Soil compaction is an increasing problem in global agriculture, causing more severe effects when soil dries. Since insensitivity to the plant hormone ethylene maintains root elongation in compact soil, wheat cultivars with reduced sensitivity to ethylene were hypothesised to have greater root and shoot growth in compact soil, and higher plant water status when this soil dried. Screening wheat cultivars revealed root-applied ethephon solution or exposure to ethylene gas inhibited root elongation of the cultivar Chewink#1 more than Kutz. These cultivars were glasshouse-grown in soil columns with a factorial combination of soil compaction and drying, and in field trials with different tillage or irrigation treatments. Although both cultivars had similar root and shoot biomass in loose soil irrespective of soil moisture, Kutz accumulated more biomass than Chewink#1 in compact soil. Greater root development of Kutz deeper in the soil profile (also occurring in field experiments) was associated with cultivar differences in water relations, as Kutz maintained higher stomatal conductance and leaf water potential, with lower foliar ABA concentration, as compact soil dried. Although further investigations with specific wheat alleles conferring ethylene sensitivity are needed, cultivars with less ethylene-sensitive root growth may grow better in compact soils, as observed in rice.

In natural environments, plants are continuously exposed to multiple abiotic stresses, such as high salinity and excess ultraviolet (UV)-B radiation. While responses to individual stresses are well understood, less is known about their combined impact. Here, we treated quinoa (Chenopodium quinoa) seedlings with salt (0 and 200 mM NaCl) under either photosynthetically active radiation (PAR) or PAR supplemented with UV-B radiation (313 nm, 1 hour/day, 1.71 W/m2) to investigate their response to combined salt and UV-B stress. While salinity had minimal effects on plant growth, it decreased stomatal conductance and photochemical efficiency by 36–47%. UV-B supplementation mitigated the negative effects of salinity, enhancing photosynthetic efficiency and water relations in UV-B- and salt-treated plants. Enhanced leaf water relations in the combined treatment were associated with altered ion translocation and shoot compartmentalization, especially for K+. Indeed, UV-B decreased K+ accumulation in epidermal bladder cells, suggesting a redistribution from epidermal bladder cells to other leaf tissues. UV-B treatment shifted plant metabolism towards producing hydroxycinnamic acid, while quercetin levels remained unchanged, indicating minimal stress. This study describes a protective mechanism in quinoa where UV-B radiation enhances ion translocation, water relations, and metabolic adjustments, mitigating salinity stress. Our findings offer key insights into plant resilience and physiological adaptation in salt-affected environments under elevated UV-B exposure.

Nutrient management plan (NMP) tools aim to enhance crop production while minimising environmental harm from over-fertilisation by aligning applications with crop demands and with soil and atmospheric conditions. The characteristics of 14 widely used NMP tools from nine countries (Austria, Bulgaria, China, Czech Republic, Hungary, Italy, New Zealand, Spain, and United Kingdom) were compared. All tools employed a mass balance approach at the field and seasonal scales. To evaluate the tools, matrices of the presence/absence of 24 desirable characteristics, 22 nutrient cycle processes and sources, and 38 required input data were compiled. To compare the NMPs, cumulative scores were calculated for each category evaluated. Additionally, two theoretical case studies compared fertiliser recommendations for winter wheat in arable and livestock farming systems. Cluster analysis classified the 14 tools into six clusters, reflecting distinct levels of complexity, usability, adaptability, and interoperability. The number of input data required was strongly and positively correlated with the number of nitrogen (N) processes and sources considered, confirming that input demand reflects tool sophistication. More comprehensive tools tended to recommend lower N application rates in the livestock system, suggesting that simpler tools overestimated N requirements by omitting key processes. However, practical usability characteristics did not determine different recommendations. While N recommendations were broadly aligned with national guidelines, P and K recommendations showed considerably higher variability reflecting the lack of harmonised guidelines for these macronutrients.

