Managing water scarcity in European and Chinese cropping systems

Author: Karanja J. Kibe, PhD student at Fujian Agriculture and Forestry University (FAFU)

Climate change alters many variables that may affect plant growth, with decreased soil water availability and other changes to soil conditions making it more difficult for crop plants to be productive. Better understanding of mechanisms underlying plant stress resilience may help to design future crop improvement strategies. Within the SHui project, I investigated the mechanisms of tomato acclimation to drought stress, specifically the rhizosheath trait. The rhizosheath comprises soil particles that adhere to roots during soil drying, which seems to enhance plant water availability, and crop yields.

While the plant hormone ABA is well-known to maintain root growth in drying soil, its effects on rhizosheath development were not clear. Thus my work took a multidisciplinary approach involving both morphological (root hair traits using microscopy) and molecular (transcriptomics of root gene expression) measurements. Using wild-type and ABA-deficient mutant tomatoes allowed me to establish that ABA may be an important regulator of tomato rhizosheath development in drying soil, which you can read more about here. These results offer many possibilities for future investigations, but the discoveries of novel genetic factors involved in tomato stress responses offers hope for further crop improvement efforts.

I arrived in Fuzhou from Kenya having obtained a Chinese government scholarship to start my PhD under the direction of Prof Weifeng Xu in September 2017. Although my Chinese language skills were quite rudimentary, it was a truly international laboratory with students from Pakistan so I assimilated quite readily. Just before the SHui project was awarded, Prof Ian Dodd visited the laboratory to give a seminar on his research planning for SHui, along with existing collaborations with the Fuzhou group on rhizosheath biology. This helped me focus my research planning, and reinforced the need for repeated experiments to discriminate subtle phenotypes. Besides, I collaborated with my team in setting up an additional research project investigating rhizosheath trait of white lupin under soil drying and phosphorus deficiency.

Two and a half years into my project, covid-19 emerged while I was on holiday back home in Kenya. It was quite an unprecedented phenomenon that came with travel bans and other restrictions. I had to adjust my ways of working and remotely wrote manuscripts under the guidance of my mentors. My journey was never easy but eventually it was such a rewarding undertaking that I am proud of. I successfully published my work as part of the requirement for the PhD program, and will have my thesis examined in two months’ time via a Zoom discussion with three independent reviewers.

The SHui project has allowed me to meet a diverse group of international scientists, especially when Fuzhou hosted the Chinese kickoff meeting of the project. It has provided me with many valuable learning moments, thanks to my able and committed mentors. I have gained valuable transferable skills which will help me address key questions in plant stress tolerance that are of high scientific and social relevance. My team of international scientists has been very influential in this regard, thus I greatly desire to further collaborate with them in research to enhance my future career prospects.

Further reading

  • Karanja, J. K., Aslam, M. M., Qian, Z., Yankey, R., Dodd, I. C., & Xu, W. (2021). Abscisic Acid Mediates Drought-Enhanced Rhizosheath Formation in Tomato. Frontiers in Plant Science12, 1460.
  • Aslam, M. M., Karanja, J. K., Yuan, W., Zhang, Q., Zhang, J., & Xu, W. (2021). Phosphorus uptake is associated with the rhizosheath formation of mature cluster roots in white lupin under soil drying and phosphorus deficiency. Plant Physiology and Biochemistry.

On occasion of the last general assembly in September at CTU  (Prague, Czech Republic), the CTU released a new project brochure that is not available for download in our results section. CHek it out here

In “The Vadose Zone Journal”

Authors: D. Tzohar, M. Moshelion, A. Ben-Gal

Abstract

Plant root systems are exposed to spatial and temporal heterogeneity regarding water availability. In the long-term, compensation, increased uptake by roots in areas with favorable conditions in response to decreased uptake in areas under stress, is driven by root growth and distribution. In the short-term (hours–days), compensative processes are less understood. We hypothesized hydraulic compensation where local lowered water availability is accompanied by increased uptake from areas where water remains available. Our objective was to quantify instantaneous hydraulic root uptake under conditions of differential water availability. Tomato (Solanum lycopersicum L.) plants were grown in split-root weighing-drainage lysimeters in which each half of the roots could alternatively be exposed to short-term conditions of salinity. Uptake was quantified from each of the two root zone compartments. One-sided exposure to salinity immediately led to less uptake from the salt-affected compartment and increased uptake from the nontreated compartment. Compensation occurred at salinity, caused by NaCl solution of 4 dS m−1, that did not decrease uptake in plants with entire root systems exposed. At higher salinity, 6.44 dS m−1, transpiration decreased by ∼50% when the total root system was exposed. When only half of the roots were exposed, total uptake was maintained at levels of nonstressed plants with as much as 85% occurring from the nontreated compartment. The extent of compensation was not absolute and apparently a function of salinity, atmospheric demand, and duration of exposure. As long as there is no hydraulic restriction in other areas, temporary reduction in water availability in some parts of a tomato’s root zone will not affect plant-scale transpiration.

