Selection of Contrasting Parents for Drought Tolerance in Sunflower (Helianthus Annuus L.)

The aim of this research was select the best combination of contrasting parents to develop a mapping population for drought tolerance, based on phenotypic and genotypic data. Phenotyping was conducted in a greenhouse during 16 days at vegetative stage under well-watered (WW) and water-deficit (WD) conditions. Traits evaluated were: gain of leaf area (GLA), total water use (TWU), net assimilation rate (NAR), water use efficiency (WUE) and transpiration rate (TR) response to vapor pressure deficit (VPD) (slope and breakpoint). Genotyping was performed with 127 SSR markers and a cluster analyses was conducted. An important interaction was observed for NAR, WUE and breakpoint in the VPD response. Under WD conditions, all genotypes showed lower GLA and TWU, whereas NAR and WUE increased its values. All genotypes showed reduction of the slope and breakpoint in high VPD response on WD. PCA analysis explains the 80% of the total variability. PC1 discriminated HA89 and R419 due to a lower slope and higher breakpoint, while PC2 separated by water treatment based on the WUE and TWU values. Nighty nine SSR marker were amplified detecting 262 alleles. Cluster analyzes showed two main groups, one including HAR4 and B59 and the other one including five remaining genotypes. According to these results, only R419xHA64 and HA89xHAR4 had a greater genetic distance (1.08), besides a high polymorphism level between ILs (about 60%). Therefore, we conclude that these would be the best combination of contrasting parents to develop mapping populations for drought tolerance in sunflower.

Combined Effects of Hillslope-Concentrated Flows and Riverine Stream Waves on Soil Erosion in the Reservoir Riparian Zone

During the exposed season, the water level fluctuation zone of the Three Gorges Reservoir has suffered from hillslope-concentrated flows and riverine stream waves, which considerably complicates the processes and magnifies the rate of bank erosion. This study depicts the forms and patterns of integrated bank erosion in this reservoir marginal landscape, decouples the evolutionary processes involved, explores the underlying mechanisms, and quantifies the magnitude through a case study on a fine-grained sandy bank. Hillslope-concentrated flows over rainfall storm events developed continuous gullies starting from uplands and extending throughout the entire slope of the reservoir bank, characterized by relatively larger depths and widths compared with discontinuous gullies on the lower slope developed by riverine stream waves.

Fine Root Growth of Black Spruce Trees and Understory Plants in a Permafrost Forest Along a North-Facing Slope in Interior Alaska

Permafrost forests play an important role in the global carbon budget due to the huge amounts of carbon stored below ground in these ecosystems. Although fine roots are considered to be a major pathway of belowground carbon flux, separate contributions of overstory trees and understory shrubs to fine root dynamics in these forests have not been specifically characterized in relation to permafrost conditions, such as active layer thickness. In this study, we investigated fine root growth and morphology of trees and understory shrubs using ingrowth cores with two types of moss substrates (feather- and Sphagnum mosses) in permafrost black spruce (Picea mariana) stands along a north-facing slope in Interior Alaska, where active layer thickness varied substantially. Aboveground biomass, litterfall production rate, and fine root mass were also examined. Results showed that aboveground biomass, fine root mass, and fine root growth of black spruce trees tended to decrease downslope, whereas those of understory Ericaceae shrubs increased. Belowground allocation (e.g., ratio of fine root growth/leaf litter production) increased downslope in both of black spruce and understory plants. These results suggested that, at a lower slope, belowground resource availability was lower than at upper slope, but higher light availability under open canopy seemed to benefit the growth of the understory shrubs. On the other hand, understory shrubs were more responsive to the moss substrates than black spruce, in which Sphagnum moss substrates increased fine root growth of the shrubs as compared with feather moss substrates, whereas the effect was unclear for black spruce. This is probably due to higher moisture contents in Sphagnum moss substrates, which benefited the growth of small diameter (high specific root length) fine roots of understory shrubs. Hence, the contribution of understory shrubs to fine root growth was greater at lower slope than at upper slope, or in Sphagnum than in feather-moss substrates in our study site. Taken together, our data show that fine roots of Ericaceae shrubs are a key component in belowground carbon flux at permafrost black spruce forests with shallow active layer and/or with Sphagnum dominated forest floor.

