Reduce Drought Stress Research Articles

Effects of Melatonin Pre- and Post-Drought Treatment on Oxidative Stress Markers and Expression of Proline-Related Transcripts in Young Wheat Plants

Wheat can tolerate a mild water deficit, but prolonged drought causes a number of detrimental physiological changes resulting in a substantial decrease in productivity. The present study evaluates the potential of the natural plant growth regulator melatonin to alleviate the negative effects of moderate drought in two Bulgarian winter wheat cultivars at the early vegetative stage. Melatonin doses of 75 µM were root-supplemented 24 h before or after the stress period. The levels of several biometric parameters, osmolyte content and stress indicators as well as the expression of genes coding for key enzymes of the proline biosynthesis pathway were analyzed in leaves at the end of the drought stress and after two and four days of recovery. Applied alone, melatonin did not exert significant effects on most of the monitored parameters. Water deprivation negatively affected seedlings’ fresh weight and water content and increased the stress markers and osmolyte levels. These were accompanied by a high accumulation of TaP5CS and TaP5CR transcripts coding for the enzymes Δ-pyrroline-5-carboxylate synthase and Δ-pyrroline-5-carboxylate reductase, respectively. The effect of melatonin in reducing drought stress was similar whether applied before or after exposure, though slightly more effective when used as a pre-treatment.

The behavioral dimension of CO2 fertilization effect: Evidence from US harvesting records

AbstractThe CO2 fertilization effect has been demonstrated to boost crop production by enhancing photosynthesis and reducing drought stress. In addition to this biological channel, there is also a behavioral margin for the CO2 fertilization effect that was previously unnoticed. I find evidence that an additional ppm of average CO2 concentration leads to increases in the corn and soybean harvested ratios of .57 and .75 percentage points, respectively. My predictions suggest that, without considering the adjustment in harvesting decision, the crop production benefits from CO2 fertilization effect would be biasedly estimated for both corn and soybeans, which broadens the understanding of farmers’ behavioral responses to environmental stimuli and extends the knowledge on how CO2 would benefit crop production.

Soil Amendment with Biochar Reduces the Magnitude of Drought Stress in Soybean

Drought stress severely affects plant growth and causes huge economic losses worldwide. The beneficial effect of biochar to improve soil properties and plant growth is well discussed nowadays. To investigate biochar’s potential for drought stress mitigation, a two-factorial pot experiment was conducted. Factor one was drought stress (100% Field capacity (FC), 70% FC, and 40% FC) and another was biochar treatment. Cow dung biochar (CDB) and poultry manure biochar (PMB) was applied at three rates (0, 4 and 8 g pot−1). The experiment was designed following a completely randomized design with four replicates. The results showed that drought deteriorated all the studied parameters whereas biochar application significantly improved all the parameters compared to control treatment. The chlorophyll concentration was maximum at the application of CDB as 8 g pot−1 followed by PMB as 8 g pot−1 at both drought conditions (70% FC and 40% FC). Biochar application significantly improved plant height at 28 and 42 days after sowing and the highest plant height was found at the application CDB as 8 g pot−1 followed by PMB as 8 g pot−1. The highest leaflet number was found at the application of CDB at a rate of 8 g pot−1. On average, the root length and biomass at 70% and 40% FC was the highest at the application of 8 g CDB pot−1 which was 28.66% and 61.59% higher, respectively over control. The application of CDB at a rate of 8 g pot−1 increased the shoot biomass by 45.35 and 69.52% compared to control at 70% FC and 40% FC, respectively. Therefore, application of biochar could be an option to reduce drought stress in plants. J Bangladesh Agril Univ 22(3): 317-325, 2024

Genome-wide analysis of the CCT gene family and functional characterization of SlCCT6 in response to drought stress in tomato

