Reduced Water Supply Research Articles

Controlled drainage with subirrigation systems: Reduce water supply by automatic control

Controlled drainage with subirrigation (CDSI) is a viable measure to supply, retain or discharge groundwater, thereby contributing to freshwater availability in agriculture under changing environmental conditions. Relatively simple CDSI systems can be controlled manually to set a few drainage levels. More advanced systems can be controlled remotely to set any drainage level (between a technical maximum and minimum). CDSI potentially improves hydrological conditions for crop growth, but the required external water supply can be large. Therefore, the objective of this paper is to investigate whether external water supply for subirrigation can be reduced by automatic control of CDSI systems in relation to crop water demand. Field measurements of a CDSI pilot in the Dutch sandy Pleistocene uplands were combined with weather forecasts to simulate the optimal drainage level and day by day water demand and supply using the agro-hydrological Soil, Water, Atmosphere, Plant model (SWAP). Firstly, model simulations showed that the water requirement reduced by 60 mm (dry growing season), 253 mm (average growing season) and 348 mm (wet growing season) using a dynamically managed crest level (CDSI-dyn) compared to using a fixed crest level (CDSI-fix), with minor effects on crop yield. Secondly, model simulations showed that a higher hydraulic resistance to downward seepage, a higher ditch water level or deeper roots reduced the water supply (up to 100 mm). Thirdly, accepting 10 % daily crop drought and oxygen stress for CDSI-dyn reduced the water supply requirement with 235–628 mm (dry vs wet growing season) compared to CDSI-fix. In conclusion, the required water volume for CDSI could be substantially reduced by automated control of the drainage level and water supply rate, while maintaining crop yield or accepting minor reductions, which increases the potential of implementation of CDSI systems.

Influence of successive cycles of water stress on tomato production at fruiting stage

Progressive reduction of water supply was imposed during early period (S1) and late period (S2) interceded by a recovery, with a moderate stress for first case and un intensive stress for second case, at fruiting stage of tomato (Lycopersicon esculentum Mill. cv. Rio Grand). The influence of this reduction on fruit production, shoot growth, water content (WC), relative water content (RWC), leaf area (LA), specific leaf weight (SLW), total soluble solids of fruit (T.S.S.) and maturity percentage of fruit were investigated. Repetition of water stress (S1+S2) was obviously reducing the shoot growth, fresh yield, WC, LA and maturity percentage, whereas that was not achieved in dry weight of fruits (FDW), RWC, SLW and T.S.S. Since, a significant difference was founded between the effects of S2 cycle and when that has been preceded by another one S1+S2 on accumulation of dry matter of fruit. Two successive cycles of water stress were doubled of FDW by two times of that registered in control. These results indicate that, during fruiting stage, the effect of gradually exposure of a moderate water stress period, followed by recovery, thereafter by another gradually exposure of un intensive water stress period, contributed to better accumulation of dry matter in fruit by an osmotic adjusting therefore improving water use efficiency, compared to the effect of only one high intensive of water stress applied during the second period. Repetition cycle of water stress may be useful to develop management systems for a reasonable production of tomato and thus reducing the needs of irrigation water in regions facing deficit of water supplies.

Vegetation greening accelerated hydrological drought in two-thirds of river basins over China

Although the vegetation-greening-induced water supply reduction has been widely recognized, little is known about the impacts of vegetation greening on hydrological drought. Here Standardized Water Availability Index (SWAI, based on surface water-balance), driven by evapotranspiration (ET, with vegetation dynamics), was developed to quantify the impacts of vegetation greening on hydrological drought at multiple timescales over China from 1982 to 2015. The ET with vegetation dynamics was modeled by the improved PT-JPL model, and was validated with in-situ observed data from 8 flux tower sites and 4 on-site field experiments (covered with 12 different land-cover types in China). SWAI was also validated with monthly runoff records (from 59 gauging stations over different climatic regimes in China), and proved to effectively capture the response of water surplus/deficit to vegetation dynamics. Results reveal that percentage drought-affected areas increased (increased by 2 % to 9 %) and drought intensity enhanced in two-thirds of Chinese river basins due to vegetation greening. Moreover, in nearly half of the river basins in China, drought duration increased by 0.035–0.131 months, and drought frequency increased by 0.016–0.085 months/34-year. Hydrological drought accelerated by vegetation greening mainly occurred in arid and semi-arid river basins (water-limited areas), while it was not obvious in humid and sub-humid river basins due to limited energy for ET in these areas. Our work and findings provide new insights for understanding the vegetation-induced water resource shortage and have potential applications for government and water managers to timely monitor and assess the balance between ecological restoration and water resources.

