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1.
Molecules ; 29(13)2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38999110

ABSTRACT

Electrochemical biosensors have emerged as powerful tools for the ultrasensitive detection of lung cancer biomarkers like carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), and alpha fetoprotein (AFP). This review comprehensively discusses the progress and potential of nanocomposite-based electrochemical biosensors for early lung cancer diagnosis and prognosis. By integrating nanomaterials like graphene, metal nanoparticles, and conducting polymers, these sensors have achieved clinically relevant detection limits in the fg/mL to pg/mL range. We highlight the key role of nanomaterial functionalization in enhancing sensitivity, specificity, and antifouling properties. This review also examines challenges related to reproducibility and clinical translation, emphasizing the need for standardization of fabrication protocols and robust validation studies. With the rapid growth in understanding lung cancer biomarkers and innovations in sensor design, nanocomposite electrochemical biosensors hold immense potential for point-of-care lung cancer screening and personalized therapy guidance. Realizing this goal will require strategic collaboration among material scientists, engineers, and clinicians to address technical and practical hurdles. Overall, this work provides valuable insight for developing next-generation smart diagnostic devices to combat the high mortality of lung cancer.


Subject(s)
Biomarkers, Tumor , Biosensing Techniques , Electrochemical Techniques , Lung Neoplasms , Humans , Biomarkers, Tumor/analysis , Lung Neoplasms/diagnosis , Biosensing Techniques/methods , Electrochemical Techniques/methods , Carcinoembryonic Antigen/analysis , Carcinoembryonic Antigen/blood , Nanocomposites/chemistry , Graphite/chemistry
2.
Int J Mol Sci ; 25(3)2024 Jan 23.
Article in English | MEDLINE | ID: mdl-38338664

ABSTRACT

Irrigation and fertilization are essential management practices for increasing forest productivity. They also impact the soil ecosystem and the microbial population. In order to examine the soil bacterial community composition and structure in response to irrigation and fertilization in a Eucalyptus plantations, a total of 20 soil samples collected from Eucalyptus plantations were analyzed using high-throughput sequencing. Experimental treatments consisting of control (CK, no irrigation or fertilization), fertilization only (F), irrigation only (W), and irrigation and fertilization (WF). The results showed a positive correlation between soil enzyme activities (urease, cellulase, and chitinase) and fertilization treatments. These enzyme activities were also significantly correlated with the diversity of soil bacterial communities in Eucalyptus plantations.. Bacteria diversity was considerably increased under irrigation and fertilization (W, F, and WF) treatments when compared with the CK treatment. Additionally, the soil bacterial richness was increased in the Eucalyptus plantations soil under irrigation (W and WF) treatments. The Acidobacteria (38.92-47.9%), Proteobacteria (20.50-28.30%), and Chloroflexi (13.88-15.55%) were the predominant phyla found in the Eucalyptus plantations soil. Specifically, compared to the CK treatment, the relative abundance of Proteobacteria was considerably higher under the W, F, and WF treatments, while the relative abundance of Acidobacteria was considerably lower. The contents of total phosphorus, accessible potassium, and organic carbon in the soil were all positively associated with fertilization and irrigation treatments. Under the WF treatment, the abundance of bacteria associated with nitrogen and carbon metabolisms, enzyme activity, and soil nutrient contents showed an increase, indicating the positive impact of irrigation and fertilization on Eucalyptus plantations production. Collectively, these findings provide the scientific and managerial bases for improving the productivity of Eucalyptus plantations.