CCT transcription factors are important for photoperiod and abiotic stress regulation in Arabidopsis and rice. However, the CCT gene family has not been reported in tomato. Here, we systematically analyzed this. Thirty-one SlCCT genes were identified and divided into five groups (CMF, TIFY, PRR, S8, and COL), with members unevenly distributed across 12 chromosomes and the third chromosome exhibiting the most distribution. SlCCT was found to interact with an interacting protein (SlGI), transcription factor (MYB), and non-coding RNA (sly-miR156-5p) to jointly regulate the tomato stress response. cis-Acting element analysis of the SlCCT promoter region indicated large stress- and hormone-response elements in this family. Real-time PCR results indicated that SlPRR subfamily genes respond to various abiotic stresses and hormones. Tissue expression analysis revealed that several PRR subfamily genes are highly expressed in flowers, and subcellular localization analysis indicated an SlCCT6 nuclear location. Notably, SlCCT6 expression was significantly induced by drought, and its silencing reduced drought stress tolerance. Moreover, SlCCT6 overexpression enhanced tomato drought resistance by increasing antioxidant enzyme activity and activating stress-related genes, whereas SlCCT6 knockout decreased drought resistance. In conclusion, this provides valuable insights for future research on SlCCT functions.

Exploring Plastic Mulching as a Strategy for Mitigating Drought Stress and Boosting Maize Yield in the Ecuadorian Andes

Global food security faces a substantial risk stemming from water scarcity, particularly in regions heavily dependent on rainfall for agricultural purposes. In the Andean region, which is grappling with water scarcity, innovative and sustainable approaches are imperative for securing food sources. Plastic mulching has emerged as a potential solution to address water scarcity challenges by conserving soil moisture and optimizing growing conditions. A two-year field experiment was conducted that evaluated the efficacy of plastic mulching in preserving soil water content and reducing drought stress for maize. Two maize cultivars were grown with plastic mulching and conventional practices using a randomized completed block design with three replicates. The results demonstrated that employing plastic mulch led to a rise in the soil water content, particularly within the initial 30 cm of depth, resulting in variances of up to 4.71% humidity between the 20 and 30 cm depths. For the 2019 and 2020 evaluation years, plastic mulching elevated the volumetric water content in the first 30 cm of the soil by 8.39% and 14.18%, respectively. Additionally, it elevated the soil temperature by 1.26 °C and reduced the maize flowering time. Plastic mulching substantially enhanced the fresh corn yield, reaching a 162% increase compared to conventional plots. These findings underscore the potential benefits of plastic mulching in conserving the soil water content, alleviating drought and cold stress for crops in the Andean region.

Humic Acid Mitigates Drought Stress in Tomato

Drought stress, one of the most important abiotic stresses, severely limits global crop production. To increase tolerance to this stress, environmentally friendly practices are emphasised. Humic acid, one of the most important natural biostimulants, has positive effects on plant growth and yield. Recently, it has also been reported to play an important role in resistance to various abiotic stresses. However, many physiological and molecular mechanisms by which humic acid confers drought resistance have not been fully elucidated. Therefore, the effects of humic acid application on different morphological and physiological stress indicators and some antioxidative enzyme gene expressions of tomato seedlings under drought stress conditions were investigated in this study. It was found that drought stress decreased shoot fresh/dry weight, root fresh/dry weight, shoot and root length, chlorophyll and relative water content of plants by 67%, 56%, 31%, 38%, 22%, 20%, 15% and 25%, respectively. Humic acid application significantly increased these parameters, while reducing ion leakage, MDA and proline levels. The antioxidant enzyme gene expression of tomato seedlings under drought conditions showed no significant difference in SOD and APX gene expression, whereas CAT gene expression increased and GR gene expression decreased with humic acid application. Our results showed that humic acid application interacted with stress-related antioxidant enzyme gene expression and may be effective in reducing drought stress.

Study the yield and quality of bitter gourd fruit (Momordica charantia) in inoculation with two species of mycorrhizal fungi and phosphorus fertilizer under different irrigation regimes

