Plant Water Demand Research Articles

Stomatal closure as a driver of minimum leaf conductance declines at high temperature and vapor pressure deficit in Quercus.

Rising global temperatures and vapor pressure deficits (VPD) are increasing plant water demand and becoming major drivers of large-scale plant mortality. Controlling transient leaf water loss after stomatal closure (gmin) is recognized as a key trait determining how long plants survive during soil drought. Yet, substantial uncertainty remains regarding how gmin responds to elevated temperatures and VPD and the underlying mechanisms. We measured gmin in 24 Quercus species from temperate and Mediterranean climates to determine if gmin was sensitive to a coupled temperature and VPD increase. We also explored mechanistic links to phenology, climate, evolutionary history, and leaf anatomy. We found that gmin in all species exhibited a non-linear negative temperature and VPD dependence. At 25°C (VPD = 2.2 kPa), gmin varied from 1.19 to 8.09 mmol m-2 s-1 across species but converged to 0.57 ± 0.06 mmol m-2 s-1 at 45°C (VPD = 6.6 kPa). In a subset of species, the effect of temperature and VPD on gmin was reversible and linked to the degree of stomatal closure, which was greater at 45°C than at 25°C. Our results show that gmin is dependent on temperature and VPD, is highly conserved in Quercus species, and is linked to leaf anatomy and stomatal behavior.

The Optimal Drought Hardening Intensity and Salinity Level Combination for Tomato (Solanum lycopersicum L.) Cultivation under High-Yield, High-Quality and Water-Saving Multi-Objective Demands.

The extreme weather and the deteriorating water environment have exacerbated the crisis of freshwater resource insufficiency. Many studies have shown that salty water could replace freshwater to partly meet the water demand of plants. To study the effects of early-stage drought hardening and late-stage salt stress on tomatoes (Solanum lycopersicum L.), we conducted a 2-year pot experiment. Based on the multi-objective demands of high yield, high quality, and water saving, yield indicators, quality indicators, and a water-saving indicator were selected as evaluation indicators. Three irrigation levels (W1: 85% field capacity (FC), W2: 70% FC, W3: 55% FC) and three salinity levels (S2: 2 g/L, S4: 4 g/L, S6: 6 g/L) were set as nine treatments. In addition, a control treatment (CK: W1, 0 g/L) was added. Each treatment was evaluated and scored by principal component analysis. The results for 2022 and 2023 found the highest scores for CK, W2S2, W3S2 and CK, W2S4, W2S2, respectively. Based on response surface methodology, we constructed composite models of multi-objective demands, whose results indicated that 66-72% FC and 2 g/L salinity were considered the appropriate water-salt combinations for practical production. This paper will be beneficial for maintaining high yield and high quality in tomato production using salty water irrigation.

Global and regional hydrological impacts of global forest expansion

Abstract. Large-scale reforestation, afforestation, and forest restoration schemes have gained global support as climate change mitigation strategies due to their significant carbon dioxide removal (CDR) potential. However, there has been limited research into the unintended consequences of forestation from a biophysical perspective. In the Community Earth System Model version 2 (CESM2), we apply a global forestation scenario, within a Paris Agreement-compatible warming scenario, to investigate the land surface and hydroclimate response. Compared to a control scenario where land use is fixed to present-day levels, the forestation scenario is up to 2 °C cooler at low latitudes by 2100, driven by a 10 % increase in evaporative cooling in forested areas. However, afforested areas where grassland or shrubland are replaced lead to a doubling of plant water demand in some tropical regions, causing significant decreases in soil moisture (∼ 5 % globally, 5 %–10 % regionally) and water availability (∼ 10 % globally, 10 %–15 % regionally) in regions with increased forest cover. While there are some increases in low cloud and seasonal precipitation over the expanded tropical forests, with enhanced negative cloud radiative forcing, the impacts on large-scale precipitation and atmospheric circulation are limited. This contrasts with the precipitation response to simulated large-scale deforestation found in previous studies. The forestation scenario demonstrates local cooling benefits without major disruption to global hydrodynamics beyond those already projected to result from climate change, in addition to the cooling associated with CDR. However, the water demands of extensive forestation, especially afforestation, have implications for its viability, given the uncertainty in future precipitation changes.

