scholarly journals Effects of grazing on photosynthetic features and soil respiration of rangelands in the Tianshan Mountains of Northwest China

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Hua Liu ◽  
Runguo Zang ◽  
Han Y. H. Chen
Keyword(s):  
Soil Respiration ◽  
Critical Role ◽  
Carbon Assimilation ◽  
Northwest China ◽  
Tianshan Mountains ◽  
Daily Maximum ◽  
Photosynthetic Parameters ◽  
Leaf Photosynthesis ◽  
Use Efficiency ◽  
Global Carbon

Abstract Rangelands play a critical role in the global carbon cycle. However, the eco-physiological mechanisms associated with the effects of grazing on leaf photosynthesis and soil respiration remain poorly understood. To examine the impacts of grazing on leaf photosynthesis and soil respiration, we measured the photosynthetic parameters of the dominant species (Trifolium repens) and the soil respiration in grazed and ungrazed rangelands in the Tianshan Mountains of China. We found that grazing reduced the daily maximum net photosynthetic rate and increased soil respiration rates by 35% and 15%, respectively. The photosynthetic quantum yield, dark respiratory rate, and water use efficiency of T. repens leaves were reduced in grazed plots by 33.3%, 69.2%, and 21.5%, respectively. Our results demonstrated that grazing reduced carbon assimilation while increasing soil respiration within the rangelands in the Tianshan Mountains.

scholarly journals The Effects of Saline Stress on the Growth of Two Shrub Species in the Qaidam Basin of Northwestern China

2019 ◽  
Vol 11 (3) ◽  
pp. 828 ◽  
Author(s):  
Tan Zhang ◽  
Zhenzhong Zhang ◽  
Yuanhang Li ◽  
Kangning He
Keyword(s):  
Salt Tolerance ◽  
Qaidam Basin ◽  
Northwest China ◽  
Scientific Basis ◽  
Soil Salinization ◽  
Saline Stress ◽  
Photosynthetic Parameters ◽  
Lycium Barbarum ◽  
Use Efficiency ◽  
Selection Of

Soil salinization is a serious issue in the Qaidam Basin and significantly limits economic development. To explore the salt tolerance of two shrubs in this area, we determined several parameters, including the Soil and Plant Analyzer Development (SPAD), net photosynthetic rate (Pn), transpiration rate (Tr), intercellular carbon dioxide (Ci, μmol mol−1), stomatal conductance (Gs, umol m−2s−1), and water use efficiency (WUE) under different salt concentrations (0, 100, 200, 300, and 400 mmol·L−1). In addition, the shrubs of Elaeagnus angustifolia and Lycium barbarum of salt tolerance were evaluated. The photosynthetic parameters of E. angustifolia were more sensitive to salinity than those of L. barbarum, and SPAD, Pn, Tr, and WUE of E. angustifolia decreased significantly with increasing salt concentrations (P < 0.05), while in L. barbarum, SPAD, Pn, and Tr decreased significantly with increasing salt concentrations (P < 0.05), but the WUE of L. barbarum showed no significantly variation under the salt concentration gradient. The results of correlation matrix of photosynthetic index also indicated that the minimum salt tolerance of E. angustifolia and L. barbarum were 108.4 and 246.3 mmol·L−1, respectively. Our results provide a scientific basis for the selection of salt-tolerant plant species in of northwest China.

Guard Cell Metabolism and Stomatal Function

2020 ◽  
Vol 71 (1) ◽  
pp. 273-302 ◽  
Author(s):  
Tracy Lawson ◽  
Jack Matthews
Keyword(s):  
Stomatal Conductance ◽  
Guard Cell ◽  
Cell Metabolism ◽  
Critical Role ◽  
Carbon Assimilation ◽  
Plant Productivity ◽  
Behavioral Characteristics ◽  
Regulatory Pathways ◽  
Stomatal Behavior ◽  
Use Efficiency