Households’ willingness-to-pay for different strategies aimed at reducing water supply network dysfunctions. A French case-study

ABSTRACT Using an original contingent valuation, this study compares the Willingness-To-Pay (WTP) of households for three water pipes renewal programs focused respectively on water quality, reducing leaks in networks and preventing breaks. A survey was conducted in southwest France: respondents were asked to rank the different renewal programs and then state the maximum amount they would be willing to pay in order to benefit from each. Results of a Heckman model suggest that variables influencing the probability of refusing to pay for a non-economic reason and the WTP differ from one program to another, which validates this choice of model. WTP estimates are not of the same order of magnitude whatever the program, and remained relatively low when compared to the actual water bill. While asset management is often only seen as an activity calling for specialised technical knowledge, users are able to perceive the outcome of that management process.

Boosting Tomato Resilience in Tanzania: Grafting to Combat Bacterial Wilt and Abiotic Stress

The grafting technique has successfully mitigated crop losses from diseases and stress in vegetable production; however, vegetable grafting in Tanzania is very limited. Field and greenhouse experiments conducted in Tanzania’s mainland and islands compared the response of tomato determinate cv. ‘Tanya’ to production challenges when ungrafted and grafted onto five tomato rootstocks (‘Hawaii 7796’, ‘Tengeru 1997’, ‘Tengeru 2010’, ‘R3034’, and ‘Shelter’), one eggplant variety (‘EG 203’), and one wild Solanum species (Solanum elaeagnifolium). The visual symptoms of bacterial wilt varied significantly with location and season, ranging from 8 to 100%, attributed to varying bacterial wilt pressures and strains of Ralstonia solanacearum isolated (Phylotype I sequevars 17, 18, and 31). ‘EG203’ and ‘Hawaii 7796’ emerged as the most effective rootstocks, reducing wilting by 49.8 and 51.0% and improving yield by 57.2% and 27.7% on average across experiments conducted in three locations (Moshi, Pemba, and Unguja) over two seasons. Combining reduced water supply with grafting resulted in an average reduction in wilting of 76%, while also boosting yields by an average of 3.6 times in experiments conducted in Arusha over two seasons. Grafting onto ‘Hawaii 7796’ and ‘Shelter’ significantly improved ‘Tanya’ yields by 38.3% and 41.6% on average over two seasons, only under standard nutrient application rates. While certain rootstocks improved crop performance, yields across various sites and seasons were significantly hampered by pest pressure. These findings support grafting’s potential to mitigate damage from common stresses, emphasizing the need for further research to identify suitable rootstocks for optimizing returns on investments in grafted plants in Tanzania.

Estimation of Energy Consumption and CO2 Emissions of the Water Supply Sector: A Seoul Metropolitan City (SMC) Case Study

A model that computes the per-unit process energy consumption, energy intensity, CO2 emission, and CO2 intensity of water treatment plants is developed. This model is used to estimate the total energy consumption of six water treatment plants in Seoul Metropolitan City (SMC), which is comprised 80–85% for finished water pumping, 6–10% for ozone disinfection, 2–4% for rapid mixing, and 1–3% for non-process loads. The model results are validated against actual data for 2020 and 2021. The net energy consumption considering renewable energy production and use is then calculated, and the corresponding level of CO2 emissions is predicted. Four scenarios based on the projected water requirements for the year 2045 were evaluated as follows: increased energy efficiency in finished water pumping (Scenario 1), increased renewable energy production in water treatment plants (Scenario 2), increased energy efficiency in raw water pumping (Scenario 3), and reduced water supply per capita (Scenario 4). Compared to a baseline do-nothing scenario (Scenario 0), the net energy consumption is reduced by 3.57%, 2.61%, 3.42%, and 4.67% for Scenarios 1–4, respectively. Scenario 4, which is a water-driven approach, is best for reducing CO2 emissions, while Scenario 1 and 3, which are energy-driven approaches, are more effective at reducing CO2 intensity.

