Moderate Drought Research Articles

Multi-omics analysis reveals the transcription factor AtuMYB306 improves drought tolerance by regulating flavonoid metabolism in Chinese chive (Allium tuberosum Rottler)

Drought is one of the most detrimental stresses that severely constrains plant growth and productivity. Although Chinese chive (Allium tuberosum Rottler) is a vegetable species that is cultivated and consumed worldwide, few studies have investigated how this species responds to drought. In this study, we conducted transcriptomics, metabolomics, and proteomics analyses on chive seedlings exposed to different water availability conditions (mild drought, moderate drought, severe drought, and re-watering) and found that the accumulation of flavonoids in chive leaves was substantially altered under drought stress. Gene co-expression regulatory network analysis, conducted by integrating transcriptome and metabolome data, revealed a chive R2R3-MYB transcription factor, AtuMYB306, as a central regulator of flavonoid synthesis. Overexpression of AtuMYB306 significantly improved osmotic stress tolerance and enhanced flavonoid content in Arabidopsis. We further demonstrated that AtuMYB306 directly binds to the promoters of three flavonoid biosynthetic genes (Atu4CL, AtuF3H, and AtuF3’H) and activates their expression. These results suggest that AtuMYB306 improves drought tolerance in Chinese chive by enhancing flavonoid biosynthesis to scavenge reactive oxygen species (ROS) generated under water-deficit conditions. Thus, our findings provide evidence that AtuMYB306 playing a pivotal role in improving drought resistance in Chinese chive.

Miscanthus sinensis 'Variegatus' Variegated Japanese Silver Grass

This document provides an overview of Miscanthus sinensis ‘Variegatus’, commonly known as variegated Japanese silver grass or maiden grass. It describes the plant’s distinctive features, including its variegated leaves, pink flowers, and upright growth habit. The document highlights its uses in landscaping, such as mass planting, borders, and as an accent plant. It also covers the plant’s adaptability to various soil types, its moderate drought tolerance, and its invasive potential. Additionally, it mentions other cultivars of Miscanthus sinensis and provides guidance on planting and maintenance. Original publication date October 1999.

Climate change induced heat and drought stress hamper climate change mitigation in German cereal production

ContextAgricultural production and climate change strongly influence each other and there are significant efforts to minimize negative impacts in both directions. In particular, breeding progress has succeeded in reducing the carbon footprint (CFP) of cereals over time. However, there is widespread certainty that climate change-related weather extremes have led to stagnation of cereal yields in many global production regions. Research questionWe assume that climate change-related yield stagnation is also evident in variety trials in Germany, which has to date only been shown for on-farm yields. Furthermore, we expect that the stagnation in yields also leads to a stagnation in the downward trend of CFP, and that heat and drought stress in particular increase the CFP of cereals. In addition, we hypothesize that the site-specific soil quality largely determines stress induced increases in CFP. MethodsWe conduct a partial life cycle assessment (LCA) with German variety trial data from 1993 to 2021 and determine the greenhouse gas emissions per unit of land (GHGL), as well as the CFP of winter wheat, winter rye, and winter barley. Further, we evaluate the time trends of yield, GHGL, and CFP using linear and quadratic plateau models. In addition, we calculate spatio-dynamic weather indices (WIs) for moderate, severe and extreme heat and drought stress. Using mixed models, we estimate the explanatory power and effect size of heat and drought WIs on the CFP. Finally, we present the spatial differences of heat and drought on the CFP at different soil qualities. ResultsWe show yield plateaus in all crops and stagnating GHGL trends, resulting in a stagnation of the downward trend of CFP, especially for rye and barley. We highlight that heat and drought increase the CFP of all crops. However, the impact of heat and drought on the CFP varies greatly with soil quality across all crops. ConclusionsWe conclude that climate change-induced weather extremes are major challenges not only for cereal production and food security but also for climate change mitigation in the agricultural sector, highlighting the importance of high-yield locations, alongside variety selection and resource-efficient management, for climate change mitigation. SignificanceThis study is the first that proves significant yield stagnation in German variety trials. Moreover, this study is the first to analyze the impact of heat and drought stress on cereal CFP, with novel results that proof that climate adaptation will become a crucial aspect of climate change mitigation in field crops.

