scholarly journals Potential involvement of root auxins in drought tolerance by modulating nocturnal and daytime water use in wheat

2019 ◽  
Author(s):  
Walid Sadok ◽  
Rémy Schoppach
Keyword(s):  
Water Use ◽  
Hydraulic Properties ◽  
Mapping Population ◽  
Vapour Pressure Deficit ◽  
Water Saving ◽  
Molecular Evidence ◽  
Night Time ◽  
Hydraulic Limitation ◽  
Whole Plant ◽  
Nocturnal Transpiration

AbstractThe ability of wheat genotypes to save water by reducing their transpiration rate (TR) under times of the day with high vapour pressure deficit (VPD) has been linked to increasing yields in terminal drought environments. Further, recent evidence shows that reducing nocturnal transpiration (TRN) could amplify water-saving. Previous research indicates that such traits involve a root-based hydraulic limitation, but the contribution of hormones, particularly auxin and abscisic acid (ABA) has not been explored to explain the shoot-root link. In this investigation, based on physiological, genetic and molecular evidence gathered on a mapping population, we hypothesized that root auxin accumulation regulates whole-plant water use during both times of the day. Eight double-haploid lines were selected from a mapping population descending from two parents with contrasted water-saving strategies and root hydraulic properties. These spanned the entire range of slopes of TR responses to VPD and TRN encountered in the population. On those lines, we examined daytime/night-time auxin and ABA contents in the roots and the leaves in relation to hydraulic traits that included whole-plant TR, plant hydraulic conductance (KPlant), slopes of TR responses to VPD and leaf-level anatomical traits. Root auxin levels were consistently genotype-dependent in this group irrespective of experiments and times of the day. Daytime root auxin concentrations were found to be strongly and negatively correlated with daytime TR, KPlant and the slope of TR response to VPD. Night-time root auxin levels significantly and negatively correlated with TRN. In addition, daytime and night-time leaf auxin and ABA concentrations did not correlate with any of the examined traits. The above results indicate that accumulation of auxin in the root system reduces daytime and night-time water use and modulates plant hydraulic properties to enable the expression of water-saving traits that have been associated with enhanced yields under drought.

scholarly journals Potential involvement of root auxins in drought tolerance by modulating nocturnal and daytime water use in wheat

2019 ◽  
Vol 124 (6) ◽  
pp. 969-978 ◽  
Author(s):  
Walid Sadok ◽  
Rémy Schoppach
Keyword(s):  
Water Use ◽  
Hydraulic Properties ◽  
Mapping Population ◽  
Vapour Pressure Deficit ◽  
Water Saving ◽  
Molecular Evidence ◽  
Night Time ◽  
Hydraulic Limitation ◽  
Whole Plant ◽  
Nocturnal Transpiration

Abstract Background and Aims The ability of wheat genotypes to save water by reducing their transpiration rate (TR) at times of the day with high vapour pressure deficit (VPD) has been linked to increasing yields in terminal drought environments. Further, recent evidence shows that reducing nocturnal transpiration (TRN) could amplify water saving. Previous research indicates that such traits involve a root-based hydraulic limitation, but the contribution of hormones, particularly auxin and abscisic acid (ABA), has not been explored to explain the shoot–root link. In this investigation, based on physiological, genetic and molecular evidence gathered on a mapping population, we hypothesized that root auxin accumulation regulates whole-plant water use during both times of the day. Methods Eight double-haploid lines were selected from a mapping population descending from two parents with contrasting water-saving strategies and root hydraulic properties. These spanned the entire range of slopes of TR responses to VPD and TRN encountered in the population. We examined daytime/night-time auxin and ABA contents in the roots and the leaves in relation to hydraulic traits that included whole-plant TR, plant hydraulic conductance (KPlant), slopes of TR responses to VPD and leaf-level anatomical traits. Key Results Root auxin levels were consistently genotype-dependent in this group irrespective of experiments and times of the day. Daytime root auxin concentrations were found to be strongly and negatively correlated with daytime TR, KPlant and the slope of TR response to VPD. Night-time root auxin levels significantly and negatively correlated with TRN. In addition, daytime and night-time leaf auxin and ABA concentrations did not correlate with any of the examined traits. Conclusions The above results indicate that accumulation of auxin in the root system reduces daytime and night-time water use and modulates plant hydraulic properties to enable the expression of water-saving traits that have been associated with enhanced yields under drought.

scholarly journals Tolerance of combined drought and heat stress is associated with transpiration maintenance and water soluble carbohydrates in wheat grains

2020 ◽  
Author(s):  
Abdeljalil El Habti ◽  
Delphine Fleury ◽  
Nathaniel Jewell ◽  
Trevor Garnett ◽  
Penny J. Tricker
Keyword(s):  
Heat Stress ◽  
Water Use ◽  
Vapour Pressure Deficit ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Plant Water ◽  
Plant Water Use ◽  
Whole Plant ◽  
Water Soluble Carbohydrates ◽  
Drought And Heat Stress