The control of gaseous exchange between the leaf and external atmosphere is governed by stomatal conductance ( gs); therefore, stomata play a critical role in photosynthesis and transpiration and overall plant productivity. Stomatal conductance is determined by both anatomical features and behavioral characteristics. Here we review some of the osmoregulatory pathways in guard cell metabolism, genes and signals that determine stomatal function and patterning, and the recent work that explores coordination between gs and carbon assimilation ( A) and the influence of spatial distribution of functional stomata on underlying mesophyll anatomy. We also evaluate the current literature on mesophyll-driven signals that may coordinate stomatal behavior with mesophyll carbon assimilation and explore stomatal kinetics as a possible target to improve A and water use efficiency. By understanding these processes, we can start to provide insight into manipulation of these regulatory pathways to improve stomatal behavior and identify novel unexploited targets for altering stomatal behavior and improving crop plant productivity.

scholarly journals Overexpression of MdATG8i improves water use efficiency in transgenic apple by modulating photosynthesis, osmotic balance, and autophagic activity under moderate water deficit

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xin Jia ◽  
Ke Mao ◽  
Ping Wang ◽  
Yu Wang ◽  
Xumei Jia ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Deficit ◽  
Water Use ◽  
Photosynthetic Capacity ◽  
Critical Role ◽  
Drought Conditions ◽  
Moderate Drought ◽  
Use Efficiency ◽  
Autophagic Activity

AbstractWater deficit is one of the major limiting factors for apple (Malus domestica) production on the Loess Plateau, a major apple cultivation area in China. The identification of genes related to the regulation of water use efficiency (WUE) is a crucial aspect of crop breeding programs. As a conserved degradation and recycling mechanism in eukaryotes, autophagy has been reported to participate in various stress responses. However, the relationship between autophagy and WUE regulation has not been explored. We have shown that a crucial autophagy protein in apple, MdATG8i, plays a role in improving salt tolerance. Here, we explored its biological function in response to long-term moderate drought stress. The results showed that MdATG8i-overexpressing (MdATG8i-OE) apple plants exhibited higher WUE than wild-type (WT) plants under long-term moderate drought conditions. Plant WUE can be increased by improving photosynthetic efficiency. Osmoregulation plays a critical role in plant stress resistance and adaptation. Under long-term drought conditions, the photosynthetic capacity and accumulation of sugar and amino acids were higher in MdATG8i-OE plants than in WT plants. The increased photosynthetic capacity in the OE plants could be attributed to their ability to maintain optimal stomatal aperture, organized chloroplasts, and strong antioxidant activity. MdATG8i overexpression also promoted autophagic activity, which was likely related to the changes described above. In summary, our results demonstrate that MdATG8i-OE apple lines exhibited higher WUE than WT under long-term moderate drought conditions because they maintained robust photosynthesis, effective osmotic adjustment processes, and strong autophagic activity.

scholarly journals Spatial–Temporal Evolution Characteristics and Influencing Factors of Agricultural Water Use Efficiency in Northwest China—Based on a Super-DEA Model and a Spatial Panel Econometric Model

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 632
Author(s):  
Weinan Lu ◽  
Wenxin Liu ◽  
Mengyang Hou ◽  
Yuanjie Deng ◽  
Yue Deng ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Water Resource ◽  
Arid Regions ◽  
Econometric Model ◽  
Northwest China ◽  
Agricultural Water ◽  
Agricultural Water Use ◽  
Use Efficiency ◽  
Semi Arid

Improving agricultural water use efficiency (AWUE) is an important way to solve the shortage of water resources in arid and semi-arid regions. This study used the Super-DEA (data envelopment analysis) to measure the AWUE of 52 cities in Northwest China from 2000 to 2018. Based on spatial and temporal perspectives, it applied Exploratory Spatial Data Analysis (ESDA) to explore the dynamic evolution and regional differences of AWUE. A spatial econometric model was then used to analyze the main factors that influence the AWUE in Northwest China. The results showed firstly that the overall AWUE in Northwest China from 2000 to 2018 presented a steady upward trend. However, only a few cities achieved effective agricultural water usage by 2018, and the differences among cities were obvious. Secondly, AWUE showed an obvious spatial autocorrelation in Northwest China and showed significant high–high and low–low agglomeration characteristics. Thirdly, economic growth, urbanization development, and effective irrigation have significant, positive effects on AWUE, while per capita water resource has a significant, negative influence. Finally, when improving the AWUE in arid and semi-arid regions, plans should be formulated according to local conditions. The results of this study can provide new ideas on the study of AWUE in arid and semi-arid regions and provide references for the formulation of regional agricultural water resource utilization policies as well.

