Water uptake by crop roots is influenced by many factors. In this study, on the basis of previous studies, root water uptake models were established with the root weight as a dependent variable from the perspective of...Water uptake by crop roots is influenced by many factors. In this study, on the basis of previous studies, root water uptake models were established with the root weight as a dependent variable from the perspective of root biomass changes according to the theory of soil water dynamics. The established models were verified and evaluated using two indicators: root-mean-square error (RMSE) and mean absolute percentage error (MAPE). The results indicated that the annual variation range of root-mean-square error (RMSE) was 0.477-1.231, with an aver- age of 0.810; the annual variation range of mean absolute percentage error (MAPE) was 1.082%-4.052%, with an average of 2.520%, suggesting that the simulation accuracy basically met the requirements. The established numerical models of root water uptake and the compiled program exhibit high simulation accuracy, which can perfectly simulate soil water dynamics during the growth period of crops under nat- ural conditions.展开更多
Lucerne (Medicago sativa L.) is a deep-rooted perennial leguminous forage with high evapo-transpiration rate exceeding the annual precipitation in semi-arid areas of Northwest China. Groundwater might be the potenti...Lucerne (Medicago sativa L.) is a deep-rooted perennial leguminous forage with high evapo-transpiration rate exceeding the annual precipitation in semi-arid areas of Northwest China. Groundwater might be the potential water sources of lucerne in the area with shallow groundwater table. In this study, stable isotopic compositions of oxygen and hydrogen (6180 and 8D) of different water sources and xylem sap were analyzed to determine the seasonal (April, June, July and August) and topographic (three slope positions) variations in water sources for lucerne growing in Ningxia eastern semi-arid area adjacent to Mu Us Desert characterized by shallow groundwater table. IsoSource software was used to calculate the probable contribution of different water sources to the total plant water uptake. Stomatal conductance, stem water potential, carbon isotope discrimination (A13C) of whole plant were also determined for evaluating the water status of lucerne growing at different slope positions. The results showed that soil water content increased as the elevation decreased. Oxygen compositions of soil water in the 0-40 cm profile fluctuated considerably. Soil water 8180 values in deep profile (〉3.5 m) were similar to those in groundwater, implying the recharge of groundwater to this soil layer. Highest water utilization rate from deep soil profile (below 350 cm) was recorded for lucerne grown at the slope position 1 (groundwater table depth of 3.5-3.9 m) in April, June and July. The lucernes at slope position 2 (groundwater table depth of 5.8-6.4 m) and slope position 3 (groundwater table depth 7.1-8.3 m) mostly used water from deep soil layers (below 350 cm) during dry period, and turned to use water from superficial soil layer in wet period. Higher yield, A13C value of whole plant and stomatal conductance were observed for lucerne grown at the slope position 1 than those at other slope positions. These results indicated that groundwater is a significant water source for transpiration of lucerne grown in Ningxia semi-arid area with shallow groundwater table where lucerne grassland is suggested to be established so as to obtain better yield performance.展开更多
To examine the potential heterosis for water uptake by maize roots, the hydraulic properties of roots in the F1 hybrid (Hudan 4) were compared with those of its inbred parents ( 478 and Tian 4) at cellular, singl...To examine the potential heterosis for water uptake by maize roots, the hydraulic properties of roots in the F1 hybrid (Hudan 4) were compared with those of its inbred parents ( 478 and Tian 4) at cellular, single-root and whole-root system levels under well-watered and water-deficit conditions. The cell hydraulic conductivity (Lpc) decreased under water deficit, but the Lpc of the F1 was higher than that of its inbred parents with or without stress from water deficit. Marked reductions in Lpc were observed following Hg2+ treatment. The hydrostatic hydraulic conductivity of single roots (hydrostatic Lpsr) varied among genotypes under the two water treatments, with the highest in the F1 and the lowest in 478. Radial hydraulic conductivity (radial Lpsr) and axial hydraulic conductance (Lax) of the three genotypes varied similarly as Lpsr. The variations in hydraulic parameters were related to root anatomy. Radial Lpsr was negatively correlated with the ratio of cortex width to root diameter (R2=-0.77, P〈0.01), whereas Lax was positively correlated with the diameter of the central xylem vessel (R2=0.75, P〈0.01) and the cross-sectional area of xylem vessels (R2=0.93, P〈0.01 ). Hydraulic conductivity (Lpwr) and conductance (Lwr) of the whole-root system followed the same trend under the two water treatments, with the highest values in the F1. The results demonstrated that heterosis for water uptake by roots of the F1 occurred at cellular, single-root and whole-root system levels under well-watered and water-deficit conditions.展开更多
Water-deficit (WD) is a major abiotic stress constraining crop productivity worldwide. Zhenshan 97 is a drought-susceptible rice genotype, while IRAT109 is a drought-resistant one. However, the physiological basis o...Water-deficit (WD) is a major abiotic stress constraining crop productivity worldwide. Zhenshan 97 is a drought-susceptible rice genotype, while IRAT109 is a drought-resistant one. However, the physiological basis of the difference remains unclear. These two genotypes had similar total water uptake rates under both WD and well-watered (WW) conditions, and their water uptake rates under WD were significantly decreased compared with those under WW. However, the water uptake rate via the cell-to-cell pathway was significantly increased in Zhenshan 97 but decreased in IRAT109 under WD, whereas the opposite trends were observed through the apoplastic pathway. These results indicated that the stress responses and relative contributions of these two water uptake pathways were associated with rice genotype under WD. The expression levels of OsPIP2;4 and OsPIP2;5 genes were significantly higher in roots of Zhenshan 97 than in IRAT109 under the two conditions. OsPIP2;4 expression in roots was significantly up-regulated under WD, while OsPIP2;5 expression showed no significant change. These results suggest that the expression levels of OsPIP2;4 and OsPIP2;5 in rice are dependent on genotype and water availability. Compared with Zhenshan 97, IRAT109 had a higher root dry weight, water uptake rate and xylem sap flow rate, and lower leaf water potential and root porosity under WD, which might be responsible for the drought resistance in IRAT109.展开更多
Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins(AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coro...Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins(AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coronatine(COR), enhanced maize(Zea mays) root water uptake capacity under artificial water deficiency conditions. COR treatment induced the expression of the AQP gene Plasma membrane intrinsic protein 2;5(ZmPIP2;5).In vivo and in vitro experiments indicated that COR also directly acts on ZmPIP2;5 to improve water uptake in maize and Xenopus oocytes. The leaf water potential and hydraulic conductivity of roots growing under hyperosmotic conditions were higher in ZmPIP2;5-overexpression lines and lower in the zmpip2;5 knockout mutant, compared to wild-type plants. Based on a comparison between ZmPIP2;5 and other PIP2s, we predicted that COR may bind to the functional site in loop E of ZmPIP2;5. We confirmed this prediction by surface plasmon resonance technology and a microscale thermophoresis assay, and showed that deleting the binding motif greatly reduced COR binding. We identified the N241 residue as the COR-specific binding site, which may activate the channel of the AQP tetramer and increase water transport activity,which may facilitate water uptake under hyperosmotic stress.展开更多
