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Due to global climate change, droughts are likely to become more frequent and more severe in many regions such as in South Africa. In Limpopo, observed high climate variability and projected future climate change will likely increase future maize production risks. This paper evaluates drought patterns in Limpopo at two representative sites. We studied how drought patterns are projected to change under future climatic conditions as an important step in identifying adaptation measures (e.g., breeding maize ideotypes resilient to future conditions). Thirty-year time horizons were analyzed, considering three emission scenarios and five global climate models. We applied the WOFOST crop model to simulate maize crop growth and yield formation over South Africa's summer season. We considered three different crop emergence dates. Drought indices indicated that mainly in the scenario SSP5-8.5 (2051–2080), Univen and Syferkuil will experience worsened drought conditions (DC) in the future. Maize yield tends to decline and future changes in the emergence date seem to impact yield significantly. A possible alternative is to delay sowing date to November or December to reduce the potential yield losses. The grain filling period tends to decrease in the future, and a decrease in the duration of the growth cycle is very likely. Combinations of changed sowing time with more drought tolerant maize cultivars having a longer post-anthesis phase will likely reduce the potential negative impact of climate change on maize. [ABSTRACT FROM AUTHOR]

Drought stress is among the significant forms of abiotic stresses that unfavourably affects maize survival as well as the development from germination to maturity. This paper, therefore, reviewed drought stress effects in maize plants and expatiated on the plausible adoptable mitigation measures to employ in curbing these effects as well. Water shortage prompts drought stress that alters the morphological, physiological and biochemical activities in maize plants. The major drought stress implications on the plant's survival are mostly in the area of altered metabolic functions, including nutrient metabolism, cell membrane integrity, water relationships, plant yield, photosynthetic processes, osmotic adjustment, and the pigment content. Mitigating strategies, such as the breeding of drought-tolerant varieties, genomic applications for drought tolerance enhancement in maize plants, as well as the use of rhizobacteria and endophytic bacteria, can be employed in alleviating drought stress and ensuring optimal maize productivity. [ABSTRACT FROM AUTHOR]

Background: Drought stress poses a significant challenge to agricultural productivity, particularly in regions with limited water availability. Maize, a staple crop worldwide, is highly susceptible to drought stress, leading to reduced seed germination, stunted growth and ultimately diminished yields. Addressing this issue, in this study various phytohormones and polyamines were used as priming agents for seeds to evaluate its performance to mitigate drought stress in maize seed germination and vigour. It plays crucial roles in regulating plant growth and development, as well as responses to various environmental stresses, including drought. These hormones modulate physiological and biochemical processes, leading to adaptive changes that helps maize plants to cope with water scarcity. Methods: The experiment was conducted by exposing maize seeds primed with different phytohormones and polyamines in optimum along with non primed seeds (control) to various levels of PEG concentration ranging from -0.2 MPa to -1.0 MPa for creating drought stress. Primed seeds subjected to a germination test. The seedling growth parameters and seed vigour were evaluated to analyse better performing seed priming treatment to mitigate drought stress. Result: From the experiment it is concluded that increase in concentration of PEG (from -0.2 Mpa to -1.0 MPa) decreased the seed germination and seed vigour traits in maize. Among seed priming treatments, seeds primed with melatonin 150 μM showed greater performance seedling vigour and its related traits even under water deficit stress condition. In conclusion, seed priming with melatonin exhibited superior efficacy in mitigating drought stress in maize. This finding highlights the potential of melatonin as a promising seed priming agent for enhancing drought tolerance in maize seeds. As seed priming is simple, easy and cost effective method, farmers can use this technology as one of their practice to eliminate the effect of drought stress in maize crop. [ABSTRACT FROM AUTHOR]