Microbial Consortia Versus Single-Strain Inoculants as Drought Stress Protectants in Potato Affected by the Form of N Supply

This study investigated the drought protection effects of six fungal and bacterial inoculants and ten consortia thereof on vegetative growth, nutritional status, and tuberization of potato under controlled and field conditions. It was hypothesized that microbial consortia offer improved drought protection as compared with single strains, due to complementary or synergistic effects, with differential impacts also of N fertilization management. Under NO3− fertilization, a 70% reduction in water supply over six weeks reduced shoot and tuber biomass of non-inoculated plants by 30% and 50%, respectively, and induced phosphate (P) limitation compared to the well-watered control. The P nutritional status was significantly increased above the deficiency threshold by three single-strain inoculants and eight consortia. This was associated with the presence of the arbuscular mycorrhizal fungus (AMF) inoculant Rhizophagus irregularis MUCL41833 (five cases) and stimulation of root growth (five cases). Additionally, Bacillus amyloliquefaciens FZB42 and AMF + Pseudomonas brassicacearum 3Re2-7 significantly reduced irreversible drought-induced leaf damage after recovery to well-watered conditions. However, the microbial inoculants did not mitigate drought-induced reductions in tuber biomass, neither in greenhouse nor in field experiments. By contrast, NH4+-dominated fertilization significantly increased tuber biomass under drought stress (534%), which was further increased by additional AMF inoculation (951%). This coincided with (i) improved enzymatic detoxification of drought-induced reactive oxygen species (ROS), (ii) improved osmotic adjustment in the shoot tissue (glycine betaine accumulation), (iii) increased shoot concentrations of ABA, jasmonic acid, and indole acetic acid, involved in drought stress signaling and tuberization, and (iv) reduced irreversible drought-induced leaf damage. Additional application of bacterial inoculants further improved ROS detoxification by increasing the production of antioxidants but stimulated biomass allocation towards shoot growth at the expense of tuber development. The results demonstrated that microbial consortia could increase the probability of drought protection effects influenced by the form of N supply. However, protective effects on vegetative growth do not necessarily translate into yield benefits, which can be achieved by adequate combination of inoculants and fertilizers.

Phenology, gas exchange, biomass accumulation, and irrigated rice yield under alternative irrigation managements

AbstractIn Brazil, rice production is predominantly concentrated in the South region, employing a continuous flood irrigation system throughout the crop cycle. However, this irrigation management strategy in the tropical region contributes to low water‐use efficiency owing to adverse climatic conditions. Furthermore, with climate change projections indicating reduced water availability, the study aims to investigate the impact of alternative irrigation management strategies on the phenological development, gas exchange, biomass accumulation, and productivity of tropical irrigated rice. Three alternative irrigation management approaches—intermittent flood irrigation with aeration (IFA), intermittent flood irrigation throughout the growth cycle (IFC), and intermittent flooding up to the flowering stage (IFF)—were compared with the traditional continuous flood irrigation throughout the growth cycle. Phenological data, gas exchange, growth, and productivity dynamics were subject to analysis, providing overarching insights into management practices. Notably, irrigation management exhibited no influence on the vegetative phase of the crop. The implementation of intermittent flood irrigation facilitated a reduction in water supply without compromising the physiological performance of tropical irrigated rice. Strategies promoting judicious water utilization, such as IFA and IFC, can be readily integrated into the cultivation of tropical irrigated rice without detriment to grain yield or harvest index.

Diminishing carryover benefits of earlier spring vegetation growth.