We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model (IsoSource) to determine water uptake depths and estimate proportional contribution of po...We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model (IsoSource) to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine (Pinus sylvestris var. mongolica) plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil (up to 80 cm in this study). Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.展开更多
To study the effects of local nitrogen supply on water and nutrient absorption, French bean (Phaseolus vulgaris L.) plants were grown in a split root system. Five treatments supplied with different nitrogen forms we...To study the effects of local nitrogen supply on water and nutrient absorption, French bean (Phaseolus vulgaris L.) plants were grown in a split root system. Five treatments supplied with different nitrogen forms were compared: homogeneous nitrate (NN) and homogenous ammonium (AA) supply, spatially separated supply of nitrate and ammonium (NA), half of the root system supplied with N-free nutrient solution, the other half with either nitrate (NO) or ammonium (AO). The results showed that 10 d after onset of treatments, root dry matter (DM) in the nitratesupplied vessels treated with NA was more than two times higher than that in the ammonium-supplied vessels. Water uptake from the nitrate-supplied vessels treated with NA was 281% higher than under ammonium supply. In treatments NO and AO, the local supply of N resulted in clearly higher root DM, and water uptake from the nitratesupplied vessels was 82% higher than in the -N vessels. However, in AO plants, water uptake from the -N nutrient solution was 129% higher than from the ammonium-supplied vessels. This indicates a compensatory effect, which resulted in almost identical rates of total water uptake of treatments AA and AO, which had comparable shoot DM and leaf area. Ammonium supply reduced potassium and magnesium absorption. Water uptake was positively correlated with N, Mg and K uptake.展开更多
A field experiment using PVC growth tubes was conducted in the Loess Plateau of China to determine the effective root depth(ERD)of winter wheat and its relationship with root distributions and soil water conditions.Th...A field experiment using PVC growth tubes was conducted in the Loess Plateau of China to determine the effective root depth(ERD)of winter wheat and its relationship with root distributions and soil water conditions.The water stable isotopes technique was used to estimate the water uptake contributions of different root depths during the growth stages.On the basis of IsoSource and the Romero-Saltos model,the ERD was 0-40 cm in the majority of the growth stage.However,in the heading and filling stages,the ERD could reach 60%-75%of the maximum root depth.Furthermore,the contributions to water uptake of different root depths were correlated with variations in soil water and root length density(r=0.395 and 0.368,respectively;p<0.05).However,by path analysis,the low decisive coefficient indicated that root distribution and soil water content did not always follow the same trend as water uptake.The conclusions of this study can help with understanding winter wheat water uptake mechanisms in arid and semi-arid regions and increasing water use efficiency.展开更多
Water storage pit irrigation is a new method suitable for apple trees.It comes with advantages such as water saving,water retention and drought resistance.A precise study of soil water movement and root water uptake i...Water storage pit irrigation is a new method suitable for apple trees.It comes with advantages such as water saving,water retention and drought resistance.A precise study of soil water movement and root water uptake is essential to analyse and show the advantages of the method.In this study,a mathematical model(WSPI-WR model)for 3D soil water movement and root water uptake under water storage pit irrigation was established based on soil water dynamics and soil moisture and root distributions.Moreover,this model also considers the soil evaporation,pit wall evaporation and water level variation in the pit.The finite element method was used to solve the model,and the law of mass conservation was used to analyse the water level variation.The model was validated by experimental data of the sap flow of apple trees and soil moisture in the orchard.Results showed that the WSPI-WR model is highly accurate in simulating the root water uptake and soil water distributions.The WSPI-WR model can be used to simulate root water uptake and soil water movement under water storage pit irrigation.The simulation showed that orchard soil water content and root water uptake rate centers on the storage pit with an ellipsoid distribution.The maximum distribution region of soil water and root water uptake rate was near the bottom of the pit.Distribution can reduce soil evaporation in the orchard and improve the soil water use efficiency in the middle-deep soil.展开更多
Significant advancement in anion exchange membrane(AEM)fuel cell(AEMFC)technology is important in the field of renewable energy.AEMs with comb-shaped architectures have attracted considerable research interest because...Significant advancement in anion exchange membrane(AEM)fuel cell(AEMFC)technology is important in the field of renewable energy.AEMs with comb-shaped architectures have attracted considerable research interest because of some unique features,including high anion conductivity,low swelling,and high alkaline stability.Here,we report preparation,characterization,and performance evaluation of a novel comb-shaped cross-linked AEM synthesized by the thiol-ene click and Menshutkin reactions.The prepared ionomer decreases the trade-off between the water uptake and the conductivity.The thiol-ene click reaction was used to synthesize the 1,14-di(1H-imidazol-1-yl)-6,9-dioxa-3,12-dithiatetradecane(IDDT)cross-linker.IDDT was then introduced into the brominated poly(2,6-dimethyl-1,4-phenylene oxide)backbone by the Menshutkin reaction.The prepared ionomers show high thermomechanical stability,which is needed in AEMFC technology.The CLINK-15-100 membrane(ion exchange capacity 1.23 mmol/g)shows relatively good conductivities of 19.66 and 34.91 mS/cm at 30 and 60℃,respectively.Interestingly,the membrane shows water uptake of only 14.22%at room temperature,which is considerably lower than many previously reported membranes.After 16 days of alkaline treatment in 1 M NaOH solution at 60℃,the CLINK-15-100 membrane retains 77%of its initial conductivity,which is much better than the traditional quaternized poly(2,6-dimethyl-1,4-phenylene oxide)membrane.展开更多
As root water uptake(RWU)is an important link in the water and heat exchange between plants and ambient air,improving its parameterization is key to enhancing the performance of land surface model simulations.Althou...As root water uptake(RWU)is an important link in the water and heat exchange between plants and ambient air,improving its parameterization is key to enhancing the performance of land surface model simulations.Although different types of RWU functions have been adopted in land surface models,there is no evidence as to which scheme most applicable to maize farmland ecosystems.Based on the 2007–09 data collected at the farmland ecosystem field station in Jinzhou,the RWU function in the Common Land Model(Co LM)was optimized with scheme options in light of factors determining whether roots absorb water from a certain soil layer(W_x)and whether the baseline cumulative root efficiency required for maximum plant transpiration(W_c)is reached.The sensibility of the parameters of the optimization scheme was investigated,and then the effects of the optimized RWU function on water and heat flux simulation were evaluated.The results indicate that the model simulation was not sensitive to W_x but was significantly impacted by W_c.With the original model,soil humidity was somewhat underestimated for precipitation-free days;soil temperature was simulated with obvious interannual and seasonal differences and remarkable underestimations for the maize late-growth stage;and sensible and latent heat fluxes were overestimated and underestimated,respectively,for years with relatively less precipitation,and both were simulated with high accuracy for years with relatively more precipitation.The optimized RWU process resulted in a significant improvement of Co LM’s performance in simulating soil humidity,temperature,sensible heat,and latent heat,for dry years.In conclusion,the optimized RWU scheme available for the Co LM model is applicable to the simulation of water and heat flux for maize farmland ecosystems in arid areas.展开更多
