Water Stress Research Articles

Innovating for sustainability in food and beverage companies: the role of governance and environmental factors in climate change mitigation

PurposeFocusing on the food and beverage (F&B) sectors, this study aims to identify combinations of external environmental factors (natural disasters and water stress) and internal corporate governance factors (corporate social responsibility [CSR] sustainability committee, board gender diversity and stakeholder engagement) that lead to the integration of climate change mitigation innovation and technologies.Design/methodology/approachA fuzzy set qualitative comparative analysis (fsQCA) was conducted on a global sample of 262 listed companies in the F&B sectors. Two additional analyses were performed for European and Asian companies.FindingsIn the three models, the presence of CSR sustainability committees and stakeholder engagement was crucial for achieving the integration of climate change mitigation innovation and technologies. The relevance of board gender diversity differs between the European and Asian models, highlighting potential regional influences on corporate climate innovation decisions. The combination of external and internal factors is the key to justifying different approaches to achieving climate innovation.Originality/valueThis study offers insights into the factors driving the integration of climate change mitigation innovation and technologies into company strategies. Related strategies must combine external and internal factors to enhance the climate resilience and competitiveness of F&B companies while reducing their environmental impact.

Agricultural drought monitoring and early warning at the regional scale using a remote sensing-based combined index.

Early detection of agricultural drought can alert farmers and authorities, enhancing the resilience of the food sector. A framework is proposed for developing a novel regional agricultural drought index (RegCDI) by combining remotely sensed vegetation health, soil moisture and crop water stress via a transparent Shannon's entropy weighting method. The framework consists of the selection of suitable datasets based on their regional performance, the aggregation of selected drought indicators, the validation of the combined index against crop yield, and the testing of predictive capabilities. The creation and performance of RegCDI are demonstrated for the drought prone Indian state of Odisha. MODIS surface reflectance is selected for crop water stress and GLDAS-2 for assessing soil moisture deficits and vegetation health. Three selected indicators (SMCI, TCI, and SIWSI-1) are combined into RegCDI for Odisha. The performance of RegCDI is evaluated (a) against other popular drought indices and (b) by comparing with seasonal crop yields. RegCDI is used to identify drought hotspots based on drought severity, duration, and propensity over the study area. A reforecast evaluation of RegCDI (up to three months ahead) showed that the indicators based on soil moisture deficit and crop water stress could predict drought conditions up to two months ahead with no less than 80% accuracy. This demonstrated the potential of the RegCDI framework and its component indicators for early warning of drought in Odisha.

Long-term analysis of reference evapotranspiration variations in the lower Bhavani basin

Evapotranspiration is a crucial component of the hydrological cycle and is profoundly influenced by climate change. Assessing regional evapotranspiration changes is essential for effective water resource management. The study investigated the dynamics of reference evapotranspiration in the Lower Bhavani Basin, a region with diverse landscapes increasingly vulnerable to climatic variability. Reference evapotranspiration data from the Food and Agriculture Organization using the AgERA5 dataset was analyzed to assess annual and seasonal trends from 2000 to 2022. The result showed that the mean yearly reference evapotranspiration in the basin is 1672.87 mm, with a significant decline of 3.53 mm per year. Seasonal analysis revealed a consistent decreasing trend across all seasons, with the southwest monsoon season showing the most significant reduction in evapotranspiration rates. The notable shift in the annual evapotranspiration rate was observed in 2016, highlighting the impact of climate change. Further, temperature, solar radiation and relative humidity were identified as the dominant factors influencing evapotranspiration rates in the basin. The relative moisture index indicated prevalent dry conditions, making the region susceptible to water stress. The findings provide critical insights for regional water resources management and accentuate the need for sustainable water management strategies to mitigate the impacts of climate change.