Spring vegetation growth can benefit summer growth by increasing foliage area and carbon sequestration potential, or impair it by consuming additional resources needed for sustaining subsequent growth. However, the prevalent driving mechanism and its temporal changes remain unknown. Using satellite observations and long-term atmospheric CO2 records, here we show a weakening trend of the linkage between spring and summer vegetation growth/productivity in the Northern Hemisphere during 1982-2021. This weakening is driven by warmer and more extreme hot weather that becomes unfavourable for peak-season growth, shifting peak plant functioning away from earlier periods. This is further exacerbated by seasonally growing ecosystem water stress due to reduced water supply and enhanced water demand. Our finding suggests that beneficial carryover effects of spring growth on summer growth are diminishing or even reversing, acting as an early warning sign of the ongoing shift of climatic effects from stimulating to suppressing plant photosynthesis during the early to peak seasons.

To study the effect of anti-transparent on propagation parameters of mulberry under polyhouse conditions with reduced water supply

To study the effect of anti-transparent on propagation parameters of mulberry under polyhouse conditions with reduced water supply

ӨЗБЕКІСТАН ТАУ МҰЗДЫҚТАРЫ КӘЗІРГІ УАҚЫТТАҒЫ ЖАҒДАЙЫ

The condition of glaciers in the mountainous regions of Uzbekistan, in the upper reaches of the Piskem, Kashkadarya and Surkandarya rivers, is considered. As well as a reduction in fresh water supplies due to global warming. The results of studies of glaciers in recent years are presented.

Allelopathic interactions of brown mustard (Brassica juncea L.) with other aromatic plants during germination and seedling development

Organic compounds originating from plant metabolism and reaching the environment may inhibit or stimulate germination and early developmental processes of other plants grown in the vicinity. The aim of this study was to investigate the allelopathic interactions of brown mustard with four other aromatic plants (summer savoury, coriander, caraway and common sage). While health-promoting metabolites of brown mustard are thoroughly investigated and the plant receives an increasing interest from cultivators of aromatic and medicinal plants, its allelopathic interactions with other aromatic plants are poorly documented. The experiments were performed in closed germination vessels, under controlled conditions. The influence of the presence or absence of light, as well as of a sufficient or reduced water supply on the co-germination of brown mustard seeds with each of the other four aromatic plants was also evaluated. The presence of brown mustard reduced the germination velocity of caraway, coriander, sage and savoury. It inhibited stem elongation, but stimulated root growth of savoury. Shoot growth of coriander seedlings was enhanced by the vicinity of brown mustard plantlets. Caraway slowed down the germination of brown mustard seeds, but it stimulated root and stem elongation of the seedlings. The presence of savoury enhanced the fresh biomass production of brown mustard. Common sage inhibited root growth, but stimulated stem elongation of brown mustard plantlets. Most of the allelopathic effects were more pronounced under water shortage than under sufficient water supply. Positive interspecific influences on biomass production were, in most cases, more pronounced in the presence of light. The findings may contribute to optimization of brown mustard cultivation in small parcels, in the vicinity of other aromatic plants, some allelopathic interactions being able to stimulate growth and developmental processes in an environmental-friendly and cost-effective manner.

Effect of Deficit Irrigation on Growth Parameters of the Salvia splendens L. Plant

This study aims to investigate alterations in the developmental parameters of Salvia splendens L., a commonly utilized seasonal flower associated with excessive water consumption in urban green spaces, through the implementation of deficit irrigation practices. Four distinct irrigation treatments, which entailed maintaining the evaporation pot’s water level at 100% (control), 75%, 50%, and 25% of the pot’s water-holding capacity, were established. This study scrutinized 18 growth parameters to assess the impact of varying water application levels. The findings of this research revealed that Salvia splendens L. plants exhibited more substantial improvements in 17 out of 18 assessed parameters when subjected to 75% water application (representing a 25% reduction in water supply) in comparison to 100% water application (with no reduction). Notably, the only parameter negatively affected by reduced water availability in Salvia splendens L. was the diameter of the flowers. Thus, it is recommended to reduce water application by 25% when cultivating Salvia splendens L. in urban areas. Such a measure is expected to yield substantial water conservation benefits in urban landscaping. Consequently, it is advisable to promote the frequent utilization of Salvia splendens L. plants in urban green spaces, given their robust development even under conditions of water scarcity.