Soil water content significantly influenced uptake and distribution of ^15N in both Newhall and Yamasitaka. The content of ^15N uptake in treated plants was less than that in controlled plants, under 20% soil water co...Soil water content significantly influenced uptake and distribution of ^15N in both Newhall and Yamasitaka. The content of ^15N uptake in treated plants was less than that in controlled plants, under 20% soil water content, ^15N was only taken up 16.02% by Newhall and 10.11% by Yamasitaka. The most ^15N was detained in root and old shoots under water stress. Protein concentration in two cultivars significantly decreased by water deficit stress, protein content of Newhall and Yamasitaka in controlled plants was 16.29 mg/g fresh weight and 15.89 mg/g fresh weight, but at 20% of water content, these were 9.60 mg/g fresh weight and 9.02 mg/g fresh weight. Water stress increased concentration of NH3-NH4^+, Arginine and Proline. Compared with control plants, concentrations of NH3-NH4^+ in both Newhall and Yamasitaka at 20% water content treatment increased 5.83 fold and 5.71 fold, Arginine increased 197% and 205%, and Proline increased 112% and 132%.展开更多
Background:Water migration and use are important processes in trees.However,it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere t...Background:Water migration and use are important processes in trees.However,it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration.Therefore,it is necessary to quantify the water transpired and stored in plants.Method:The δ^(2)H/δ^(18)O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species,including the proportions of water used for transpiration and water storage.Results:Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources.Platycladus orientalis primarily used groundwater(30.5%)and the 60-100-cm soil layer(21.6%)throughout the experimental period and was sensitive to precipitation,absorbing water from the 0-20-cm layer(26.6%)during the rainy season.Quercus variabilis absorbed water from all sources(15.7%-36.5%)except from the 40-60-cm soil layer during the dry season.In addition,it did not change its water source but increased its groundwater uptake during the rainy season.The annual mean water fluxes of P.orientalis and Q.variabilis were 374.69 and 469.50 mm·year−1,with 93.49% and 93.91% of the water used for transpiration,respectively.However,nocturnal sap flow in P.orientalis and Q.variabilis was mainly used for water storage in the trunk rather than transpiration,which effectively alleviated drought stress and facilitated the transport of nutrients.Conclusions:The water stored in both species comprised 6%-7% of the total water fluxes and,therefore,should be considered in water balance models.展开更多
Caragana korshinskii Kom.and Tamarix ramosissima Ledeb.are pioneer shrubs for water and soil conservation,and for windbreak and sand fixation in arid and semi-arid areas.Understanding the water use characteristics of ...Caragana korshinskii Kom.and Tamarix ramosissima Ledeb.are pioneer shrubs for water and soil conservation,and for windbreak and sand fixation in arid and semi-arid areas.Understanding the water use characteristics of different pioneer shrubs at different ages is of great importance for their survival when extreme rainfall occurs.In recent years,the stable isotope tracing technique has been used in exploring the water use strategies of plants.However,the widespreadδ^(2)H offsets of stem water from its potential sources result in conflicting interpretations of water utilization of plants in arid and semi-arid areas.In this study,we used three sets of hydrogen and oxygen stable isotope data(δ^(2)H andδ^(18)O,correctedδ^(2)H_c1 based on SW-excess andδ^(18)O,and correctedδ^(2)H_c2 based on−8.1‰andδ^(18)O)as inputs for the MixSIAR model to explore the water use characteristics of C.korshinskii and T.ramosissima at different ages and in response to rainfall.The results showed thatδ^(2)H_c1 andδ^(18)O have the best performance,and the contribution rate of deep soil water was underestimated because ofδ^(2)H offset.During the dry periods,C.korshinskii and T.ramosissima at different ages both obtained mostly water from deeper soil layers.After rainfall,the proportions of surface(0-10 cm)and shallow(10-40 cm)soil water for C.korshinskii and T.ramosissima at different ages both increased.Nevertheless,there were different response mechanisms of these two plants for rainfall.In addition,C.korshinskii absorbed various potential water sources,while T.ramosissima only used deep water.These flexible water use characteristics of C.korshinskii and T.ramosissima might facilitate the coexistence of plants once extreme rainfall occurs.Thus,reasonable allocation of different plants may be a good vegetation restoration program in western Chinese Loess Plateau.展开更多
The influence of water deficit as main cane yield limiting factor in Ivory Coast was investigated on SUCAF Ferke 2 and Sucrivoire Zuenoula sugarcane commercial plantations. A soil water balance model was used to asses...The influence of water deficit as main cane yield limiting factor in Ivory Coast was investigated on SUCAF Ferke 2 and Sucrivoire Zuenoula sugarcane commercial plantations. A soil water balance model was used to assess crop water uptake over two critical growth stages, namely stem elongation and yield formation, to be correlated with cane yields. Under simulated rainfed conditions, average yields performed on yearly basis (from 1991 to 1997) in both sites were highly dependent (linearly) on average crop water satisfaction ratio (ETa/ETm) over these critical growth stages. Under real field conditions in Ferke 2 (irrigation water being considered in addition to rainfall), cane yields of early as well as late maturing sugarcane varieties obtained on yearly basis were dependent on average crop water satisfaction ratio over both growth stages. In Zudnoula, cane yield fluctuations were generally not predicted by crop water satisfaction ratio, regardless the cropping season considered. However, average cane yields obtained from year to year over the study period in both sugarcane schemes were highly dependent on the average crop water uptake ratio. This shows the important contribution of water in predicting yearly variations of average cane yields produced on Ivorian sugarcane commercial plantations.展开更多
Understanding plant water-use patterns is important for improving water-use efficiency and for sustainable vegetation restoration in arid and semi-arid regions. However, seasonal variations in water sources and their ...Understanding plant water-use patterns is important for improving water-use efficiency and for sustainable vegetation restoration in arid and semi-arid regions. However, seasonal variations in water sources and their control by different sand-fixing plants in water-limited desert ecosystems remain poorly understood. In this study, stable isotopic ratios of hydrogen(δ^(2)H) and oxygen(δ^(18)O) in precipitation, soil water, groundwater, and xylem water were determined to document seasonal changes in water uptake by three representative plant species(Pinus sylvestris var. mongolica Litv., Amygdalus pedunculata Pall., and Salix psammophila) in the northeastern Mu Us sandy land, Northwest China. Based on the depth distribution and temporal variation of measured gravimetric soil water content(SWC), the soil water profile of the three species stands was divided into active(0.01 g g^(-1)< SWC < 0.08 g g^(-1), 20%< coefficient of variation(CV) < 45%), stable(0.02 g g^(-1)< SWC < 0.05 g g^(-1), CV < 20%), and moist(0.08 g g^(-1)< SWC < 0.20 g g^(-1), CV >45%) layers. Annually, P. sylvestris, A. pedunculata, and S. psammophila obtained most water from deep(59.2%±9.7%, moist layer and groundwater),intermediate(57.4%±9.8%, stable and moist layers), and shallow(54.4%±10.5%, active and stable layers) sources, respectively. Seasonally, the three plant species absorbed more than 60% of their total water uptake from the moist layer and groundwater in the early(June) dry season;then, they switched to the active and stable layers in the rainy season(July–September) for water resources(50.1%–62.5%). In the late(October–November) dry season, P. sylvestris(54.5%–66.2%) and A. pedunculata(52.9%–63.6%) mainly used water from stable and moist layers, whereas S. psammophila(52.6%–70.7%) still extracted water predominantly from active and stable layers. Variations in the soil water profile induced by seasonal fluctuations in precipitation and groundwater levels and discrepancies in plant phenology, root distribution, and water demand are the main factors affecting the seasonal water-use patterns of artificial sand-fixing plants. Our study addresses the issue of plant water uptake with knowledge of proportional source-water use and reveals important implications for future vegetation restoration and water management in the Mu Us sandy land and similar desert regions around the world.展开更多
