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1.
Sci Total Environ ; 805: 150364, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-34818800

RESUMO

Water and salt stress often occur simultaneously in heavily irrigated arid agricultural areas, yet they are usually studied in isolation. To understand the physiological bases of water use efficiency (WUE) of field-grown maize (Zea mays) at multi-scales under combined water and salt stress, we investigated the joint effects of water and salt stress on physiology, growth, yield, and WUE of two genotypes (XY335 and ZD958). We measured leaf stomatal conductance (gs), net photosynthesis rate (A) and hydraulic traits, whole-plant growth and water use (ET), and final biomass and grain yield. Leaf osmotic adjustment was a key trait of the physiological differences between XY335 and ZD958 under water and salt stress. Although the responses of the two genotypes were different, mild water and salt stress improved intrinsic water use efficiency (iWUE = A/gs) by (i) decreasing gsvia increasing osmotic adjustment and hydraulic resistance, and (ii) declining A via increasing stomatal limitations rather than reducing photosynthetic capacity. Joint water and salt stress had a synergistic effect on reproductive growth and grain formation of maize. Mild water and salt stress reduced ET, stabilized grain yield, and improved grain WUE via declining gs, maintaining photosynthetic capacity, and improving harvest index. Collectively, our study provides a novel insight into the physiological mechanisms of WUE and demonstrates an approach for the efficient management of water and salt by using a growth stage-based deficit irrigation strategy or/and selecting genotypes with strong osmotic adjustment capacity and high harvest index.


Assuntos
Água , Zea mays , Osmose , Fotossíntese , Folhas de Planta , Estresse Salino
2.
Front Plant Sci ; 11: 712, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32582246

RESUMO

Carbohydrate concentrations in fruit are closely related to the availability of water and mineral nutrients. Water stress and minerals alter the assimilation, operation, and distribution of carbohydrates, thereby affecting the fruit quality. The SUGAR model was used to investigate the carbon balance in tomato fruit during different growth stages when available water was varied and potassium added. Further, we quantitatively studied the distribution of photoassimilates such as structural carbohydrates, soluble sugars, and starch in fruit and evaluated their response to water and potassium supply. The results revealed that the carbon allocation and transformation dynamically changed during the all growth stages; in fact, variation in carbon content showed similar trends for different water along with potassium treatments, carbon allocation during the early development stages was mainly to starch and structural carbon compounds. The relative rate of carbon conversion of soluble sugars to structural carbon compounds (k 3) and of soluble sugars to starch (k 5m ) peaked during the initial stage and then dropped during fruit growth and development stages. Carbon was primarily allocated as soluble sugars and starch was converted to soluble sugars at fruit maturation. k 3(t) and k 5m (t) approached zero at the end of the growth stage, mainly due to sugar accumulation. Potassium application can significantly raise carbon flows imported (C supply ) from the phloem into the fruit and thus increased carbon allocation to soluble sugars over the entire growth period. Potassium addition during the fruit maturation stage decreased the content of starch and other carbon compounds. Water deficit regulated carbon allocation and increased soluble sugar content but reduced structural carbon content, thereby improving fruit quality.

3.
J Exp Bot ; 71(16): 5010-5026, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32472678

RESUMO

Although fleshy fruit is mainly made up of water, little is known about the impact of its water status on sugar metabolism and its composition. In order to verify whether fruit water status is an important driver of carbohydrate composition in tomato fruit, an adaptation of the SUGAR model proposed previously by M. Génard and M. Souty was used. Two versions of the model, with or without integrating the influence of fruit water content on carbohydrate metabolism, were proposed and then assessed with the data sets from two genotypes, Levovil and Cervil, grown under different conditions. The results showed that, for both genotypes, soluble sugars and starch were better fitted by the model when the effects of water content on carbohydrate metabolism were taken into consideration. Water content might play a regulatory role in the carbon metabolism from sugars to compounds other than sugars and starch in Cervil fruit, and from sugars to starch in Levovil fruit. While water content influences tomato fruit carbohydrate concentrations by both metabolism and dilution/dehydration effects in the early developmental stage, it is mainly by dilution/dehydration effects in the late stage. The possible mechanisms underlying the effect of the fruit water content on carbohydrate metabolism are also discussed.