Assessment of the effect of climate change on the yields and water footprint of crops in arid area

ABSTRACT Investigating the actual amount of water used by agricultural crop yield is very important. This research evaluates the impact of climate change on water demand, yields, and green and blue water footprint of barberry and jujube plants under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. The results show that the amount of precipitation in the future under three scenarios varies from −13.08 to 5.13 mm during the future period. It shows maximum temperature changes from 1.07 to 1.25 °C and minimum temperature changes from 1.15 to 1.54 °C. The maximum and minimum temperatures under all three scenarios have an increasing trend compared to the base period. The results show that the values of water requirement, blue water footprint, green water footprint, total water footprint, and finally the relative values of both crop yields increase in all three scenarios in the future period (2022–2038) compared to the base period (2021–2005). Furthermore, according to the three proposed scenarios, the water footprint of the barberry crop in the future is estimated to be 98.74% blue water and 1.24% green water. The jujube crop's water footprint consists of 98.81% blue water and 1.20% green water.

Optimization model of water-fertilizer coupling in garden plant cultivation based on big data analysis

This study is dedicated to the development of an Internet of Things (IoT)-based water-fertilizer coupling optimization model for landscape plant cultivation using big data analysis technology to solve the problems of resource wastage and unstable plant growth quality in traditional water-fertilizer management. Through real-time monitoring of soil, climate and plant physiological indicators, combined with autoregressive moving average model and other prediction means, to achieve accurate prediction of plant water and fertilizer demand and dynamic coupling management. The model is able to customize personalized water and fertilizer supply strategies according to plant species, growth stages and environmental conditions, thus enhancing the efficiency of water and fertilizer utilization, promoting healthy plant growth, and enhancing the effect of urban greening.

Deficit Irrigation Effects on Cotton Growth Cycle and Preliminary Optimization of Irrigation Strategies in Arid Environment.

With the changing global climate, drought stress will pose a considerable challenge to the sustainable development of agriculture in arid regions. The objective of this study was to explore the resistance and water demand of cotton plants to water stress during the flowering and boll setting stage. The experimental plot was in Huaxing Farm of Changji city. The plots were irrigated, respectively, at 100% (as the control), 90%, 85% and 80% of the general irrigation amount in the local area. The relationship between the various measured indexes and final yield under different deficit irrigation (DI) treatments was studied. The results showed that deficit irrigation impacted the growth and development processes of cotton during the flowering and boll setting stage. There was a high negative correlation (R2 > 0.95) between the maximum leaf area index and yield. Similarly, there was a high correlation between malondialdehyde content and yield. Meanwhile, 90% of the local cotton irrigation contributed to water saving and even increasing cotton yield. Furthermore, based on the results, the study made an initial optimization to the local irrigation scheme by utilizing the DSSAT model. It was found that changing the irrigation interval to 12 days during the stage could further enhance cotton yield and conserve resources.

Mitigating drought mortality by incorporating topography into variable forest thinning strategies

Abstract Drought-induced productivity reductions and tree mortality have been increasing in recent decades in forests around the globe. Developing adaptation strategies hinges on an adequate understanding of the mechanisms governing the drought vulnerability of forest stands. Prescribed reduction in stand density has been used as a management tool to reduce water stress and wildfire risk, but the processes that modulate fine-scale variations in plant water supply and water demand are largely missing in ecosystem models. We used an ecohydrological model that couples plant hydraulics with groundwater hydrology to examine how within-stand variations in tree spatial arrangements and topography might mitigate forest vulnerability to drought at individual-tree and stand scales. Our results demonstrated thinning generally ameliorated plant hydraulic stress and improved carbon and water fluxes of the remaining trees, although the effectiveness varied by climate and topography. Variable thinning that adjusted thinning intensity based on topography-mediated water availability achieved higher stand productivity and lower mortality risk, compared to evenly-spaced thinning at comparable intensities. The results from numerical experiments provided mechanistic evidence that topography mediates the effectiveness of thinning and highlighted the need for an explicit consideration of within-stand heterogeneity in trees and abiotic environments when designing forest thinning to mitigate drought impacts.