Subject(s)
Eucalyptus , Soil , Soil/chemistry , Ecosystem , Bacteria , Proteobacteria , Acidobacteria , Carbon , Fertilization , Soil Microbiology
3.
Nurse Educ Pract ; 75: 103880, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38219504

ABSTRACT

BACKGROUND: The hidden curriculum in baccalaureate nursing programs is a means of moral education. Evaluation of the curriculum by students and faculty can increase awareness of its characteristics, which could be useful for planning and further development. OBJECTIVES: This study's aim was to translate the Hidden Curriculum Evaluation Scale in Nursing Education (HCES-N) to Chinese, adapt the scale to the Chinese culture and evaluate its validity and reliability in a sample of undergraduate nursing students. DESIGN: Psychometric assessment of a tool using two cross-sectional surveys. SETTINGS: University-based schools of nursing in seven provinces and cities of China. PARTICIPANTS: Undergraduate nursing students in a baccalaureate program. METHODS: The English version of the HCES-N was translated to Chinese using the Brislin translation model. The test-retest, internal consistency and split-half reliabilities of the HCES-N were examined in a sample of 1016 undergraduate nursing students. Exploratory factor analysis and confirmatory factor analysis were conducted to examine the scale's content validity. RESULTS: The exploratory factor analysis of the final 44-item HCES-N revealed three common factors and a cumulative variance contribution rate of 73.535%. The results of the confirmatory factor analysis showed that the final 44-item, 3-factor model was adequate for the s cale's structure (Chi-square/df = 6.59, RMSEA = 0.074, SRMR = 0.040, CFI = 0.911 and TLI = 0.905). The results confirmed that the Chinese version of HCES-N had good internal consistency (Cronbach α = 0.945); the scale's split-half-reliability was 0.794 and its test-retest reliability after two weeks was 0.894. CONCLUSION: The Chinese version of the HCES-N has good reliability and validity and it can be used to assess the hidden curriculum in baccalaureate nursing programs.


Subject(s)
Education, Nursing, Baccalaureate , Education, Nursing , Students, Nursing , Humans , Education, Nursing, Baccalaureate/methods , Psychometrics/methods , Reproducibility of Results , Cross-Sectional Studies , Surveys and Questionnaires , China
4.
Glob Public Health ; 18(1): 2236680, 2023 01.
Article in English | MEDLINE | ID: mdl-37515821

ABSTRACT

This study examines three aspects of successful aging including subjective health, cognitive ability, and social participation and their relations with environmental conditions and environmental awareness. We used the seemingly uncorrelated regression and multilevel models to estimate the joint relationship by combining the Chinese General Social Survey (2013 and 2021) (N = 5404 and 1580 accordingly) and the Chinese Statistical Yearbook and used propensity score analysis to identify potential endogenous issues. The first finding is that older people who were men, married, lived in urban areas, or received social security had an edge in aging successfully. Secondly, the adverse effects of environmental pollution on older adults' cognitive ability and social participation can be reduced by the protective effects of environmental awareness. Additionally, air pollution had more apparent effects, and water pollution was more modest in social involvement. This study offers empirical results to enhance the well-being of the older population by lifting their environmental perception and improving environmental quality.


Subject(s)
Aging , Air Pollution , Male , Humans , Aged , Female , Air Pollution/adverse effects , China , Water Pollution/analysis , Environmental Pollution/analysis
5.
Front Microbiol ; 14: 1113616, 2023.
Article in English | MEDLINE | ID: mdl-37056748

ABSTRACT

Climatic change causes obvious seasonal meteorological drought in southern China, yet there is a lack of comprehensive in situ studies on the effects of drought in Eucalyptus plantations. Here, a 50% throughfall reduction (TR) experiment was conducted to investigate the seasonal variations of soil bacterial and fungal communities and functions in a subtropical Eucalyptus plantation and their responses to TR treatment. Soil samples were collected from control (CK) and TR plots in the dry and rainy seasons and were subjected to high-throughput sequencing analysis. Results showed that TR treatment significantly reduced soil water content (SWC) in the rainy season. In CK and TR treatments, fungal alpha-diversity decreased in the rainy season while bacterial alpha-diversity did not change significantly between dry and rainy seasons. Moreover, bacterial networks were more affected by seasonal variations compared with fungal networks. Redundancy analysis showed that alkali hydrolyzed nitrogen and SWC contributed the most to the bacterial and fungal communities, respectively. Functional prediction indicated that the expression of soil bacterial metabolic functions and symbiotic fungi decreased in the rainy season. In conclusion, seasonal variations have a stronger effect on soil microbial community composition, diversity, and function compared with TR treatment. These findings could be used to develop management practices for subtropical Eucalyptus plantations and help maintain soil microbial diversity to sustain long-term ecosystem function and services in response to future changes in precipitation patterns.