Impact of Climate Change on the Chemical Compositions and Antioxidant Activity of Mentha pulegium L.

A central position in Moroccan ethnobotany is held by the Mentha genus, serving as a vital reference for aromatic and medicinal plants within the Lamiaceae family. The profound importance of Mentha species in the daily lives of Moroccans is recognized, and the primary objective of this study is to assess the impact of rising temperatures and decreasing precipitation on the primary and secondary metabolites of Mentha pulegium under the following climatic conditions: sample 1, cultivated under standard temperature and precipitation conditions during the first year; sample 2, subjected to an 8 °C temperature increase and a 25% reduction in water supply; and sample 3, exposed to a 12 °C temperature rise and a 50% decrease in water availability. Phytochemical screening results reveal a progressive decline in primary metabolites from sample 1 to sample 3 due to the increase in temperature and decrease in precipitation. Conversely, a distinct trend is observed in secondary metabolites and the yield of essential oil, increasing from sample 1 to sample 2 as the temperature rises and precipitation decreases. Remarkably, in sample 3, the yield of essential oil decreases as climatic conditions further deteriorate. Additionally, GC analysis demonstrates that modifications in the chemical compositions of essential oils occur because of the disruption of climatic parameters, particularly in the major compounds. Similarly, changes in climatic parameters significantly influence antioxidant activity, with sample 2 exhibiting the highest activity, as reflected by an IC50 value (half-maximal inhibitory concentration) of 14,874.04 μg/mL, followed by the third sample at 8488.43 μg/mL, whereas the first sample exhibits the lowest activity at 4505.02 μg/mL. In summary, the complex relationship between climatic factors and the chemical composition of Mentha pulegium is highlighted by our experiment, emphasizing its implications for medicinal properties within an ecological context.

Studying the impacts of deep uncertainties on water resources system in Ba River Basin through the combined use of a climate stress-test and land use change

Study regionBa River Basin, Viet Nam. Study focusThe impacts of deep uncertainties on the water resources system in the Ba River Basin are explored through the combined use of a climate stress-test and land use change. The performance of the water resources system is assessed using water supply reliability under various climate conditions and land use. A MIKE HYDRO Basin model is developed with 7 irrigation regions, 45 irrigation users, 8 regular users, 48 reservoirs, and 10 hydropower plants. 40 different combinations of climate conditions and land use change were simulated. New hydrological insights for the regionClimatic and land use change is expected to reduce water supply reliability in the river basin by between 2.1% and 5.2%. The most significant reliability decrease is in Nam Bac An Khe (−29.4%), while the most increase is in Upper Ayun (+10.9%). The spatial variation of climatic change impact is high and is reflected in the reliability range. The reliability range of Upper Ayun and Ayun Pa is narrow (1.2% in Upper Ayun and 0.7% in Ayun Pa). In contrast, the reliability range of Nam Bac An Khe, Krong Pa, Krong Hnang, and Upper Dong Cam is wide (14.3% in Nam Bac An Khe, 12.7% in Krong Pa, 12.4% in Krong Hnang, 11.7% in Upper Dong Cam, and 3.4% in Lower Dong Cam).

Effect of nutrient solution concentrations and irrigation levels combined with humic acid on physiological and quality characteristics of rocket crop (Eruca sativa (mill.) thell.)