Variable Responses of Plant Water Use to Soil Water Availability in Robinia Pseudoacacia under Prolonged Drought

Abstract Large-scale afforestation on the Loess Plateau has been subjected to more frequent and severe drought due to climate change. However, there is a lack of definite evidence elucidating the adjustments in water supply-demand relationships under prolonged drought. In this study, we investigated the responses of plant characteristics related to plant water supply and demand in 2-year-old Robinia pseudoacacia seedlings to soil water availability (SWA). We systemically analyzed the acclimation of plant water use to prolonged drought. A logistic function was used to fit relationships between normalized net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), soil-root hydraulic conductance (Ksr), root-leaf hydraulic conductance (Krl), and whole plant hydraulic conductance (Kplant) with SWA. The results revealed significant difference in responses of these parameters to SWA (p < .001). The sensitivities of Pn, Tr, and Gs to drought increased from 60-day to 120-day drought, contributing to reduce water consumption. Meanwhile, the relative stable sensitivities of hydraulic conductance (Ksr, Ksr, and Kplant) promoted a consistent water supply at different ecological levels. Additionally, coordination between Gs with hydraulic conductance helped maintain normal physiological activities under drought. These findings enhance our understanding of adjustments in plant water use in response to prolonged drought in Robinia pseudoacacia. Study Implications: Our findings have implications for better understanding the acclimation of Robinia pseudoacacia to prolonged drought. First, our results suggest decreased water demand (water consumption) by Robinia pseudoacacia under prolonged drought because the sensitivities of net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) to drought increased from 60-day to 120-day drought treatments. Second, our study indicates a relative stable water supply (soil-root, root-leaf, and whole plant hydraulic conductance; Ksr, Krl, and Kplant) of Robinia pseudoacacia at different ecological levels under prolonged drought. Finally, our research has implications for the coordination of stomatal and hydraulic regulation.

Soil Water Dynamic and its Response to Rainfalls in an Apple Orchard of the Loess Plateau, China: Implication for Irrigation Management

Soil water is the main water source for plants, which is replenished by rainfall in the water-limited agricultural systems. Quantifying temporal dynamics of water soil deficit and its replenishment by rainfall can evaluate whether soil water meet the water demand for plants. This would provide accurate guide for when and how the irrigation practices conducted. However, this topic has not been deeply elucidated. In this study, soil water content at varied soil depths and precipitation were continuously monitored during two growing seasons in an apple orchard in the Loess Plateau of China. Soil water storage, soil water deficit and replenishment were also quantified. The results showed that soil water content varied temporally due to the impacts of rainfalls. Soil water storage at 0 ~ 200 cm depth ranged from 272.5 mm to 355.6 mm and the degree of soil water deficit ranged from 0.34 to 0.53 correspondingly. Meanwhile, replenishment of soil water by rainfall was 13.00% in 2017 and 9.78% in 2018, respectively. The qualitative relationship between monthly rainfalls and replenishment indicated that soil water was replenished by rainwater only at soil layers shallower than 160 cm. From the temporal dynamics of soil water content and deficit conditions, soil water could meet the water demand at the fruit expanding stage of apple trees. Irrigation measures should be taken to reduce the soil drought stress at this stage. This study provided an effective hydrological basis to improve the irrigation management of orchards and the efficiency of water resource.

The role of changing land use and irrigation scheduling in groundwater depletion mitigation in a humid region

Many agricultural production regions in the world have been experiencing groundwater resource depletion, which threatens water and food security if mitigation practices are not developed and implemented. To understand how changing land use and irrigation schedule impact groundwater, a coupled SWAT-MODFLOW model was applied to determine groundwater depletion mitigation strategy in a humid region, the Big Sunflower River Watershed (BSRW) in Mississippi, USA. It was found that converting grasslands to forests contributed to reducing groundwater declining. Simulated results indicated that the watershed lost 749, 586, and 381 mm yr−1 of water through surface runoff in the wet, normal and dry years, respectively. The amount of groundwater that moved into the vadose zone to help satisfy crop water demand ranged from 700 to 750 mm yr−1. Precipitation increased the groundwater recharge during the rainy season from fall to spring. Annual recharge rate was only 34–50 mm. Groundwater level dropped 0.2–0.5 m in crop irrigation seasons (May to August). Land use dataset showed 81 % of the area is cropland, with soybean, corn, rice, and cotton accounting for 64 % of the total cropland area in BSRW. The planted area of corn and soybean significantly increased while the area of cotton area was tremendously reduced. Corn, soybean, and rice consumed approximately 96 % of the total amount of groundwater irrigation. This study indicated that irrigation scheduling based on plant water demand could save 47 % of groundwater currently used by conventional irrigation. The improved irrigation schedule could reduce groundwater decline by 0.01–2.05 m across the watershed, and mitigate the declines by 1.35–2.05 m in the depression cone in the central east part of the watershed. The results can assist with planning land and water use and developing sustainable groundwater management practices focused on locations of high groundwater withdrawals in other regions around the world.