Assuntos
Lycopersicon esculentum , Metabolismo dos Carboidratos , Carboidratos , Frutas , Lycopersicon esculentum/genética , Água
4.
Plant Cell Environ ; 43(3): 563-578, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31721225

RESUMO

Plants can modify xylem anatomy and hydraulic properties to adjust to water status. Elevated [CO2 ] can increase plant water potential via reduced stomatal conductance and water loss. This raises the question of whether elevated [CO2 ], which thus improves plant water status, will reduce the impacts of soil water deficit on xylem anatomy and hydraulic properties of plants. To analyse the impacts of water and [CO2 ] on maize stem xylem anatomy and hydraulic properties, we exposed potted maize plants to varying [CO2 ] levels (400, 700, 900, and 1,200 ppm) and water levels (full irrigation and deficit irrigation). Results showed that at current [CO2 ], vessel diameter, vessel roundness, stem cross-section area, specific hydraulic conductivity, and vulnerability to embolism decreased under deficit irrigation; yet, these impacts of deficit irrigation were reduced at elevated [CO2 ]. Across all treatments, midday stem water potential was tightly correlated with xylem traits and displayed similar responses. A distinct trade-off between efficiency and safety in stem xylem water transportation in response to water deficit was observed at current [CO2 ] but not observed at elevated [CO2 ]. The results of this study enhance our knowledge of plant hydraulic acclimation under future climate environments and provide insights into trade-offs in xylem structure and function.


Assuntos
Dióxido de Carbono/farmacologia , Caules de Planta/fisiologia , Água/metabolismo , Xilema/anatomia & histologia , Zea mays/fisiologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Caules de Planta/efeitos dos fármacos , Xilema/efeitos dos fármacos , Zea mays/efeitos dos fármacos , Zea mays/crescimento & desenvolvimento
5.
J Exp Bot ; 71(4): 1249-1264, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-31750924

RESUMO

Fruit is important for human health, and applying deficit irrigation in fruit production is a strategy to regulate fruit quality and support environmental sustainability. Responses of different fruit quality variables to deficit irrigation have been widely documented, and much progress has been made in understanding the mechanisms of these responses. We review the effects of water shortage on fruit water accumulation considering water transport from the parent plant into the fruit determined by hydraulic properties of the pathway (including xylem water transport and transmembrane water transport regulated by aquaporins) and the driving force for water movement. We discuss water relations and solute metabolism that affect the main fruit quality variables (e.g. size, flavour, nutrition, and firmness) at the cellular level under water shortage. We also summarize the most recent advances in the understanding of responses of the main fruit quality variables to water shortage, considering the effects of variety, the severity of water deficit imposed, and the developmental stage of the fruit. We finally identify knowledge gaps and suggest avenues for future research. This review provides new insights into the stress physiology of fleshy fruit, which will be beneficial for the sustainable production of high-quality fruit under deficit irrigation.


Assuntos
Lycopersicon esculentum , Frutas , Água , Insegurança Hídrica , Xilema
6.
Front Plant Sci ; 10: 160, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30873187

RESUMO

Interactive effects of reduced irrigation and salt stress on leaf physiological parameters, biomass accumulation, and water use efficiency (WUE) of tomato plants at leaf and whole plant scales were investigated in a field experiment during 2016 and a greenhouse experiment during 2017. Experiment utilized two irrigation regimes (full, 2/3 of full irrigation) and four soil salt regimes (0, 0.3, 0.6, 0.9% in 2016 season; and 0, 0.2, 0.3, 0.4% in 2017 season). Three salts, sodium chloride, magnesium sulfate, and calcium sulfate (mass ratio of 2:2:1), were homogeneously mixed with soil prior to packing into containers (0.024 m3). Li-COR 6400 was used to measure tomato leaf physiological parameters. Instantaneous water use efficiency (WUEins, µmol mmol-1) and intrinsic water use efficiency (WUEint, µmol mol-1) were determined at leaf scale, yield water use efficiency (WUEY, g L-1), and dry biomass water use efficiency (WUEDM, g L-1) were determined at whole plant scale. Plants irrigated with 2/3 of full irrigation with zero soil-salt treatment had higher dry biomass and yield per plant, resulting in the highest WUEDM and WUEY at whole plant scale. Increasing soil salinity decreased dry biomass and yield, leading to greater decreases in whole plant WUEDM and WUEY under both irrigation treatments. At full irrigation, no decreases in stomatal conductance (gs, mol m-2 s-1) and slight increase in photosynthetic rate (Pn, µmol m-2 s-1) led to higher WUEint at leaf scale during both years. Under full and reduced irrigation, increasing soil salt content decreased Pn and transpiration rate (Tr, mmol m-2 s-1) and led to reductions in WUEins at the leaf scale. However, compared to full irrigation, reduced irrigation improved WUEins with a significant decline in Tr in no salt and 0.3% soil-salt treatments during both years. For soil salt content of 0.6%, stomatal limitation due to salt stress resulted in higher WUEint, but soil salt content of 0.9% decreased WUEint due to non-stomatal limitation. Soil salt content significantly decreased sap flow, with the maximum variation of daily sap flow per plant of 7.96-31.37 g/h in 2016 and 12.52-36.02 g h-1 in 2017. Sap flow rate was linearly related to air temperature (Ta, °C), solar radiation (Rs, W m-2), and vapor pressure deficit (VPD, kPa). These results advance knowledge on tomato response to abiotic stresses and could improve management of tomato production in water- and salt-stressed areas.