Low germination and vigor of rice seed associated with dry-seed broadcasting are common problems encountered by rice growers.The objectives of this study were to evaluate the role of potassium nitrate(KNO3)on the pa...Low germination and vigor of rice seed associated with dry-seed broadcasting are common problems encountered by rice growers.The objectives of this study were to evaluate the role of potassium nitrate(KNO3)on the pattern of seed imbibition and to determine the effect of seed priming with KNO3 on the germination percentage,speed and uniformity of germination in rice seed.Experiment 1 compared the patterns of seed imbibition of six concentrations of KNO3(0,0.25,0.50,1.00,1.50,and 2.00%)in two rice cultivars-KDML105 and RD15.The results showed that soaking rice seed in KNO3 at higher concentrations could delay the imbibition time.The higher concentrations of KNO3 delayed the imbibition time of rice seed and took a longer time to reach the end of phases 1 and 2 compared to the lower concentrations.The patterns of seed imbibition using distilled water of both rice cultivars(KDML105 and RD15)were quite similar,but with different concentrations of KNO3,the imbibition time taken to reach the end of phases 1 and 2 was slightly postponed in KDML105 suggesting that different rice cultivars may need different imbibition times for soaking seed in the priming process.Experiment 2 evaluated the effects of seed priming with 1.0 and 2.0%KNO3 at different imbibition times.It was found that priming with 1.0%KNO3 showed better seed germination than priming with 2.0%KNO3 and seed priming with 1.0%KNO3 at the imbibition time of early phase 2(or 28 h for KDML105)improved seed germination and increased both the speed and uniformity of seed germination.The results of this study show promise for the use of priming with 1.0%KNO3 soaked until early phase 2 of seed imbibition for improving the seed germination and vigor of rice in dry seed broadcasting.展开更多
Growing soybeans in different row-spacings introduces competition. Competition begins when the immediate supply of a single necessary factor falls below the combined demands of all plants. This paper reviews the main ...Growing soybeans in different row-spacings introduces competition. Competition begins when the immediate supply of a single necessary factor falls below the combined demands of all plants. This paper reviews the main competition factors of genotypes, light, water, nutrients and weed in responses to row spacings for the past four decades. It demonstrated that responses of soybean genotypes to row width differ among cultivars, which depend on seasonal rainfall and irrigation. Determinate types produce more yield in narrow-rows, and cultivars with lodging resistance should be adopted in narrow-spacings, but indeterminate soybean should also be used to optimize yields in certain system. Narrow-compared with wide-row soybean (Glycine max) cultivation increases light interception (LI) and dominant components for the increase come from LAI, light extinction coefficients and branch types. Water use efficiency (WUE) and evapotranspiration are not influenced by row spacing, but seed yield could be increased if irrigation is applied. Nutrient uptake is significantly affected by row spacing, seed yields and uptake of N, P, K in plants increases with decreasing row spacing, and the effects depend on the fertilizer levels. Other factors rather than row spacing affect nitrogen fixation. Weed density, peak time and periodicity of weed emergence are not affected by row spacing, but better complementary weed control by the herbicides at the used doses can be obtained in narrow spacing due to the reduced weed number and dry weight. More researches are required to investigate the physiological responses, nutrient and water uptake and translocation, light utilization at different layers of canopy and soil environment changes in different row-spacings.展开更多
Microbially induced carbonate precipitation(MICP)is a promising technique for the autonomous healing of concrete cracks.In this study,the effect of pH on MICP was investigated.The results indicate that the MICP proces...Microbially induced carbonate precipitation(MICP)is a promising technique for the autonomous healing of concrete cracks.In this study,the effect of pH on MICP was investigated.The results indicate that the MICP process was inhibited when the pH was higher than 11.Both vaterite and calcite were produced when the pH was<8,whereas only calcite was produced when the pH was>8.Recycled concrete aggregates(RCA)coated with sodium silicate have been proposed as protective carriers for microbial healing agents.Although the presence of the coated RCA resulted in a loss of the splitting tension strength of the concrete,the loaded healing agents were highly efficient in self-healing cracks.Concrete incorporated with 20%RCA loaded with healing agents exhibited the best self-healing performance.When the initial crack widths were between 0.3 and 0.4 mm,the 7-d mean healing rate was approximately 90%.At 28 d,the crack area filling ratio was 86.4%,while its water tightness recovery ratio was 74.4%and 29.8%,respectively,for rapid and slow absorption.This study suggests that RCA coated with sodium silicate is an effective method for packaging microbial healing agents and has great potential for developing cost-effective self-healing concrete.展开更多
In arid and semiarid areas,water uptake (non-rainfall water) serves as an important water source for plants,biological soil crusts,insects and small animals.In this study,a measurement program was undertaken to invest...In arid and semiarid areas,water uptake (non-rainfall water) serves as an important water source for plants,biological soil crusts,insects and small animals.In this study,a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert.In the study region,water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake,and was mainly taken up by a water vapor adsorption mechanism;the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%).The formation of crusts promoted water uptake,but the increased uptake did not occur immediately after inoculation or crusts formation.The water taken up from the atmosphere increased significantly from day 15 after inoculation,and the soil water content was markedly enhanced from day 20 after inoculation.It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts,and these variables increased even during dry periods when some algae are likely to have died.展开更多
文摘Water uptake by crop roots is influenced by many factors. In this study, on the basis of previous studies, root water uptake models were established with the root weight as a dependent variable from the perspective of root biomass changes according to the theory of soil water dynamics. The established models were verified and evaluated using two indicators: root-mean-square error (RMSE) and mean absolute percentage error (MAPE). The results indicated that the annual variation range of root-mean-square error (RMSE) was 0.477-1.231, with an aver- age of 0.810; the annual variation range of mean absolute percentage error (MAPE) was 1.082%-4.052%, with an average of 2.520%, suggesting that the simulation accuracy basically met the requirements. The established numerical models of root water uptake and the compiled program exhibit high simulation accuracy, which can perfectly simulate soil water dynamics during the growth period of crops under nat- ural conditions.