Exploring Northwest China's agricultural water-saving strategy: analysis of water use efficiency based on an SE-DEA model conducted in Xi'an, Shaanxi Province

2016 ◽  
Vol 74 (5) ◽  
pp. 1106-1115 ◽  
Author(s):  
L. Mu ◽  
L. Fang ◽  
H. Wang ◽  
L. Chen ◽  
Y. Yang ◽  
...  
Keyword(s):  
Water Resources ◽  
Water Use Efficiency ◽  
Water Use ◽  
Water Demand ◽  
Water Governance ◽  
Northwest China ◽  
Water Saving ◽  
Shaanxi Province ◽  
Agricultural Water ◽  
Use Efficiency

Worldwide, water scarcity threatens delivery of water to urban centers. Increasing water use efficiency (WUE) is often recommended to reduce water demand, especially in water-scarce areas. In this paper, agricultural water use efficiency (AWUE) is examined using the super-efficient data envelopment analysis (DEA) approach in Xi'an in Northwest China at a temporal and spatial level. The grey systems analysis technique was then adopted to identify the factors that influenced the efficiency differentials under the shortage of water resources. From the perspective of temporal scales, the AWUE increased year by year during 2004–2012, and the highest (2.05) was obtained in 2009. Additionally, the AWUE was the best in the urban area at the spatial scale. Moreover, the key influencing factors of the AWUE are the financial situations and agricultural water-saving technology. Finally, we identified several knowledge gaps and proposed water-saving strategies for increasing AWUE and reducing its water demand by: (1) improving irrigation practices (timing and amounts) based on compatible water-saving techniques; (2) maximizing regional WUE by managing water resources and allocation at regional scales as well as enhancing coordination among Chinese water governance institutes.

Adaptive responses to drought of two Retama raetam subspecies from Tunisia

2021 ◽  
Author(s):  
Ricardo GIL ◽  
Dhikra ZAYOUD ◽  
Zeineb OUERGHI ◽  
Monica BOSCAIU ◽  
Oscar VICENTE ◽  
...  
Keyword(s):  
Drought Stress ◽  
Glycine Betaine ◽  
Soluble Sugars ◽  
Co2 Concentration ◽  
Photosynthetic Parameters ◽  
Adaptive Responses ◽  
Retama Raetam ◽  
Physiological Adaptations ◽  
Use Efficiency ◽  
Desert Climate

Abstract Aims The survival and ecological distribution of plants in arid habitats are mainly conditioned by water availability and physiological adaptations to withstand drought. In the present study, we have compared the physiological responses to drought of two Retama raetam (retama) subspecies from Tunisia, one of them living under the desert climate (subsp. raetam) and the other one growing on the coast (subsp. bovei). Methods To physiologically characterize the two R. raetam subspecies, and to elucidate their main mechanisms underlying their tolerance to drought stress, parameters related to seed germination, growth, photosynthesis (net photosynthetic rate, intracellular CO2 concentration, transpiration rate, stomatal conductance and water use efficiency), and accumulation of osmolytes (proline, glycine betaine and soluble sugars) were determined in four-month-old plants subjected to stress for up to one month. Important findings Drought significantly inhibited germination, growth, and all the evaluated photosynthetic parameters. Plants of R. raetam subsp. bovei were severely affected by drought after three weeks of treatment when photosynthesis rates were up to 7-fold lower than in the controls. At the same time, proline and glycine betaine significantly accumulated compared to the irrigated controls, but much less than in R. raetam subsp. raetam; in the latter subspecies, proline and glycine betaine increased to levels 24-fold and 6-fold higher, respectively, than in the corresponding controls. In summary, the population living in the desert region exhibited stronger tolerance to drought stress than that adapted to the semiarid littoral climate, suggesting that tolerance in R. raetam is dependent on accumulation of osmolytes.

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