Precise, real time and non-destructive assessment of plant water status is important for advancing plant physiological understanding, optimizing water usage, improving crop resilience and supporting precision agriculture in the face of increasingly variable climatic conditions. Classical methods for measuring plant water status reviewed in Part 1 of this two-part review have significant limitations for field level applications, providing only discrete, single-point measurements and potentially altering plant physiology through destructive sampling. This second of a two-part review synthesizes recent advances in non-destructive approaches for measuring plant water status, evaluating their principles, applications and limitations. We review techniques such as ZIM-probe, terahertz spectroscopic techniques, microwave remote sensing, infrared transmission sensor, microtensiometers, dendrometers and leaf thickness sensors, light detection and ranging (i.e. LiDAR), imaging spectroscopy, NMR relaxation, spectroscopy based on equivalent water thickness, spectral indices, derivative spectra, post-continuum removal indicators, visible and near-infrared spectroscopy, and infrared thermography. These emerging techniques facilitate high-resolution, real-time monitoring of water status across leaf, canopy and ecosystem scales. This comprehensive comparison provides guidance for selecting most appropriate technique based on experimental objectives, guiding applications ranging from single leaf to canopy scale ecosystem assessment. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Social Impact Statement Climate change threatens millions of farmers worldwide by exposing crops to multiple concurrent or sequential environmental stresses such as drought, heat, waterlogging, and diseases. Although crops have long been selected under naturally occurring multi-stress conditions, breeding pipelines largely focus on optimal or single-stress environments, leaving complex stress combinations under-addressed. Developing crop cultivars that withstand multiple stress scenarios is essential for ensuring food security, food safety, and strengthening farmer resilience. Breeding for multi-stress resilience seems feasible but requires international collaboration among applied crop scientists, pure biologists, and policymakers to develop climate-resilient crops that sustain people and ecosystems. Summary Climate change is increasing the frequency and intensity of combined abiotic and biotic stressors that may occur simultaneously or sequentially, dramatically reducing crop growth and yield stability. Plant breeding activities primarily target crop improvement for a single stressor, limiting crop resilience under complex environmental conditions. This opinion paper highlights the complexity of crop breeding for multi-stress growing conditions and discusses major challenges and opportunities to enable plant breeders to develop more climate-resilient crops. It also outlines the importance of integrating conventional breeding approaches with multi-omics and novel breeding technologies to develop multi-stress resilient crop cultivars. Identifying and validating key regulatory genes involved in multi-stress resilience and evaluating their performance across diverse genetic backgrounds, environments, and stress combination scenarios are needed. Although achieving complete multi-stress resilience remains an immense challenge, advances in integrative approaches and cross-disciplinary collaboration are steadily improving the potential to enhance crop resilience to multiple environmental stresses.

Exogenous cadmium (Cd) stimulates abscisic acid (ABA) accumulation in planta, enhancing Cd tolerance by maintaining growth and limiting Cd accumulation. Since rhizobacteria that metabolise ABA may compromise Cd tolerance, tomato Ailsa-Craig plants were grown in vitro with or without 80 µM CdCl2, and with or without ABA-metabolising Rhodococcus sp. P1Y and Novosphingobium sp. P6W and the Cd-tolerant, 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing Variovorax paradoxus 5 C-2 (negative control). Root colonisation of the ABA-metabolising strains was circa 50

As a result of the changing climate, water scarcity poses a significant threat to crop and pasture production. Although soil water content can indicate drought, its measurements often provide limited spatial resolution and are weakly correlated with plant water status, producing misleading drought assessments. Accurately measuring plant water status is essential to understand nutrient uptake, thermal regulation and stomatal behavior. Water status, primarily determined by turgor pressure and its crucial component of leaf water potential regulate plant physiological functions. These variables depend on the energy state of water, determining essential processes such as stomatal conductance and cell expansion. Becaus directly measuring turgor pressure may be impractical, leaf water content and relative water content are reliable proxies for assessing water status. In Part 1 of a two-part review, we provide insights into using leaf water content as a reliable proxy for assessing water status and synthesize classical, destructive methods for measuring plant water status, encompassing gravimetric techniques, Scholander pressure chamber and psychrometric techniques. These classical approaches provide direct, physically interpretable and mechanically based measurements of water content, water potential and turgor-related parameters. Operational principles, procedural considerations and physiological insights accompany each method. These destructive measurements determine water status accurately, forming the essential calibration and validation backbone for modern non-destructive approaches discussed in Part 2. Integrating these classical measurements with concurrent soil moisture data provides reliable guidance for irrigation management, optimizing water usage and improving crop resilience in the face of increasingly variable climatic conditions. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Abscisic acid (ABA) is a key phytohormone in plant responses to water deficit. Although there is extensive evidence that roots can synthesise ABA, recent findings suggest that local synthesis in response to dehydration contributes little to the root ABA pool compared to shoot-sourced ABA. To understand how root ABA synthesis and basipetal phloem transport regulate root ABA accumulation, expression of genes encoding ABA biosynthesis and metabolism enzymes was assessed in response to dehydration of detached roots and soil drying of attached roots sourced from intact or girdled soybean plants. Both dehydration and soil drying caused significant ABA accumulation in detached and attached roots, respectively, but less in girdled plants. This indicates root ABA biosynthesis is limited mainly by interrupting the import of ABA precursors and not ABA itself. Lower root ABA concentrations in girdled plants were not due to downregulated NCED gene expression, which was similar (detached roots) or even strongly upregulated (attached roots) in response to dehydration compared to roots from intact plants. This may partially compensate for the lack of ABA precursors. Thus, soybean root ABA accumulation in response to dehydration depends on enhanced ABA biosynthesis more than ABA import from shoots.