Drought is known to be the most important constraint to the growth and yield of agricultural products in the world, and plant symbiosis with arbuscular mycorrhizal fungi (AMF) can be a way to reduce drought stress negative impacts. A two-year experiment to investigate the factorial combination of mycorrhizal fungi (Glomus mosseae, Glomus intraradices, Control) and phosphorus fertilizer (application and non-application of phosphorus) on fruit yield and phenolic acids changes bitter gourd under different irrigation regimes as a split factorial based on a randomized complete block design. Three irrigation regimes, including irrigation after 20%, 50%, and 80% available soil water content depletion (ASWD), were considered in the main plots. The results showed that under water deficit stress, fruit yield and physiological (photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), RWC, total chlorophyll, and root colonization) parameters decreased compared to 20% ASWD, and biochemical (proline, soluble sugar, MDA, CAT, SOD, phenol) parameters and fruit phenolic acids (caffeic acid, coumaric acid, ferulic acid) increased. However, the inoculation of AMF and phosphorus fertilizer in three irrigation regimes decreased MDA content, but physiological and biochemical parameters and fruit phenolic acids were increased. In this study, the factorial combination of AMF and sufficient phosphorus improved the resistance of bitter gourd to water deficit, and this not only improved fruit yield but also increased fruit phenolic acids under 80% ASWD, which can be an innovation in the management of water resources and the production industry of medicinal plants with high antioxidant properties in water deficit areas.

Alleviating the drought stress and improving the plant resistance properties of Triticum aestivum via biopriming with aspergillus fumigatus

BackgroundWheat (Triticum aestivum L.) is one of the most widely grown and vital cereal crops, containing a high percentage of basic nutrients such as carbohydrates and proteins. Drought stress is one of the most significant limitations on wheat productivity. Due to climate change influences plant development and growth, physiological processes, grain quality, and yield. Drought stress has elicited a wide range of plant responses, namely physiological and molecular adaptations. Biopriming is one of the recent attempts to combat drought stress. Mitigating the harmful impact of abiotic stresses on crops by deploying extreme-habitat-adapted symbiotic microbes. The purpose of this study was to see how biopriming Triticum aestivum grains affected the effects of inoculating endophytic fungi Aspergillus fumigatus ON307213 isolated from stressed wheat plants in four model agricultural plants (Gemmiza-7, Sids-1, Sakha8, and Giza 168). And its viability in reducing drought stress through the use of phenotypic parameters such as root and shoot fresh and dry weight, shoot and root length, and so on. On a biochemical and physiological level, enzymatic parameters such as catalase and superoxidase dismutase are used. Total phenolics, flavonoids, and photosynthetic pigments are non-enzymatic parameters. Making use of molecular techniques such as reverse transcriptase polymerase chain reaction (RT-PCR).ResultsIt has been found that using Aspergillus fumigatus as a biological biopriming tool can positively impact wheat plants experiencing drought stress. The total biomass of stressed wheat plants that had been bio-primed rose by more than 40% as compared to wheat plants that had not been bio-primed. A. fumigatus biopriming either increased or decreased the amount of enzymatic and non-enzymatic substances on biochemical scales, aside from the noticeable increase in photosynthetic pigment that occurs in plants that have been bio-primed and stressed. Drought-resistant genes show a biopriming influence in gene expression.ConclusionsThis is the first paper to describe the practicality of a. fumigatus biopriming and its effect on minimizing the degrading effects of drought through water limitation. It suggests the potential applications of arid habitat-adapted endophytes in agricultural systems.

Detection and evaluation of anthropogenic impacts on natural forest ecosystems from long-term tree-ring observations

Anthropogenic interventions lead to various direct and indirect impacts on natural ecosystems that are often hindered by natural long-term variability, and thus their detection and evaluation remain challenging. Ecological systems are strongly affected by climate variations that typically exhibit long-term correlations capable of imitating or hindering external trends in finite-time observations, thus complicating their detection and correct attribution to either anthropogenic interventions or natural variability. Here we focus on the quantitative assessment of the alterations in the tree-ring width (TRW) of four tree species in response to the changes in the soil water regime following a drainage experiment in a dwarf-shrub type peatland forest. We consider the long-term effects of the intervention, focusing on two characteristic quantities: the durations of clusters when significant discrepancies with relevant controls could be observed in every single consecutive year, and relative trends in the data reflecting long-term, gradual changes in the ecosystem. By extrapolating pre-drainage TRW dynamics and adjusting for recent climate variations using a multivariate model, we simulate surrogate data series that act as additional controls for the post-drainage time period. By comparing the long-term dynamics of the observational TRW data series against both natural and surrogate controls over several decades following the drainage experiment, we evaluate long-term alterations and gradual trends in the tree growth dynamics and reassess the statistical significance of these effects, taking into account long-term correlations in the natural TRW variations. Our results also indicate pronounced alterations in the drought stress response characterized by significant negative trends in the tree growth dynamics following the 2010 heatwave and associated flash drought in the drained area, while no similar effect could be observed in the undrained area, indicating that the increased productivity of the forest ecosystem following the drainage likely comes at the cost of its reduced drought stress resilience.