Effect of Different Levels of Potash on Growth, Yield Attributes and Yields of Transplanted Kharif Rice (Oryza sativa L.) in Southern Odisha

The occurrence of drought in the early monsoon period and the role of potassium in resisting water stress motivated me to imitate a field experiment which was conducted during Kharif, 2022-23 at the Post Graduate Research Farm (18.805378800N latitude, 84.1790850E longitude) of the M.S. Swaminathan School of Agriculture, Gajapati, Odisha, on a sandy clay loam soil. The experiment was laid out in Randomized Block Design with three replications and eight treatments. The treatments were: K0 (control) 0 Kg K ha-1, K10 :10 Kg K ha-1, K20: 20 Kg K ha-1, K30 : 30 Kg K ha-1, K40 : 40 Kg K ha-1, K50 : 50 Kg K ha-1, K60: 60 Kg K ha-1, K70 : 70 Kg K ha-1. Rice variety Shatabdi was the test crop. The recommended N and P2O5 (80-40 kg ha-1) were applied to all treatments. The effect of Potassium levels significantly influenced the crop growth parameters like the number of tillers, dry matter accumulation, leaf area index, number of panicles per unit area, panicle length, number of spikelet’s per panicle, number of filled spikelet’s per panicle, percentage of filled spikelet’s and finally grain and straw yields, the treatments K70 recorded best results in terms of dry matter accumulation (775g m-2), leaf area index (3.3), number of tillers m-2 (350.6), number of panicles m-2 (351.6), panicle length (29.6cm), number of spikelet’s panicle-1 (183), number of filled spikelet’s panicle-1 (163), percentage of filled spikelet’s (89.4)and grain and straw yields (5138kgha-1 and 6836 kgha-1, respectively). A continuous increasing trend was recorded with an increase in potassium level from K0 to K70. The harvest index efficiency was maximum under K40. In the present study, all parameters showed a positive response to an increase in potassium levels.

Fruit growth and water use of two pear cultivars grown in South Africa: implications for precision irrigation scheduling

In South Africa, as in other semi-arid countries, sustainable production of high-value crops requires precise management of limited water resources. We investigated daily and seasonal changes in stem and fruit growth as indicators of water stress in pear (Pyrus communis L.) trees, in the Western Cape Province. Stem and fruit growth data were collected hourly throughout the 2022–2023 growing season on 2 cultivars commonly planted in South Africa – Packham’s Triumph and Forelle. Soil water content, tree sap flow, and orchard microclimate were also monitored. Fruit maximum daily shrinkage (MDS) was highly sensitive to soil water deficit and more sensitive than stem size changes. However, the patterns of fruit MDS for both cultivars changed as the season progressed. Early in the season (October–December), there was a strong correlation between fruit MDS and soil water deficit (R2 ~ 0.72). The fruit shrunk with increasing soil water deficit as water loss through transpiration exceeded gains through xylem and phloem inflows. In contrast, daytime fruit size swelled from late December until harvest (February/March), likely because of the dominance of phloem inflows and decreased peel transpiration as the fruit matured. Correlation between fruit expansion and soil water deficit was weaker (R2 ~ 0.32) during the later stage even though fruit growth continued until harvest. Stem MDS consistently showed midday shrinkage throughout the season in response to soil water deficit, but with more scatter (R2~ 0.37). Seasonal total transpiration was greater for Forelle (733 mm) than Packham’s Triumph (539 mm) because of the higher leaf area index of the Forelle and the longer growing season. This study suggests that pear fruit growth data can provide accurate estimates of tree water status, but only during the early stages of growth. Towards maturity, fruit size changes respond indirectly to water deficit, possibly through reductions in photosynthesis.

