves disadvantages, such as low prediction accuracy, poor promotion value and unfavorable efficiency, owing to the complex composition of construction projects, a large number of personnel, long working periods and high levels of uncertainty. To address these concerns, a prediction index system and a prediction model were developed. First, the factors influencing construction cost were first identified, a prediction index system including 14 secondary indexes was constructed and the methods of obtaining data were presented elaborately. A prediction model based on the Random Forest (RF) algorithm was then constructed. Bird Swarm Algorithm (BSA) was used to optimize RF parameters and thereby avoid the effect of the random selection of RF parameters on prediction accuracy. Finally, the engineering data of a construction company in Xinyu, China were selected as a case study. The case study showed that the maximum relative error of the proposed model was only 1.24%, which met the requirements of engineering practice. For the selected cases, the minimum prediction index system that met the requirement of prediction accuracy included 11 secondary indexes. Compared with classical metaheuristic optimization algorithms (Particle Swarm Optimization, Genetic Algorithms, Tabu Search, Simulated Annealing, Ant Colony Optimization, Differential Evolution and Artificial Fish School), BSA could more quickly determine the optimal combination of calculation parameters, on average. Compared with the classical and latest forecasting methods (Back Propagation Neural Network, Support Vector Machines, Stacked Auto-Encoders and Extreme Learning Machine), the proposed model exhibited higher forecasting accuracy and efficiency. The prediction model proposed in this study could better support the prediction of construction cost, and the prediction results provided a basis for optimizing the cost management of construction projects.

4.
Ann Bot ; 131(3): 437-450, 2023 04 04.
Artículo en Inglés | MEDLINE | ID: mdl-36749684

RESUMEN

BACKGROUND AND AIMS: For a comprehensive understanding of the mechanisms of changing plant photosynthetic capacity during plant evolutionary history, knowledge of leaf gas exchange and optical properties are essential, both of which relate strongly to mesophyll anatomy. Although ferns are suitable for investigating the evolutionary history of photosynthetic capacity, comprehensive research of fern species has yet to be undertaken in this regard. METHODS: We investigated leaf optical properties, gas exchange and mesophyll anatomy of fern species with a wide range of divergence time, using 66 ferns from natural habitats and eight glasshouse-grown ferns. We used a spectroradiometer and an integrating sphere to measure light absorptance and reflectance by the leaves. KEY RESULTS: The more newly divergent fern species had a thicker mesophyll, a larger surface area of chloroplasts facing the intercellular airspaces (Sc), thicker cell walls and large light absorptance. Although no trend with divergence time was obtained in leaf photosynthetic capacity on a leaf-area basis, when the traits were expressed on a mesophyll-thickness basis, trends in leaf photosynthetic capacity became apparent. On a mesophyll-thickness basis, the more newly divergent species had a low maximum photosynthesis rate, accompanied by a low Sc. CONCLUSIONS: We found a strong link between light capture, mesophyll anatomy and photosynthesis rate in fern species for the first time. The thick mesophyll of the more newly divergent ferns does not necessarily relate to the high photosynthetic capacity on a leaf-area basis. Rather, the thick mesophyll accompanied by thick cell walls allowed the ferns to adapt to a wider range of environments through increasing leaf toughness, which would contribute to the diversification of fern species.


Asunto(s)
Helechos , Células del Mesófilo , Hojas de la Planta/anatomía & histología , Fotosíntesis , Cloroplastos , Dióxido de Carbono/metabolismo
5.
Ann Bot ; 130(3): 265-283, 2022 09 19.
Artículo en Inglés | MEDLINE | ID: mdl-35947983