Soil and Vegetation Patterns Along a Toposequence in a Dolomite Peak-cluster Depression Catchment

AimA deeper understanding of relationships between soil and vegetation is a prerequisite for accelerating karst area vegetation restoration. Remarkable achievements have been made at regional and individual plant scales, but research on the relationship between soil and vegetation is insufficient at the hillslope catena scale in karst areas.MethodsSoils and vegetation were investigated along a toposequence (upper-, middle-, lower-slope, and depression) of a dolomite peak-cluster depression catchment.ResultsA continuous soil catena pattern was developed along the toposequence. From the top to bottom of soil catena, soil thickness, fine soil mass ratio, nutrient stocks, and epikarst thickness gradually increased, while gravel mass ratio, pH, and saturated hydraulic conductivity gradually decreased. However, nutrient contents showed no significant change trends along the soil catena. There was a strong spatial association between soil types and dominant vegetation communities. The associations were as follows: herbs associated with entisols in the upper-slope; herbs and shrubs with inceptisols in the middle-slope; shrubs with semi-alfisols in the lower-slope; and trees with alfisols in the depression. ConclusionsThe dolomite rocks displayed an evenly progressive karstification process. This led to an undeveloped underground karstic network incapable of transporting soil materials into underground. Soil materials still accumulated at different topographic positions surface and formed a continuous catena. Parameters for nutrient stock may be more suitable for assessing soil productivity and to guide vegetation restoration key factors in karst regions than nutrient content parameters.

Compressor Stability At Pulsating Condition via Gas Dynamics Responses Analysis

The compressor is operated at unsteady exit conditions in many scenarios such as the instability of combustion in gas turbine and denotation engine. The aerodynamic stability of the compressor is inevitably influenced by the unsteady operating environment. In this paper, a 1D model that combines pulsation and unsteady responses of the compressor is developed to investigate the stability of the compressor system. The results show that the onset of surge and the transient responses of the compressor during surge are well predicted by the method. The amplitude of the component at surge frequency obtained by FFT method is applied as a criterion to quantitively evaluate the onset and the strength of the surge. Compressor stability is enhanced at pulsating conditions due to the interaction between forced oscillation of pulsation and self-sustained oscillation of surge. An analytical model is established to understand the mechanism of the enhancement of compressor stability under pulsation. The change of total energy of the compressing system is proposed to evaluate the influence of pulsating conditions. Specifically, the energy change is reduced for pulsation conditions due to two aspects: the lower slope of compressor characteristic curve due to the lag-effect of compressor responses and the higher energy dissipation due to the non-linear throttling effect.

Effect of Slope Positions on Properties of Soils of some Forest reserves in South-West Nigeria

Topography has an influence on soil erosion and consequently on the properties of soils. The effect of slope position on soil properties is of great importance in soil suitability assessment. This study assessed the effect of topographic position on the characteristics of soil of basement complex rocks derived soils under Teak (Tectona grandis) and Gmelina (Gmelina arborea) plantations in Osun sacred grove, Onigambari and Omo forest reserves situated within South-West Nigeria. Three soil profiles were dug in each landuse type, sited at the upper, middle and lower slope positions along a toposequence. Soil samples were collected according to their pedogenetic horizons and were analyzed using standard methods. Results showed variations in colour, depth of soil profile, soil structure, texture, drainage and soil consistence. The high sand content dominated the particle size fraction in all the soils formed from the three locations, and base saturation was rated very high with values >90% irrespective of the toposequence or slope position. The result of correlation analysis between slope position and content of N, P, K and CEC showed a significant relationship irrespective of locations with N(r = 0.019< 0.05) respectively. Despite variation in soil properties as influenced by topography, the studied soils can sustain the current land use type. It was concluded that soils on different topographic positions should be managed differently.