Combined metabolome and transcriptome analysis reveal the mechanism of water stress in Ophiocordyceps sinensis

BackgroundOphiocordyceps sinensis (O. sinensis) is the dominant bacterium in the asexual stage of Chinese cordyceps, and its growth usually suffers from water stress. Thus, simulating its ecological growth environment is crucial for artificial cultivation. This study aimed to reveal the mechanism underlying the water stress tolerance of Ophiocordyceps sinensis (O. sinensis) by combining metabolomic and transcriptome analyses to identify crucial pathways related to differentially expressed genes (DEGs) and metabolites (DEMs) involved in the response to water stress.ResultsGene coexpression analysis revealed that many genes related to ‘betalain biosynthesis’, ‘tyrosine metabolism’, ‘linoleic acid metabolism’, ‘fructose and mannose metabolism’, and ‘starch and sucrose metabolism’ were highly upregulated after 20d-water stress. Metabolomic analysis revealed that many metabolites regulated by these genes in these metabolic pathways were markedly decreased. On the one hand, we surmised that carbohydrate metabolism and the β-oxidation pathway worked cooperatively to generate enough acyl-CoA and then entered the TCA cycle to provide energy when exposed to water stress. On the other hand, the betalain biosynthesis and tyrosine metabolism pathway might play crucial roles in response to water stress in O. sinensis by enhancing cell osmotic potential and producing osmoregulatory substances (betaine) and antioxidant pigments (eumelanin).ConclusionsOverall, our findings provide important information for further exploration of the mechanism underlying the water stress tolerance of O. sinensis for the industrialization of artificial cultivation of Chinese cordyceps.

APPLICATION OF GEO-INFORMATICS IN THE MAPPING OF AREAS VULNERABLE TO SURFACE WATER STRESS IN KADUNA STATE, NIGERIA

The main purpose of this paper is to identify water-stressed areas as a response to land use/land cover (LULC), climate variability, and increasing population in Kaduna State using Remote Sensing and Geographic Information systems. To achieve this aim, the paper set out to identify/map out areas vulnerable to water stress in the study area. The Meteorological data for the study were sourced from twelve remotely sensed stations around Kaduna State for thirty-seven years (1984 to 2021), land use data from remotely sensed satellite imageries that covered thirty-seven years, and projected population for thirty-seven years respectively. There are several indices used to compute water stress and the paper opted for indices that could monitor climate variability and surface water resources. Thereafter, the six indicators were standardized, weighted, and aggregated in Microsoft Excel, and imported into the ArcGIS 10.2.1 environment, and a weightier vulnerability model analysis was used to determine the weights of each variable’s contribution to water stress. The result achieved indicated that: 54.41% of the entire study area is vulnerable to water stress, 15.80% is moderately vulnerable, 26.23% is less vulnerable and 3.56% is not vulnerable to water stress within the period under study. Furthermore, Birnin Gwari, Chikun, Igabi, Ikara, and Kajuru Local Government Areas (LGAs) were the most vulnerable areas in the State while not vulnerable areas are; Kauru, Kagarko, and Jaba LGAs. The paper recommends the implementation of water conservation measures which include the creation of wetlands and shelter belts in areas vulnerable to water stress.

TRANSCRIPTIONAL ANALYSIS OF SOYBEAN (Glycine max) GENES RELATED TO WATER DEFICIT

ABSTRACT The soybean crop has been gaining worldwide prominence, being widely disseminated due to its various forms of use in different segments. Genetic and environmental factors are decisive in the quality of this culture. A feature related to the environmental factor that has gained prominence is the water deficit. Molecular events are initiated by the perception of water stress, involving a complex genetic network. Studies in recent decades have already identified some genes related to water stress in plants, it is known that the dehydration-responsive element binding protein (DREB) plays an important role in the response to water deficit. Therefore, this work aimed to analyze the expression of genes related to water deficit in soybean. For the analysis of gene expression, leaves of soybean (Glycine max (L.) Merrill), cultivar M9144 RR, submitted to the following treatments were used: 25V25R – plants subjected to water deficit throughout the cycle, being irrigated with 25% of ETpc and 100V100R – plants that did not experience water deficit, being irrigated with 100% of ETpc throughout the cycle. The quantification of the relative expression of the genes GmDREB1 and GmDREB5 showed that the water stress suffered by the cultivar was greater in the reproductive stage. Keywords: Transcription factors, development stages, gene expression.