RESUMEN

BACKGROUND: Plants invest photosynthates in construction and maintenance of their structures and functions. Such investments are considered costs. These costs are recovered by the CO2 assimilation rate (A) in the leaves, and thus A is regarded as the immediate, short-term benefit. In photosynthesizing leaves, CO2 diffusion from the air to the carboxylation site is hindered by several structural and biochemical barriers. CO2 diffusion from the intercellular air space to the chloroplast stroma is obstructed by the mesophyll resistance. The inverses is the mesophyll conductance (gm). Whether various plants realize an optimal gm, and how much investment is needed for a relevant gm, remain unsolved. SCOPE: This review examines relationships among leaf construction costs (CC), leaf maintenance costs (MC) and gm in various plants under diverse growth conditions. Through a literature survey, we demonstrate a strong linear relationship between leaf mass per area (LMA) and leaf CC. The overall correlation of CC vs. gm across plant phylogenetic groups is weak, but significant trends are evident within specific groups and/or environments. Investment in CC is necessary for an increase in LMA and mesophyll cell surface area (Smes). This allows the leaf to accommodate more chloroplasts, thus increasing A. However, increases in LMA and/or Smes often accompany other changes, such as cell wall thickening, which diminishes gm. Such factors that make the correlations of CC and gm elusive are identified. CONCLUSIONS: For evaluation of the contribution of gm to recover CC, leaf life span is the key factor. The estimation of MC in relation to gm, especially in terms of costs required to regulate aquaporins, could be essential for efficient control of gm over the short term. Over the long term, costs are mainly reflected in CC, while benefits also include ultimate fitness attributes in terms of integrated carbon gain over the life of a leaf, plant survival and reproductive output.


Asunto(s)
Dióxido de Carbono , Fotosíntesis , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Análisis Costo-Beneficio , Células del Mesófilo , Filogenia , Hojas de la Planta/fisiología
6.
Plant Cell Environ ; 45(4): 1286-1297, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35128680

RESUMEN

Across plant species and biomes, a conserved set of leaf traits govern the economic strategy used to assimilate and invest carbon. As plants age, they face new challenges that may require shifts in this leaf economic strategy. In this study, we investigate the role of the developmental transition, vegetative phase change (VPC), in altering carbon economics as plants age. We used overexpression of microRNA 156 (miR156), the master regulator of VPC, to modulate the timing of VPC in Populus tremula x alba, Arabidopsis thaliana and Zea mays to understand the impact of this transition on leaf economic traits, including construction cost, payback time and return on investment. Here, we find that VPC causes a shift from a low-cost, quick return juvenile strategy to a high-cost, high-return adult strategy. The juvenile strategy is advantageous in light-limited conditions, whereas the adult strategy provides greater returns in high light. The transition between these strategies is correlated with the developmental decline in the level of miR156, suggesting that is regulated by the miR156/SPL pathway. Our results provide an ecophysiological explanation for the existence of juvenile and adult leaf types and suggest that natural selection for these alternative economic strategies could be an important factor in plant evolution.


Asunto(s)
Arabidopsis , MicroARNs , Populus , Arabidopsis/genética , Arabidopsis/metabolismo , Carbono/metabolismo , Regulación de la Expresión Génica de las Plantas , MicroARNs/genética , MicroARNs/metabolismo , Hojas de la Planta/metabolismo , Populus/genética , Populus/metabolismo
7.
Tree Physiol ; 42(5): 1002-1015, 2022 05 09.
Artículo en Inglés | MEDLINE | ID: mdl-34875097