Drought is the main meteorological disaster that affects the yield and quality of spring maize on the Loess Plateau. This study used data of the spring maize growth period, relative soil humidity, and yield at 18 agricultural meteorological observation stations on the Loess Plateau from 1997 to 2013 to determine the drought category based on the yield reduction rate. Through the drought index according to the conformity rate of category standard and individual case verification, a refined suitability drought index of spring maize on the Loess Plateau was constructed, and the spatial distribution characteristics of drought in different growth stages of spring maize were analyzed. The results showed the following: (1) The number of days in the whole growth period of spring maize in all regions of the Loess Plateau has been extended. The average sowing date of spring maize in the northwest region of the Loess Plateau was 9 April, and that in the east and central regions was 26 April. In terms of spatial distribution, each growth period was gradually delayed from west to east. (2) The correlation between relative soil humidity and yield of spring maize at the jointing stage and heading stage was the best, followed by the milky stage and mature stage, and the relative soil humidity at the sowing stage and emergence stage had little effect on the yield. (3) According to the national drought category standard "Drought Category of Spring Maize in the North", based on the data of yield reduction rate, the drought index of spring maize on the Loess Plateau was refined by region and growth stage. The drought category index values of spring maize in different growth stages and regions changed according to the revised drought category standard, with 71.4% of the sites in the sowing seedling stage and 85.7% of the sites in the seedling jointing stage, and the revised drought category was more severe than the national drought category standard, while at 57.1% of the sites in the jointing and tasseling stages and 71.4% in the tasseling and milking stages, the revised drought category was less severe than the national drought category standard. (4) Based on the revised refined drought index for spring maize on the Loess Plateau, the spatial distribution of drought occurrence frequency across different growth stages of spring maize on the Loess Plateau was analyzed. The frequency of drought occurrence during the seeding and emergence stages was 25–75%. With the change in growth stages, the high-value area of drought occurrence frequency gradually moved northward, and the overall frequency of drought occurrence decreased. For the milky mature stage, the frequency of drought occurrence in a few regions was around 42%, and the drought frequency in most regions was between 8% and 33%. [ABSTRACT FROM AUTHOR]

Co-occurring extreme heat, drought, and moisture events are increasing under global warming and pose serious threats to ecosystem and food security. However, how to effectively link compound agrometeorological disasters (CADs) with climate change has not been well assessed. In this study, we focus on the comprehensive influence of large-scale climate factors on CADs rather than extreme meteorological elements. The results indicate that there are two main CADs of spring maize in Shenyang, Northeast China (NEC), including concurrent drought and cold damage (DC) and drought in multiple growth periods (MD). The related circulation anomalies at mid–high latitudes are identified as four patterns, namely, the Northeast Asia Low (NEAL) and Ural High (UH) patterns affecting DC, the Baikal High and Okhotsk Low (BHOL), and the Northeast Asia High (NEAH) patterns leading to MD. The vertical profile and water vapor transport anomalies further demonstrate the influence mechanism of large-scale circulation on compound heat–moisture stresses. This study highlights the role of atmospheric circulation, which can provide effective predictors for these synergistic agrometeorological disasters. [ABSTRACT FROM AUTHOR]

Maize is a crop of significant economic importance. In the northeast region of Brazil, it serves as the foundation of family support for the majority of farmers. However, achieving high levels of productivity requires an adequate water supply throughout its growth cycle. The northeast semi-arid region experiences low rainfall and high potential evapotranspiration, directly affecting maize development and leading to severe declines in productivity. In this study, genetic selection and proteomic analysis are proposed as a strategy to identify the tolerance of maize cultivars against water stress. The experiments were conducted under two water regimes using randomized block designs with three replicates. Development and productivity traits were evaluated, and genetic parameters were estimated using mixed linear models. Selection for water stress tolerance was based on the harmonic mean of the relative performance of genotypic values. Total protein extraction from maize leaves followed the protocol established by the phenol method, and peptides were analyzed through mass spectrometry. The AG8677P cultivar demonstrated remarkable productivity under drought stress conditions, and proteins related to various fundamentally important biological processes for the tolerance mechanism were identified. The combination of genetic selection with proteomic analysis proves to be an efficient strategy, even in the face of limited resources and a small number of treatments. [ABSTRACT FROM AUTHOR]

