分类: 生物学 >> 植物学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》
摘要: Wolfberry (Lycium barbarum L.) is important for health care and ecological protection. However, it faces problems of low productivity and resource utilization during planting. Exploring reasonable models for water and nitrogen management is important for solving these problems. Based on field trials in 2021 and 2022, this study analyzed the effects of controlling soil water and nitrogen application levels on wolfberry height, stem diameter, crown width, yield, and water (WUE) and nitrogen use efficiency (NUE). The upper and lower limits of soil water were controlled by the percentage of soil water content to field water capacity (f), and four water levels, i.e., adequate irrigation (W0, 75%85% f), mild water deficit (W1, 65%75% f), moderate water deficit (W2, 55%65% f), and severe water deficit (W3, 45%55% f) were used, and three nitrogen application levels, i.e., no nitrogen (N0, 0 kg/hm2), low nitrogen (N1, 150 kg/hm2), medium nitrogen (N2, 300 kg/hm2), and high nitrogen (N3, 450 kg/hm2) were implied. The results showed that irrigation and nitrogen application significantly affected plant height, stem diameter, and crown width of wolfberry at different growth stages (P<0.01), and their maximum values were observed in W1N2, W0N2, and W1N3 treatments. Dry weight per plant and yield of wolfberry first increased and then decreased with increasing nitrogen application under the same water treatment. Dry weight per hundred grains and dry weight percentage increased with increasing nitrogen application under W0 treatment. However, under other water treatments, the values first increased and then decreased with increasing nitrogen application. Yield and its component of wolfberry first increased and then decreased as water deficit increased under the same nitrogen treatment. Irrigation water use efficiency (IWUE, 8.46 kg/(hm2mm)), WUE (6.83 kg/(hm2mm)), partial factor productivity of nitrogen (PFPN, 2.56 kg/kg), and NUE (14.29 kg/kg) reached their highest values in W2N2, W1N2, W1N2, and W1N1 treatments. Results of principal component analysis (PCA) showed that yield, WUE, and NUE were better in W1N2 treatment, making it a suitable water and nitrogen management mode for the irrigation area of the Yellow River in the Gansu Province, China and similar planting areas.
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2020-05-31 合作期刊: 《干旱区科学》
摘要: In arid areas, ecological degradation aroused by over-exploitation of fresh water, expansion of artificial oasis and shrinkage of natural oasis, has drawn attention of many scholars and officials. The water and ecological footprints can be used to quantitatively evaluate the water consumption of social-economic activities and their influence on the eco-environments. In addition, increase of the water footprint indicates the expansion of artificial oasis, and the influence on the natural oasis could be reflected by the variation of the ecological footprint. This study was conducted to answer a scientific question that what is the quantitative relationship between the expansion of the artificial oasis and the degradation of the natural oasis in the arid environments of Xinjiang, China. Thus, based on the social-economic data, water consumption data and meteorological data during 2001–2015, we calculated the water and ecological footprints to express the human-related pressure exerted on the water resources and arid environments in Xinjiang (including 14 prefectures and cities), and explore the relationship between the water and ecological footprints and its mechanism by using the coupling analysis and Granger causality test. The results show that both the water and ecological footprints of Xinjiang increased significantly during 2001–2015, and the increasing rate of the ecological footprint was much faster than that of the water footprint. The coupling degree between the water and ecological footprints was relatively high at the temporal scale and varied at the spatial scale. Among the 14 prefectures and cities examined in Xinjiang, the greater social-economic development (such as in Karamay and Urumqi) was associated with the lower coupling degree between the two footprints. Increases in the water footprint will cause the ecological footprint to increase, such that a 1-unit increase in the consumption of water resources would lead to 2–3 units of ecological degradation. The quantitative relationship between the increases of the water and ecological footprints, together with the intensities of water consumption both in the natural and artificial oases of Tarim River Basin, have approved the fact that the formation and expansion of 1 unit of the artificial oasis would bring about the degradation of 2 units of the natural oasis. These conclusions not only provide a technical basis for sustainable development in Xinjiang, but also offer a theoretical guide and scientific information that could be used in similar arid areas around the world.