Trees in Sponge Cities—A Systematic Review of Trees as a Component of Blue-Green Infrastructure, Vegetation Engineering Principles, and Stormwater Management

Combining street trees with stormwater management measures can, in some circumstances, both increase tree vitality and reduce the risk of flooding by directing stormwater into tree pits. Using systematic review methods, this study aimed to provide an overview of the vegetation engineering systems being researched and applied that combine tree planting with urban stormwater management. We also sought to identify the positive as well as possible negative impacts on urban hydrology and tree health. It has been shown that diverting rainwater from impervious surfaces into tree pits has considerable potential for stormwater management and for improving tree health by reducing drought stress in urban trees. Worldwide approaches to optimizing tree pits for rainwater infiltration and water supply are promising. Different systems and substrate types have been tested, and street trees generally show good vitality, although systematic long-term monitoring of tree vitality has rarely been undertaken. There is still a need for research into temporary water storage for dry periods.

Effects of γ-polyglutamic acid on grassland sandy soil properties and plant functional traits exposed to drought stress

The current study provides field experimental data that support the use of γ-polyglutamic acid (γ-PGA) in drought stress and proposes its application in grassland management. We hypothesized that water treatment combined with PGA application to sandy soil would reduce drought stress in grasslands more effectively than watering alone. A randomized block design was used, with three replicate watering blocks (no watering, weekly watering, and monthly watering) and PGA treatments at four different concentrations (0%, 0.3%, 1%, and 2% PGA). The results showed that PGA acts as a biostimulant, alleviating the effects of stress in plants by: (1) increasing the availability of ions, especially K+, Zn2+, Mn2+, Fe2+/3+, Ca2+, and Mg2+, as well as N-NH4+, and N-NO3−, (2) elongating plant roots, (3) increasing the aboveground biomass, (4) improving the resprouting capacity of the dominant grass Nardus stricta, and (5) improving the regeneration of dicotyledons. In the case of meadows on sandy soils, the use of low PGA concentrations (0.3% or 1%) was the most beneficial for the availability of macro- and microelements and improving the functional traits of plants. Irrigation had a greater effect than using PGA only for the dicotyledon to monocotyledon ratio.

Zn-quantum dot biochar regulates antioxidants and nutrient uptake to improve rapeseed growth and yield in drought stress

Drought stress is one of the major abiotic factors that cause a significant decline in the crop's productivity. It can disturb photosynthesis by inducing oxidative stress by producing reactive oxygen species. Recently, the use of quantum has gained the attention of scientists due to its potential positive impacts on plants under stress conditions. That's why a current study was conducted to explore the impact of Zn-quantum dot biochar (QDB) on rapeseed growth under drought stress. There were four levels of QDB, i.e., control (no QDB), 0.2 %, 0.4 %, and 0.8 %, applied on a w/w basis in soil under normal irrigation and drought stress. Results showed that 0.8 %QDB performed significantly better in improving seedling's emergence, plant height, number of branches/plants, number of pods/plants, pod length, seed weight/plant, 1000 seeds weight, and total biomass of rapeseed under normal irrigation and drought stress. At 0.2 %, 0.4 %, and 0.8 % QDB levels, the photosynthetic rate was 9.19 %, 11.78 %, and 13.46 % higher than the control under drought stress. Compared to the control, the transpiration rate increased by 61.40 % with 0.2 % QDB, 123.46 % with 0.4 % QDB, and 199.71 % with 0.8 % QDB. The percentage increase in stomatal conductance ranged from 44 % for 0.2 % QDB to 129 % for 0.8 % QDB under drought stress. In conclusion, 0.8 %QDB can potentially reduce drought stress and improve the leaf water contents and nutrient uptake in rapeseed.

