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Impacts of combined salinity and drought stress on plant physiological responses

Primary Supervisor: Dr Laura Vickers, Harper Adams University

Secondary supervisor: Dr Juliet Coates, University of Birmingham

PhD project title: Impacts of combined salinity and drought stress on plant physiological responses

University of Registration: Harper Adams University

Project outline:

Salinity is one of the most important abiotic stresses affecting agricultural productivity. Often caused by irrigation water, high evaporation rates, poor water management, and low rainfall in arid and semiarid regions. Salinity stress reduces stomatal conductance, transpiration, leaf chlorophyll and photosynthetic rate (Bayuelo-Jimenez et al 2012; Gama et al 2007; Nxele et al 2016). It can promote ROS production and manifest as an osmotic stress disrupting homeostasis and ion distributions in the plant cell (Munns and Termaat, 1986; Serrano et al 1999; Zhu 2001). In coastal, arid and semiarid areas drought is often coupled with the abiotic stress of salinity. Plant physiological responses to drought have common features to salinity; osmotic stress, stomatal closure and a reduction in biomass. Whilst mild drought and salinity have been indicated as working synergistically in reducing crop yields there are few studies that have combined these stresses (Paul et al 2019). As these stresses have been indicated in having an interaction, the aim of this project is to understand the physiological and biochemical interaction between salinity and water stress.

This project will investigate whether salinity and drought enhance or ameliorate each other’s effects in a variety of cultivars of a crop species (decided after a literature consultation, likely to be Phaseolus vulgaris). Whilst the detailed objectives and experiments will be developed following a thorough review of the literature, at this stage the probable objectives could include:

  1. Establish a media-based hydroponic and substrate system, and polyethylene covered mesocosm field system to evaluate the effect of salinity and drought
  2. Quantify (using measurements of chlorophyll fluorescence, photosynthetic rate, transpiration, stomatal conductance and chlorophyll) the level of interaction between water and salinity stress responses
  3. Determine the individual and combined impacts of drought and salinity on ROS production, cell membrane integrity, and cellular ion distribution (using for instance confocal and/or fluorescence microscopy, and gas chromatography)
  4. Determine if drought mitigation strategies (such as antitranspirants a polymer that reduces transpiration to conserve water, Mphande et al., 2020) ameliorate the impacts of drought when combined with salinity stress

These objectives will be tested in hydroponic and substrate based systems within the glasshouses at HAU and polyethylene covered mesocosms in the field, where whole crop level physiological responses will be recorded. Ion analysis will occur within the Princess Margaret laboratories at Harper Adams (using gas chromatography), and confocal and fluorescence microscopy will be undertaken at the UoB BALM facility.

Suggested reading

  1. Paul, K., Pauk J., Kondic-Spika, A., Grausgruber, H., Allahverdiyev, T., Sass, L. and Vass, I. (2019). Co-occurrence of Mild Salinity and Dought Synergistically Enhances Biomass and Grain Retardation in Wheat. Frontiers in Plant Science 10, 501
  2. https://www.frontiersin.org/articles/10.3389/fpls.2019.00501/full
  3. Mphande, W., Kettlewell, P.S., Grove, I.G. and Farrell, A.D. (2020). The potential of antitranspirants in drought management of arable crops: A review. Agricultural Water Management 236, 106143 https://www.sciencedirect.com/science/article/abs/pii/S0378377419316282

BBSRC Strategic Research Priority: Sustainable Agriculture and Food: Plant and Crop Science

    Techniques that will be undertaken during the project:

    The student will gain experience of:

    At HAU - managing water stress and salinity stress experiments, and measurements of soil water, plant water status, thermal imaging, yield components and other physiological measures as identified from the literature search e.g. soil matrices, photosynthetic rate, stomatal conductance, chlorophyll fluorescence, osmolyte and ion concentrations in leaves.

    In the laboratory at UoB - microscopy techniques including high-resolution confocal imaging and live imaging to analyse membrane integrity, ion and ROS distribution in response to salinity and drought stress.

    Contact: Dr Laura Vickers, Harper Adams University