Climate change has become the biggest global challenge to agriculture and food production. In the context of current environmental changes, the aim of this study is to identify the optimal sowing season that leads to obtaining high and constant yields. The study followed the reaction of 7 native maize hybrids to cultivation in 3 different sowing seasons, over a period of 3 years. The data obtained show us that the best yield results are obtained on mid-early hybrids (9327- 9843 kg/ha). Sowing maize too early, are obtained lower yields than for maize sown at 10ºC in the soil, with a very significant difference of 1337 kg/ha. Favorable climatic conditions in 2020 and 2021 emerge from the average yields obtained in the two years, 10343 kg/ha (2020) respectively 9424 kg/ha (2021). The climatic conditions of 2022 were less favorable, summer drought having a negative effect on average maize yield, which was around 6924 kg/ha. [ABSTRACT FROM AUTHOR]

Drought is a major environmental threat that limits crop growth, development, and productivity worldwide. Improving drought resistance with genetic engineering methods is necessary to tackle global climate change. It is well known that NAC (NAM, ATAF and CUC) transcription factors play a critical role in coping with drought stress in plants. In this study, we identified an NAC transcription factor ZmNAC20, which regulates drought stress response in maize. ZmNAC20 expression was rapidly upregulated by drought and abscisic acid (ABA). Under drought conditions, the ZmNAC20-overexpressing plants had higher relative water content and survival rate than the wild-type maize inbred B104, suggesting that overexpression of ZmNAC20 improved drought resistance in maize. The detached leaves of ZmNAC20-overexpressing plants lost less water than those of wild-type B104 after dehydration. Overexpression of ZmNAC20 promoted stomatal closure in response to ABA. ZmNAC20 was localized in the nucleus and regulated the expression of many genes involved in drought stress response using RNA-Seq analysis. The study indicated that ZmNAC20 improved drought resistance by promoting stomatal closure and activating the expression of stress-responsible genes in maize. Our findings provide a valuable gene and new clues on improving crop drought resistance. [ABSTRACT FROM AUTHOR]

Recent global warming and more frequent droughts are causing significant damage to maize production. A reliable estimate of drought intensity and duration is essential for testing maize hybrids to drought tolerance. For this purpose, the self-calibrating 10-day palmer drought severity index (scPDSI) and standardized precipitation index (SPI) for 1, 2, 3, 6, 9, 18, 27, and 36 10-day scales were used to estimate the effects of drought on grain yield of 32 maize hybrids evaluated in 2017 and 2018 at eight experimental locations in the Pannonian part of Croatia. Time series of observed 10-day mean air temperature, relative humidity, and precipitation totals for a set of "reference" weather stations of the croatian meteorological and hydrological service (DHMZ) for the period 1981–2018 were used to calculate the scPDSI and SPI indices. According to the 10-day scPDSI and SPI for different time scales, 2018 proved to be a "normal year," while 2017 experienced a "mild to moderate drought," which resulted in a 13% reduction in maize grain yield at eight experimental locations compared to 2018. The correlation between grain yield and drought indices for summer months was the highest for the 10-day scPDSI. To some extent, correlations between summer months' SPI for the 3 10-day time scale and maize grain yield were comparable to the corresponding correlations for the 10-day scPDSI. However, for other SPI time scales considered, the corresponding correlations were weaker and less informative. The dependence of grain yield on scPDSI values was not the same for all hybrids, indicating their different tolerance to drought. The reduction in grain yield due to drought was primarily caused by insufficient grain filling (lower 1000-grain weight) and, to some extent, by a reduction in the number of grains. In this study, application of 10-day scPDSI data proved to be more relevant in detecting effects of drought on agronomic traits than application of SPI data for the most time scales. [ABSTRACT FROM AUTHOR]