基金funded by the National Natural Science Foundation of China(31160478)the National Program on Key Basic Research Project of China(2012CB723206)the Agricultural Breeding Project of Ningxia Hui Autonomous Region(2014NYYZ0401)
文摘Lucerne (Medicago sativa L.) is a deep-rooted perennial leguminous forage with high evapo-transpiration rate exceeding the annual precipitation in semi-arid areas of Northwest China. Groundwater might be the potential water sources of lucerne in the area with shallow groundwater table. In this study, stable isotopic compositions of oxygen and hydrogen (6180 and 8D) of different water sources and xylem sap were analyzed to determine the seasonal (April, June, July and August) and topographic (three slope positions) variations in water sources for lucerne growing in Ningxia eastern semi-arid area adjacent to Mu Us Desert characterized by shallow groundwater table. IsoSource software was used to calculate the probable contribution of different water sources to the total plant water uptake. Stomatal conductance, stem water potential, carbon isotope discrimination (A13C) of whole plant were also determined for evaluating the water status of lucerne growing at different slope positions. The results showed that soil water content increased as the elevation decreased. Oxygen compositions of soil water in the 0-40 cm profile fluctuated considerably. Soil water 8180 values in deep profile (〉3.5 m) were similar to those in groundwater, implying the recharge of groundwater to this soil layer. Highest water utilization rate from deep soil profile (below 350 cm) was recorded for lucerne grown at the slope position 1 (groundwater table depth of 3.5-3.9 m) in April, June and July. The lucernes at slope position 2 (groundwater table depth of 5.8-6.4 m) and slope position 3 (groundwater table depth 7.1-8.3 m) mostly used water from deep soil layers (below 350 cm) during dry period, and turned to use water from superficial soil layer in wet period. Higher yield, A13C value of whole plant and stomatal conductance were observed for lucerne grown at the slope position 1 than those at other slope positions. These results indicated that groundwater is a significant water source for transpiration of lucerne grown in Ningxia semi-arid area with shallow groundwater table where lucerne grassland is suggested to be established so as to obtain better yield performance.
基金supported by the National Basic Research Program of China (2009CB118604)the National Natural Science Foundation of China (30971714)the Project 111 of the Ministry of Education of China (B12007)
文摘To examine the potential heterosis for water uptake by maize roots, the hydraulic properties of roots in the F1 hybrid (Hudan 4) were compared with those of its inbred parents ( 478 and Tian 4) at cellular, single-root and whole-root system levels under well-watered and water-deficit conditions. The cell hydraulic conductivity (Lpc) decreased under water deficit, but the Lpc of the F1 was higher than that of its inbred parents with or without stress from water deficit. Marked reductions in Lpc were observed following Hg2+ treatment. The hydrostatic hydraulic conductivity of single roots (hydrostatic Lpsr) varied among genotypes under the two water treatments, with the highest in the F1 and the lowest in 478. Radial hydraulic conductivity (radial Lpsr) and axial hydraulic conductance (Lax) of the three genotypes varied similarly as Lpsr. The variations in hydraulic parameters were related to root anatomy. Radial Lpsr was negatively correlated with the ratio of cortex width to root diameter (R2=-0.77, P〈0.01), whereas Lax was positively correlated with the diameter of the central xylem vessel (R2=0.75, P〈0.01) and the cross-sectional area of xylem vessels (R2=0.93, P〈0.01 ). Hydraulic conductivity (Lpwr) and conductance (Lwr) of the whole-root system followed the same trend under the two water treatments, with the highest values in the F1. The results demonstrated that heterosis for water uptake by roots of the F1 occurred at cellular, single-root and whole-root system levels under well-watered and water-deficit conditions.
基金jointly supported by the National Science&Technology Pillar Program(Grant No.2013BAD07B10)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110146110021)
文摘Water-deficit (WD) is a major abiotic stress constraining crop productivity worldwide. Zhenshan 97 is a drought-susceptible rice genotype, while IRAT109 is a drought-resistant one. However, the physiological basis of the difference remains unclear. These two genotypes had similar total water uptake rates under both WD and well-watered (WW) conditions, and their water uptake rates under WD were significantly decreased compared with those under WW. However, the water uptake rate via the cell-to-cell pathway was significantly increased in Zhenshan 97 but decreased in IRAT109 under WD, whereas the opposite trends were observed through the apoplastic pathway. These results indicated that the stress responses and relative contributions of these two water uptake pathways were associated with rice genotype under WD. The expression levels of OsPIP2;4 and OsPIP2;5 genes were significantly higher in roots of Zhenshan 97 than in IRAT109 under the two conditions. OsPIP2;4 expression in roots was significantly up-regulated under WD, while OsPIP2;5 expression showed no significant change. These results suggest that the expression levels of OsPIP2;4 and OsPIP2;5 in rice are dependent on genotype and water availability. Compared with Zhenshan 97, IRAT109 had a higher root dry weight, water uptake rate and xylem sap flow rate, and lower leaf water potential and root porosity under WD, which might be responsible for the drought resistance in IRAT109.
基金supported by the National Key Research and Development Program of China (2016YFD0300102-4)。
文摘Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins(AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coronatine(COR), enhanced maize(Zea mays) root water uptake capacity under artificial water deficiency conditions. COR treatment induced the expression of the AQP gene Plasma membrane intrinsic protein 2;5(ZmPIP2;5).In vivo and in vitro experiments indicated that COR also directly acts on ZmPIP2;5 to improve water uptake in maize and Xenopus oocytes. The leaf water potential and hydraulic conductivity of roots growing under hyperosmotic conditions were higher in ZmPIP2;5-overexpression lines and lower in the zmpip2;5 knockout mutant, compared to wild-type plants. Based on a comparison between ZmPIP2;5 and other PIP2s, we predicted that COR may bind to the functional site in loop E of ZmPIP2;5. We confirmed this prediction by surface plasmon resonance technology and a microscale thermophoresis assay, and showed that deleting the binding motif greatly reduced COR binding. We identified the N241 residue as the COR-specific binding site, which may activate the channel of the AQP tetramer and increase water transport activity,which may facilitate water uptake under hyperosmotic stress.