Water resources pose a considerable limitation in arid and semi-arid regions like Iran, primarily due to the scarcity of rainfall and heightened evaporation rates. Within open hydroponic systems, a significant concern arises from the depletion of nutrient solutions utilized for crop fertigation. This predicament subsequently gives rise to environmental issues of note and a discernible surge in production expenses. Application of humic acid (HA), as a plant biostimulant, enhances plant tolerance to reduced water supply and counterbalances the effects of diluted nutrient solutions. A greenhouse experiment was conducted to investigate the impact of applying HA (600 ppm) in conjunction with three nutrient solution concentrations (complete nutrient solution (NSc), 75% NSc (NS1), and 50% NSc (NS2)), as well as two irrigation levels (100 and 50% of plant water requirement, IL100 and IL50, respectively). The treatment under IL50 was referred to as ½ NSc, ½ NS1, and ½ NS2. The findings showed that almost all of the traits studied were significantly affected by the applied treatments. The highest yield (409.4 g m−2), leaf area (34.67 cm−2 plant), biomass (1.092 g−1 plant), membrane stability index (90.47%), chlorophyll a (0.99 mg g−1 FW), chlorophyll b (0.413 mg g−1 FW), total chlorophyll (1.54 mg g−1 FW), carotenoid (0.437 mg g−1 FW), vitamin C (730.7 mg ascorbic acid kg−1 FW), amino acid (236.8 µg g−1 FW) and nitrate reductase activity (102.8 µg NO2 - mg Protein−1 h−1) were observed in NSc + HA. In addition, the highest carbohydrate (46.99 mg g−1 FW), phenol (1129 mg GAE Kg−1 FW), and flavonoid content (1133 mg Catechin Kg−1 FW) and antioxidant activity (74.75%) were observed in ½ NS1 + HA. In addition, the highest relative water content (86.62%) and nitrate content (1106 mg kg−1 FW) were recorded in NS2 + HA and NSc, respectively. The application of HA combined with different concentrations of the nutrient solution under both irrigation levels caused an increase in most of the parameters studied in rocket plants compared to respective treatments without HA application. In addition, the results obtained confirmed that HA could compensate for the stress caused by a shortage of nutrients and water in the nutrient solution in this crop.

Hydro-climatic variability anomalies over south America with El Nio-southern oscillation: Precipitation Anomalies and their socio-economic impact in the Colombia country

This paper reviews climatic anomalies in Colombia, and South America, primarily based on CMIP6 model with data from the World Bank Group and the Climatic Data Store API under the emission scenarios SSP1-2.6 and SSP5-8.5. Due to the processing of atmospheric dynamics, ENSO directly affects the northern part of South America and indirectly affects subtropical South America. El Nio years are distinguished by higher incidence of dry weather extremes, and during neutral or La Nia years are likelier to experience wet weather extremes. Overall, western part of Colombia is colder than the southeast since it incorporates a portion of the Andes Mountains. Each of the four seasons has rising temperatures ranging from 2.2 to 5.2 , with the nation's southern, eastern, and northern regions suffering the highest increases. The west of Colombia experiences more rain throughout the year than the rest of the country, which has the highest precipitation in the spring and summer. Droughts and reduced water supply carried on by rising temperatures could damage infrastructure, damage the environment, loss of revenue, and severe societal effects when combined with flooding brought on by higher precipitation and rainfall anomalies.

GRACE-based dynamic assessment of hydrological drought trigger thresholds induced by meteorological drought and possible driving mechanisms

Determining the threshold at which meteorological drought triggers hydrological drought is critical for early warning and proper mitigation of drought. However, drought trigger thresholds are difficult to determine owing to the nonlinearity between meteorological and hydrological drought, and their dynamics have not been explored. To this end, we introduce a precipitation-driven drought trigger threshold framework. This framework considers the multiscale characteristics of cumulative precipitation anomalies and incorporates the drought severity index of terrestrial water storage anomalies to characterize hydrological drought. The dynamics of trigger thresholds over time and the main drivers of these variations are further explored over China. The results show that hydrological drought is more sensitive to meteorological drought in south China, with some regions showing weak or negative correlations mainly determined by the differences between climate change and human activities. The risk of drought outbreak in the central, northeastern and southern regions of China is high, with trigger thresholds showing a dynamic decreasing trend over time (corresponding to lower cumulative precipitation anomalies), indicating weakened resistance to meteorological drought. Rising temperature is the main factor affecting dynamic changes in the trigger threshold. The drought trigger threshold framework proposed in this study is also applicable for assessments in other regions around the world. This study provides valuable insights and new approaches for understanding the mechanisms of hydrological drought formation. Furthermore, these results are expected to severe as a scientific basis for government departments to reduce water supply stress on human and natural systems and to develop adaptive management strategies.