Synergistic cotreatment of cooling tower blowdown and produced waters: Modeling strategies for a comprehensive wastewater treatment simulation

Cooling tower blowdown from thermoelectric power plants and produced water from hydraulic fracturing may soften when mixed due to the complimentary chemistry of the two wastewaters. The potential benefit of low effort softening warrants the investigation of a cotreatment process concerning these industrial wastewaters. The synergy is expected to lessen chemical demand for softening and further enable sustainable practices such as designing for a zero-liquid discharge (ZLD) process. The treatment process may then provide a treated effluent suitable for use as blowdown makeup. In this study, the feasibility and effectiveness of a cotreatment train is explored through simulation of chemical softening, filtration, reverse osmosis (RO), multi-effect distillation (MED), and electrolysis unit operations within a comprehensive process model. Innovative modeling strategies are necessary to result in a meaningful process model when considering the significant complexity of the water chemistry for this treatment train. Through the methodology described in this work, a feasible process design is presented as a base case for treatment of experimentally characterized blowdown and produced water samples obtained in the northern Appalachian region. Thereafter, the base case also establishes a platform for more detailed process analyses of different scenarios in future work. Detailed descriptions of modeling methodologies, process design decisions, and simulation results are provided as a perspective on comprehensive modeling of multi-technology treatment trains for complex feedwaters. With the results of the cotreatment simulation, it is determined that the total water recovery of the process may serve to completely makeup the blowdown rate and partially make up the evaporative losses of a theoretical thermoelectric plant's water demand. This complete recovery is evaluated to require 18,343.531 kW of a chemical energy equivalent, 1184.971 kW of electricity, and 68,126.291MJh−1 of power plant steam to result in 408.532m3h−1 of treated water effluent at a quality of approximately 0.135gL−1 total dissolved solids for the base case design.

Domestic Effluent Treated for the Cultivation of Anthurium (Anthurium Andraeanum Lind.)

Purpose: The objective of this research was to evaluate the growth and production of anthurium (Anthurium andraeanum Lind.) irrigated with dilutions of treated domestic effluent (EDT), aiming to reduce the use of water and recycle the nutrients present in the effluent. Theoretical framework: Faced with the scarcity and irregularity of rainfall in the Recôncavo da Bahia, it emphasizes the need and urgency in the search for alternative sources of water for irrigation, such as wastewater, with the potential to supply the water and nutritional demands of plants, especially those with less restriction, like ornamentals. Method/design/approach: The experimental design was completely randomized, using five dilutions of EDT (0, 25, 50, 75 and 100%) in drinking water, with four replications. Plant height, number of leaves, leaf area, number of flowers and shoot dry mass were evaluated. Results and conclusion: Plants irrigated with EDT dilutions and fertilized with 50% of the recommended nitrogen and potassium showed growth and production similar to plants irrigated with water supply and fertilized with 100% of the recommended mineral fertilizer, which allows recommending the use of EDT for irrigation of anthurium with 50% reduction of mineral fertilization. Research implications: The results obtained reinforce the importance of taking advantage of the nutrient content present in the effluent, with the possibility of partially replacing mineral fertilizers, favoring savings in quality water and mineral fertilizers. Originality/value: Savings of good quality water and mineral fertilizers, in addition to providing a safe destination for the effluent.