RESUMEN

Rising atmospheric CO2 concentration ([CO2]) and nitrogen (N) deposition are changing plant growth, physiological characteristics and chemical compositions; however, few studies have explored such impacts in a heavy metal-contaminated environment. In this study, we conducted an open-top chamber experiment to explore the impacts of 2 years of elevated atmospheric [CO2] and N addition on the growth, physiological characteristics and chemical compositions of five subtropical tree species in a cadmium (Cd)-contaminated environment. Results showed that N addition significantly increased concentration of leaf N and protein in five tree species and also decreased payback time (PBT) and leaf carbon:nitrogen ratios and increased tree relative height growth rate (RGR-H) and basal diameter growth rate (RGR-B) in Liquidambar formosana Hance and Syzygium hainanense Chang et Miau. Elevated [CO2] increased leaf maximum photosynthetic rate (Amax) and concentration of total non-structural carbohydrates and shortened PBT to offset the negative effect of Cd contamination on RGR-B in Acacia auriculiformis A. Cunn. ex Benth. The combined effects of elevated [CO2] and N addition did not exceed their separate effects on RGR-H and RGR-B in Castanopsis hystrix Hook. f. & Thomson ex A. DC. and Cinnamomum camphora (L.) presl. The addition of N significantly increased the concentration of leaf Cd by 162.1% and 338.0%, and plant Cd bio-concentration factor by 464% and 861% in C. hystrix and C. camphora, respectively, compared with only Cd addition. Among the five tree species, the decrease in PBT and the increase in Amax, RGR-B and concentrations of leaf protein in response to N and Cd addition under elevated [CO2] were on average 86.7% higher in A. auriculiformis than other species, suggesting that the mitigation of the negative effects of Cd pollution by elevated [CO2] and N addition among five species was species-specific. Overall, we concluded that N addition and elevated [CO2] reduced Cd toxicity and increased the growth rate in A. auriculiformis, S. hainanense and L. formosana, while it maintained the growth rate in C. hystrix and C. camphora by differently increasing photosynthetic rate, altering the leaf chemical compositions and shortening PBT.


Asunto(s)
Nitrógeno , Árboles , Cadmio/metabolismo , Dióxido de Carbono/metabolismo , Nitrógeno/metabolismo , Fotosíntesis/fisiología , Hojas de la Planta/fisiología , Suelo/química , Árboles/fisiología
8.
Healthcare (Basel) ; 9(7)2021 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-34356266

RESUMEN

The need for 24/7 operation, and the increasing requests of high-quality healthcare services contribute to framing healthcare facilities as a complex topic, also due to the changing and challenging environment and huge impact on the community. Due to its complexity, it is difficult to properly estimate the construction cost in a preliminary phase where easy-to-use parameters are often necessary. Therefore, this paper aims to provide an overview of the issue with reference to the Italian context and proposes an estimation framework for analyzing hospital facilities' construction cost. First, contributions from literature reviews and 14 case studies were analyzed to identify specific cost components. Then, a questionnaire was administered to construction companies and experts in the field to obtain data coming from practical and real cases. The results obtained from all of the contributions are an overview of the construction cost components. Starting from the data collected and analyzed, a preliminary estimation tool is proposed to identify the minimum and maximum variation in the cost when programming the construction of a hospital, starting from the feasibility phase or the early design stage. The framework involves different factors, such as the number of beds, complexity, typology, localization, technology degree and the type of maintenance and management techniques. This study explores the several elements that compose the cost of a hospital facility and highlights future developments including maintenance and management costs during hospital facilities' lifecycle.

9.
Artículo en Inglés | MEDLINE | ID: mdl-33628872

RESUMEN

Estimating regional costs of green infrastructure (GI) and low-impact development (LID) stormwater management controls is an important issue for many municipalities and water utilities in the United States. The National Stormwater Calculator (NSWC) is a site-scale, planning-level tool. A regional cost estimation methodology was recently added to the NSWC, enabling users to estimate region-specific capital and maintenance costs of commonly used GI controls. This paper discusses the approach used to estimate and regionalize costs in the NSWC.

10.
Mar Pollut Bull ; 163: 111958, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33444997

RESUMEN

Exotic species especially Asteraceae plants severely invade wetlands in Shenzhen Bay, an important part of the coast wetland in Guangdong-Hong Kong-Macau Bay Area, China. However, the reasons causing their expansion are unclear. The leaf traits and expansion indices of six invasive Asteraceae plants from the Overseas Chinese Town (OCT) wetland were studied and the results showed that nearly 45% of the total plant species (31 out of 69 species) in the OCT wetland, belonging to 15 families and 27 genera, were exotic invasive species. The expansion indices of six Asteraceae species negatively correlated with their leaf construction cost based on mass (CCM), caloric values and carbon concentration, but their relations with ash content were positive. Multiple linear regression analysis revealed that CCM was the most important factor affecting the expansion of an exotic species, indicating CCM may be an important reason causing the expansion of exotic species in coastal wetlands.