7.
Sci Total Environ ; 645: 1183-1193, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30248843

RESUMO

Investigations of the water and energy balance in large river basins is one of the most important and contemporary issues, which is helpful to guide agricultural production and regional water resource management. Traditionally, water and energy balance have been assessed by field-scale experiments. However, it is not easy to find the effective ways for a whole region using limited observed data from on-farm experiments. In our study, the effects of irrigation water on surface water and energy balance fluxes are examined by employing the Variable Infiltration Capacity (VIC) model and irrigation scheme, for the upper and middle reaches of the Heihe River Basin in Northwest China. The model simulations are calibrated and validated using both streamflow records at a gauge station and eddy covariance observations at two stations. Besides, three irrigation scenarios are set as full irrigation, 90% and 75% of irrigation water requirement (IWR). The results showed the infiltration curve parameter (b) and the thickness of lower soil moisture layer (d2) are the most sensitive model parameters. Long-term irrigation activities lead to a greater evapotranspiration (or latent heat). With considering local irrigation water-using coefficient for the period 2001-2010 of 0.527, the total IWR is about 2.81 × 109 m3/year (the net IWR is about 1.48 × 109 m3/year). Compared with the no-irrigation baseline, the increase in latent heat flux (about 4.45 W/m2) or the significant decrease in Bowen Ratio (about 1.05) due to full irrigation activities is accompanied by a decrease in annual average surface temperature (about 0.076 °C) for the middle reaches of the Heihe River basin during the 10-year period.

8.
Sci Total Environ ; 619-620: 1170-1182, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29734596

RESUMO

Water scarcity and salt stress are two main limitations for agricultural production. Groundwater evapotranspiration (ETg) with upward salt movement plays an important role in crop water use and water productivity in arid regions, and it can compensate the impact of deficit irrigation on crop production. Thus, comprehensive impacts of shallow groundwater and deficit irrigation on crop water use results in an improvement of irrigation water productivity (IWP). However, it is difficult to quantify the effects of groundwater and deficit irrigation on IWP. In this study, we built an IWP evaluation model coupled with a water and salt balance model and a crop yield estimation model. As a valuable tool of IWP simulation, the calibrated model was used to investigate the coupling response of sunflower IWP to irrigation water depths (IWDs), groundwater table depth (GTDs) and groundwater salinities (GSs). A total of 210 scenarios were run in which five irrigation water depths (IWDs) and seven groundwater table depths (GTDs) and six groundwater salinities (GSs) were used. Results indicate that increasing GS clearly increases the negative effect on a crop's actual evapotranspiration (ETa) as salt accumulation in root zone. When GS is low (0.5-1g/L), increasing GTD produces more positive effect than negative effect. In regard to relatively high GS (2-5g/L), the negative effect of shallow-saline groundwater reaches a maximum at 2m GTD. Additionally, the salt concentration in the root zone maximizes its value at 2.0m GTD. In most cases, increasing GTD and GS reduces the benefits of irrigation water and IWP. The IWP increases with decreasing irrigation water. Overall, in arid regions, capillary rise of shallow groundwater can compensate for the lack of irrigation water and improve IWP. By improving irrigation schedules and taking advantages of shallow saline groundwater, we can obtain higher IWP.