Modeling and Application of Drought Monitoring with Adaptive Spatial Heterogeneity Using Eco–Geographic Zoning: A Case Study of Drought Monitoring in Yunnan Province, China

Drought, characterized by frequent occurrences, an extended duration, and a wide range of destruction, has become one of the natural disasters posing a significant threat to both socioeconomic progress and agricultural livelihoods. Large-scale geographical environments often exhibit obvious spatial heterogeneity, leading to significant spatial differences in drought’s development and outcomes. However, traditional drought monitoring models have not taken into account the impact of regional spatial heterogeneity on drought, resulting in evaluation results that do not match the actual situation. In response to the above-mentioned issues, this study proposes the establishment of ecological–geographic zoning to adapt to the spatially stratified heterogeneous characteristics of large-scale drought monitoring. First, based on the principles of ecological and geographical zoning, an appropriate index system was selected to carry out ecological and geographical zoning for Yunnan Province. Second, based on the zoning results and using data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) and the Tropical Rainfall Measuring Mission (TRMM) 3B43, the vegetation condition index (VCI), the temperature condition index (TCI), the precipitation condition index (TRCI), and three topographic factors including the digital elevation model (DEM), slope (SLOPE), and aspect (ASPECT) were selected as model parameters. Multiple linear regression models were then used to establish integrated drought monitoring frameworks at different eco–geographical zoning scales. Finally, the standardized precipitation evapotranspiration index (SPEI) was used to evaluate the monitoring effects of the model, and the spatiotemporal variation patterns and characteristics of winter and spring droughts in Yunnan Province from 2008–2019 were further analyzed. The results show that (1) compared to the traditional non-zonal models, the drought monitoring model constructed based on ecological–geographic zoning has a higher correlation and greater accuracy with the SPEI and (2) Yunnan Province experiences periodic and seasonal drought patterns, with spring being the peak period of drought occurrence and moderate drought and light drought being the main types of drought in Yunnan Province. Therefore, we believe that ecological–geographic zoning can better adapt to geographical spatial heterogeneity characteristics, and the zonal drought monitoring model constructed can more effectively identify the actual occurrence of drought in large regions. This research finding can provide reference for the formulation of drought response policies in large-scale regions.

Spatiotemporal Variation Patterns of Drought in Liaoning Province, China, Based on Copula Theory

Liaoning Province, a crucial agricultural region in Northeast China, has endured frequent drought disasters in recent years, significantly affecting both agricultural production and the ecological environment. Conducting drought research is of paramount importance for formulating scientific drought monitoring and prevention strategies, ensuring agricultural production and ecological safety. This study developed a Comprehensive Joint Drought Index (CJDI) using the empirical Copula function to systematically analyze drought events in Liaoning Province from 1981 to 2020. Through the application of MK trend tests, Morlet wavelet analysis, and run theory, the spatiotemporal variation patterns and recurrence characteristics of drought in Liaoning Province were thoroughly investigated. The results show that, compared to the three classic drought indices, Standardized Precipitation Index (SPI), Evaporative Demand Drought Index (EDDI), and Standardized Precipitation Evapotranspiration Index (SPEI), CJDI has the highest accuracy in monitoring actual drought events. From 1981 to 2020, drought intensity in all regions of Liaoning Province (east, west, south, and north) exhibited an upward trend, with the western region experiencing the most significant increase, as evidenced by an MK test Z-value of −4.53. Drought events in Liaoning Province show clear seasonality, with the most significant periodic fluctuations in spring (main cycles of 5–20 years, longer cycles of 40–57 years), while the frequency and variability of drought events in autumn and winter are lower. Mild droughts frequently occur in Liaoning Province, with joint and co-occurrence recurrence periods ranging from 1.0 to 1.8 years. Moderate droughts have shorter joint recurrence periods in the eastern region (1.2–1.4 years) and longer in the western and southern regions (1.4–2.2 years), with the longest co-occurrence recurrence period in the southern region (3.0–4.0 years). Severe and extreme droughts are less frequent in Liaoning Province. This study provides a scientific foundation for drought monitoring and prevention in Liaoning Province and serves as a valuable reference for developing agricultural production strategies to adapt to climate change.