基金the National Science Foundation of China (30770339)
文摘We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model (IsoSource) to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine (Pinus sylvestris var. mongolica) plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil (up to 80 cm in this study). Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.
基金Supported by the Deutsche Forschungsgemeinschaft (Sa359/9) and the National Natural Science Foundation of China (30400279).Acknowledgements We thank Barbel Biegler and Anne ThieBen (Institute of Plant Nutrition and Soil Science, Kiel University, Germany) for skilled technical help.
文摘To study the effects of local nitrogen supply on water and nutrient absorption, French bean (Phaseolus vulgaris L.) plants were grown in a split root system. Five treatments supplied with different nitrogen forms were compared: homogeneous nitrate (NN) and homogenous ammonium (AA) supply, spatially separated supply of nitrate and ammonium (NA), half of the root system supplied with N-free nutrient solution, the other half with either nitrate (NO) or ammonium (AO). The results showed that 10 d after onset of treatments, root dry matter (DM) in the nitratesupplied vessels treated with NA was more than two times higher than that in the ammonium-supplied vessels. Water uptake from the nitrate-supplied vessels treated with NA was 281% higher than under ammonium supply. In treatments NO and AO, the local supply of N resulted in clearly higher root DM, and water uptake from the nitratesupplied vessels was 82% higher than in the -N vessels. However, in AO plants, water uptake from the -N nutrient solution was 129% higher than from the ammonium-supplied vessels. This indicates a compensatory effect, which resulted in almost identical rates of total water uptake of treatments AA and AO, which had comparable shoot DM and leaf area. Ammonium supply reduced potassium and magnesium absorption. Water uptake was positively correlated with N, Mg and K uptake.
基金the National Natural Science Foundation of China(51579168)the Program for Science and Technology Development of Shanxi Province(20140311016-6)the Program for Graduate Student Education and Innovation of Shanxi Province(2016BY065).
文摘A field experiment using PVC growth tubes was conducted in the Loess Plateau of China to determine the effective root depth(ERD)of winter wheat and its relationship with root distributions and soil water conditions.The water stable isotopes technique was used to estimate the water uptake contributions of different root depths during the growth stages.On the basis of IsoSource and the Romero-Saltos model,the ERD was 0-40 cm in the majority of the growth stage.However,in the heading and filling stages,the ERD could reach 60%-75%of the maximum root depth.Furthermore,the contributions to water uptake of different root depths were correlated with variations in soil water and root length density(r=0.395 and 0.368,respectively;p<0.05).However,by path analysis,the low decisive coefficient indicated that root distribution and soil water content did not always follow the same trend as water uptake.The conclusions of this study can help with understanding winter wheat water uptake mechanisms in arid and semi-arid regions and increasing water use efficiency.
基金supported by the Chinese National Natural Science Foundation(grant numbers 51109154,51579168,U1803112)the Shanxi Province National Natural Science Foundation(grant number 201601D011053).
文摘Water storage pit irrigation is a new method suitable for apple trees.It comes with advantages such as water saving,water retention and drought resistance.A precise study of soil water movement and root water uptake is essential to analyse and show the advantages of the method.In this study,a mathematical model(WSPI-WR model)for 3D soil water movement and root water uptake under water storage pit irrigation was established based on soil water dynamics and soil moisture and root distributions.Moreover,this model also considers the soil evaporation,pit wall evaporation and water level variation in the pit.The finite element method was used to solve the model,and the law of mass conservation was used to analyse the water level variation.The model was validated by experimental data of the sap flow of apple trees and soil moisture in the orchard.Results showed that the WSPI-WR model is highly accurate in simulating the root water uptake and soil water distributions.The WSPI-WR model can be used to simulate root water uptake and soil water movement under water storage pit irrigation.The simulation showed that orchard soil water content and root water uptake rate centers on the storage pit with an ellipsoid distribution.The maximum distribution region of soil water and root water uptake rate was near the bottom of the pit.Distribution can reduce soil evaporation in the orchard and improve the soil water use efficiency in the middle-deep soil.
基金Financial support from the National Science Foundation of China(Nos.91534203,21490581)is gratefully acknowledged.A scholarship from the CAS-TWAS Presidents Fellowship is highly appreciated.
文摘Significant advancement in anion exchange membrane(AEM)fuel cell(AEMFC)technology is important in the field of renewable energy.AEMs with comb-shaped architectures have attracted considerable research interest because of some unique features,including high anion conductivity,low swelling,and high alkaline stability.Here,we report preparation,characterization,and performance evaluation of a novel comb-shaped cross-linked AEM synthesized by the thiol-ene click and Menshutkin reactions.The prepared ionomer decreases the trade-off between the water uptake and the conductivity.The thiol-ene click reaction was used to synthesize the 1,14-di(1H-imidazol-1-yl)-6,9-dioxa-3,12-dithiatetradecane(IDDT)cross-linker.IDDT was then introduced into the brominated poly(2,6-dimethyl-1,4-phenylene oxide)backbone by the Menshutkin reaction.The prepared ionomers show high thermomechanical stability,which is needed in AEMFC technology.The CLINK-15-100 membrane(ion exchange capacity 1.23 mmol/g)shows relatively good conductivities of 19.66 and 34.91 mS/cm at 30 and 60℃,respectively.Interestingly,the membrane shows water uptake of only 14.22%at room temperature,which is considerably lower than many previously reported membranes.After 16 days of alkaline treatment in 1 M NaOH solution at 60℃,the CLINK-15-100 membrane retains 77%of its initial conductivity,which is much better than the traditional quaternized poly(2,6-dimethyl-1,4-phenylene oxide)membrane.
基金Supported by the National Natural Science Foundation of China(41305058)Cultivation Plan for Young Agricultural Science and Technology Talents of Liaoning Province(2015060 and 2014060)Key Agricultural Science and Industrialization Project of the Science and Technology Department of Liaoning Province(2014210003)
文摘As root water uptake(RWU)is an important link in the water and heat exchange between plants and ambient air,improving its parameterization is key to enhancing the performance of land surface model simulations.Although different types of RWU functions have been adopted in land surface models,there is no evidence as to which scheme most applicable to maize farmland ecosystems.Based on the 2007–09 data collected at the farmland ecosystem field station in Jinzhou,the RWU function in the Common Land Model(Co LM)was optimized with scheme options in light of factors determining whether roots absorb water from a certain soil layer(W_x)and whether the baseline cumulative root efficiency required for maximum plant transpiration(W_c)is reached.The sensibility of the parameters of the optimization scheme was investigated,and then the effects of the optimized RWU function on water and heat flux simulation were evaluated.The results indicate that the model simulation was not sensitive to W_x but was significantly impacted by W_c.With the original model,soil humidity was somewhat underestimated for precipitation-free days;soil temperature was simulated with obvious interannual and seasonal differences and remarkable underestimations for the maize late-growth stage;and sensible and latent heat fluxes were overestimated and underestimated,respectively,for years with relatively less precipitation,and both were simulated with high accuracy for years with relatively more precipitation.The optimized RWU process resulted in a significant improvement of Co LM’s performance in simulating soil humidity,temperature,sensible heat,and latent heat,for dry years.In conclusion,the optimized RWU scheme available for the Co LM model is applicable to the simulation of water and heat flux for maize farmland ecosystems in arid areas.