9.
Sci Rep ; 7(1): 17256, 2017 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-29222451

RESUMO

Alternate partial root-zone drip irrigation (ADI) or fertigation has favorable effect on crop water- and nitrogen- use efficiencies (WUE and NUE). However, the advantage of combined application of ADI and nitrogen fertigation on crop WUE and NUE remains unclear. A pot experiment was conducted to investigate the impact of three irrigation methods (CDI conventional drip irrigation (both halves of pot irrigated), ADI (both halves of pot alternatively irrigated) and FDI fixed partial root-zone drip irrigation (fixed half of pot irrigated)) and five nitrogen treatments (F0 no N supplied, F1-F4 0.2, 0.18, 0.16 and 0.14 g N per kg soil via fertigation) on sweet-waxy maize. Compared with CDI, ADI reduced water consumption by 19.9%, but increased water use efficiency based on dry seed yield (WUEs) by 32.3%, and also enhanced nitrogen apparent recovery fraction (Nrf) and nitrogen agronomic efficiency (NAE). F1-F4 augmented dry mass accumulation, dry seed yield and total nitrogen uptake if compared to F0. Moreover, F2-ADI had higher shoot and total dry masses, WUEs, total nitrogen uptake, Nrf and NAE. Thus ADI increased nitrogen uptake, WUE and NUE of sweet-waxy maize with nitrogen fertigation of 0.18 g N per kg soil in this study.

10.
Sci Rep ; 7(1): 8805, 2017 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-28821792

RESUMO

Evapotranspiration (ET) is a major component linking the water, energy, and carbon cycles. Understanding changes in ET and the relative contribution rates of human activity and of climate change at the basin scale is important for sound water resources management. In this study, changes in ET in the Heihe agricultural region in northwest China during 1984-2014 were examined using remotely-sensed ET data with the Soil and Water Assessment Tool (SWAT). Correlation analysis identified the dominant factors that influence change in ET per unit area and those that influence change in total ET. Factor analysis identified the relative contribution rates of the dominant factors in each case. The results show that human activity, which includes factors for agronomy and irrigation, and climate change, including factors for precipitation and relative humidity, both contribute to increases in ET per unit area at rates of 60.93% and 28.01%, respectively. Human activity, including the same factors, and climate change, including factors for relative humidity and wind speed, contribute to increases in total ET at rates of 53.86% and 35.68%, respectively. Overall, in the Heihe agricultural region, the contribution of human agricultural activities to increased ET was significantly greater than that of climate change.

11.
Sci Rep ; 6: 37971, 2016 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-27905483

RESUMO

Quantifying the influence of driving factors on irrigation water productivity (IWP) is vital for efficient agricultural water use. This study analyzed contributions of agronomic practice and climatic factors to the changes of IWP, based on the data from 1981 to 2012 in Hexi Corridor, Northwest China. Cobb-Douglas production functions were developed by the partial least squares method and contribution rates of the driving factors were calculated. Results showed that IWP and its driving factors increased during the study period, with different changing patterns. IWP was significantly correlated with the agronomic practice factors, daily mean temperature and solar radiation of the crop growing period. The agronomic practice factors including irrigation, fertilization, agricultural film, and agricultural pesticide contributed 20.6%, 32.8%, 42.3% and 11.1% respectively to the increase of IWP; and the contribution rates of the climatic factors, i.e. daily mean temperature and solar radiation, are -0.9% and 0.9%. And the contributions of these factors changed in different sub-periods. It is concluded that agronomic practice factors influenced IWP much more than climatic factors. The improvement of IWP should rely on advanced water-saving technology and application of optimum (need-based) fertilizer, agricultural film and pesticide, ensuring efficient use of agronomic inputs in the study area.