AbstractWheat (Triticum aestivum L.) production is increasingly challenged by simultaneous drought and heatwaves. We assessed the effect of both stresses combined on whole plant water use and carbohydrate partitioning in eight bread wheat genotypes that showed contrasting tolerance. Plant water use was monitored throughout growth, and water-soluble carbohydrates (WSC) and starch were measured following a three-day heat treatment during drought. WSC were predominantly allocated to the spike in modern Australian varieties, whereas the stem contained most WSC in older genotypes. Combined drought and heat stress increased WSC partitioning to the spike in older genotypes but not in the modern varieties. Glucose and fructose concentrations in grains measured 12 days after anthesis were associated with final grain weight in the main spike. At the whole plant level, combined drought and heat stress differentially altered daily water use and transpiration response to vapour pressure deficit during grain filling, compared to drought only. Final grain yield was increasingly associated with aboveground biomass and total water use with increasing stress intensity. Ability to maintain transpiration, especially following combined drought and heat stress, appears essential for maintaining wheat productivity.One sentence summaryHigher yield following drought and heat stress in wheats that maintain transpiration and have higher water-soluble carbohydrates content in grains.

scholarly journals The contribution of PIP2-type aquaporins to photosynthetic response to increased vapour pressure deficit

2021 ◽  
Author(s):  
D Israel ◽  
S Khan ◽  
C R Warren ◽  
J J Zwiazek ◽  
T M Robson
Keyword(s):  
Vapour Pressure Deficit ◽  
Air Humidity ◽  
Wild Type ◽  
Knockout Mutant ◽  
Evaporative Demand ◽  
Co2 Transport ◽  
Whole Plant ◽  
Knockout Mutants ◽  
Leaf Level ◽  
Low Humidity

Abstract The roles of different plasma membrane aquaporins (PIPs) in leaf-level gas exchange of Arabidopsis thaliana were examined using knockout mutants. Since multiple Arabidopsis PIPs are implicated in CO2 transport across cell membranes, we focused on identifying the effects of the knockout mutations on photosynthesis, and whether they are mediated through the control of stomatal conductance of water vapour (gs), mesophyll conductance of CO2 (gm) or both. We grew Arabidopsis plants in low and high humidity environments and found that the contribution of PIPs to gs was larger under low air humidity when the evaporative demand was high, whereas any effect of lacking PIP function was minimal under higher humidity. The pip2;4 knockout mutant had 44% higher gs than the wild type plants under low humidity, which in turn resulted in an increased net photosynthetic rate (Anet). We also observed a 23% increase in whole-plant transpiration (E) for this knockout mutant. The lack of functional AtPIP2;5 did not affect gs or E, but resulted in homeostasis of gm despite changes of humidity, indicating a possible role in regulating CO2 membrane permeability. CO2 transport measurements in yeast expressing AtPIP2;5 confirmed that this aquaporin is indeed permeable to CO2.

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

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

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

scholarly journals Water saving through international trade of agricultural products

2006 ◽  
Vol 10 (3) ◽  
pp. 455-468 ◽  
Author(s):  
A. K. Chapagain ◽  
A. Y. Hoekstra ◽  
H. H. G. Savenije
Keyword(s):  
Water Resources ◽  
Water Use ◽  
Virtual Water ◽  
Water Saving ◽  
Agricultural Products ◽  
Green Water ◽  
Blue Water ◽  
Water Flows ◽  
Global Water ◽  
National Water

Abstract. Many nations save domestic water resources by importing water-intensive products and exporting commodities that are less water intensive. National water saving through the import of a product can imply saving water at a global level if the flow is from sites with high to sites with low water productivity. The paper analyses the consequences of international virtual water flows on the global and national water budgets. The assessment shows that the total amount of water that would have been required in the importing countries if all imported agricultural products would have been produced domestically is 1605 Gm3/yr. These products are however being produced with only 1253 Gm3/yr in the exporting countries, saving global water resources by 352 Gm3/yr. This saving is 28 per cent of the international virtual water flows related to the trade of agricultural products and 6 per cent of the global water use in agriculture. National policy makers are however not interested in global water savings but in the status of national water resources. Egypt imports wheat and in doing so saves 3.6 Gm3/yr of its national water resources. Water use for producing export commodities can be beneficial, as for instance in Cote d'Ivoire, Ghana and Brazil, where the use of green water resources (mainly through rain-fed agriculture) for the production of stimulant crops for export has a positive economic impact on the national economy. However, export of 28 Gm3/yr of national water from Thailand related to rice export is at the cost of additional pressure on its blue water resources. Importing a product which has a relatively high ratio of green to blue virtual water content saves global blue water resources that generally have a higher opportunity cost than green water.

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