A group III WRKY transcription factor, SlWRKY52, positively regulates drought tolerance in tomato

Drought severely limits crop growth and development, reducing productivity. WRKY transcription factors play crucial roles in regulating diverse aspects of plant growth, development, and responses to stress. Despite this, the functions of tomato WRKYs (SlWRKYs) in response to drought stress remain incompletely understood. Thus, we isolated SlWRKY52, a member of the group III SlWRKYs from the tomato variety ‘Ailsa Craig’, and investigated its role in drought stress responses. SlWRKY52 is an unstable hydrophilic protein chiefly located in the nucleus, which promoter region features cis-acting elements engaged in drought stress response. It was expressed in all tomato tissues and its expression was rapidly induced by drought stress. SlWRKY52 overexpression lines conferred enhanced drought stress resistance in tomato: its involved in abscisic acid (ABA) synthesis, resulted in rapid, ABA-dependent stomatal closure, reduced leaf water loss, lessened photosynthetic damage, higher antioxidant enzyme activity, decreased oxidative damage parameters, increased osmoregulatory substance content, accelerated reactive oxygen species scavenging, and increased expression of regulatory interaction, ABA biosynthesis, and abiotic stress response-related genes. Conversely, the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 nuclease mutant lines of SlWRKY52 reduced drought stress tolerance. In conclusion, our findings suggest that SlWRKY52 acts as a positive regulator of drought tolerance in tomato and has the potential to be used as a target gene for further molecular breeding.

Water use strategy determines the effectiveness of internal water storage for trees growing in biofilters subject to repeated droughts

Impervious surfaces create large volumes of stormwater which degrades receiving waterways. Incorporating trees into biofilters can increase evapotranspiration and therefore reduce stormwater runoff. Tree species with i) high water use, ii) drought tolerance and iii) rapid and full recovery after drought have been suggested for biofilters to maximise runoff reduction while minimising drought stress. Moisture availability fluctuates greatly in biofilter substrates and trees growing in biofilters will likely experience multiple, extended drought events that increase trade-offs between these traits. Providing an internal water storage has the potential to reduce tree drought stress and increase evapotranspiration. Two urban tree species (Agonis flexuosa and Callistemon viminalis) were grown in plastic drums with biofilter profiles. Three irrigation treatments were used: well-watered, drought with an internal water storage and drought without an internal water storage. Transpiration, leaf water potential and biomass were measured to determine the effect of biofilter internal water storage and repeated drought events on tree water use, drought stress and growth. Biofilter internal water storage improved water use and reduced drought stress for A. flexuosa, whereas C. viminalis reduced leaf loss but saw no change in water use or drought stress. A. flexuosa with biofilter internal water storage was able to recover transpiration to well-watered levels after repeated droughts, while C. viminalis experienced reduced recovery ability. It is recommended all biofilters planted with trees should have internal water storage. In systems with lower moisture availability a species with more stomatal control, such as A. flexuosa, is recommended. If selecting a species with less stomatal control, such as C. viminalis, the internal water storage volume needs to be increased to avoid drought stress.

Influence of green roof plant density and redirecting rainfall via runoff zones on rainfall retention and plant drought stress

Green roofs are a promising engineered ecosystem designed to reduce stormwater runoff and restore vegetation cover in cities. Plants can contribute to rainfall retention by rapidly depleting water in the substrate, however, this increases the risk of plant drought stress. This study determined whether lower plant density or preferentially redirecting rainfall to plants on green roofs could reduce drought stress without reducing rainfall retention. Plant density was manipulated, and metal structures were installed above the substrate surfaces to redirect the flow of rainwater towards plants (runoff zones). Green roof modules were used to test three plant density treatments: unplanted, half-planted (10 plants/m2) and fully-planted (18 plants/m2), and two runoff zone treatments which were installed in unplanted and half-planted modules. It was expected that 1) green roofs with greater plant density would experience more drought stress (i.e., lower leaf water status), and 2) green roofs with runoff zones would show higher ET and hence retention compared with those without runoff zones, as water will be directed to plants (run-on zones), facilitating growth. Contrary to the hypothesis, evapotranspiration (ET) and rainfall retention were similar for half-planted and fully-planted modules, such that ∼82 % of applied rainfall was retained. While both vegetation treatments dried out the substrates before rainfall was applied, the fully-planted modules dried out quicker and showed significantly lower leaf water status than half-planted modules. This indicates that planting at lower density may reduce plant drought stress, without reducing rainfall retention. Installing runoff zones marginally reduced ET and rainfall retention, likely due to shading by the runoff zone structures reducing evaporation from the substrate. However, runoff also occurred earlier where runoff zones were installed as they likely created preferential flow paths that reduced soil moisture and therefore ET and retention. Despite reduced rainfall retention, plants in modules with runoff zones showed significantly higher leaf water status. Reducing plant density therefore represents a simple means of reducing plant stress on green roofs without reducing rainfall retention. Installing runoff zones on green roofs is a novel approach that could reduce plant drought stress, particularly in hot and dry climates, albeit at a small cost of reduced rainfall retention.