6.
Sci Total Environ ; 861: 160607, 2023 Feb 25.
Article in English | MEDLINE | ID: mdl-36460101

ABSTRACT

People may perceive and expose negative sentiments in days with PM2.5 pollutions, but evidence is still insufficient about the joint effects of PM2.5 and socioeconomic factors on human sentiments. In this study, a total of 8032 facial photos of urban green space visitors were obtained from Sina Weibo in 50 cities of East China and rated for happy, sad, neutral scores and net positive emotion index (NPE; happy minus sad). Seasonal air PM2.5 concentrations were collected from days when people exposed faces in cities that were categorized to medium, large, outsize, and mega sizes according to resident populations (RPs). In summer, people posted lower sad score (11.28 %) than in winter (13.51 %; P = 0.0357) and higher NPE (35.86 %) than in autumn (30.92 %; P = 0.0009). Multivariate linear regression on natural logarithms revealed that factors of gross domestic product per capita (parameter estimate: 0.45), RP (0.59), non-production electricity consumption (0.34), and length of road transport (0.34) together generated positive contributions to posted happy score, while the total retail trade of consumer goods (-1.25) and PM2.5 (-0.50) were perceived as joint depressors on NPE. Overall, cities with more rich households and activated retail sales attracted more people who exposed smiles in weathers with PM2.5 compared to cities where local economy is reliable on heavy industry. The summertime in mega cities will be recommended to enjoy a higher frequency to perceive satisfaction due to exposure to low PM2.5.


Subject(s)
Air Pollutants , Air Pollution , Humans , Cities , Urbanization , Air Pollutants/analysis , Particulate Matter/analysis , Pilot Projects , Air Pollution/analysis , Parks, Recreational , Environmental Monitoring/methods , China , Socioeconomic Factors , Emotions
7.
Front Plant Sci ; 13: 1010178, 2022.
Article in English | MEDLINE | ID: mdl-36247588

ABSTRACT

Despite the importance of non-structural carbohydrates (NSC) for growth and survival in woody plants, we know little about whole-tree NSC storage. Here, Catalpa bungei trees fertilized using different schedules, including water and fertilizer integration, hole application, and no fertilization, were used to measure the spatial variations of sugar, starch, and NSC concentrations in the leaf, branch, stem, bark, and root. By calculating the volume of whole-tree NSC pools and the contribution of distinct organs, we were also able to compare the storage under various fertilization regimes. We found that the spatial distribution patterns of each organ undergoing different fertilization regimes were remarkably similar. Height-related increases in the sugar and NSC concentrations of the leaf and bark were observed. The concentrations of sugar and NSC in the branch did not appear to vary longitudinally or horizontally. The sugar and NSC concentrations in the stem fluctuated with height, first falling and then rising. The coarse root contained larger amounts of NSC components in comparison to fine root. Contrary to no fertilization, fertilization enhanced the distribution ratio of the leaf, branch, and stem NSC pools while decreasing the distribution ratio of the root NSC pool. Particularly, the addition of fertilizer and water significantly increased the biomass of the organs, enhancing the carbon sink of each organ and whole-tree in comparison to other fertilization regimes. Our main goal was to strengthen the empirical groundwork for comprehending the functional significance of NSC allocation and stock variations at the organ-level of C. bungei trees.