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2020-05-31 合作期刊: 《干旱区科学》
摘要: Tamarix taklamakanensis, a dominant species in the Taklimakan Desert of China, plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability. This study aimed to determine the water use strategies of T. taklamakanensis in the Taklimakan Desert under a falling groundwater depth. Four typical T. taklamakanensis nabkha habitats (sandy desert of Tazhong site, saline desert-alluvial plain of Qiemo site, desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site) were selected with different climate, soil, groundwater and plant cover conditions. Stable isotope values of hydrogen and oxygen were measured for plant xylem water, soil water (soil depths within 0–500 cm), snowmelt water and groundwater in the different habitats. Four potential water sources for T. taklamakanensis, defined as shallow, middle and deep soil water, as well as groundwater, were investigated using a Bayesian isotope mixing model. It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation, but through the river runoff from snowmelt water in the nearby mountain ranges. The surface soil water content was quickly depleted by strong evaporation, groundwater depth was relatively shallow and the height of T. taklamakanensis nabkha was relatively low, thus T. taklamakanensis primarily utilized the middle (23%±1%) and deep (31%±5%) soil water and groundwater (36%±2%) within the sandy desert habitat. T. taklamakanensis mainly used the deep soil water (55%±4%) and a small amount of groundwater (25%±2%) within the saline desert-alluvial plain habitat, where the soil water content was relatively high and the groundwater depth was shallow. In contrast, within the desert-oasis ecotone in the Qira and Aral sites, T. taklamakanensis primarily utilized the deep soil water (35%±1% and 38%±2%, respectively) and may also use groundwater because the height of T. taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low, which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities. Consequently, T. taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources (deep soil water and groundwater), reflecting its adaptations to the different habitats in the arid desert environment. These findings improve our understanding on determining the water sources and water use strategies of T. taklamakanensis in the Taklimakan Desert.
分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-12
摘要: The oxygen-evolving center (OEC) in photosystem II catalyzes a water splitting reaction. Great efforts have already been made to artificially synthesize the OEC, in order to elucidate the structure-function relationship and the mechanism of the reaction. Now, a new synthetic model makes the best mimic yet of the OEC. This recent study opens up the possibility to study the mechanism of photosystem II and photosynthesis in general for applications in renewable energy and synthetic biology.
分类: 生物学 >> 生物物理学 >> 生物力学与生物流变学 提交时间: 2016-05-11
摘要: A natural biomaterial has been discovered with bactericidal activities, which is mainly attributed to its nanopatterned surface structure. The surface of Clanger cicada (Psaltoda claripennis) wings has been identified as a natural bactericidal material, which has lead to the emergence of research on the development of novel antibacterial surfaces. From the interactions between bacterial biofilms and nanopatterned surface structures, a new mechanical model is proposed that investigates the rupture of bacterial cells within the framework of the "stretching" theory. The effect of surface nanoroughness on the survival of bacterial cells is evaluated by determining the stretching ability of their cell walls. The results, calculated using Gram-positive and Gram-negative bacteria as examples, show a correlation between the stretching of the cell wall and the geometric parameters of the surface structures. The theoretical results indicate that for a given cell rigidity, the bactericidal nature of the surface is determined by the geometric parameters of the surface structures. (C) 2015 Elsevier Ltd. All rights reserved.
分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04
摘要: The Southern High Plains (SHP) region of Texas in the United States, where cotton is grown in a vast acreage, has the potential to grow cellulosic bioenergy crops such as perennial grasses and biomass sorghum (Sorghum bicolor). Evaluation of hydrological responses and biofuel production potential of hypothetical land use change from cotton (Gossypium hirsutum L.) to cellulosic bioenergy crops enables better understanding of the associated key agroecosystem processes and provides for the feasibility assessment of the targeted land use change in the SHP. The Soil and Water Assessment Tool (SWAT) was used to assess the impacts of replacing cotton with perennial Alamo switchgrass (Panicum virgatum L.), Miscanthusgiganteus (Miscanthus sinensis Anderss. [Poaceae]), big bluestem (Andropogon gerardii) and annual biomass sorghum on water balances, water use efficiency and biofuel production potential in the Double Mountain Fork Brazos watershed. Under perennial grass scenarios, the average (19942009) annual surface runoff from the entire watershed decreased by 68% relative to the baseline cotton scenario. In contrast, surface runoff increased by about 5% under the biomass sorghum scenario. Perennial grass land use change scenarios suggested an increase in average annual percolation within a range of 322% and maintenance of a higher soil water content during August to April compared to the baseline cotton scenario. About 19.1, 11.1, 3.2 and 8.8 Mgha1 of biomass could potentially be produced if cotton area in the watershed would hypothetically be replaced by Miscanthus, switchgrass, big bluestem and biomass sorghum, respectively. Finally, Miscanthus and switchgrass were found to be ideal bioenergy crops for the dryland and irrigated systems, respectively, in the study watershed due to their higher water use efficiency, better water conservation effects, greater biomass and biofuel production potential, and minimum crop management requirements.