The Effects of Bio-Fertilizer by Arbuscular Mycorrhizal Fungi and Phosphate Solubilizing Bacteria on the Growth and Productivity of Barley under Deficit of Water Irrigation Conditions

Bio-fertilizers are the most important and effective method used to reduce the quantities of chemical fertilizers consumed and reduce dependence on them in agricultural production to avoid their harmful effects on the environment and public health as well as reduce the cost of agricultural production in light of increasing pollution and under adverse conditions for production and climate change. A bio-fertilizer depends primarily on the use of beneficial microorganisms such as arbuscular mycorrhizal fungi (AMF) to improve the uptake of nutrients, improve plant growth, productivity, and grain yield. Crop production faces many challenges, and drought is one of the majority of the significant factors limiting crop production worldwide, especially in semi-arid regions. The objective of this study was to evaluate the effects of AMF and phosphate solubilizing bacteria (PSB), plus three rates of the recommended dose of phosphorus (RDP) fertilizer on yield, yield components, and nutrients uptake, in addition to evaluating the beneficial effects of these combinations to develop Phosphorus (P) management under three levels of irrigation water, i.e., three irrigations (normal or well-watered), two irrigations (moderate drought), and one irrigation (severe drought) on barley (Hordeum vulgare L.). The results showed that the treatment with AMF bio-fertilizer yielded the highest values of plant height, spike length, spike weight, number of grains/spike, 1000-grain weight, grain yield, straw yield, biological yield, and harvest index. Moreover, the grain and straw uptake of nitrogen (N), P, and potassium (K) (kg ha−1) in the two seasons under the three levels of irrigation, respectively, were superior followed by the inoculation by PSB. While the treatment without bio-fertilizer yielded the lowest values of these traits of barley, the treatment with bio-fertilizer yielded the increased percentage of the grain yield by 17.27%, 17.33% with applying AMF, and 10.31%, 10.40% with treatment by PSB. Treatment with AMF or PSB (Phosphorien), plus rates of phosphorus fertilizer under conditions of irrigation water shortage, whether irrigation was performed once or twice, led to an increase in grain yield and other characteristics compared to the same fertilization rates without inoculation. The results of this study showed that the use of bio-fertilizers led to an increase in plant tolerance to drought stress, and this was demonstrated by an increase in various traits with the use of treatments that include bio-fertilizers. Therefore, it is suggested to inoculate the seeds with AMF or PSB plus adding phosphate fertilizers at the recommended dose under drought conditions.

The OsNAC41-RoLe1-OsAGAP module promotes root development and drought resistance in upland rice

Drought is a major environmental stress limiting crop yields worldwide. Upland rice (Oryza sativa) has evolved complex genetic mechanisms for adaptative growth under drought stress. However, few genetic variants that mediate drought resistance in upland rice have been identified, and little is known about the evolution of this trait during rice domestication. In this study, using a genome-wide association study we identified ROOT LENGTH 1 (RoLe1) that controls rice root length and drought resistance. We found that a G-to-T polymorphism in the RoLe1 promoter causes increased binding of the transcription factor OsNAC41 and thereby enhanced expression of RoLe1. We further showed that RoLe1 interacts with OsAGAP, an ARF-GTPase activating protein involved in auxin-dependent root development, and interferes with its function to modulate root development. Interestingly, RoLe1 could enhance crop yield by increasing the seed-setting rate under moderate drought conditions. Genomic evolutionary analysis revealed that a newly arisen favorable allelic variant, proRoLe1−526T, originated from the midwest Asia and was retained in upland rice during domestication. Collectively, our study identifies an OsNAC41-RoLe1-OsAGAP module that promotes upland rice root development and drought resistance, providing promising genetic targets for molecular breeding of drought-resistant rice varieties.

Drought assessment in Kabul River basin using machine learnings

Droughts significantly impact water resources and agriculture, leading to economic losses and potential human fatalities. This study aims to predict droughts by analysing changes in the Standardised Precipitation Evapotranspiration Index (SPEI) for the Kabul River basin using data from 1981 to 2022. The research is divided into three phases: calculating SPEI, splitting the dataset into training (80%) and testing (20%) subsets, and evaluating model performance. Various machine learning algorithms, including XGBoost, Decision tree, AdaBoost, and KNN, were employed alongside different climatic variables. The models were assessed using statistical metrics such as R², RMSE, MAE, MSE for regression, and confusion matrix, accuracy, precision, recall, F1 score, ROC AUC, and Log loss for classification. Results showed strong performance, with R² values of 0.97, 0.86, 0.92, and 0.96 for XGBoost, KNN, Decision tree, and AdaBoost, respectively. SPEI demonstrated significant potential for drought forecasting, and spatial distribution mapping revealed persistent moderate drought occurrences.