8.
Front Microbiol ; 13: 948875, 2022.
Article in English | MEDLINE | ID: mdl-36118227

ABSTRACT

Fertilization is a fundamental aspect of global forest management that enhances forest productivity and drastically affects soil microbial communities. However, few studies have investigated the differences and similarities in the responses of below-ground microbial communities to different fertilization schemes. The effects of fertilization regimes on the composition and diversity of soil fungal and bacterial communities were investigated in a young Catalpa bungei plantation in Shandong Province, Eastern China. Soil microbial communities were assessed undergoing three types of fertilization: (i) no fertilization (CK), (ii) hole fertilization (HF), and (iii) the integration of water and fertilizer (WF). We further analyzed the effects of soil depth (i.e., 0-20 and 20-40 cm) on the structure of soil microbial communities. Our results indicated that the diversity of bacteria (e.g., Chao1 and Shannon indices) reduced undergoing fertilization, and WF had a higher negative impact on bacterial diversity than HF. A lower bacterial diversity was observed in the subsoil compared to the topsoil. In contrast to bacterial diversity, fungal diversity had a slightly increasing trend in the fertilized environments. The primary bacterial function was metabolism, which was independent of fertilization or soil depth. Among fungal functional guilds, symbiotic soil fungi decreased obviously in the fertilized stand, whereas saprotrophic fungi increased slowly. According to the structural equation models (SEM), the diversity and composition of bacterial and fungal communities were jointly regulated by soil nutrients (including N and P contents) directly affected by fertilization and soil layer. These findings could be used to develop management practices in temperate forests and help sustain soil microbial diversity to maintain long-term ecosystem function and services.

9.
J Vasc Access ; : 11297298221075166, 2022 Jun 08.
Article in English | MEDLINE | ID: mdl-35674111

ABSTRACT

OBJECTIVE: To establish a multidisciplinary management model based on Delphi method to guide nursing practice and reduce the incidence of CVAD-associated Skin Impairment (CASI) in tumor patients. METHODS: On the basis of literature review and focus group interview, the initial item pool of CASI management model for cancer patients was determined. The Delphi method was used to conduct two rounds of letter consultation with 36 authoritative and representative experts to determine the content and weight of indicators of CASI multidisciplinary management model for cancer patients. RESULTS: Most of the research group were experts with bachelor degree or above. More than 90% of experts have worked for more than 10 years; Areas of expertise include oncology care, venous therapy, wound stomatology, and dermatology. The recovery rate of the two rounds of expert correspondence questionnaire was 100%. The authority coefficient of experts was 0.898, indicating a good degree of authority. Kendall's harmony coefficients were 0.193 and 0.250, with statistically significant differences (p < 0.001). After two rounds of expert letter consultation, a multidisciplinary management model of CASI for cancer patients was initially formed, which included 15 first-level prevention indexes and 38 second-level prevention indexes of CASI for cancer patients. There were 9 first-level indexes and 16 second-level indexes of CASI treatment in tumor patients. CONCLUSION: Cancer patients based on Delphi method to construct CASI multidisciplinary management model has high reliability and scientificity, multidisciplinary management model in the management of patients with tumor CASI exploration will provide new methods for central venous catheter nursing and the new way of thinking, will also be intravenous fluids will provide a scientific basis for professional development and quality improvement and practical experience.