分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04
摘要: Environmental or ecological footprints have been widely used in recent years as indicators of resource consumption and waste absorption presented in terms of biologically productive land area [in global hectares (gha)] required per capita with prevailing technology. In contrast, carbon footprints are the amount of carbon (or carbon dioxide equivalent) emissions for such activities in units of mass or weight (like kilograms per functional unit), but can be translated into a component of the environmental footprint (on a gha basis). The carbon and environmental footprints associated with the world production of liquid biofuels have been computed for the period 20102050. Estimates of future global biofuel production were adopted from the 2011 International Energy Agency (IEA) technology roadmap for transport biofuels. This suggests that, although first generation biofuels will dominate the market up to 2020, advanced or second generation biofuels might constitute some 75% of biofuel production by 2050. The overall environmental footprint was estimated to be 0.29 billion (bn) gha in 2010 and is likely to grow to around 2.57 bn gha by 2050. It was then disaggregated into various components: bioproductive land, built land, carbon emissions, embodied energy, materials and waste, transport, and water consumption. This component-based approach has enabled the examination of the Manufactured and Natural Capital elements of the four capitals model of sustainability quite broadly, along with specific issues (such as the linkages associated with the so-called energylandwater nexus). Bioproductive land use was found to exhibit the largest footprint component (a 48% share in 2050), followed by the carbon footprint (23%), embodied energy (16%), and then the water footprint (9%). Footprint components related to built land, transport and waste arisings were all found to account for an insignificant proportion to the overall environmental footprint, together amounting to only about 2%
分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04
摘要: We developed a biochar model within the Agricultural Production Systems sIMulator (APSIM) software that integrates biochar knowledge and enables simulation of biochar effects within cropping systems. The model has algorithms that mechanistically connect biochar to soil organic carbon (SOC), soil water, bulk density (BD), pH, cation exchange capacity, and organic and mineral nitrogen. Soil moisture (SW)temperaturenitrogen limitations on the rate of biochar decomposition were included as well as biochar-induced priming effect on SOC mineralization. The model has 10 parameters that capture the diversity of biochar types, 15 parameters that address biochar-soil interactions and 4 constants. The range of values and their sensitivity is reported. The biochar model was connected to APSIM's maize and wheat crop models to investigate long-term (30years) biochar effects on US maize and Australia wheat in various soils. Results from this sensitivity analysis showed that the effect of biochar was the largest in a sandy soil (Australian wheat) and the smallest in clay loam soil (US maize). On average across cropping systems and soils the order of sensitivity and the magnitude of the response of biochar to various soil-plant processes was (from high to low): SOC (11% to 86%) > N2O emissions (10% to 43%43%)>plant available water content (0.6% to 12.9%) > BD (6.5% to 1.7%) > pH (0.8% to 6.3%) > net N mineralization (19% to 10%)>CO2 emissions (2.0% to 4.3%)>water filled pore space (3.7% to 3.4%)>grain yield (3.3% to 1.8%)>biomass (1.6% to 1.4%). Our analysis showed that biochar has a larger impact on environmental outcomes rather than agricultural production. The mechanistic model has the potential to optimize biochar application strategies to enhance environmental and agronomic outcomes but more work is needed to fill knowledge gaps identified in this work.
分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04
摘要: Genetic analyses have suggested that the clonal reproduction of Arundo donax has resulted in low genetic diversity. However, an earlier common garden phenotyping experiment identified specimens of A. donax with contrasting biomass yields (ecotypes 6 and 20). We utilized the same well-established stands to investigate the photosynthetic and stress physiology of the A. donax ecotypes under irrigated and drought conditions. Ecotype 6 produced the largest yields in both treatments. The A. donax ecotypes exhibited identical high leaf-level rates of photosynthesis (PN) and stomatal conductance (Gs) in the well-watered treatment. Soil drying induced reductions in PN and Gs, decreased use of light energy for photochemistry, impaired function of photosystem II and increased heat dissipation similarly in the two ecotypes. Levels of biologically active free-abscisic acid (ABA) and fixed glycosylated-ABA increased earlier in response to the onset of water deficit in ecotype 6; however, as drought progressed, the ecotypes showed similar increases in both forms of ABA. This may suggest that because of the low genetic variability in A. donax the genes responding to drought might have been activated similarly in the two ecotypes, resulting in identical physiological responses to water deficit. Despite the lack of physiological ecotypic differences that could be associated with yield, A. donax retained a high degree of PN and biomass gain under water deficit stress conditions. This may enable utilization of A. donax as a fast growing biomass crop in rain-fed marginal lands in hot drought prone climates.
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2016-05-04
摘要: The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050. Together with rising economic growth, this is forecast to result in a 50% increase in fuel demand, which will have to be met while reducing carbon dioxide (CO2) emissions by 5080% to maintain social, political, energy and climate security. This tension between rising fuel demand and the requirement for rapid global decarbonization highlights the need to fast-track the coordinated development and deployment of efficient cost-effective renewable technologies for the production of CO2 neutral energy. Currently, only 20% of global energy is provided as electricity, while 80% is provided as fuel. Hydrogen (H2) is the most advanced CO2-free fuel and provides a common energy currency as it can be produced via a range of renewable technologies, including photovoltaic (PV), wind, wave and biological systems such as microalgae, to power the next generation of H2 fuel cells. Microalgae production systems for carbon-based fuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating the potential of microalgal technologies for the commercial production of solar-driven H2 from water. It summarizes key global technology drivers, the potential and theoretical limits of microalgal H2 production systems, emerging strategies to engineer next-generation systems and how these fit into an evolving H2 economy.