Asunto(s)
Asteraceae , Humedales , China , Hong Kong , Humanos , Macao , Hojas de la Planta
11.
Plants (Basel) ; 9(11)2020 Nov 06.
Artículo en Inglés | MEDLINE | ID: mdl-33172149

RESUMEN

E107 and E132 are pea mutants that nodulate poorly. Because they have a shoot-controlled nodulation phenotype, we asked if their mutated genes were implicated in the autoregulation of nodulation (AON), a mechanism which consists of two systemic circuits, the positive CEP/CRA2 and the negative CLE/SUNN, coordinated via NIN and miR2111. We further characterized the mutants' phenotype by studying nodule distribution and nodulation efficiency. E107 was similar to wild-type (WT) in its nodule distribution, but E132 had an extended nodulation zone with nodules forming distally on its lateral roots. Moreover, we tested whether their shoots produced a compound inhibitory to nodulation. We made ethyl-acetate extracts of roots and shoots of both mutants and WT, which we applied to rhizobia-inoculated WT seedlings and to pure rhizobial cultures. Whereas free-living bacteria were unaffected by any of the extracts, WT treated with shoot extracts from either inoculated mutant had fewer nodules than that of control. E107 and E132 shoot extracts led to a 50% and a 35% reduction in nodule number, respectively. We propose that E107 and E132 belong to a new sub-class of AON mutants, i.e., hypo-nodulators, and that their respective gene products are acting in the AON descending branch, upstream of TML signaling.

12.
Data Brief ; 32: 106068, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32775578

RESUMEN

Coronavirus Disease 2019 (COVID-19) has been identified as a global pandemic by the World Health Organization (WHO). The breakout of COVID-19 in various countries and regions brings a great threat to people's life and adds an unprecedented high pressure on healthcare systems. Due to the high infectivity of COVID-19, high standard negative pressure isolation units are required to accommodate the patients with COVID-19 and protect health workers. A novel prefabricated negative pressure isolation medical unit was designed and constructed in Shenzhen, China to help to accommodate the patients with COVID-19. This article provides detailed construction cost, time and testing data for this isolation medical unit. Considering the construction happened during the lockdown in Shenzhen (and in China), the construction cost and time can provide precious and rare information as well as guidelines to construct or expand appropriate medical facilities to accommodate the patients with COVID-19.

13.
New Phytol ; 228(6): 1796-1810, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32712991

RESUMEN

Leaf venation networks evolved along several functional axes, including resource transport, damage resistance, mechanical strength, and construction cost. Because functions may depend on architectural features at different scales, network architecture may vary across spatial scales to satisfy functional tradeoffs. We develop a framework for quantifying network architecture with multiscale statistics describing elongation ratios, circularity ratios, vein density, and minimum spanning tree ratios. We quantify vein networks for leaves of 260 southeast Asian tree species in samples of up to 2 cm2 , pairing multiscale statistics with traits representing axes of resource transport, damage resistance, mechanical strength, and cost. We show that these multiscale statistics clearly differentiate species' architecture and delineate a phenotype space that shifts at larger scales; functional linkages vary with scale and are weak, with vein density, minimum spanning tree ratio, and circularity ratio linked to mechanical strength (measured by force to punch) and elongation ratio and circularity ratio linked to damage resistance (measured by tannins); and phylogenetic conservatism of network architecture is low but scale-dependent. This work provides tools to quantify the function and evolution of venation networks. Future studies including primary and secondary veins may uncover additional insights.


