scholarly journals SurEau.c : a mechanistic model of plant water relations under extreme drought

Author(s):  
Hervé Cochard ◽  
François Pimont ◽  
Julien Ruffault ◽  
Nicolas Martin-StPaul

SummaryWe describe the operating principle of the detailed version of the soil-plant-atmosphere model SurEau that allows, among other things, to predict the risk of hydraulic failure under extreme drought. It is based on the formalization of key physiological processes of plant response to water stress. The hydraulic functioning of the plant is at the core of this model, which focuses on both water flows and water pools using variable hydraulic conductances. The model considers the elementary flow of water from the soil to the atmosphere through different plant organs (roots, trunk branches, leaves and buds) that are described by their symplasm and their apoplasm compartments. Within each organ the flow of water between the apoplasm and the symplasm is also represented; as well as the flow outside the system, from the symplasm of each organ to the atmosphere, through the cuticular conductance. For each organ, the symplasm is described by a pressure volume curves and the apoplasm by the vulnerability curve to cavitation of the xylem. The model can thus compute the loss of conductance caused by cavitation, a leading mechanisms of plant desiccation and drought-induced mortality. Some example simulations are shown to illustrate how the model works.

Author(s):  
J. Wolfenden ◽  
T. A. Mansfield

SynopsisThe physiological and biochemical features of plants that are responsible for determining susceptibility or tolerance to air pollutants have often proved hard to identify. In recent years, however, there has been new experimental evidence of responses which may be of critical importance. These include (a) changes in stomatal behaviour, affecting plant-water relations, (b) alterations in carbon and nitrogen assimilation and partitioning which can influence root growth, and (c) interference with the processes of winter hardening. Evidence of these changes to physiological processes, and the ways in which responses to pollutants may become more significant to plant survival in the presence of other environmental stresses, are discussed. The longer-term consequences, or secondary responses, such as effects on associations with other organisms, are also briefly reviewed. We have also examined the possibility that ecosystems may be overloaded with inputs of nitrogen from the atmosphere.


Weed Science ◽  
1979 ◽  
Vol 27 (4) ◽  
pp. 437-443 ◽  
Author(s):  
David T. Patterson

Definitions and properties of light, the effects of light on plant growth and physiological processes, and methodology and terminology for the measurement and reporting of light are reviewed. Alternatives to photometric methods now generally used in studies of the effects of light on plants in weed research are proposed. For studies of leaf energy budgets and plant water relations, the irradiance may be appropriately measured with radiometric methods and the data reported as W [watts] m-2. For studies of photosynthesis, the photosynthetic photon flux density may be measured and the data reported as μE [einsteins] m-2s-1or μmol [μmoles of photons] m-2s-1. Different types of instruments are described and sources for these instruments are provided.


2021 ◽  
Author(s):  
Sheng-Nan Ouyang ◽  
Arthur Gessler ◽  
Matthias Saurer ◽  
Frank Hagedorn ◽  
De-Cai Gao ◽  
...  

Abstract The role of carbon (C) and nutrient uptake, allocation, storage and especially their interactions in survival and recovery of trees under increased frequencies and intensities of drought events is not well understood. A full factorial experiment with four soil water content regimes ranging from extreme drought to well-watered conditions and two fertilization levels was carried out. We aimed to investigate whether nutrient addition mitigates drought effects on downy oak (Quercus pubescens Willd.) and whether storage pools of non-structural carbohydrates (NSC) are modified to enhance survival after 2.5 years of drought and recovery after drought relief. Physiological traits, such as photosynthesis, predawn leaf water potential as well as tissue biomass together with pools and dynamics of NSC and nutrients at the whole-tree level were investigated. Our results showed that fertilization played a minor role in saplings’ physiological processes to cope with drought and drought relief, but reduced sapling mortality during extreme drought. Irrespective of nutrient supply, Q. pubescens showed increased soluble sugar concentration in all tissues with increasing drought intensity, mostly because of starch degradation. After 28 days of drought relief, tissue sugar concentrations decreased, reaching comparable values to those of well-watered plants. Only during the recovery process from extreme drought, root NSC concentration strongly declined, leading to an almost complete NSC depletion after 28 days of rewetting, simultaneously with new leaves flushing. These findings suggest that extreme drought can lead to root C exhaustion. After drought relief, the repair and regrowth of organs can even exacerbate the root C depletion. We concluded that under future climate conditions with repeated drought events, the insufficient and lagged C replenishment in roots might eventually lead to C starvation and further mortality.


1975 ◽  
Vol 55 (1) ◽  
pp. 20-24 ◽  
Author(s):  
John Mexal ◽  
James T. Fisher ◽  
Janet Osteryoung ◽  
C. P. Patrick Reid

Soil Science ◽  
1992 ◽  
Vol 153 (2) ◽  
pp. 87-93 ◽  
Author(s):  
P. MOLDRUP ◽  
D. E. ROLSTON ◽  
J. AA. HANSEN ◽  
T. YAMAGUCHI

2002 ◽  
Vol 25 (2) ◽  
pp. 319-331 ◽  
Author(s):  
S. D. Wullschleger ◽  
T. J. Tschaplinski ◽  
R. J. Norby

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