A nature-based solution to reduce soil water vertical leakage in arid sandy land

Quick water seepage in sandy soils results in a serious restriction for ecological restoration, becoming a worldwide urgent research issue in arid areas. Search for practical solutions are focused on reserving the limited rainfall into topsoil layer to meet plant water demand. Based on fieldwork, this study evaluates the blocking effects of Pisha sandstone on soil water leakage, by inserting sandstone layers in the different soil depths (10–15 cm, 20–25 cm, 30–35 cm), which act as isolation layers within the sandy soil. Results showed that the inserted Pisha sandstone layers significantly decreased the soil water infiltration rates at the different stages and cumulative infiltration. The inserted sandstone layer at the depth of 10–15 cm presented the highest permeability resistance, and its initial infiltration rate, stable infiltration rate and average infiltration rate decreased by 102.42 mm h−1, 144.30 mm h−1 and 132.79 mm h−1, respectively. Meanwhile, the soil water content in the 5–10, 20–25, and 30–35 cm soil layers increased by 2.17%, 2.20%, and 1.37%, respectively, due to the inserted Pisha sandstones. This experimental study proves that the insertion of Pisha sandstones effectively hinders the downward penetration of soil water in sandy soil. These findings provide a new alternative for an effective solution of the fast water leakage problem of sandy land.

Restoration of Grassland Improves Soil Infiltration Capacity in Water-Wind Erosion Crisscross Region of China’s Loess Plateau

Soil water infiltration is a key mechanism for meeting plant water demand and groundwater recharge cycles; however, unreasonable land use practices cause reduced infiltration capacity and greater soil erosion. To date, differences in the properties of aeolian sandy soil and Pisha sandstone soil under different utilization methods as well as in soil properties, aggregates, and infiltration among kind of soil types, remain poorly understood. In this work, 54 soil samples of cropland and grassland were selected to identify the unique characteristics of soil infiltration processes under transition from cropland to grassland and contributions of soil properties to soil infiltrability in the Loess Plateau of China. The results showed that converting cropland to grassland could enhance the stable infiltration capacity of shallow soils of aeolian sandy soil and loess soil by 43.6% and 35.7%, respectively. Compared with cropland, the root properties and soil aggregate formation of the three soil types increased during grassland use, with the largest increase in soil organic matter content (32.14%) and total porosities (6.4%). As determined by the ring knife method, the saturated infiltration capacity of Pisha sandstone soil was significantly lower than in aeolian sandy soil and loess soil (p < 0.5). Moreover, its saturated infiltration capacity of cropland was better than grassland. Spearman’s correlation analysis and structural equation modeling (SEM) revealed that soil infiltration capacity appeared to be the most influenced by soil organic matter, and aggregate structure. These results highlight that fifteen years of returning cropland to grassland is not enough to affect the infiltration ability of deep soil (≥20 cm), and this improvement requires longer term maintenance.

Reduction of rainfall infiltration in soil slope using a controllable biocementation method

Reasonable control of rainwater infiltration rate can ensure that soil slope will not fail due to rapid infiltration of rainwater in heavy rainfall, and at the same time, more rainwater can be infiltrated in light rainfall to meet the water demand of animals and plants. In this study, based on microbial-induced calcium carbonate precipitation (MICP) technique, a controllable bio-method for rainfall infiltration of soil slope was proposed. To have a comprehensive understanding the relationship among the rainwater infiltration control capacity, biocement treated soil permeability, slope angle and rainfall intensity, a series of physical modelling experiments of rainfall diversion on slopes with three types of soils and three slope angles were carried out in the presence of various rainfall intensities. Experimental results indicated that the proposed bio-method had the ability of controlling rainwater infiltration in term of varying rounds of biocement spraying treatment. In general, it was found that the rainwater infiltration decreases with the increase in slope angle and rainfall intensity. In the worst case of smallest slope angle (15°) and lightest rainfall intensity (n = 50 mm/h), more than 82.6%, 92.2% and 84.4% of rainwater were prevented from infiltration into the MICP treated natural sand, fine sand and medium sand, respectively, while the untreated soils were not able to prevent the rainwater infiltration at all. The corresponding maximum local uniaxial compressive strength for the MICP treated natural sand, fine sand and medium sand, respectively, were found to be 2.3 MPa, 2.0 MPa, 2.6 MPa, whereas the flexural stresses were 0.46 MPa, 0.33 MPa, 0.67 MPa, which could resist rainfall droplet impact force. Overall, the proposed bio-method showed good rainwater infiltration control capacity and high bearing strength against the impact of heavy rainfalls, suggesting a good potential to mitigate the rainfall-induced landslides.