12.
PLoS One ; 11(10): e0165738, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27798692

RESUMO

There is a growing interest in precision viticulture with the development of global positioning system and geographical information system technologies. Limited information is available on spatial variation of bud behavior and its possible association with soil properties. The objective of this study was to investigate spatial variability of bud burst percentage and its association with soil properties based on 2-year experiments at a vineyard of arid northwest China. Geostatistical approach was used to describe the spatial variation in bud burst percentage within the vineyard. Partial least square regressions (PLSRs) of bud burst percentage with soil properties were used to evaluate the contribution of soil properties to overall spatial variability in bud burst percentage for the high, medium and low bud burst percentage groups. Within the vineyard, the coefficient of variation (CV) of bud burst percentage was 20% and 15% for 2012 and 2013 respectively. Bud burst percentage within the vineyard showed moderate spatial variability, and the overall spatial pattern of bud burst percentage was similar between the two years. Soil properties alone explained 31% and 37% of the total spatial variation respectively for the low group of 2012 and 2013, and 16% and 24% for the high group of 2012 and 2013 respectively. For the low group, the fraction of variations explained by soil properties was found similar between the two years, while there was substantial difference for the high group. The findings are expected to lay a good foundation for developing remedy measures in the areas with low bud burst percentage, thus in turn improving the overall grape yield and quality.


Assuntos
Sistemas de Informação Geográfica , Modelos Teóricos , Solo
13.
J Exp Bot ; 66(8): 2253-69, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25873664

RESUMO

More than 70% of fresh water is used in agriculture in many parts of the world, but competition for domestic and industrial water use is intense. For future global food security, water use in agriculture must become sustainable. Agricultural water-use efficiency and water productivity can be improved at different points from the stomatal to the regional scale. A promising approach is the use of deficit irrigation, which can both save water and induce plant physiological regulations such as stomatal opening and reproductive and vegetative growth. At the scales of the irrigation district, the catchment, and the region, there can be many other components to a sustainable water-resources strategy. There is much interest in whether crop water use can be regulated as a function of understanding of physiological responses. If this is the case, then agricultural water resources can be reallocated to the benefit of the broader community. We summarize the extent of use and impact of deficit irrigation within China. A sustainable strategy for allocation of agricultural water resources for food security is proposed. Our intention is to build an integrative system to control crop water use during different cropping stages and actively regulate the plant's growth, productivity, and development based on physiological responses. This is done with a view to improving the allocation of limited agricultural water resources.


Assuntos
Irrigação Agrícola , Agricultura , Conservação dos Recursos Naturais , Abastecimento de Alimentos , Abastecimento de Água , China
14.
PLoS One ; 9(4): e95584, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24752329

RESUMO

The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET). Canopy stomatal conductance (Gsc), an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called "big-leaf" model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1) the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2) leaf area for the sunlit and shaded fractions; and (3) a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98), with RMSE of 0.6120 mm s-1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL) agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and partitioning λET.


Assuntos
Produtos Agrícolas/fisiologia , Modelos Biológicos , Estômatos de Plantas/fisiologia , Transpiração Vegetal/fisiologia , Ritmo Circadiano , Luz , Fotossíntese
15.
J Exp Bot ; 63(3): 1145-53, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22121199

RESUMO

The physiological basis for the advantage of alternate partial root-zone irrigation (PRI) over common deficit irrigation (DI) in improving crop water use efficiency (WUE) remains largely elusive. Here leaf gas exchange characteristics and photosynthetic CO(2)-response and light-response curves for maize (Zea mays L.) leaves exposed to PRI and DI were analysed under three N-fertilization rates, namely 75, 150, and 300 mg N kg(-1) soil. Measurements of net photosynthetic rate (A(n)) and stomatal conductance (g(s)) showed that, across the three N-fertilization rates, the intrinsic WUE was significantly higher in PRI than in DI leaves. Analysis of the CO(2)-response curve revealed that both carboxylation efficiency (CE) and the CO(2)-saturated photosynthetic rate (A(sat)) were significantly higher in PRI than in DI leaves across the three N-fertilization rates; whereas the N-fertilization rates did not influence the shape of the curves. The enhanced CE and A(sat) in the PRI leaves was accompanied by significant decreases in carbon isotope discrimination (Δ(13)C) and bundle-sheath cell leakiness to CO(2) (Φ). Analysis of the light-response curve indicated that, across the three N-fertilization rates, the quantum yield (α) and light-saturated gross photosynthetic rate (A(max)) were identical for the two irrigation treatments; whilst the convexity (κ) of the curve was significantly greater in PRI than in DI leaves, which coincided with the greater CE and A(sat) derived from the CO(2)-response curve at a photosynthetic photon flux density of 1500 µmol m(-2) s(-1). Collectively, the results suggest that, in comparison with the DI treatment, PRI improves photosynthetic capacity parameters CE, A(sat), and κ of maize leaves and that contributes to the greater intrinsic WUE in those plants.