Impact of climatic disturbances on the chemical compositions and metabolites of Salvia officinalis

Abstract Aromatic and medicinal plants in ecosystems are subject to various climatic disturbances that impact their morphological and physiological processes. Although plants have mechanisms to adapt to their climatic conditions, such as periods of drought and lack of precipitation, their metabolism is still affected. This study aimed to predict and evaluate the behavior of Salvia officinalis under climatic disturbances. Over a period of 4 years in a controlled environment, three treatments were applied to the plant: Treatment 1 with normal monthly average temperature and precipitation in the first year; Treatment 2 with a temperature increase of 5°C and a 50% reduction in water supply in the second year; and Treatment 3 with a temperature increase of 10°C and a 75% reduction in water supply in the fourth year. The results show that the percentage of primary metabolites, including nutritional values, changed with increasing temperature and decreasing precipitation. Treatment 1 had 7.13% protein, 6.21% carbohydrate, 1.35% lipid, and 4% dietary fiber, while Treatment 2 had 7.05% protein, 5.12% carbohydrate, 1.01% lipid, and 3.01% dietary fiber, and Treatment 3 had 6.86% protein, 3.02% carbohydrate, 0.52% lipid, and 2.34% dietary fiber. The mineral composition of the plant also changed with each treatment, with Mg decreasing from 10.02 to 8.55 to 0.05%, Fe decreasing from 8.18 to 8 to 7.62%, K decreasing from 5.55 to 5.05 to 4.02%, Mn decreasing from 5.54 to 5.11 to 3.48%, Ca decreasing from 4.65 to 2.75 to 1.23%, and P decreasing from 3.37 to 3.05 to 2.25%. Regarding secondary metabolites, the percentage of alkaloids, flavonoids, saponins, coumarins, tannins, and essential oil yield changed as well. Treatment 2 showed an increase in secondary metabolites, while Treatment 3 showed a decrease. Alkaloids increased from 9.56 to 13.68 to 11.3%, flavonoids increased from 7.53 to 13.48 to 10.49%, saponins increased from 5.23 to 7.44 to 6%, coumarins increased from 3.35 to 4.85 to 3.99%, tannins increased from 2.26 to 3.22 to 2.62%, and essential oil yield increased from 0.53 to 0.80 to 0.62%. Gas chromatography analysis revealed that the major compounds of the essential oils of Salvia officinalis, such as α-thujone, manool, β-caryophyllene, α-humulene, viridiflorol, 1,8-cineol, and camphor, were also modified by temperature and water stress.

A Machine Learning Framework for Predicting and Understanding the Canadian Drought Monitor

AbstractDrought is a costly natural disaster that impacts economies and ecosystems worldwide, so monitoring drought and communicating its impacts to individuals, communities, industry, and governments is important for mitigation, adaptation, and decision‐making. This research describes a novel machine learning framework to predict and understand the Canadian Drought Monitor (CDM). This fully automated approach is trained on nearly two decades of expert analysis and would assist the comprehensive monitoring of drought impacts without the continued requirement of ground support, a benefit in many data‐limited areas across the country. The framework also integrates the Shapley Additive Explanation (SHAP) variable importance metric to provide insight into drought dynamics in near real‐time, demonstrating its usefulness for understanding the value of different data sets for drought assessments and dispelling the commonly held misconception that machine learning models are not useful for inference. The results demonstrate that the model can effectively predict the CDM maps and realistically capture the evolution of drought events over time. A SHAP analysis found that the Prairie drought of 2015 was related to a strong El Niño event that reduced water supply to a region already facing long‐term water deficits, and the subsequent reduction in groundwater availability was detected by the Gravity Recovery and Climate Experiment satellite. Overall, this research shows strong potential to streamline the CDM methodology, integrate scientific insight into operations in near real‐time using SHAP values, and provide an avenue to retrospectively extend the CDM for evaluating current and future drought events in a historical context.