Multi-Index Approach to Assess and Monitor Meteorological and Agricultural Drought in the Mediterranean Region: Case of the Upper Oum Er Rabia Watershed, Morocco

Drought is a severe disaster, increasingly exacerbated by climate change, and poses significant challenges worldwide, particularly in arid and semi-arid regions like Morocco. This study aims to assess and monitor drought using a multi-index approach to provide a comprehensive understanding of its spatio-temporal dynamics at both meteorological and agricultural levels. The research focuses on the Upper Oum Er Rabia watershed, which spans 35,000 km2 and contributes approximately a quarter of Morocco’s renewable water resources. We propose a methodology that combines ERA5 temperature data from remote sensing with ground-based precipitation data to analyze drought characteristics. Three meteorological indices were utilized: the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Reconnaissance Drought Index (RDI). Additionally, three remote-sensing indices were employed to capture agricultural drought: the Normalized Difference Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI), and the Crop Water Stress Index (CWSI), with a total of 528 NDVI and EVI images and 1016 CWSI images generated through Google Earth Engine (GEE), using machine-learning techniques. Trend analyses were conducted to monitor drought patterns spatio-temporally. Our results reveal that the three-month interval is critical for effective drought monitoring and evaluation. Among the indices, SPEI emerged as the most effective for capturing drought in combination with remote-sensing data, while CWSI exhibited the highest correlation with SPEI over the three-month period, outperforming NDVI and EVI. The trend analysis indicates a significant precipitation deficit, alongside increasing trends in temperature and evapotranspiration over both the short and long term. Furthermore, all drought indices (SPI, SPEI, and RDI) demonstrate an intensification of drought conditions. Adaptation strategies are essential for managing water resources in the Upper Oum Er Rabia watershed under these evolving climate conditions. Continuous monitoring of climate variables and drought indices will be crucial for tracking changes and informing future water management strategies.

Will They Continue to Endure: How Conflict and “Climate-Induced” Migration is Affecting the Lake Chad Region

The effects of climate change are undoubtedly global. Reports show that West Africa is in a precarious position, regarding some of the worst consequences of climate change, occasioning extreme events, such as violent conflict, insecurity, and loss of livelihoods in the Lake Chad region. The impact on human lives is full-blown as ‘climate-induced’ migration results in drought, desertification, and the intensifying water stress has on human migration in the region. Notably, the deterioration of individual and local living conditions has compelled inhabitants of the region in Nigeria to migrate to neighboring states as Internally Displaced Persons (IDPs) or ‘environmental refugees” in neighboring countries. However, existing studies focused on the impact and patterns of migration in West Africa thereby creating a “knowledge gap” on how ‘climate-induced’ migration is affecting the Lake Chad region. This paper employs secondary data collection, analyzing dynamic trends and patterns of climate change and challenges management. Findings revealed that while the activities of terrorists and insurgent groups have strongly impacted migration within the Lake Chad region, the continuous “dryness” and the ever-changing climate conditions, such as rising temperature, desertification, flooding, and drought have dramatically worsened and contributed to the mass decision to leave the region.

Impact of Fire Recurrence and Water Stress on the Root Nucleolar Activity of Maritime Pine (Pinus pinaster Ait.) Individuals Whose Seeds Were Harvested in Post-Fire Naturally Regenerated Stands

The main role of the nucleolus is ribosomal biogenesis, but it also responds to stress with changes in number, area, and/or morphology. Nucleoli with transcriptionally active ribosomal RNA genes are selectively stained by silver nitrate. Hypothesising that fire recurrence and/or polyethylene glycol (PEG)-induced water stress would cause nucleolar changes in Pinus pinaster roots, nucleolar parameters were analysed upon the germination of seeds harvested in post-fire naturally regenerated stands with different fire regimes. An unburned stand was used as a control. The nucleoli number varied from 1 to 15 among stands and PEG treatments, but a mode of five or six nucleoli was found. The number of nucleoli per interphase (N) increased (p < 0.001) with fire recurrence (stand effect). Increasing PEG concentration (treatment effect) decreased the nucleoli number, notably in the stand with the highest fire recurrence. The nucleolar area decreased (p < 0.001) with increased nucleoli number, fire recurrence, and/or PEG concentration. Fire recurrence and water scarcity are forecasted for future climate scenarios. As demonstrated earlier, these factors could influence protein synthesis or the cell cycle’s regularity, which are crucial processes for root growth and pine seedling establishment. Furthermore, this work revealed that nucleolar parameters could be suitable biomarkers for pine stress studies.