Asunto(s)
Hojas de la Planta , Fenotipo , Filogenia
14.
Mar Pollut Bull ; 152: 110897, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31957670

RESUMEN

Laguncularia racemosa and Sonneratia apetala are fast-growing exotic mangrove species in Southern China and widely used for afforestation. However, the invasiveness of the two exotic species is still unclear. We compared structural and physiological traits and energy-use related traits between L. racemosa and S. apetala, and with two natives (Kandelia obovata and Aegiceras corniculatum) in northern Fujian. Results showed that leaf construction cost based on mass (CCM) and caloric values of L. racemosa were significantly lower than S. apetala, and the two natives had highest CCM. Because lower CCM, L. racemosa grew faster with a taller height (4.83 m) and wider ground diameter circumference (40.03 cm) than S. apetala (4.43 m tall and 35.63 cm wide) and the two natives (2.42 m tall and 26.78 cm wide). These findings indicated that L. racemosa could be more invasive than S. apetala in mangrove forests in northern Fujian, China where it still grew well, which deserves more attention.


Asunto(s)
Combretaceae , Rhizophoraceae , China , Bosques , Hojas de la Planta
15.
Plant Physiol Biochem ; 147: 181-190, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31865164

RESUMEN

Exotic plants in semiarid region have developed strategies for efficient use or capture of resources. They have become invasive and outperform native species. To understand which factors could explain the success of invasive woody species in a semiarid region, several physiological traits were analyzed in young plants of two invasive and two native species exposed to different water availability. Invasive plants showed low leaf construction cost, high phosphorus and nitrogen contents, reduced loss of instantaneous energy use efficiency, and smaller specific leaf area when compared to native species. This strategy led to a higher biomass gain and a high root/shoot ratio in both water treatments. After rehydration, invasive plants showed faster recovery and higher rates of CO2 assimilation. This resilience is fundamental for species in semiarid regions, and also increase uptake of nutrients. Maintaining a high photosynthetic rate, whenever there is water availability is a strategy that increases the performance of the species in relation to biomass gain. The low leaf construction cost and the fast recovery of the photosynthetic metabolism of invasive plants after limiting water resources explains the success of these species, and suggests that their potential may increase under prolonged and severe drought seasons.


Asunto(s)
Sequías , Bosques , Hojas de la Planta , Estrés Fisiológico , Especies Introducidas , Fotosíntesis , Hojas de la Planta/fisiología , Estaciones del Año , Árboles , Clima Tropical
16.
Plant Physiol Biochem ; 139: 307-313, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30927693

RESUMEN

Under drought and soil salinity, plants usually respond to accumulate inorganic and organic osmolytes for adaptation, that would induce changes in energy consumption strategy of plants. Moderate soil salinity would enable plants to lower energy consumption for osmotic adjustment by passively absorbing more Na+. This action would keep more energies for growth of drought-stressed plants. Thus, Na+ accumulation might be an energy-efficient strategy for plants to cope with drought was speculated. To support this speculation, we assessed the effects of soil salinity on osmotic adjustment and energy utilization under drought in this study. Our results indicated that the ratio and content of inorganic osmolytes was significantly higher under drought-saline stress (D + S) than those under single drought stress (D), while the osmolarity and contents of organic osmolytes of D + S were significantly lower than those of D. This indicated that moderate soil salinity could enable soybean seedlings to consume relatively lower energies to produce less organic osmolytes and accumulate more inorganic ions for osmotic adjustment coping with drought. Meanwhile the water content, cell turgor, ash content, and specific leaf area and biomass of D + S were significantly higher than those of D, but the leaf construction cost of D + S was significantly lower than those of D. This suggested that moderate soil salinity could enhance water retention, and reduce the photoassimilate and energy consumption of droughty soybean seedlings. This work would help to understand the positive effects of moderate soil salinity on plant growth on the level of osmotic adjustment and energy consumption strategy.


Asunto(s)
Sequías , /metabolismo , Ósmosis/efectos de los fármacos , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Cloruro de Sodio/farmacología
17.
Braz. j. microbiol ; 49(1): 45-53, Jan.-Mar. 2018. tab, graf
Artículo en Inglés | LILACS | ID: biblio-889199

RESUMEN

ABSTRACT Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9 MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1 g) and osmotic potential (0.54 MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum.