Heat stress is a primary abiotic stress for plant growth, particularly temperate plant species. There is increasing evidence that pre-exposing plants to mild stress (stress priming) can enhance plant tolerance to a later heat event, a phenomenon known as acquired stress tolerance. Plant tolerance to heat or thermotolerance can be improved through prior exposure to short-term, mild, or moderate levels of heat shock, drought, or cold stress. This review summarizes current literature on the effectiveness of stress priming on heat tolerance, as manifested by improved physiological health, growth and yield production in various plant species. It discusses underlying mechanisms of acquired heat tolerance through priming of plants by prior exposure to heat, drought or cold stress, focusing on molecular regulation, photosynthesis, antioxidant metabolism, hormone metabolism, and metabolic reprogramming. Additionally, this review offers future research perspectives to further understand cross-stress tolerance mechanisms and strategies for improving plant tolerance to different abiotic stress through priming.

Deficit irrigation was applied to Monastrell grapevines grafted on five different rootstocks (140Ru, 1103P, 41B, 110R and 161-49C) in south-eastern Spain for six years (2012-2017). The rootstocks modified fine root growth and soil respiration in the rhizosphere, soil-plant hydraulics, plant-water relations, leaf gas exchange, hormone signalling and primary and secondary metabolism. 161-49C vines showed a greater growth in fine root length density (RLD) in the rhizosphere (0-40 cm deep) and a higher root-to-shoot ratio compared with 140Ru or 110R. Both 161-49C and 1103P exhibited a tighter control of leaf water loss at low Psi s and high VPD. 161-49C vines had a lower root water uptake and water/nutrient transport capacity and, thus, were more water-stressed, water stress adaptation being related to higher hormone signalling aboveground (e.g., abscisic acid, ABA), greater activation of secondary metabolism in leaves and berries, and lower vine water use. In contrast, high-vigour/ productive 140Ru had a lower RLD, but significantly higher soil respiration and [ABA]root.Vines grafted on 140Ru also showed greater root water uptake and increased whole-plant hydraulic conductance compared with the other rootstocks. This enhanced vine water status, leaf gas exchange, vegetative development, yield, and vine water use. The 140Ru rootstock conferred a greater leaf photosynthetic capacity, related to higher leaf N and chlorophyll contents, as well as a longer duration of leaf greenness. Thus, a rootstock conferring high vigor, such as 140Ru (and also 110R) with an effective root/water transport system, capable of maintaining high water uptake capacity and carbon gain would result in a more effective use of water under prolonged moderate/severe RDI. In contrast, 161-49C and 1103P were the most yield-sensitive and reactive rootstocks regarding water stress and high VPD, and are more suitable for less restrictive RDI strategies in these semiarid conditions.

Agricultural intensification has simplified landscapes thereby reducing biodiversity, depleting natural resources, and threatening ecosystem services. Resilience to abiotic stress is therefore decreasing, creating uncertainty about effects of climate change on agricultural production and environmental degradation. While much research has focused on the direct benefits of increased plant diversity for crop productivity, there is limited evidence on how diversity and species selection affect soil stabilisation. How cover crops bind soil (rhizosheath development) has attracted little attention even though they can decrease soil erodibility. A field trial investigated the impact of cover crop diversity on rhizosheath development and soil erodibility by conducting overland flow simulations. Species (Secale cereale, Brassica juncea, Vicia faba) were chosen for their suitability to UK environmental conditions. Results established that root biomass increased with cover crop diversity and was determined by the presence of Vicia faba. Rhizosheath formation was not affected by crop diversity and was greater in treatments containing Secale cereale. Overland flow simulations showed neither rhizosheath mass nor species diversity had an impact on soil erodibility, and the field variability of soil structural and hydraulic properties had a greater influence. By providing evidence for increased plant diversity effects on agroecosystem function, this work will inform land managers about cropping practices to conserve soil function and aid in delivering environmental policy targets.