Water Stress Adaptations by Rhododendron arboreum Smith in The Himalayan Treeline Environment

Drought is amongst the most important climatic events which can severely impact natural ecosystems. The under-canopy Indian Himalayan tree species are less studied on water stress in harsh climatic conditions. Rhododendron arboreum is an ecologically and economically important tree species and distributed between 1500–3500 m asl in the Himalayan ecosystems. In this study, we have tried to assess the water stress adaptations by R. arboreum near the treeline ecotone located at 30°11´02˝N and 79°39´36˝E between 3100 and 3500 m asl elevation. Water potential (Ψ) was measured using a Pressure chamber and leaf conductance with the help of AP4 porometer. Soil moisture (Sm) across the depths was highly variable (p<0.05). The pre-dawn water potential (ΨPD) of R. arboreum tree varied between -0.12 and -0.91 MPa. ANOVA showed that the ΨPD of R. arboreum seedlings varied significantly across the years, seasons, and sites (p<0.05). The decline in osmotic potential at full turgor (Ψπ100) was -1.18 to -1.20 MPa in trees and -1.42 to -1.72 MPa in seedlings. The morning leaf conductance (gwAM) of R. arboreum trees ranged from 58.00 to 271.68 m mol m-2 sec-1. Correlation showed that the maximum leaf conductance in R. arboreum trees was observed when the ΨPD was -0.5 to -0.9 MPa. Water uptake function in plants is generally affected by winter frost which can change the Ψ, osmotic potential, and leaf conductance of plants. The ΨPD in the species was relatively high across all seasons in the treeline areas to disrupt physiological activities.

Effects of water stress on chlorophyll fluorescence and growth of Rorippa amphibia: a well-adjusted invasive plant in China

Effects of water stress on chlorophyll fluorescence and growth of Rorippa amphibia: a well-adjusted invasive plant in China

Hyperspectral Imaging Reveals Differential Carotenoid and Chlorophyll Temporal Dynamics and Spatial Patterns in Scots Pine Under Water Stress.

Drought-related die-off events have been observed throughout Europe in Scots pine (Pinus sylvestris L.). Such events are exacerbated by carbon starvation that is, an imbalance of photosynthetic productivity and resource usage. Recent evidence suggests that optically measurable photosynthetic pigments such as chlorophylls and carotenoids respond to water stress (WS). However, there is a lack of measurements using imaging spectroscopy, and the mechanisms linking xanthophyll-related changes in reflectance captured by the photochemical reflectance index (PRI) and chlorophyll changes in red edge position (REP) to WS are not understood. To probe this, we conducted a greenhouse experiment where 3-year-old Pinus sylvestris saplings were subjected to water limitation and followed using hyperspectral imaging (HSI) spectroscopy, water status and photosynthetic measurements. Carotenoids (e.g., xanthophyll cycle) and chlorophylls responded to WS, which was observed using the HSI-derived indices PRI and REP respectively. The spatial-temporal response in these two pigment-reflectance groupings differed. The spatial distribution of PRI represented the light intensity around the time of the measurement, whereas REP reflected the daily averaged light intensity over the experimental course. A further difference was noted upon rewatering, where the carotenoid-related PRI partially recovered but the chlorophyll-related REP did not.

Genetic loci associated with sorghum drought tolerance in multiple environments and their sensitivity to environmental covariables.