Wildfires Improve Forest Growth Resilience to Drought

In seasonally dry forests, wildfires can reduce competition for soil water among trees and improve forest resilience to drought. We tested this idea by comparing tree-ring growth patterns of Pinus pinea stands subjected to two prescribed burning intensities (H, high; L, low) and compared them with unburned (U) control stands in southwestern Spain. Then, we assessed post-growth resilience to two droughts that occurred before (2005) and after (2012) the prescribed burning (2007). Resilience was quantified as changes in radial growth using resilience indices and as changes in cover and greenness using the NDVI. The NDVI sharply dropped after the fire, and minor drops were also observed after the 2005 and 2012 droughts. We found that post-drought growth and resilience were improved in the H stands, where growth also showed the lowest coherence among individual trees and the lowest correlation with water year precipitation. In contrast, trees from the L site showed the highest correlations with precipitation and the drought index. These findings suggest that tree growth recovered better after drought and responded less to water shortage in the H trees. Therefore, high-intensity fires are linked to reduced drought stress in Mediterranean pine forests.

Efficacy of priming wheat (Triticum aestivum) seeds with a benzothiazine derivative to improve drought stress tolerance.

We evaluated the effects of different concentrations (0.05 and 0.15mM) of a benzothiazine (BTh) derivative on wheat (Triticum aestivum L.) in normal (100% field water capacity, FWC) and drought (60% FWC) conditions. Various morphological and physiological characteristics, and the uptake of osmo-protectants and nutrients were measured under the two FWC conditions. Results show that the drought conditions significantly reduced plant growth, affected plant composition, reduced the concentrations of photosynthetic pigments and affected gaseous exchange attributes, stomatal behaviour, and uptake fluxes of essential nutrients, while increasing the contents of different osmo-protectants and enzymatic and non-enzymatic antioxidants to decrease the production of reactive oxygen species (ROS) within the cells/tissues. However, seed priming with BTh reduced water stress conditions by increasing plant growth and biomass, photosynthetic pigments, stomatal behaviour, different gaseous exchange attributes, and uptake fluxes of essential nutrients compared with unprimed plants. In addition, the plant has a strong antioxidant defense system, which further increased its activities under BTh derivative treatments, to scavenge ROS production and maintain cell turgor under water stress conditions. In conclusion, drought stress-induced oxidative stress and altered the growth of T. aestivum, whereas seed priming increased plant growth and antioxidant production by improving the plant tolerance to drought. We suggest that seed priming with a BTh derivative as an effective priming technique in T. aestivum for reducing drought stress tends to benefit a grower in terms of better growth to fulfil the market demand for food cereals.

Substrate composition impacts long-term vegetation development on blue-green roofs: Insights from an experimental roof and greenhouse study