An integrated approach for managing drought risks in the eastern himalayan region of India

Climate Risk Assessment (CRA), when applied through an integrated approach, enables the evaluation of hazard, exposure, and vulnerability within a unified framework, recognizing the interconnections between climate risks and both natural and social systems. This study uses Sikkim, a small state in the Indian Eastern Himalayan Region, as a case study to conduct a climate risk assessment of agricultural drought at the sub-national level. The objective was to identify the district most at risk from agricultural drought and determine the primary contributors to drought risk to support the development of effective adaptation strategies. The findings reveal that while all districts in Sikkim are moderately drought-prone, the main factor contributing to drought risk is the high sensitivity of the agricultural sector to drought and the limited adaptive capacity of farmers. Many marginal and small farmers rely on rainfed irrigation and have poor adaptive capacity, making them highly vulnerable to even moderate drought conditions. The study highlights that while mitigating drought hazards is important, it is a complex and long-term endeavor. Therefore, strengthening farmers' resilience by reducing their sensitivity and enhancing their adaptive capacity is essential for effectively reducing drought risks in Sikkim.

Rewatering after drought: Unravelling the drought thresholds and function recovery-limiting factors in maize leaves.

Drought and subsequent rewatering are common in agriculture, where recovery from mild droughts is easier than from severe ones. The specific drought threshold and factors limiting recovery are under-researched. This study subjected maize plants to varying drought degrees before rewatering, and measuring plant water status, gas exchange, hydraulic conductance, hormone levels, and cellular damage throughout. We discovered that stomatal reopening in plants was inhibited with leaf water potentials below about -1.7 MPa, hindering postdrought photosynthetic recovery. Neither hydraulic loss nor abscisic acid (ABA) content was the factor inhibited stomatal reopening on the second day following moderate drought stress and rewatering. But stomatal reopening was significantly correlated to the interaction between hydraulic signals and ABA content under severe drought. Extended drought led to leaf death at about -2.8 MPa or 57% relative water content, influenced by reduced rehydration capacity, not hydraulic failure. The lethal threshold remained relatively constant across leaf stages, but the recoverable safety margin (RSM), that is, the water potential difference between stomatal closure and recovery capacity loss, significantly decreased with leaf aging due to delayed stomatal closure during drought. Our findings indicate hydraulic failure alone does not cause maize leaf death, highlighting the importance of RSM in future research.

Evaluation of drought tolerance in various clones of Ceiba pentandra (Linn.) Gaertn: A comparative study

This study focuses on the drought tolerance of Ceiba pentandra (Kapok tree), an emergent tree of the tropical rainforest, bye valuating 25 different clones collected from Tamil Nadu. The research assessed drought tolerance through Relative Water Content (RWC) and Chlorophyll Stability Index (CSI). Among the clones, MTPCPP15 from Varusanadu demonstrated superior water retention and moderate drought tolerance, making it the most suitable for semi-arid and rain fed regions. The findings suggest that this clone is well-adapted to water-stress conditions, making it a viable option for drought-prone areas.

Inter-subspecies diversity of maize to drought stress with physio-biochemical, enzymatic and molecular responses.