Climate change can limit yields of naturally resilient crops, like sorghum, challenging global food security. Agriculture under an erratic climate requires tapping into a reservoir of flexible adaptive loci that can lead to lasting yield stability under multiple abiotic stress conditions. Domesticated in the hot and dry regions of Africa, sorghum is considered a harsh crop, which is adapted to important stress factors closely related to climate change. To investigate the genetic basis of drought stress adaptation in sorghum, we used a multi-environment multi-locus genome-wide association study (MEML-GWAS) in a subset of a diverse sorghum association panel (SAP) phenotyped for performance both under well-watered and water stress conditions. We selected environments in Brazil that foreshadow agriculture where both drought and temperature stresses coincide as in many tropical agricultural frontiers. Drought reduced average grain yield (Gy) by up to 50% and also affected flowering time (Ft) and plant height (Ph). We found 15 markers associated with Gy on all sorghum chromosomes except for chromosomes 7 and 9, in addition to loci associated with phenology traits. Loci associated with Gy strongly interacted with the environment in a complex way, while loci associated with phenology traits were less affected by G × E. Studying environmental covariables potentially underpinning G × E, increases in relative humidity and evapotranspiration favored and disfavored grain yield, respectively. High temperatures influenced G × E and reduced sorghum yields, with a ~ 100kgha-1 average decrease in grain yield for each unit increase in maximum temperature between 29 and 38°C. Extreme G × E for sorghum stress resilience poses an additional challenge to breed crops for moving, erratic weather conditions.

Examining the impact of water scarcity on agricultural output in the Gulf Cooperation Council (GCC) region

AbstractThis research paper examines the impact of water scarcity on agricultural output in the Gulf Cooperation Council (GCC) region. It highlights the increasing global water scarcity and its consequences, including the prevalence of water‐stressed areas and the adverse effects on human health and economic sectors. The paper focuses on the GCC region, known for its water scarcity and desertification, exacerbated by climate change and pollution. The study aims to investigate the relationship between water stress levels and agricultural productivity, evaluating the effects of freshwater withdrawals, fertilizer consumption, and agricultural methane emissions on crop production. Additionally, it explores the connection between agricultural output and net national income per capita. By addressing these research questions, the study contributes to the understanding of agricultural water scarcity and its implications for global food security and sustainability. The paper utilizes data from the World Bank to analyze crop production in the GCC countries from 2001 to 2020, shedding light on the influence of water scarcity on agricultural landscapes. The research highlights the efforts made by GCC countries to enhance food security, including strategic investments in agricultural lands and bilateral agreements. It also discusses the challenges faced by specific countries within the region, such as Saudi Arabia, the United Arab Emirates (UAE), and Kuwait, in terms of agricultural production and water constraints. Overall, the paper provides insights into the complexities of agricultural water scarcity and its effects on the GCC region, emphasizing the need for sustainable solutions to ensure food security and economic stability.

Characterizing the hysteretic effects of water and salinity stresses on root-water-uptake

Characterizing the effects of previous water and salinity stresses is critical for the evaluation of plant water status, which, in turn, is essential for understanding soil-plant water relations and optimizing irrigation schemes. Recent research has found that hysteresis of plant response following water stress alone can be described by an exponential function of the stress degree on the previous day. To explore and quantify the effects of hysteresis concerning salinity stress and combined water-salinity stress, a hydroponic experiment and a soil column experiment on winter wheat, and a field experiment on cotton were conducted. Like water stress, previous salinity stress and combined water-salinity stress also resulted in hysteretic effects on root-water-uptake. Leaf stomatal conductance and plant transpiration rate of stressed crops could only recover gradually from a previous stressed status after re-watering. When stress was mild, compensatory recovery was found, while incomplete recovery occurred when stress was severe. Although the recovery process was closely related to stress history and type, a recovery coefficient was quantified universally with an exponential function of the stress extent on the previous day (with a coefficient of determination R2 ≥ 0.60). Consideration of hysteresis for water and salinity stresses with a mathematical model led to significant improvement in the simulation of both relative transpiration rate (R2 = 0.94, root mean squared error RMSE = 0.04, maximal absolute error MAE = 0.12) and soil water content (R2 = 0.90, RMSE = 0.01 cm3 cm–3, MAE = 0.03 cm3 cm–3), especially during the recovery periods severely affected by historical stress. Consideration of hysteresis is expected to benefit regulation of soil water and salinity and thus enhance water use efficiency. However, the mechanisms underlying hysteresis, especially the compensatory recovery mechanisms, still need to be further investigated.