Asunto(s)
Cucurbita/microbiología , Micorrizas/fisiología , Hongos/fisiología , Suelo/química , Agua/análisis , Agua/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Biomasa , Cucurbita/crecimiento & desarrollo , Cucurbita/fisiología , Micorrizas/aislamiento & purificación , Micorrizas/clasificación , Clima Desértico , Salinidad , Sequías , Hongos/aislamiento & purificación , Hongos/clasificación , México
18.
Front Plant Sci ; 9: 117, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29472939

RESUMEN

It is important to understand how eco-physiological characteristics shift in forests when elucidating the mechanisms underlying species replacement and the process of succession and stabilization. In this study, the dominant species at three typical successional stages (early-, mid-, and late-succession) in the subtropical forests of China were selected. At each stage, we compared the leaf construction costs (CC), payback time (PBT), leaf area based N content (NA), maximum CO2 assimilation rate (Pmax), specific leaf area (SLA), photosynthetic nitrogen use efficiency (PNUE), and leaf N allocated to carboxylation (NC), and to bioenergetics (NB). The relationships between these leaf functional traits were also determined. The results showed that the early-succession forest is characterized with significantly lower leaf CC, PBT, NA, but higher Pmax, SLA, PNUE, NC, and NB, in relation to the late-succession forest. From the early- to the late-succession forests, the relationship between Pmax and leaf CC strengthened, whereas the relationships between NB, NC, PNUE, and leaf CC weakened. Thus, the dominant species are able to decrease the allocation of the photosynthetic N fraction to carboxylation and bioenergetics during forest succession. The shift in these leaf functional traits and their linkages might represent a fundamental physiological mechanism that occurs during forest succession and stabilization.

19.
Braz J Microbiol ; 49(1): 45-53, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-28887008

RESUMEN

Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1g) and osmotic potential (0.54MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum.


Asunto(s)
Cucurbita/microbiología , Hongos/fisiología , Micorrizas/fisiología , Biomasa , Cucurbita/crecimiento & desarrollo , Cucurbita/fisiología , Clima Desértico , Sequías , Hongos/clasificación , Hongos/aislamiento & purificación , México , Micorrizas/clasificación , Micorrizas/aislamiento & purificación , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Salinidad , Suelo/química , Agua/análisis , Agua/metabolismo
20.
Rev. ing. bioméd ; 11(22): 53-58, jul.-dic. 2017. tab, graf
Artículo en Español | LILACS | ID: biblio-901825

RESUMEN

Resumen En este artículo se presenta el costo promedio por metro cuadrado en Colombia para el diseño y construcción de hospitales de tercer nivel de complejidad mediante la comparación del costo de diseño y construcción por metro cuadrado obtenido en otros países y en proyectos nacionales. Debido al total de la población colombiana y al número de camas disponibles existe un déficit del 42.3%, teniendo 1.5 camas por cada mil habitantes. De acuerdo con lo recomendado por la Organización Mundial de la Salud (OMS) este debe ser de 2.6 camas por cada mil habitantes. Por consiguiente, se requieren más proyectos de diseño y construcción de hospitales en los próximos años.


Abstract This article states the average cost per square meter in Colombia for the design and construction of third level complexity hospitals by comparing the design and construction square meter cost obtained in other countries and national projects. Due to the Colombian population and the number of beds there is a deficit of 42.3%, having 1.5 beds per thousand habitants. As recommended by the World Health Organization (WHO) which is 2.6 beds per thousand inhabitants. Therefore, more hospital design and construction projects are required in years to come.


Resumo Neste artigo obtém-se o custo promédio por metro quadrado na Colômbia para o desenho e construção de hospitais de terceiro nível de complexidade, mediante a comparação do custo de desenho e construção por metro quadrado obtido em outros países e em projetos nacionais. Devido à população Colombiana e ao número de camas há um déficit de 42.3%, tendo 1.5 camas por cada mil habitantes. De acordo com o recomendado pela OMS que é 2.6 camas por cada mil habitantes. Pelo que se requerem mais projetos de desenho e construção de hospitais nos próximos anos.

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