Drought is the most significant factor limiting maize production, given that maize is a crop with a high water demand. Therefore, studies investigating the mechanisms underlying the drought tolerance of maize are of great importance. There are no studies comparing drought tolerance among economically important subspecies of maize. This study aimed to reveal the differences between the physio-biochemical, enzymatic, and molecular mechanisms of drought tolerance in dent (Zea mays indentata), popcorn (Zea mays everta), and sugar (Zea mays saccharata) maize under control (no-stress), moderate, and severe drought stress. Three distinct irrigation regimes were employed to assess the impact of varying levels of drought stress on maize plants at the V14 growth stage. These included normal irrigation (80% field capacity), moderate drought (50% field capacity), and severe drought (30% field capacity). All plants were grown under controlled conditions. The following parameters were analyzed: leaf relative water content (RWC), loss of turgidity (LOT), proline (PRO) and soluble protein (SPR) contents, membrane durability index (MDI), malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, the antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Additionally, the expression of heat shock proteins (HSPs) was examined at the transcriptional and translational levels. The effects of severe drought were more pronounced in sugar maize, which had a relatively high loss of RWC and turgor, membrane damage, enzyme activities, and HSP90 gene expression. Dent maize, which is capable of maintaining its RWC and turgor in both moderate and severe droughts, and employs its defense mechanism effectively by maintaining antioxidant enzyme activities at a certain level despite less MDA and H2O2 accumulation, exhibited relatively high drought tolerance. Despite the high levels of MDA and H2O2 in popcorn maize, the up-regulation of antioxidant enzyme activities and HSP70 gene and protein expression indicated that the drought coping mechanism is activated. In particular, the positive correlation of HSP70 with PRO and HSP90 with enzyme activities is a significant result for studies examining the relationships between HSPs and other stress response systems. The discrepancies between the transcriptional and translational findings provide an opportunity for more comprehensive investigations into the role of HSPs in stress conditions.

Improved identification and monitoring of meteorological, agricultural, and hydrological droughts using the modified nonstationary drought indices in the Yellow River Basin of China

Non-stationarity in hydro-meteorological series complicates drought monitoring and assessment. Our study aimed to better identify and monitor meteorological, agricultural and hydrological droughts in the Yellow River Basin (YRB) of China. We constructed nonstationary standardized precipitation index (NSPI), nonstationary standardized precipitation evapotranspiration index (NSPEI), nonstationary standardized soil moisture index (NSSMI) and nonstationary standardized runoff index (NSRI) based on the Generalized Additive Models for Location, Scale, and Shape (GAMLSS). We also investigated the performance of NSPI/NSPEI/NSSMI/NSRI by comparing them with historical drought events. Our results revealed that: (1) The probability distribution function (PDF), smoothing function (SF), and degrees of freedom (DF) significantly influenced the fitting effect of the GAMLSS model. The PDF emerged as the most critical factor in determining fitting accuracy, while SF and DF played crucial roles in preventing overfitting and accurately depicting data variations. (2) Stationary GAMLSS models were primarily suited for time series with lower-scales (1- and 3-month scales), whereas nonstationary models exhibited better suitability for time series with higher-scale (6- and 12-month scales). (3) NSPI and NSPEI demonstrated heightened sensitivity in identifying meteorological droughts, with NSPEI showing greater precision in determining drought intensity and duration. However, compared to SSMI, while NSSMI aligned more closely with historical agricultural drought events, it exhibited limited responsiveness to mild and moderate drought. (4) NSRI indicated that hydrological droughts in the tributaries of the YRB were significantly influenced by meteorological droughts, and the intensity of hydrological drought was stronger than that in the mainstream of the YRB. In conclusion, the nonstationary drought indices could better identify drought events in the period of climate change, and provide valuable information for drought management in the climate change environment.

The reaction of the photosynthetic apparatus of different resistance modern varieties of winter wheat to the effect of moderate drought

The reaction of the photosynthetic apparatus of different resistance modern varieties of winter wheat to the effect of moderate drought

Analysis of Meteorological Drought for Selected Districts of Saurashtra Region of Gujarat