Green roofs provide ecosystem services and can promote biodiversity in urban areas. Blue-green roofs have an additional water storage compartment under the substrate to reduce roof water runoff, thereby also reducing drought stress which is beneficial for green roof vegetation. In order to study which blue-green roof design supports the highest plant diversity, we assessed the effect of different substrates and seed mixtures on vegetation development in a short-term greenhouse experiment and long-term blue-green roof experiment. A ten-week full-factorial greenhouse experiment was performed for six substrate composition and four seed mixture treatments. On an experimental blue-green roof, we annually surveyed plants from 2013 to 2021 in nine different treatments (five replicates each), that varied in substrate composition, substrate depth and seed mixture that was initially applied. Two treatments resembled conventional non-green roofs (100% gravel) and conventional extensive Sedum green roofs. The results of the greenhouse experiment showed that seed mixture is more important than substrate composition in shaping the initial species richness and species composition. However, on the experimental roof the substrate composition was an important determinant of species richness and species composition long-term. Plant species richness on the experimental roof was lowest in the gravel treatment (resembling conventional non-green roofs), and highest in treatments where locally collected soil was used, likely due to additional species that appeared from the seed bank present in the transplanted soil. Soil was never completely covered with vegetation on unfertilized substrates that contained 20% or less dense and organic materials. Plant species richness on conventional Sedum roof substrate was higher on the experimental blue-green roof compared to an adjacent non-blue roof, highlighting that blue-green roofs can promote biodiversity more than conventional green roofs. For future construction of blue-green roofs in our region, we recommend the addition of 30% locally collected soil to a 6 cm deep lightweight substrate to maximize long-term plant cover and plant species richness.

Preliminary Evaluation of the Application of Algae-Based Biostimulants on Almond.

To improve almond performance under water limitations, the use of algae-based biostimulants may become a useful tool to reduce drought stress. However, besides possible effects on plant behavior, changes in fruit characteristics must also be considered. In this work, a preliminary study on the effect of two levels of an Ascophyllum nodosum-based biostimulant in the chemical characteristics of fruits from rain-fed cv. Marinada almond trees was carried out. The use of the recommended manufacturer's dosage resulted in a decreased content of soluble sugars and proteins when compared to the use of half the recommended dosage and the control assays (water only). Similarly, and although no significant differences were recorded, the content of bioactive compounds (ortho-diphenols, total phenolics, and flavonoids) tended to increase in non-treated trees. Finally, sensory analysis of treated and non-treated fruits did not record any changes in the perceived attributes, showing that no negative effects on consumers' acceptance will be caused by the application of this product. Long-term studies are needed to further confirm these results, also aimed at the monitoring of leaf gas exchange and water status parameters of trees.

Comparison of lauric acid and 12-hydroxylauric acid in the alleviation of drought stress in peach (Prunus persica (L.) Batsch).

Water shortage is a key factor that can restrict peach tree growth. Plants produce fatty acids and the fatty acid derivatives lauric acid (LA) and 12-hydroxylauric acid (LA-OH), which are involved in abiotic stress responses, but the underlying stress response mechanisms remain unclear. In this study, physiological examination revealed that in Prunus persica (L.) Batsch, pretreatment with 50 ppm LA-OH and LA reduced drought stress, efficiently maintained the leaf relative water content, and controlled the relative conductivity increase. Under drought stress, LA-OH and LA treatments prevented the degradation of photosynthetic pigments, increased the degree of leaf stomatal opening and enhanced the net photosynthetic rate. Compared with drought stress, LA-OH and LA treatment effectively increased the net photosynthetic rate by 204.55% and 115.91%, respectively, while increasing the Fv/Fm by 2.75% and 7.75%, respectively, but NPQ decreased by 7.67% and 37.54%, respectively. In addition, the level of reactive oxygen species increased under drought stress. The content of O2 - in LA-OH and LA treatment decreased by 12.91% and 11.24% compared to CK-D, respectively, and the content of H2O2 decreased by 13.73% and 19.94%, respectively. At the same time, the content of malondialdehyde (MDA) decreased by 55.56% and 58.48%, respectively. We believe that the main reason is that LA-OH and LA treatment have improved the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). The application of exogenous LA increased the levels of soluble sugars, soluble proteins, proline and free amino acids under drought stress, and maintained the osmotic balance of cells. Compared with CK-D treatment, it increased by 24.11%, 16.89%, 29.3% and 15.04%, respectively. At the same time, the application of exogenous LA-OH also obtained similar results. In conclusion, exogenous LA-OH and LA can alleviate the damage to peach seedlings caused by drought stress by enhancing the photosynthetic and antioxidant capacities, increasing the activities of protective enzymes and regulating the contents of osmotic regulators, but the molecular mechanism is still in need of further exploration.