Bt maize is being increasingly cultivated worldwide as the effects of climate change are increasing globally. Bt maize IE09S034 and its near-isogenic non-Bt maize Zong 31 were used to investigate whether climate change alters the effects of Bt maize on soil Collembola. Warming and drought conditions were simulated using open-top chambers (OTC), and their effects on soil Collembola were evaluated. We found that the maize type had no significant effect on Collembola; however, the abundance and diversity of Collembola were significantly higher in the OTC than outside at the seedling stage; they were significantly lower in the OTC at the heading and mature stages. The interactions of the maize type with the OTC had no effect on these parameters. Therefore, Bt maize had no significant effect on soil Collembola, and the effects of climate warming and drought on soil Collembola depended on the ambient climatic conditions. When the temperature was low, collembolan abundance and diversity were promoted by warming; however, when the temperature was high and the humidity was low, collembolan abundance and diversity were inhibited by warming and drought. The climate changes simulated by the OTC did not alter the effects of Bt maize on soil Collembola. [ABSTRACT FROM AUTHOR]

Heat stress in combination with drought has become the biggest concern and threat for maize yield production, especially in arid and hot regions. Accordingly, different optimal solutions should be considered in order to maintain maize production and reduce the risk of heat stress under the changing climate. In the current study, the risk of heat stress across Iranian maize agro-ecosystems was analyzed in terms of both intensity and frequency. The study areas comprised 16 provinces and 24 locations classified into five climate categories: arid and hot, arid and temperate, semi-arid and hot, semi-arid and temperate, and semi-arid and cold. The impact of heat stress on maize under a future climate was based on a 5‐multi‐model ensemble under two optimistic and pessimistic emission scenarios (RCP4.5 and RCP8.5, respectively) for 2040–2070 using the APSIM crop model. Simulation results illustrated that in the period of 2040–2070, intensity and the frequency of heat stress events increased by 2.37 °C and 79.7%, respectively, during maize flowering time compared to the baseline. The risk of heat stress would be almost 100% in hot regions in the future climate under current management practices, mostly because of the increasing high-risk window for heat stress which will result in a yield reduction of 0.83 t ha−1. However, under optimal management practices,farmers will economically obtain acceptable yields (6.6 t ha−1). The results also indicated that the high-risk windows in the future will be lengthening from 12 to 33 days in different climate types. Rising temperatures in cold regions as a result of global warming would provide better climate situations for maize growth, so that under optimistic emission scenarios and optimal management practices, farmers will be able to boost grain yield up to 9.2 t ha−1. Overall, it is concluded that farmers in hot and temperate regions need to be persuaded to choose optimal sowing dates and new maize cultivars which are well adapted to each climate to reduce heat stress risk and to shift maize production to cold regions. [ABSTRACT FROM AUTHOR]

Background and Aims Drought limits maize production in many regions of the world, and this is likely to intensify in future. Elevated atmospheric CO2 (e CO2) can mitigate this by reducing stomatal conductance and water loss without reducing yield. The magnitude of this effect depends on the interaction of e CO2 and drought severity, but scarce data collected under severe drought conditions limit predictions of future maize production. Methods We compared the severe drought × e CO2 responses of six maize genotypes from semi-arid and sub-humid growing regions. Key Results Genotypic differences were apparent in growth, gas exchange, water relations, grain quality, and biomass at maturity, but the response to e CO2 was consistent. Plants under drought and e CO2 had similar biomass and yield to irrigated plants at ambient CO2. Reduced stomatal conductance and water loss preserved soil moisture equivalent to 35 mm of rainfall and allowed sustained photosynthesis at higher rates for a longer period after watering stopped. Under irrigation, e CO2 improved maize growth but not grain yield. Conclusions The results suggest that e CO2 may extend the future land area available to rainfed maize cultivation, but cannot circumvent the absence of seasonal rainfall that restricts maize growth. Elevated CO2 will reduce water requirements of irrigated maize when atmospheric conditions drive high evapotranspiration. [ABSTRACT FROM AUTHOR]