10.
Article in English | MEDLINE | ID: mdl-36612777

ABSTRACT

Urban residents have a higher risk of hypertension and psychological stress than rural residents. Aside from medical interventions, understanding how to control hypertension and alleviate the stress of urban populations has become a public concern. As an alternative medical measure, forest therapy has shown the effects of normalizing blood pressure (BP) and reducing stress increasingly in recent literature, but this is still inconclusive. In order to systematically verify forest therapy's effects on the BP and mental stress of urban residents, we conducted meta-analyses to assess the changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), and salivary cortisol concentration (SCC; a stress biomarker) between the forest therapy group and urban control group. We searched 4 online databases, and 21 studies on BP involving 2270 participants and 13 studies on SCC involving 1786 participants were included. Through the meta-analysis, the mean difference and confidence interval (CI) estimates indicated that forest therapy significantly reduced participants' SBP −3.44 (95% CI −5.74, −1.14), DBP −3.07 (95% CI −5.59, −0.54), and SCC −0.07 (95% CI −0.10, −0.04), as compared with urban control. Yet, there was substantial heterogeneity (I2 = 72.87−88.59%) among these studies. We also found that each prediction interval (PI) for SBP (95% PI −13.30, 6.42), DBP (95% PI −15.54, 9.41), and SCC (95% PI −0.18, 0.05) were all much wider than the CIs and contained values above 0. This means that forest therapy may reduce SBP, DBP, and SCC on average, but may not exclude adverse results. Meta-regression analyses showed that participants' age and baseline SBP levels determined the heterogeneity among SBP studies. After forest therapy, older participants and those with higher baseline SBP levels had greater SBP-lowering effects. Among DBP studies, the primary source of heterogeneity was participants' baseline DBP levels; participants with higher baseline DBP levels had greater DBP reduction. In subgroup analyses, we discovered that longer-term forest therapy programs (≥20 min) resulted in a greater reduction in BP and SCC than shorter-term forest therapy programs (<20 min). Additionally, seated viewing, walking, or multi-session programs in forests were observed to have similar effects on reducing BP and SCC. Despite extensive analyses, the study did not identify any sources of heterogeneity among forest therapy programs for lowering SCC levels. Overall, we conclude that forest therapy programs have beneficial therapeutic effects on urban residents' physio-psychological health through lowering BP and relieving stress (reducing SCC). This finding provides solid evidence of the contribution of forest therapy to urban residents' health and wellbeing.


Subject(s)
Hydrocortisone , Hypertension , Humans , Blood Pressure , Hydrocortisone/therapeutic use , Urban Population
11.
Sci Rep ; 7: 42761, 2017 02 21.
Article in English | MEDLINE | ID: mdl-28220832

ABSTRACT

Carbon and water fluxes are key properties of ecosystem processes and functions. A better understanding of their temporal dynamics and coupling mechanism between these fluxes will help us improve ecosystem management for mitigation as well as adaption to future climatic change. From 2003 to 2009, carbon and water flux data were obtained by the eddy covariance method over an old-growth forest in the lower subtropical China. The 7 years of observational data indicated that the water-use efficiency (WUE) of the old-growth forest exhibited weak inter-annual variability. The mean annual WUE ranged from 1.70 to 1.98 g C kg-1 H2O. An analysis of the effects of environmental variables on the monthly gross primary productivity (GPP) and evapotranspiration (ET) indicated that solar radiation, air temperature, precipitation and vapor pressure deficit (VPD) produced similar effects on the monthly GPP and ET, which suggests that photosynthesis and ET were similarly driven by the climatic variables. At the monthly scale, the WUE decreased significantly as the precipitation and soil moisture content increased. However, a significant correlation was not detected between the WUE and the VPD at the monthly scale. Moisture conditions tend to be major drivers of the ecosystem WUE.


Subject(s)
Biomass , Forests , Magnoliopsida/physiology , Trees/physiology , Water Cycle , Carbon Cycle , China , Humidity , Magnoliopsida/growth & development , Trees/growth & development , Tropical Climate , Water/metabolism
12.
Ying Yong Sheng Tai Xue Bao ; 25(6): 1639-44, 2014 Jun.
Article in Chinese | MEDLINE | ID: mdl-25223018