Drought, in particular, is a complex and recurring phenomenon triggered by insufficient precipitation or changes in its distribution, often resulting in decreased water availability. It evolves slowly, affecting large populations' access to food and water, disrupting the entire hydrological cycle, and causing long-term economic losses. The present study attempts a comprehensive analysis of meteorological drought characteristics for selected districts (Junagadh, Amreli, Jamnagar, and Rajkot) in the semi-arid Saurashtra region of Gujarat. The analysis of meteorological drought was performed using rainfall (RF), maximum temperature (Tmax), and minimum temperature (Tmin) data from four stations (each district has one station) for the 43 years duration (1981–2023). The Standardized Precipitation Evapotranspiration Index (SPEI) is utilized across multiple timescales to assess the number of drought affected years, occurrence of drought and drought parameters (total drought duration, magnitude, and intensity). The meteorological drought incidence varied significantly across Junagadh, Amreli, Jamnagar and Rajkot, with Junagadh experiencing droughts in 29% of years, Amreli in 32%, and higher rates in Jamnagar (37%) and Rajkot (36%). The most severe drought years in the four districts were 1987 and 2002, with additional major droughts occurred in 1985, 1986, 1987, 1993, 2002 and 2012. These districts also faced consecutive droughts from 1985 to 1987 and again from 1999 to 2002.Analysis of drought parameters in Junagadh, Amreli, Jamnagar and Rajkot districts showed that drought duration (DD) ranged from 29.46% (Junagadh) to 35.85% (Jamnagar) of months, drought magnitude (DM) varied between -37.58% (Jamnagar) and -34.10% (Junagadh), and drought intensity (DI) spanned from -1.17 (Rajkot) to -1.04 (Junagadh). The analysis of drought occurrence in all districts shows that mild and moderate droughts have been most frequent while severe and extreme droughts have been less common. The study's findings enhance water managers' understanding of how climate change influences drought patterns in the region, thereby assisting policymakers in conducting effective drought risk assessments.

Utilizing the Google Earth Engine for Agricultural Drought Conditions and Hazard Assessment Using Drought Indices in the Najd Region, Sultanate of Oman

Accurately evaluating drought and its effects on the natural environment is difficult in regions with limited climate monitoring stations, particularly in the hyper-arid region of the Sultanate of Oman. Rising global temperatures and increasing incidences of insufficient precipitation have turned drought into a major natural disaster worldwide. In Oman, drought constitutes a major threat to food security. In this study, drought indices (DIs), such as temperature condition index (TCI), vegetation condition index (VCI), and vegetation health index (VHI), which integrate data on drought streamflow, were applied using moderate resolution imaging spectroradiometer (MODIS) data and the Google Earth Engine (GEE) platform to monitor agricultural drought and assess the drought risks using the drought hazard index (DHI) during the period of 2001–2023. This approach allowed us to explore the spatial and temporal complexities of drought patterns in the Najd region. As a result, the detailed analysis of the TCI values exhibited temporal variations over the study period, with notable minimum values observed in specific years (2001, 2005, 2009, 2010, 2014, 2015, 2016, 2017, 2019, 2020, and 2021), and there was a discernible trend of increasing temperatures from 2014 to 2023 compared to earlier years. According to the VCI index, several years, including 2001, 2003, 2006, 2008, 2009, 2013, 2015, 2016, 2017, 2018, 2020, 2021, 2022, and 2023, were characterized by mild drought conditions. Except for 2005 and 2007, all studied years were classified as moderate drought years based on the VHI index. The Pearson correlation coefficient analysis (PCA) was utilized to observe the correlation between DIs, and a high positive correlation between VHI and VCI (0.829, p < 0.01) was found. Based on DHI index spatial analysis, the northern regions of the study area faced the most severe drought hazards, with severity gradually diminishing towards the south and east, and approximately 44% of the total area fell under moderate drought risk, while the remaining 56% was classified as facing very severe drought risk. This study emphasizes the importance of continued monitoring, proactive measures, and effective adaptation strategies to address the heightened risk of drought and its impacts on local ecosystems and communities.

Cannot outrun the past: age, nutrition, and cohort influence horn size in pronghorn