Different phytohormones can act as root-to-shoot signalling molecules in response to soil drying. Recent findings suggest that root ABA levels are predominantly leaf-sourced and not locally synthesized, thus, ABA exported from the roots in the xylem is mostly recycled from the shoot. To explain the differential root hormone accumulation observed under partial rootzone drying (PRD) that imposes distinct dry and wet parts of the root zone, we grafted "two-root, one-shoot" soybean plants to independently assess xylem export of different phytohormones from either part of the root zone. Grafts were subjected to a combination of girdling (either part, all, or none of the rootzone) and irrigation (homogenously well-watered (WW) and PRD). PRD did not increase foliar ABA but decreased stomatal conductance, attributed to decreased leaf water potential and/or increased xylem sap ABA, JA, or ACC concentrations. In contrast, the foliar ABA increments that accompanied girdling-induced stomatal closure were proportional to the root fraction to which phloem transport was interrupted. Irrespective of girdling, root ABA accumulation (and xylem ABA export from) was highest in the dry PRD rootzone, xylem jasmonic acid (JA) in the wet PRD rootzone, and xylem ACC in both rootzones of PRD plants. Thus, soil drying of the dry root zone and transient overwatering of the wet root zone enhanced ACC export in PRD plants. We conclude that root water status during PRD enhances root ABA, JA and ACC synthesis and xylem export, independent of shoot-to-root transport.

Background and aimsPotato tubers comprise 83% water at harvest, but surprisingly few studies address tuber water relations in drying soil. This study aims to understand whether soil drying alters tuber water fluxes and their effect on tuber volume growth.MethodsTuber water content and volume growth were investigated every 4 h using magnetic resonance imaging (MRI) during soil drying and re-watering, with leaf gas exchange, leaf water potential and foliar abscisic acid (ABA) concentration measured concurrently.ResultsTubers of well-watered plants showed a diurnal growth pattern with their volume and average water content (TWC) increasing overnight. Withholding irrigation caused typical shoot drought stress responses (e.g. stomatal closure), dampened fluctuations in total TWC and paused nocturnal volume growth. Irrespective of soil moisture, tubers lost water (likely to the shoot) during the daytime when the plant transpires, while tuber water loss to the soil was minimal. Re-watering restored tuber volume growth and average TWC due to root water uptake and transport to the tuber.ConclusionsPotato tubers can supply water to the shoot. Nocturnal water influx needs to exceed daytime water efflux for net tuber volume growth, which should be considered in irrigation management.

While much research has focused on the benefits of cover crop diversity for crop productivity, there is limited evidence on how root diversity and species selection stabilise soil. Although cover crops can potentially improve on-farm soil and water management, how they bind soil (through rhizosheath development) and whether multi-species cover crops offer additional benefits has attracted little attention. This study aimed to assess rhizosheath persistence in field-grown cover crops and their mixtures to understand the impact of species diversity on soil binding capacity. Brassica juncea, Secale cereale and Vicia faba were sown as monocultures and mixtures in a winter cover crop field trial near Dundee, Scotland. Soil cores were collected three times during January-March 2023. Measurements included rhizosheath mass, root length, and root hair length and density. While overall rhizosheath mass decreased by 27

Soybean (Glycine max) is a globally important crop for oil, grain and feed; however, drought stress limits its yield and quality. Ethylene alters plant development, stress responses and yield, but the molecular mechanism(s) by which it regulates these processes have not been fully elucidated. Here we show the regulatory factors EIN2L, EIL3, and EIL4 modulate stomatal movement and drought induced-ABA response. Plants with a triple EIN2L, EIL3, and EIL4 CRISPR/Cas9 knockout showed attenuated darkness, ABA- and ethylene-mediated stomatal closure, with altered expression of genes related to ROS, NO and the anionic channels SLAHs. Furthermore, EIN2L, EIL3, and EIL4 regulators positively regulate ethylene synthesis genes (ACS and ACO) during darkness and ABA synthesis (NCED3) and sensitivity (PYL8) genes following ABA treatment. Higher photosynthesis of well-watered plants and stomatal opening of the knockout line, along with its diminished sensitivity to ABA, enhanced water use thereby increasing sensitivity to drought. Selecting for allelic variation in EIN2L, EIL3, and EIL4 genes could better adapt soybean cultivars to the prevailing soil water availability, according to whether water conserving (WT alleles) or water-spending (knockout lines) traits enhance crop yields.