Uni- and Multivariate Analyses for the Characterization of Popcorn Inbred Lines for Drought Tolerance at Seedling and Vegetative Stages

Water deficit is the main limiting factor in rainfed agricultural production, negatively affecting germination and vegetative development. The objectives of this work were to characterize inbred lines for drought tolerance, to identify the most important root and shoot morphological traits for discriminating genotypes, to compare the efficiency of identifying contrasting inbred lines using uni- and multivariate methods, and to evaluate the effectiveness of identifying drought-tolerant genotypes at seedling and vegetative stages. We assessed 28 popcorn inbred lines and three maize single crosses, two drought-tolerant and one drought-sensitive. At the seedling stage, drought was induced on germitest paper moistened with polyethylene glycol 6000. At the vegetative stage, we applied water stress using lysimeters. We measured root and shoot morphological traits under water stress and no stress and processed the relative values. Uni- and multivariate methods, alone or in combination, were equally efficient for identifying contrasting inbred lines for drought tolerance. The confidence interval and Dunnett’s test worked very well when contrasting controls were included. Principal component analysis allowed to discriminate genotypes and identify the most important traits for discriminating them. At the seedling stage, inbred line 22-1824-2 was the most drought-tolerant and 22-1877-3 the most sensitive. At the vegetative stage, inbred lines 22-1920-1 and 22-1867-4 were the most tolerant and 22-1860-5 was the most sensitive. Root length, volume, dry weight, and surface area, as well as water content, were the most important traits for discriminating genotypes. Due to distinct tolerance mechanisms, drought tolerance should be assessed at both stages.

Can nitrogen availability impact plant performance under water stress? A review of traits, mechanisms, and whole plant effects

Can nitrogen availability impact plant performance under water stress? A review of traits, mechanisms, and whole plant effects

Seasonal shifts in depth-to-water uptake by young thinned and overstocked lodgepole pine (Pinus contorta) forests under drought conditions in the Okanagan Valley, British Columbia, Canada

Abstract. As drought and prolonged water stress become more prevalent in dry regions under climate change, preserving water resources becomes a focal point for maintaining forest health. Forest regeneration after forest loss or disturbance can lead to overstocked juvenile stands with high water demands and low water-use efficiency. Forest thinning is a common practice with the goal of improving tree health, carbon storage, and water use while decreasing stand demands in arid and semi-arid regions. However, little is known about the impacts of stand density on seasonal variation in depth-to-water uptake or the magnitude of the effect of growing season drought conditions on water availability. Existing reports are highly variable by climatic region, species, and thinning intensity. In this study, stable isotope ratios of deuterium (δ2H) and oxygen (δ18O) in water collected from various soil depths and from branches of lodgepole pine (Pinus contorta) under different degrees of thinning (control: 27 000 stems per hectare; moderately thinned: 4500 stems per hectare; heavily thinned: 1100 stems per hectare) over the growing season were analyzed using the MixSIAR Bayesian mixing model to calculate the relative contributions of different water sources in the Okanagan Valley in the interior of British Columbia, Canada. We found that under drought conditions the lodgepole pine trees shifted their depth-to-water uptake through the growing season (June to October) to rely more heavily on older precipitation events that percolated through the soil profile when shallow soil water became less accessible. Decreased forest density subsequent to forest thinning did not cause a significant difference in the isotopic composition of branch water but did cause changes in the timing and relative proportion of water utilized from different depths. Thinned lodgepole pine stands were able to maintain water uptake from 35 cm below the soil profile, whereas the overstocked stands relied on a larger proportion of deep soil water and groundwater towards the end of the growing season. Our results support other findings by indicating that, although lodgepole pines are drought-tolerant and have dimorphic root systems, they do not shift back from deep water sources to shallow soil water when soil water availability increases following precipitation events at the end of the growing season.