基金Acknowledgment The authors acknowledge the financial support of the CARS-3 (China Agricultural Research System) and National Natural Science Foundation of China (31071763) and suggestions of Dr. C.J. Lovatt,Professor of Plant Physiology, University of California, Riverside.
文摘Soil water content significantly influenced uptake and distribution of ^15N in both Newhall and Yamasitaka. The content of ^15N uptake in treated plants was less than that in controlled plants, under 20% soil water content, ^15N was only taken up 16.02% by Newhall and 10.11% by Yamasitaka. The most ^15N was detained in root and old shoots under water stress. Protein concentration in two cultivars significantly decreased by water deficit stress, protein content of Newhall and Yamasitaka in controlled plants was 16.29 mg/g fresh weight and 15.89 mg/g fresh weight, but at 20% of water content, these were 9.60 mg/g fresh weight and 9.02 mg/g fresh weight. Water stress increased concentration of NH3-NH4^+, Arginine and Proline. Compared with control plants, concentrations of NH3-NH4^+ in both Newhall and Yamasitaka at 20% water content treatment increased 5.83 fold and 5.71 fold, Arginine increased 197% and 205%, and Proline increased 112% and 132%.
基金funded by the National Natural Science Foundation of China(No.42007182)the self made experimental teaching instruments of Nanjing Forestry University in 2021(nlzzyq202127).
文摘Background:Water migration and use are important processes in trees.However,it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration.Therefore,it is necessary to quantify the water transpired and stored in plants.Method:The δ^(2)H/δ^(18)O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species,including the proportions of water used for transpiration and water storage.Results:Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources.Platycladus orientalis primarily used groundwater(30.5%)and the 60-100-cm soil layer(21.6%)throughout the experimental period and was sensitive to precipitation,absorbing water from the 0-20-cm layer(26.6%)during the rainy season.Quercus variabilis absorbed water from all sources(15.7%-36.5%)except from the 40-60-cm soil layer during the dry season.In addition,it did not change its water source but increased its groundwater uptake during the rainy season.The annual mean water fluxes of P.orientalis and Q.variabilis were 374.69 and 469.50 mm·year−1,with 93.49% and 93.91% of the water used for transpiration,respectively.However,nocturnal sap flow in P.orientalis and Q.variabilis was mainly used for water storage in the trunk rather than transpiration,which effectively alleviated drought stress and facilitated the transport of nutrients.Conclusions:The water stored in both species comprised 6%-7% of the total water fluxes and,therefore,should be considered in water balance models.
基金This study was funded by the National Natural Science Foundation of China(41771035,42071047)the Foundation for Distinguished Young Scholars of Gansu Province(20JR10RA112)+1 种基金the Northwest Normal University(NWNU-LKZD2021-04)the Department of Education of Gansu Province:"Innovation Star"Program of Excellent Postgraduates(2021CXZX-217).
文摘Caragana korshinskii Kom.and Tamarix ramosissima Ledeb.are pioneer shrubs for water and soil conservation,and for windbreak and sand fixation in arid and semi-arid areas.Understanding the water use characteristics of different pioneer shrubs at different ages is of great importance for their survival when extreme rainfall occurs.In recent years,the stable isotope tracing technique has been used in exploring the water use strategies of plants.However,the widespreadδ^(2)H offsets of stem water from its potential sources result in conflicting interpretations of water utilization of plants in arid and semi-arid areas.In this study,we used three sets of hydrogen and oxygen stable isotope data(δ^(2)H andδ^(18)O,correctedδ^(2)H_c1 based on SW-excess andδ^(18)O,and correctedδ^(2)H_c2 based on−8.1‰andδ^(18)O)as inputs for the MixSIAR model to explore the water use characteristics of C.korshinskii and T.ramosissima at different ages and in response to rainfall.The results showed thatδ^(2)H_c1 andδ^(18)O have the best performance,and the contribution rate of deep soil water was underestimated because ofδ^(2)H offset.During the dry periods,C.korshinskii and T.ramosissima at different ages both obtained mostly water from deeper soil layers.After rainfall,the proportions of surface(0-10 cm)and shallow(10-40 cm)soil water for C.korshinskii and T.ramosissima at different ages both increased.Nevertheless,there were different response mechanisms of these two plants for rainfall.In addition,C.korshinskii absorbed various potential water sources,while T.ramosissima only used deep water.These flexible water use characteristics of C.korshinskii and T.ramosissima might facilitate the coexistence of plants once extreme rainfall occurs.Thus,reasonable allocation of different plants may be a good vegetation restoration program in western Chinese Loess Plateau.
文摘The influence of water deficit as main cane yield limiting factor in Ivory Coast was investigated on SUCAF Ferke 2 and Sucrivoire Zuenoula sugarcane commercial plantations. A soil water balance model was used to assess crop water uptake over two critical growth stages, namely stem elongation and yield formation, to be correlated with cane yields. Under simulated rainfed conditions, average yields performed on yearly basis (from 1991 to 1997) in both sites were highly dependent (linearly) on average crop water satisfaction ratio (ETa/ETm) over these critical growth stages. Under real field conditions in Ferke 2 (irrigation water being considered in addition to rainfall), cane yields of early as well as late maturing sugarcane varieties obtained on yearly basis were dependent on average crop water satisfaction ratio over both growth stages. In Zudnoula, cane yield fluctuations were generally not predicted by crop water satisfaction ratio, regardless the cropping season considered. However, average cane yields obtained from year to year over the study period in both sugarcane schemes were highly dependent on the average crop water uptake ratio. This shows the important contribution of water in predicting yearly variations of average cane yields produced on Ivorian sugarcane commercial plantations.