Characteristics of Soil C, N, and P Stoichiometry as Affected by Land Use and Slope Position in the Three Gorges Reservoir Area, Southwest China

Land use change and slope position are commonly identified as the key factors affecting the soil organic carbon (C), total nitrogen (N), and total phosphorus (P) traits in distinct ecological scales. However, the directions of these effects are still unclear in some fragile terrestrial ecosystems. This study aimed to determine the characteristics of soil C, N, and P concentrations and stoichiometry as affected by different land uses and slope positions in a representative purple soil hillslope in Three Gorges Reservoir Area (TGRA), China, which is experiencing severe soil erosion and non-point source pollution. A total of 108 soil samples were collected from secondary forest, orchard plantation, and cropland on the upper, middle, and lower slopes, respectively. Soil C, N, and P concentrations and their stoichiometric ratios were determined. The results showed that soil C concentration was not affected by land use, while soil N and P concentrations were both the highest in orchard plantation rather than in secondary forest and cropland, resulting in the lowest C:N, C:P, and N:P ratios in the orchard plantation. Soil C and N concentrations synchronously decreased from upper slope to the lower slope, and soil P concentration was not markedly different among slope positions. This also caused the insignificant difference in soil C:N ratio and the remarkably lowest C:P and N:P ratios on the lower slope. There were significant interactive effects of land use and slope position on the study soil variables except soil P concentration. Our results highlight the effects of land use and slope position on soil C, N, and P traits and point to the decoupling of linkages between soil P and soil C as well as N due to the severe soil erosion and overuse of fertilization in the TGRA.

The Stable Isotope Characteristics of Precipitation in the Middle East Highlighting the Link between the Köppen Climate Classifications and the δ18O and δ2H Values of Precipitation

The Middle East is faced with a water shortage crisis due to its semiarid and arid climate. In this paper, precipitation as an important part of the water cycle was evaluated in 43 stations across the Middle East using the stable isotope technique to study the parameters which influence the stable isotope content of precipitation. First, the stepwise regression model was applied to determine the main geographical and climatological factors affecting the stable isotopes in precipitation. Secondly, the stepwise model was also used to simulate the stable isotope values in precipitation. Furthermore, due to the notable climatic variations across the Middle East, the precipitation sampling stations were classified into six groups based on the Köppen climate zones. Significant variations in the stable isotope values of precipitation were observed in the stations of each climate zone. Finally, the Middle East meteoric water line was developed for the dry and wet periods based on the average stable isotopes in the studied stations. The developed lines showed a lower slope compared to the GMWL due to the higher air temperature and relative humidity in the Middle East compared to the average global conditions. To conclude, the stable isotope contents in precipitation showed significant temporal and spatial variations due to the notable climatic variations across the Middle East.

The use of xenopericardium in reconstructive surgery in patients with breast cancer

Objective: to analyze the possibility of using xenopericardium for breast reconstruction in cancer Materials and methods: the article presents a clinical case of a patient diagnosed with breast cancer who underwent a subcutaneous mastectomy with simultaneous reconstruction with an endoprosthesis and a xenopericardium to strengthen the lower slope of the breast. Results: in our study, a good cosmetic result was obtained, and the presence of xenopericardium does not affect the conduct of postoperative courses of chemotherapy and radiation therapy. Conclusion: we present the first experience of using bovine pericardium in Russia for breast reconstruction in patients with breast cancer. Xenopericardium BioLAB-PP/PA of domestic origin was used to strengthen the lower slope of the reconstructed MJ using a silicone implant.

Living Benthic Foraminifera from the Surface and Subsurface Sediment Layers Applied to the Environmental Characterization of the Brazilian Continental Slope (SW Atlantic)

Living benthic foraminifera (>63 µm) were studied to characterize the continental slope of the Potiguar Basin (SW Atlantic). Foraminifers from the surface (0–2 cm), subsurface (2–5 cm), and integrated (0–5 cm) sediment layers were analyzed to verify their contribution to environmental characterization. It was also estimated if and which changes occur when the subsurface is added. Sampling stations were distributed in five transects in four isobaths (150, 400, 1000, and 2000 m). Sediment samples were fixed with 4% buffered formaldehyde and stained with Bengal rose. Were recorded 396 species in the surface layer, 228 in the subsurface, and 449 in integrating both layers. This study did not include tubular agglutinated species. The assemblages from 150 m isobath indicated the upper slope, from 400 m indicated the middle slope and the ones from the 2000 m indicated the lower slope. The surface layer’s assemblage at 1000 m isobath was more similar to the middle slope; in contrast, its subsurface layer´s assemblage had more similarity with the lower slope. Rarefaction curves, Permanova, and NMDS routines indicated a high resemblance between surface and integrated layers. Therefore, the first two centimeters were sufficient to characterize this region based on living benthic foraminifera.