ABSTRACT

The water consumption, water consumption rate, net photosynthetic rate (Pn), transpiration rate (Tr) and water use efficiency (WUE) of Eucalyptus urophylla x E. grandis DH33-27, E. urophylla x E. grandis DH32-29, E. grandis H1, Corymbia ptychocarpa and an indigenous tree species Bischofia javanica were studied in normal soil moisture condition. The average daily water consumption of the five tree species was in the order of E. urophylla x E. grandis DH32-29 (188.47 +/- 14. 91) g > E. urophylla x E. grandis DH33-27 (169.27 +/- 16.26) g > E. grandis H1 (118.65 +/- 5.32) g > B. javanica (38.12 +/- 1.46) g > C. ptychocarpa (20.13 +/- 1.72) g, which had obviously positive correlation with the total leaf area of each seedling. The water consumption was mostly in the daytime, which took 90% of the whole day water consumption. The daily change of the water consumption rates of 5 kinds of seedlings followed the curve with one peak at 12:00-14:00. The total water consumption ability of Eucalyptus and Corymbia was higher than that of B. javanica. The water consumption rate of C. ptychocarpa was far higher than that of the other 4 kinds of seedlings, so its large area planting should be given full consideration to this issue. The change in water consumption rate of E. urophylla x E. grandis DH33-27 was mostly impacted by environmental temperature and humidity, because its water consumption rate was the smallest among 4 kinds of Eucalyptus and Corymbia seedlings during the daytime with high temperature and low humidity. The four clone seedlings of Eucalyptus and Corymbia showed higher photosynthetic rates and transpiration rates compared with B. javanica. Two clone seedlings of E. urophylla x E. grandis had better water-saving performance. The WUE of Eucalyptus and Corymbia was higher than that of B. javanica in general, except E. urophylla x E. Grandis DH33-27.


Subject(s)
Eucalyptus/physiology , Magnoliopsida/physiology , Myrtaceae/physiology , Water/physiology , Humidity , Photosynthesis , Plant Leaves , Plant Transpiration , Seedlings/physiology , Soil , Temperature , Trees
13.
Ying Yong Sheng Tai Xue Bao ; 21(9): 2194-200, 2010 Sep.
Article in Chinese | MEDLINE | ID: mdl-21265137

ABSTRACT

Water and fertilizer are the two main factors promoting the fast growth and high-yielding of Populus tomentosa, and thus, to study their coupling effects on the biomass of P. tomentosa seedlings has important practical significance. Taking the P. tomentosa clone 87 seedlings as test materials, a pot experiment with rotary combination design of square regression of three factors with five levels was conducted in the nursery of Beijing Forestry University from March to October 2008 to study the coupling effects of water, fertilizer N, and fertilizer P on the biomass of the seedlings, and a related regressive mathematical model was established. The results showed that water was the main factor affecting the biomass of P. tomentosa seedlings, followed by fertilizer N, and fertilizer P. With the increasing input of the three factors, the biomass of the seedlings increased, but when the input was beyond a certain level, the biomass began to decrease. There was a significant positive interactive effect between water and fertilizer N, but a less interactive effect between fertilizer N and fertilizer P and between water and fertilizer P. In our case, the optimal combination of water and fertilizer was 73.37% of field capacity + 4.14 g x plant(-1) of N fertilization + 1.41 g x plant(-1) of P fertilization, under which, the biomass of P. tomentosa seedlings achieved 68.30 g x plant(-1).


Subject(s)
Biomass , Fertilizers , Populus/growth & development , Seedlings/growth & development , Water/physiology , Regression Analysis
14.
J Integr Plant Biol ; 50(2): 168-73, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18713438