Assuntos
Irrigação Agrícola , Fotossíntese/fisiologia , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Zea mays/metabolismo , Zea mays/fisiologia , Feixe Vascular de Plantas/metabolismo , Feixe Vascular de Plantas/fisiologia
16.
Tree Physiol ; 32(3): 262-79, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22157418

RESUMO

Vineyards were planted in the arid region of northwest China to meet the local economic strategy while reducing agricultural water use. Sap flow, environmental variables, a plant characteristic (sapwood-to-leaf area ratio, A(s)/A(l)) and a canopy characteristic (leaf area index, L) were measured in a vineyard in the region during the growing season of 2009, and hourly canopy stomatal conductance (G(si)) was estimated for individual vines to quantify the relationships between G(si) and these variables. After accounting for the effects of vapor pressure deficit (D) and solar radiation (R(s)) on G(si), much of the remaining variation of reference G(si) (G(siR)) was driven by that of leaf-specific hydraulic conductivity, which in turn was driven by that of A(s)/A(l). After accounting for that effect on G(siR), appreciable temporal variation remained in the decline rate of G(siR) with decreasing vineyard-averaged relative extractable soil water (θ(E)). This variation was related to the differential decline ofθ(E) near each monitored vine, decreasing faster between irrigation events near vines where L was greater, thus adding to the spatiotemporal variation of G(siR) observed in the vineyard. We also found that the vines showed isohydric-like behavior whenθ(E) was low, but switched to anisohydric-like behavior with increasingθ(E). Modeledθ(E) and associated G(s) of a canopy with even L (1.9 m(2) m(-2)) were greater than that of the same average L but split between the lowest and highest L observed along sections of rows in the vineyard (1.2 and 2.6 m(2) m(-2)) by 6 and 12%, respectively. Our results suggest that managing sectional L near the average, rather than allowing a wide variation, can reduce soil water depletion, maintaining G(s) higher, thus potentially enhancing yield.


Assuntos
Estômatos de Plantas/fisiologia , Vitis/fisiologia , Água/fisiologia , Irrigação Agrícola , China , Secas , Meio Ambiente , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Caules de Planta/fisiologia , Caules de Planta/efeitos da radiação , Estômatos de Plantas/efeitos da radiação , Transpiração Vegetal/fisiologia , Transpiração Vegetal/efeitos da radiação , Estações do Ano , Solo , Luz Solar , Fatores de Tempo , Pressão de Vapor , Vitis/efeitos da radiação , Xilema/fisiologia , Xilema/efeitos da radiação
17.
J Exp Bot ; 62(12): 4163-72, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21527627

RESUMO

Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in the soil-root system (L(sr)) in different root zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternately on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with L(sr) in both the whole and irrigated root zones for all three irrigation methods but not with L(sr) in the non-irrigated root zone of FPRI. The total L(sr) in the irrigated root zone of two PRIs was increased by 49.0-92.0% compared with that in a half root zone of CI, suggesting that PRI has a significant compensatory effect of root water uptake. For CI, the contribution of L(sr) in a half root zone to L(sr) in the whole root zone was ∼50%. For FPRI, the L(sr) in the irrigated root zone was close to that of the whole root zone. As for APRI, the L(sr) in the irrigated root zone was greater than that of the non-irrigated root zone. In comparison, the L(sr) in the non-irrigated root zone of APRI was much higher than that in the dried zone of FPRI. The L(sr) in both the whole and irrigated root zones was linearly correlated with soil moisture in the irrigated root zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root zone. Nevertheless, the non-irrigated root zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root zone under FPRI gradually ceased to contribute to crop water uptake, suggesting that it is the APRI that can make use of all the root system for water uptake, resulting in higher water use efficiency.