基金funded by the National Natural Science Foundation of China(No.42377302)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2019052)+1 种基金the Bingwei Outstanding Young Talent Project from the Institute of Geographical Sciences and Natural Resources Research,China(2017RC203)the Open Foundation of State Key Laboratory of Urban and Regional Ecology,China(SKLURE2023-2-2)。
文摘Understanding plant water-use patterns is important for improving water-use efficiency and for sustainable vegetation restoration in arid and semi-arid regions. However, seasonal variations in water sources and their control by different sand-fixing plants in water-limited desert ecosystems remain poorly understood. In this study, stable isotopic ratios of hydrogen(δ^(2)H) and oxygen(δ^(18)O) in precipitation, soil water, groundwater, and xylem water were determined to document seasonal changes in water uptake by three representative plant species(Pinus sylvestris var. mongolica Litv., Amygdalus pedunculata Pall., and Salix psammophila) in the northeastern Mu Us sandy land, Northwest China. Based on the depth distribution and temporal variation of measured gravimetric soil water content(SWC), the soil water profile of the three species stands was divided into active(0.01 g g^(-1)< SWC < 0.08 g g^(-1), 20%< coefficient of variation(CV) < 45%), stable(0.02 g g^(-1)< SWC < 0.05 g g^(-1), CV < 20%), and moist(0.08 g g^(-1)< SWC < 0.20 g g^(-1), CV >45%) layers. Annually, P. sylvestris, A. pedunculata, and S. psammophila obtained most water from deep(59.2%±9.7%, moist layer and groundwater),intermediate(57.4%±9.8%, stable and moist layers), and shallow(54.4%±10.5%, active and stable layers) sources, respectively. Seasonally, the three plant species absorbed more than 60% of their total water uptake from the moist layer and groundwater in the early(June) dry season;then, they switched to the active and stable layers in the rainy season(July–September) for water resources(50.1%–62.5%). In the late(October–November) dry season, P. sylvestris(54.5%–66.2%) and A. pedunculata(52.9%–63.6%) mainly used water from stable and moist layers, whereas S. psammophila(52.6%–70.7%) still extracted water predominantly from active and stable layers. Variations in the soil water profile induced by seasonal fluctuations in precipitation and groundwater levels and discrepancies in plant phenology, root distribution, and water demand are the main factors affecting the seasonal water-use patterns of artificial sand-fixing plants. Our study addresses the issue of plant water uptake with knowledge of proportional source-water use and reveals important implications for future vegetation restoration and water management in the Mu Us sandy land and similar desert regions around the world.
基金financially supported by a Kasetsart University 72 Year Anniversary Graduate Scholarship, from the Graduate School, Kasetsart University, Thailand
文摘Low germination and vigor of rice seed associated with dry-seed broadcasting are common problems encountered by rice growers.The objectives of this study were to evaluate the role of potassium nitrate(KNO3)on the pattern of seed imbibition and to determine the effect of seed priming with KNO3 on the germination percentage,speed and uniformity of germination in rice seed.Experiment 1 compared the patterns of seed imbibition of six concentrations of KNO3(0,0.25,0.50,1.00,1.50,and 2.00%)in two rice cultivars-KDML105 and RD15.The results showed that soaking rice seed in KNO3 at higher concentrations could delay the imbibition time.The higher concentrations of KNO3 delayed the imbibition time of rice seed and took a longer time to reach the end of phases 1 and 2 compared to the lower concentrations.The patterns of seed imbibition using distilled water of both rice cultivars(KDML105 and RD15)were quite similar,but with different concentrations of KNO3,the imbibition time taken to reach the end of phases 1 and 2 was slightly postponed in KDML105 suggesting that different rice cultivars may need different imbibition times for soaking seed in the priming process.Experiment 2 evaluated the effects of seed priming with 1.0 and 2.0%KNO3 at different imbibition times.It was found that priming with 1.0%KNO3 showed better seed germination than priming with 2.0%KNO3 and seed priming with 1.0%KNO3 at the imbibition time of early phase 2(or 28 h for KDML105)improved seed germination and increased both the speed and uniformity of seed germination.The results of this study show promise for the use of priming with 1.0%KNO3 soaked until early phase 2 of seed imbibition for improving the seed germination and vigor of rice in dry seed broadcasting.
文摘Growing soybeans in different row-spacings introduces competition. Competition begins when the immediate supply of a single necessary factor falls below the combined demands of all plants. This paper reviews the main competition factors of genotypes, light, water, nutrients and weed in responses to row spacings for the past four decades. It demonstrated that responses of soybean genotypes to row width differ among cultivars, which depend on seasonal rainfall and irrigation. Determinate types produce more yield in narrow-rows, and cultivars with lodging resistance should be adopted in narrow-spacings, but indeterminate soybean should also be used to optimize yields in certain system. Narrow-compared with wide-row soybean (Glycine max) cultivation increases light interception (LI) and dominant components for the increase come from LAI, light extinction coefficients and branch types. Water use efficiency (WUE) and evapotranspiration are not influenced by row spacing, but seed yield could be increased if irrigation is applied. Nutrient uptake is significantly affected by row spacing, seed yields and uptake of N, P, K in plants increases with decreasing row spacing, and the effects depend on the fertilizer levels. Other factors rather than row spacing affect nitrogen fixation. Weed density, peak time and periodicity of weed emergence are not affected by row spacing, but better complementary weed control by the herbicides at the used doses can be obtained in narrow spacing due to the reduced weed number and dry weight. More researches are required to investigate the physiological responses, nutrient and water uptake and translocation, light utilization at different layers of canopy and soil environment changes in different row-spacings.
基金financial support provided by the National Key Research and Development Program of China(2019YFC1906203).
文摘Microbially induced carbonate precipitation(MICP)is a promising technique for the autonomous healing of concrete cracks.In this study,the effect of pH on MICP was investigated.The results indicate that the MICP process was inhibited when the pH was higher than 11.Both vaterite and calcite were produced when the pH was<8,whereas only calcite was produced when the pH was>8.Recycled concrete aggregates(RCA)coated with sodium silicate have been proposed as protective carriers for microbial healing agents.Although the presence of the coated RCA resulted in a loss of the splitting tension strength of the concrete,the loaded healing agents were highly efficient in self-healing cracks.Concrete incorporated with 20%RCA loaded with healing agents exhibited the best self-healing performance.When the initial crack widths were between 0.3 and 0.4 mm,the 7-d mean healing rate was approximately 90%.At 28 d,the crack area filling ratio was 86.4%,while its water tightness recovery ratio was 74.4%and 29.8%,respectively,for rapid and slow absorption.This study suggests that RCA coated with sodium silicate is an effective method for packaging microbial healing agents and has great potential for developing cost-effective self-healing concrete.
基金supported by the National Natural Science Foundation of China (Grant Nos. 30770395 and 30870470)partly by the Wuhan Science and Technology Bureau and the Inner Mongolia Planning Committee on high-tech industrialization
文摘In arid and semiarid areas,water uptake (non-rainfall water) serves as an important water source for plants,biological soil crusts,insects and small animals.In this study,a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert.In the study region,water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake,and was mainly taken up by a water vapor adsorption mechanism;the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%).The formation of crusts promoted water uptake,but the increased uptake did not occur immediately after inoculation or crusts formation.The water taken up from the atmosphere increased significantly from day 15 after inoculation,and the soil water content was markedly enhanced from day 20 after inoculation.It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts,and these variables increased even during dry periods when some algae are likely to have died.