In Asia, the rice crop sustains millions of people. However, growing demand for this crop needs to be met while simultaneously reducing its water consumption to cope with the effects of climate change. Lowland cropping systems are the most common and productive but have particularly high water requirements. High-yielding rice genotypes adapted to drier environments (such as rainfed or aerobic rice ecosystems) are needed to increase the water use efficiency of cropping. Identifying these genotypes requires fast and more accurate selection methods. It is hypothesized that applying a new quantitative selection method (the score index selection method), can usefully compare rice yield responses over different years and stress intensities to select genotypes more rapidly and efficiently. Applying the score index to previously published rice yield data for 39 genotypes grown in no -stress and two stress environments, identified three genotypes (ARB 8, IR55419-04 and ARB 7) with higher and stable yield under moderate to severe stress conditions. These genotypes are postulated to be better adapted to stress environment such as upland and aerobic environments. Importantly, the score index selection method offers improved precision than the conventional breeding selection method in identifying genotypes that are well-suited to a range of stress levels within the target environment.

While ABA is often assumed to mediate partial stomatal closure as the soil dries, other plant hormones and hydraulic signals may also be involved. We tested whether irrigation volume (% of crop evapotranspiration, ET) and placement (partial rootzone drying [PRD] or deficit irrigation [DI], which irrigate part or all of the rootzone respectively) affect this signalling by measuring stomatal conductance (gs), leaf and shoot water potential (Ψleaf, Ψshoot), shoot xylem sap ABA concentration ([X-ABA]shoot) and various foliar hormones (ABA, IAA, SA, JA, JA-Ile and cis-OPDA) in cotton plants exposed to different irrigation volumes (100%ET or 50%ET) and placements (DI or PRD). Partial rootzone drying caused stomatal closure coincident with sustained foliar ABA accumulation and minimal changes in Ψshoot, but continued soil drying of the dry compartment reversed partial stomatal closure (with gs of 100%ET PRD plants sometimes greater than well-watered plants). With 100%ET PRD, partial stomatal closure correlated with decreased soil moisture of the dry compartment and increased [ABA]leaf, but neither Ψleaf nor [X-ABA]shoot. Irrespective of irrigation placement, 50%ET significantly decreased gs, Ψleaf and Ψshoot, but significantly increased [ABA]leaf, [X-ABA]shoot, [SA]leaf, [IAA]leaf and [cis-OPDA]leaf, with stomatal closure of 50%ET PRD plants occurring earlier than 50%ET DI plants. While stomatal closure at 50%ET correlated with foliar accumulation of multiple plant hormones, foliar ABA dynamics best explained transient stomatal closure at 100%ET PRD but not stomatal re-opening with prolonged soil drying. Thus, stomatal sensitivity to drying soil (and putative regulatory signals such as ABA) depended on irrigation volume and placement.

Different soybean cultivars (Williams 82 , Union , Jindou 21 , Long Huang 1 , Long Huang 2 ) were exposed to drying soil, to investigate whether endogenous abscisic acid (ABA) concentrations and leaf water relations regulated stomatal behaviour. We measured ABA concentrations in xylem and tissue of the first and second trifoliate leaves respectively; stomatal conductance (gs ) and leaf water potential (Ψleaf ) in both leaves; and water content in soil. Cultivar variation in leaf area and g s caused different rates of soil drying, but g s and Ψ leaf declined similarly with soil drying in all cultivars. Variation in leaf xylem ABA concentration better explained stomatal responses than foliar ABA concentration in some cultivars, and was highly correlated with stomatal conductance. Xylem ABA concentration in well-watered soil was highest in Union , and in drying soil was lowest in Jindou 21 and Long Huang 2 , although the latter had the highest foliar ABA concentrations. Jindou 21 accumulated lower xylem ABA concentrations than other cultivars as soil moisture or Ψ leaf decreased, but its stomatal sensitivity to xylem ABA was greater. Because cultivars varied in both ABA accumulation and stomatal sensitivity to ABA, but had similar stomatal sensitivity to Ψ leaf , leaf water relations seem more important in regulating stomatal closure of soybean.