Braving the best (& worst) of the Cumbrian climate, 20 local farmers joined Lancaster’s SHui team at an afternoon event on 1st October, hosted by Andy Dyer of the Eden Rivers Trust on land at West View Farm Penrith, which is owned by Robert Harris and farmed by the Taylor family from Plumpton Old Hall Farm.

The Lancaster team showcased ongoing research with undersown catch crops within local maize fields, in aiming to prevent soil erosion post-harvest. Field walks were undertaken into neighbouring fields to demonstrate visual soil assessment and its importance in underpinning future payment schemes. Catch crops (rye / vetch mixes) had been planted following winter wheat harvest, with extensive root (and rhizosheath) development apparent, in fields that either had or hadn’t received treatment with the panbuster/drill combination that was showcased pre-pandemic at our last in-person event.

There was extensive discussion about the benefits of catch crops in boosting soil organic matter, along with the challenges of their establishment with unseasonal climatic variations in the autumn post-harvest. Their use as “insurance feed” within mixed livestock/arable farming systems was a common theme.

The continued use of catch and cover crops within arable rotations will become ever more important in years to come as the farming community comes to grips with the payments available and the requirements under the Sustainable Farming Incentive (SFI) Scheme from 2022 onwards. The arable and horticultural soils standard, within the current SFI pilot, requires that at least 5% of the land entered into the standard must have an established green cover on it from early to late winter. The green cover can be an autumn sown arable crop or a specifically designed mixture (such as that sown on the farm on which the event was held). The green cover will help to protect the soil surface from erosion and provide root growth to help maintain soil structure, support soil biology and minimise nutrient leaching. Each year an assessment of soil structure, soil biology and soil organic matter must be assessed on at least 20% of the land entered into the standard. Understanding soil health and how soil ecosystems perform has therefore never been more important for farmers and landowners.

Defra’s future Soil Health Action Plan (SHAPE) will be opened up for consultation early in 2022, recognising that well-managed soils can result in increased biodiversity, improved water quality and reduced carbon emissions.

Between September 22nd-24th took place our last SHui Project Board (PB) Meetings, first time with an hybrid format, with members of the team meeting on-site at CTU  (Prague, Czech Republic) while others connected online via a secure Teams channel with over 30 people attending.

  • On the 22nd of September, partners showed the project progress since our last meeting before the summer.
    22nd of September meeting

     

  • The 23rd September activities were focused on the physical attendees. They had the opportunity to enjoy a field visit at the Nučice experiment catchment and attend a workshop on GIS-assisted estimation of soil loss and sediment transport.

    Field visit at Nučice experiment catchment
  • The 24th of September was reserved for discussions on upcoming activities for the final months of the project.

Each WP leader and their teams shared their advances during the previous months and updated plans for the immediate future.

 

Author: Gunther Carl Liebhard, ECR at BOKU

Water is precious. This basic conception is so natural that there are no further words needed to describe the necessity to use it carefully and to protect it as basis of life. It also led me to my current research.

Fig. 2. Soil water status monitoring station in a soybean field.

In my thoughts to study something meaningful, I found the program “environmental engineering and water resource management”, which provides a broad technical education in the context of soil, water and environment. After my graduation, I worked at an engineering office to provide infrastructure for water supply and wastewater disposal. After five years I got the chance to go back to University and to work for the EU project “SHui”, that focuses on innovative ways to manage water scarcity in agriculture. I liked the idea to get some more time for thinking, learning, and academic exchange. But also the change of perspective had something worth striving for. In geotechnical engineering, a good soil is solidifiable and stable. In soil sciences, however, a good soil is a habitat and resource for water supply and plant production worth protecting.

 

 

Fig. 3. Soil sampling for stable isotope tracing.

The Institute for Soil Physics and Rural Water Management (SoPhy) at the University of Natural Resources and Life Sciences, Vienna (BOKU) provides everything that is required to develop innovative ways to optimize water use. In my research I can use the institute’s equipment and knowledge in the field of stable isotope tracing, soil physics, soil water status monitoring, and micrometeorology to evaluate water use in different management systems. This allows to understand mechanisms that support productive water use and which reduce unproductive water loss. In our field campaigns 2019 and 2020 at different experimental fields in the “Marchfeld” in Lower Austria, we investigated patterns of productive and unproductive water use at different settings. This included variation of water availability caused by irrigation and tillage management.

 

 

 

 

Fig. 4. SHui long-term experimental research data platform.

The new stable isotope based perspectives in plant production will hopefully contribute to a sustainable use of the natural water and soil resources. All measured data are being exploited for publications (https://www.shui-eu.org) and are shared on the SHui open research database (Fig. 4, https://shui.boku.ac.at/shui/public/start).

In this way, the data gain additional value for further investigations to optimize water use and to protect the precious resource.

 

The coronavirus pandemic has certainly changed where and how we work, with much greater use of online learning opportunities (webinars, online conferences, discussion fora) for training Early Career Researchers.