ABSTRACT

Leaf morphological and anatomical structure and carbon isotope ratio (delta13C) change with increasing tree height. To determine how tree height affects leaf characteristics, we measured the leaf area, specific leaf mass (ratio of leaf mass to leaf area [LMA]), thickness of the total leaf, cuticle, epidermis, palisade and sponge mesophyll, stomata traits and delta13C at different heights of Parashorea chinensis with methods of light and scanning electron microscopy (SEM) and isotope-ratio mass spectrometry. The correlation and stepwise regression between tree height and leaf structure traits were carried out with SPSS software. The results showed that leaf structures and delta13C differed significantly along the tree height gradient. The leaf area, thickness of sponge mesophyll and size of stomata decreased with increasing height, whereas the thickness of lamina, palisade mesophyll, epidermis, and cuticle, ratios of palisade to spongy thickness, density of stomata and vascular bundles, LMA and delta13C increased with tree height. Tree height showed a significant relationship with all leaf indices and the most significant relationship was with epidermis thickness, leaf area, cuticle thickness, delta13C. The delta13C value showed a significantly positive relationship with LMA (R = 0.934). Our results supported the hypothesis that the leaf structures exhibited more xeromorphic characteristics with the increasing gradient of tree height.


Subject(s)
Dipterocarpaceae/anatomy & histology , Dipterocarpaceae/metabolism , Plant Leaves/anatomy & histology , Plant Leaves/metabolism , Trees/anatomy & histology , Carbon Isotopes , China , Plant Stomata/ultrastructure
15.
Physiol Plant ; 117(4): 532-539, 2003 Apr.
Article in English | MEDLINE | ID: mdl-12675743

ABSTRACT

Drought adjustments were compared in black spruce (Picea mariana[Mill] B.S.P), and jack pine (Pinus banksiana[Lamb.]) by subjecting seedlings to five cycles of dehydration and rehydration. A computer-controlled root misting chamber system, supplied low (-1.5 MPa), moderate (-2.0 MPa), and severe (-2.5 MPa) dehydration, respectively, in cycles 1, 3 and 5. Although cell water relations failed to adjust to chronic dehydration, there was limited osmotic adjustment in black spruce (cycle 3), and water was re-allocated from the apoplast to the symplast in jack pine (cycles 1 and 3). Dehydration postponement was more important than dehydration tolerance. Jack pine was better able to postpone dehydration than black spruce. Specific conductivity, the hydraulic conductivity per unit stem cross-sectional area, was lower in jack pine and slower to decline during chronic dehydration. When specific conductivity was corrected for the greater leaf area in black spruce, the leaf-specific conductivity did not differ in the two species. There was no increase in needle leakage in jack pine and stomata in jack pine seedlings reopened fully after rehydration. Black spruce was more of a 'water spender', and less water stress (-2.0 MPa, cycle 3) was required to lower specific conductivity, compared to jack pine (-2.5 MPa, cycle 5). Leakage from needle membranes increased in black spruce, and stomata failed to reopen after rewatering (cycles 3 and 5). A greater needle area, smaller root system, and a higher specific conductivity lowered the water stress threshold for cavitation in black spruce, which is confined to moister sites in the boreal forest. Jack pine had a larger root system, smaller needle area and lower specific conductivity than black spruce. Because of these static features, jack pine is more drought tolerant and it is often found on sites that are too hot and dry for black spruce.

16.
Ying Yong Sheng Tai Xue Bao ; 14(9): 1411-5, 2003 Sep.
Article in Chinese | MEDLINE | ID: mdl-14732990

ABSTRACT

The hydraulic parameters of 4 years old Acer truncatum seedlings were measured by improved flushing method under the condition of controlled drought gradients in the greenhouse. It's indicated that the changes of hydraulic parameters with stem segment functional xylem diameter could be modeled by different equations. The hydraulic conductivity was influenced by the area that stem segment located. It was higher in non-constriction area than in constriction area. The existence of constriction area was in favor of the competition between individual seedlings. Hydraulic conductivity, specific conductivity and leaf specific conductivity were proportional with functional xylem diameter and twig water potential. The leaf specific conductivity of thicker branches was far higher than that of distal twigs, which was in favor of seedlings in saving those organs with more photosynthesis devotion during drought stress. The change of Huber value of same diameter branches with twig water potential was very small before defoliation, and hence, the main source of seedling's water stress came from xylem cavitation and embolism.


Subject(s)
Acer/physiology , Seedlings/physiology , Water/metabolism
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