Assuntos
Irrigação Agrícola , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/fisiologia , Solo , Água/farmacologia , Zea mays/efeitos dos fármacos , Zea mays/fisiologia , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/fisiologia , Modelos Lineares , Raízes de Plantas/anatomia & histologia , Fatores de Tempo
18.
Ying Yong Sheng Tai Xue Bao ; 19(6): 1289-95, 2008 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-18808022

RESUMO

With split-root pot experiment and using optical and electrical microscopes, the growth of root hair of maize under different irrigation patterns, i. e. , irrigated on both halves of the pot (conventional irrigation, CI), on one half only (fixed partial root zone irrigation, FPRI), and on both halves alternatively (alternate partial root zone irrigation, APRI), was observed. The observation after 40 days of treatment showed that in non-irrigated root zone of FPRI, the length proportion of root covered by vestigial root hairs was 20.96%, being higher than that in other zones. In addition to some bletting spots, the root system in irrigated zone of FPRI turned yellow, root-branching deteriorated to some extent, and the root hair density on the section with thick root hairs was lower than that in non-irrigated zone. However, both the length proportion of root covered by vestigial root hairs (15.72%) and the deterioration of root hair were lower than those in non-irrigated zone. As for CI, the root appearance and root hair growth were similar to those of the FPRI irrigated zone. As for the early and late irrigated root zones of APRI, the root hair density on the section with thick root hairs was high. The length proportion of root covered by vestigial root hairs was 9.77% and 10.38% for these two root zones, respectively, being lower than that in any root zones of FPRI and CI. It was suggested that alternative partial root zone irrigation was more beneficial to the growth of root hair than fixed partial root zone irrigation and conventional irrigation.


Assuntos
Agricultura/métodos , Raízes de Plantas/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Água/metabolismo , Água/farmacologia , Zea mays/efeitos dos fármacos , Zea mays/metabolismo
19.
Ying Yong Sheng Tai Xue Bao ; 19(2): 299-305, 2008 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-18464634

RESUMO

This paper studied the stem sap flow of grape in arid oasis region of Shiyang River basin under conventional drip irrigation (CDI), alternate drip irrigation (ADI), and fixed drip irrigation (FDI), and its relationships with meteorological conditions and soil moisture content. The results showed that the stem sap flow of grape had an obvious day-night rhythm synchronous with solar radiation, and was significantly higher under CDI than under ADI and FDI during new branch growth and flowering stages. Solar radiation and air temperature were the main meteorological factors affecting the hourly sap flow, and the daily stem sap flow had linear relationships with daily air temperature and wind speed. The correlation coefficients between the stem sap flow and the meteorological factors ranked in the order of CDI > ADI > FDI. There was a significant correlation between daily stem sap flow and reference crop evapotranspiration (ET0). Compared with CDI, ADI could save 50% of irrigation water while the stem sap flow only reduced by 6.56%, and an obvious compensation effect between stem sap flow and hydraulic conductivity was observed.


Assuntos
Clima Desértico , Caules de Planta/metabolismo , Vitis/metabolismo , Água/metabolismo , Agricultura/métodos , China , Meio Ambiente , Transpiração Vegetal , Rios , Movimentos da Água
20.
Ground Water ; 46(1): 80-90, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18181867

RESUMO

In arid regions, human activities like agriculture and industry often require large ground water extractions. Under these circumstances, appropriate ground water management policies are essential for preventing aquifer overdraft, and thereby protecting critical ecologic and economic objectives. Identification of such policies requires accurate simulation capability of the ground water system in response to hydrological, meteorological, and human factors. In this research, artificial neural networks (ANNs) were developed and applied to investigate the effects of these factors on ground water levels in the Minqin oasis, located in the lower reach of Shiyang River Basin, in Northwest China. Using data spanning 1980 through 1997, two ANNs were developed to model and simulate dynamic ground water levels for the two subregions of Xinhe and Xiqu. The ANN models achieved high predictive accuracy, validating to 0.37 m or less mean absolute error. Sensitivity analyses were conducted with the models demonstrating that agricultural ground water extraction for irrigation is the predominant factor responsible for declining ground water levels exacerbated by a reduction in regional surface water inflows. ANN simulations indicate that it is necessary to reduce the size of the irrigation area to mitigate ground water level declines in the oasis. Unlike previous research, this study demonstrates that ANN modeling can capture important temporally and spatially distributed human factors like agricultural practices and water extraction patterns on a regional basin (or subbasin) scale, providing both high-accuracy prediction capability and enhanced understanding of the critical factors influencing regional ground water conditions.


Assuntos
Redes Neurais de Computação , Abastecimento de Água , Agricultura , China , Simulação por Computador , Conservação dos Recursos Naturais , Humanos
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