Accurate estimates of land surface energy fluxes and irrigation requirements from UAV-based thermal and multispectral sensors

The two-source energy balance model estimates canopy transpiration (Tr) and soil evaporation (E) traditionally from satellite partitions of remotely sensed land surface temperature (LST) and the Priestley-Taylor equation (TSEB-PT) at seasonal time with limited accuracy. The high spatial–temporal resolution spectral data collected by unmanned aerial vehicles (UAVs) provide valuable opportunity to estimate Tr and E precisely, improve the understanding of the seasonal and the diurnal cycle of evapotranspiration (ET), and timely detect agricultural drought. The UAV data vary in spatial resolution and the uncertainty imposed on the TSEB-PT outcome has thus far not being considered. To address these challenges and prospects, a new energy flux modelling framework based on TSEB-PT for high spatial resolution thermal and multispectral UAV data is proposed in this paper. Diurnal variations of LST in agricultural fields were recorded with a thermal infrared camera installed on an UAV during drought in 2018 and 2019. Observing potato as a test crop, LST, plant biophysical parameters derived from corresponding UAV multispectral data, and meteorological forcing variables were employed as input variables to TSEB-PT. All analyses were conducted at different pixelation of the UAV data to quantify the effect of spatial resolution on the performance. The 1 m spatial resolution produced the highest correlation between Tr modelled by TSEB-PT and measured by sap flow sensors (R2 = 0.80), which was comparable to the 0.06, 0.1, 0.5 and 2 m pixel sizes (R2 = 0.76–0.78) and markedly higher than the lower resolutions of 2 to 24 m (R2 = 0.30–0.72). Modelled Tr was highly and significantly correlated with measured leaf water potential (R2 = 0.81) and stomatal conductance (R2 = 0.74). The computed irrigation requirements (IRs) reflected the field irrigation treatments, ET and conventional irrigation practices in the area with high accuracy. It was also found that using a net primary production model with explicit representation of temperature influences made it possible to distinguish effects of drought vis-a-vis heat stress on crop productivity and water use efficiency. The results showed excellent model performance for retrieving Tr and ET dynamics under drought stress and proved that the proposed remote sensing based TSEB-PT framework at UAV scale is a promising tool for the investigation of plant drought stress and water demand; this is particularly relevant for local and regional irrigations scheduling.

The Relationship between Shadow Analysis and Sustainability in University Campuses The Example of Selcuk University Alaeddin Keykubat Campus

Today’s cities show an unplanned and rapid development in direct proportion to the development of technology. As a result of rapid and unplanned development, the natural silhouette of the cities has deteriorated and the proportion of reinforced concrete structures has increased day by day. For these reasons, putting green areas in the second plan causes some ecological problems for the city. The existence and sustainability of green areas are among the most important approaches that can reduce these problems. If we look at the concept of sustainability and its derivatives, the university campuses in the city give the appearance of a small city model and the green campus, sustainable campus, eco-campus, etc. that have emerged in recent years. Due to these concepts, in this study, “Selçuk University Alaeddin Keykubat Campus”, located within the provincial borders of Konya, was chosen as the study area. The aim of the study was to determine the shadow lengths created by the buildings in the “Selçuk University Alaeddin Keykubat Campus” on the green areas and the new building or open green areas, and according to the light, shade and water requirements of the plants in the open green areas in line with the obtained data. Its contribution to ecological sustainability and green campus studies has been evaluated by revealing whether it is placed in areas with 2D (2D)-3D (3D) software and with different analysis techniques. In the light of the data obtained; It is seen that the shadow periods created by the buildings in Selcuk University Alaeddin Keykubat Campus are higher in December and February, and the shadow durations are less in other months. The shadow periods of the building’s immediate surroundings are longer than the open areas. It has been determined that the species in the vicinity of the building are adversely affected by this situation. Plants are exposed to the sun, especially in the summer months, so the water demand and consumption of plants increases.

No-tillage with straw mulching boosts wheat grain yield by improving the eco-physiological characteristics in arid regions