While learning new instrumentation suitable for field work is desirable in an outdoor, socially distanced environment, many governments have imposed restrictions on how many people can meet together outdoors thus limiting the number of trainees.

Fortunately, a vast array of instructional material is already available on the internet (if you know where to look !), especially regarding the use of specific instrumentation to make measurements, as companies seek to demonstrate the capacity and ease-of-use of their products.

SHui has collated weblinks to much of this material and make it available in a structured format that includes previously existing and new video material.

* How to measure stomatal conductance with a porometer
https://youtu.be/MBn5niHPtqc

How to measure leaf water potential with a pressure chamber in the field
https://www.youtube.com/watch?v=JDVwNBeKheI
https://www.youtube.com/watch?v=ArcHBcoWecM

* How to measure leaf (or root) water potential with a pressure chamber in the laboratory
https://youtu.be/uLtPeu2_1UY

How to measure leaf water potential via thermocouple psychrometry
https://www.youtube.com/watch?v=jzx6VRcU2VY

How to measure leaf relative water content
https://www.youtube.com/watch?v=uyUYFKnaAnk

In a refreshingly rare departure from the recent routine of online meetings, Lancaster Environment Centre hosted Tony Peloe of Delta-T Devices for a workshop covering the theory and practice of measuring soil and plant water status. To comply with University regulations on social distancing, workshop numbers were restricted to 12 (maximum capacity of the room) but nevertheless included 6 SHui-affiliated researchers: Jaime Puertolas (now a lecturer at La Laguna, Tenerife), Ryan Edge (currently Lancaster’s PDRA), Cristina McBride-Serrano (still in a technical role at Lancaster but moving to PhD studies shortly), Jing Chen (visiting from Yangzhou University, China), Yingying Ma (visiting from Northwest Agricultural & Forestry University, China) and Leonardo da Silva (visiting from University of Rio de Janeiro, Brazil). Each researcher was able to appraise the suitability of Delta-T’s extensive instrumentation range to help them address their research objectives.

Researcher familiarity with these instruments ranged from novice to highly experienced, so it was possible to pair researchers of different experience to swap best practice. Yahya Khan (visiting from University of Agriculture Faisalabad, Pakistan to research the impact of rhizobacteria on legume drought tolerance) won the “porometer calibration competition” with an error of just 3.3%, although further studies are needed to determine the influence of operator and specific porometer used, and any interaction ! In addition to briefing the group on porometer best practice, Tony introduced the extensive range of soil moisture instrumentation: PR2, SM150, WET sensor and the new digital WET150 soil sensor. After calibration exercises, sensor outputs were compared to understand the capacities of different sensors.

Selected attendee reflections were:

  • Although I am an experienced user of most of the equipment shown, there were some interesting new features and gadgets that I could learn of.
  • The workshop was already well managed and well organized. I don’t believe it needs further improvement but, it would be good if these types of workshops are arranged frequently to provide recent advancement in instrumentation and working principles.
  • Tony was incredibly knowledgeable, patient and helpful and I know my confidence has grown when using Delta-T equipment.
  • In China, such workshops would have had much greater attendance, so the smaller number of participants and relatively large numbers of the instruments allowed us hands-on personal experience and instruction.

Author: Lang Lili

Water is shortage and precious in Northwest China. That is way, during 24th May-1st June, the SHUI socio-economic team decided to dig in a water-saving investigation in Xinjiang Uygur Autonomous Region, China.

Agricultural water consumption accounts for about 87 % of the total water supply in Xinjiang. Cotton is the main planted crop there. The irrigation (e.g water) fee accounts for about 6% of the total cotton production cost. Most farmers here adopt water-saving technologies, mainly using drip irrigation under plastic film. However, for new water-saving irrigation technologies, most farmers are risk averse for the uncertainty along with new technologies. They are likely to depend on the government support.

Xinjiang is trying to promote Smart Agriculture, aiming to improve the water utilization efficient and irrigate more land with less water. Fot that reason,  SHui WP5 team is undertaking extensive cost-benefit analyses of new water-saving technologies to increase the adopting ratio of new water-saving technologies to help farmers make the right decisions.

Forty participants, with over 40% comprising ECRs, attended this event. Although participants were predominantly from EU countries, the wide appeal of the subject matter resulted in participants from outside the SHui consortium attending, including from Hungary, India and Pakistan.

Long-term data sets are essential for scientists to identify and understand agriculture’s ecological and environmental consequences to inform land managers and policy makers. They provide data that may also be used to develop theoretical models and to calibrate and validate simulation models. Long-term data can act as platforms for collaborative studies, thus promoting multidisciplinary research.  

The webinar probed the following questions:

  • What are the benefits of long-term measurements at plot and catchment scales?
  • Do we measure the relevant parameters for hydrological modeling at catchment scale?
  • How can I benefit from SHui’s long-term data curation?
  • How can I use SHui data for decision making and agro-environmental modeling?

Slides for download.