AbstractIn North America, most ungulate species exhibit life‐history traits typical of long‐lived, iteroparous species wherein young males tend to prioritize essential life functions including body growth and maintenance that constrains allocation of resources to horn, antler, and pronghorn growth. As a result, males of most ungulate species require several years of growth before reaching asymptotic body size and thereafter, peak weapon size is attained. Unique among ungulate species in North America, pronghorn possess a suite of life‐history traits resulting in a precocious (i.e., unusually early development) pace of life relative to other North American ungulates. We tested the hypothesis that the fast pace of life of pronghorn extends to precocious development of large horns, and evaluated how horn size was affected by environmental conditions during the year they were grown and the potential for cohort effects associated with environmental signatures during the year of birth. We evaluated the influence of age and the environment on horn size of pronghorn using data collected from 1,789 male pronghorn harvested from 2019 to 2022 in Wyoming, USA. Pronghorn attained 95% of their peak horn size by 3.5 years old. Climatic conditions influenced horn growth through cohort effects and year of growth pathways. Snow depth during the year of birth positively influenced horn size, whereas the effects of environmental conditions during the year of horn growth were dependent on age. For young animals, snow depth and moderate drought positively influenced horn size during the year of horn growth, but the effect was negligible for prime aged and old animals. The precocious nature of pronghorn extended to their horn growth characteristics, resulting in early attainment of a large proportion of their peak horn size. The unique ecology of pronghorn and rapid attainment of size early in life can allow for greater flexibility to balance hunter opportunity and production of large‐horned males for pronghorn as compared with other ungulates.

Assessment of future drought sensitivity shift associated with crop yield loss risk in the Anthropocene

ABSTRACT This study proposed a framework using artificial neural networks (ANNs), the designed residual regression method, and probabilistic indexing, for drought sensitivity shift analysis, associated with future yield loss risk in Anthropocene. The temporal assessment of the drought index (standardized precipitation evapotranspiration index, SPEI) illustrated prevalent occurrence of mild to moderate drought with a fluctuating trend. Furthermore, the optimal ANN model, with R2 = 0.86 for training and 0.7 for testing, was used to project yield for future analysis. The projected spatial changes in drought sensitivity patterns suggest most of the area will experience an increased sensitivity to drought in the far future (2036–2050). The estimated probability loss under the different risk levels defined by the yield reduction rate was 6.2–55.5%. Furthermore, the spatial distribution of the designed risk index (IR) revealed the districts with the highest probability of vulnerability and showed a probable increase in future vulnerability.

The effects of various degrees of meteorological drought on forest vegetation in ecologically Fragile Karst Areas of Guangxi, China

ABSTRACT Drought presents a major challenge to the management of rocky desertification and ecological restoration in the delicate karst ecosystems of Guangxi. In this study, the normalized difference vegetation index (NDVI), fractional vegetation cover (FVC) and net primary productivity (NPP) were selected as vegetation remote sensing parameters, and the spatial response characteristics of different types of vegetation in karst areas of Guangxi Province to light, moderate, severe and extreme drought were analyzed to provide scientific basis for the evaluation of the impact of drought on vegetation in karst areas. The results are as follows: (1) NDVI, FVC and NPP showed a fluctuating increasing trend from 2000 to 2022, and the increasing rates were 0.058, 6.90%, and 43.3gC.m-2 per decade respectively. During this period, the number of light, moderate and severe drought days showed a decreasing trend, but the number of extreme drought days tended to increase. (2) The negative correlation of NDVI, FVC and NPP and drought increased from moderate to extreme drought, and from light to extreme drought, the negative correlation between NDVI and FVC and drought decreased, while that of NPP increased. (3) Light and moderate droughts had obvious negative impact on Chinese fir and broad-leaved forest, whereas severe and extreme droughts had obvious negative effect on eucalyptus and bamboo forest.

Moderate Drought Stress Interferes with the Physiological State and Promotes the Accumulation of Isoflavone in Reproductive Iris domestica Rhizomes

Drought stress is one of the main factors affecting the growth and secondary metabolism of plants. Iris domestica, rich in isoflavones, is a common herbal medicine in China. In this study, the effects of drought stress and rehydration on resistance physiological characteristics and the secondary metabolism of two-year-old I. domestica during the vegetative and reproductive growth period were investigated. The results showed that the dry weight and fresh weight of rhizomes and roots under severe drought stress were significantly decreased, while those under moderate drought stress were not significantly changed. Meanwhile, the SOD activities, POD activities, MDA content and Pro content increased to resist drought at D1 and D2. In the vegetative growth period, the changes in isoflavone concentration and the expression levels of genes in isoflavone synthesis were more dramatic. Isoflavone accumulation was promoted, to some extent, in the reproductive growth period under the D1 drought treatment. In the actual production process, different measures, namely short-term stress regulation in the vegetative growth period and moderate drought stress (13.44% < soil water content ≤ 16.8%) in the reproductive growth period, need to be adopted to regulate isoflavone biosynthesis.