Straw returning to the field is a technical measure of crop production widely adopted in arid areas. It is unknown whether crop yield can be further increased by improving the eco-physiological characteristics when straw returning is applied in the crop production system. So, a three-year field experiment was conducted with various straw returning treatments for wheat production: (i) no-tillage with straw mulching (NTSM), (ii) no-tillage with straw standing (NTSS), (iii) conventional tillage with straw incorporation (CTS), and (iv) conventional tillage with no straw returning (CT, control). The eco-physiological and yield formation indicators were investigated to provide the basis for selecting the appropriate straw returning method to increase wheat yield and clarifying its regulation mechanism on eco-physiology. The results showed that NTSM and NTSS treatments had better regulation of eco-physiological characteristics and had a higher yield increase than CTS and CT. Meanwhile, NTSM had a relatively higher yield than NTSS through better regulation of eco-physiological characteristics. Compared to CT, the leaf area index of NTSM was decreased by 6.1–7.6% before the Feekes 10.0 stage of wheat, but that of NTSM was increased by 38.9–45.1% after the Feekes 10.0 stage. NTSM effectively regulated the dynamics of the photosynthetic source of green leaves during the wheat growth period. NTSM improved net photosynthetic rate by 10.2–21.4% and 11.0–21.6%, raised transpiration rate by 4.4–10.0% and 5.3–6.1%, increased leaf water use efficiency by 5.6–10.4% and 5.4–14.6%, at Feekes 11.0 and 11.2 stages of wheat, compared to CT, respectively. NTSM had higher leaf water potential (LWP) by 7.5–12.0% and soil water potential (SWP) by 8.9–24.0% from Feekes 10.3 to 11.2 stages of wheat than CT. Meanwhile, the absolute value of difference on LWP and SWP with NTSM was less than that with CT, indicating that NTSM was conducive to holding the stability of water demand for wheat plants and water supply of soil at arid conditions. Thus, NTSM had a greater grain yield of wheat by 18.6–27.3% than CT, and the high yield was attributed to the synchronous increase and cooperative development of ear number, grain number per ear, and 1 000-grain weight. NTSM had a positive effect on regulating the eco-physiological characteristics and can be recommended to enhance wheat grain yield in arid conditions.

Determining the Beginning of Potato Tuberization Period Using Plant Height Detected by Drone for Irrigation Purposes

Insolation and precipitation instability associated with climate change affects plant development patterns and water demand. The potato root system and soil properties lead to water vulnerability, impacting crop yield. Regarding potato physiology, plants stop growing when the root depth stabilizes, and then the tuberization period begins. Since this moment, water supply is required. Consequently, an approach based on plant physiology may enable farmers to detect the beginning of the irrigation period precisely. Remote sensing is a fast and precise method for obtaining surface information using non-invasive data collection. The database comprises root depth (RD) and plant height (H) data collected during 2019, 2020, and 2021. This research aims to develop a dynamic approach based on remote sensing and crop physiology to accurately determine the beginning of the tuberization period, called here the irrigation critical point (ICP). The results indicate a high correlation between RD and H (>0.85) which is independent of in-field soil and relief variations > 0.95). Further, plant growth rate corroborates the correlation results with decreasing patterns in time (R2 > 0.80), independent of environmental variations. In short, it was possible to determine the ICP based on the crop growth dynamics, independently of climate variations, field placement, or irrigation system.

Bark Beetle Effects on Fire Regimes Depend on Underlying Fuel Modifications in Semiarid Systems

AbstractAlthough natural disturbances such as wildfire, extreme weather events, and insect outbreaks play a key role in structuring ecosystems and watersheds worldwide, climate change has intensified many disturbance regimes, which can have compounding negative effects on ecosystem processes and services. Recent studies have highlighted the need to understand whether wildfire increases or decreases after large‐scale beetle outbreaks. However, observational studies have produced mixed results. To address this, we applied a coupled ecohydrologic‐fire regime‐beetle effects model (RHESSys‐WMFire‐Beetle) in a semiarid watershed in the western US. We found that in the red phase (0–5 years post‐outbreak), surface fire extent, burn probability, and surface and crown fire severity all decreased. In the gray phase (6–15 years post‐outbreak), both surface fire extent and surface and crown fire severity increased with increasing mortality. However, fire probability reached a plateau during high mortality levels (>50% in terms of carbon removed). In the old phase (one to several decades post‐outbreak), fire extent and severity still increased in all mortality levels. However, fire probability increased during low to medium mortality (≤50%) but decreased during high mortality levels (>50%). Wildfire responses also depended on the fire regime. In fuel‐limited locations, fire probability increased with increasing fuel loads, whereas in fuel‐abundant (flammability‐limited) systems, fire probability decreased due to decreases in fuel aridity from reduced plant water demand. This modeling framework can improve our understanding of the mechanisms driving wildfire responses and aid managers in predicting when and where fire hazards will increase.