Drought Stress Conditions Research Articles

Selenium Nanoparticles Boost the Drought Stress Response of Soybean by Enhancing Pigment Accumulation, Oxidative Stress Management and Ultrastructural Integrity

Drought is a persistent and devastating obstacle to crop production, affecting both humanity and livestock. The application of selenium (Se) effectively mitigates various types of abiotic stresses and enhances crop yield under unfavorable conditions. However, our understanding of how nano-Se (nSe) alleviates drought stress (DS) in soybeans is still limited. To address this gap, our study focused on assessing the effectiveness of foliar nSe application during the reproductive stage of soybeans. Three concentrations of nSe were applied to plants grown in pots filled with clay loam soil, simulating DS conditions. Our findings reveal that nSe spraying significantly promoted the accumulation of above-ground dry biomass and enhanced relative water content (RWC) and photosynthetic pigment over alone-DS treatment. Furthermore, nSe application boosted the activity and contents of protective enzymes and osmolytes, resulting in a dose-dependent reduction in electrolyte leakage (EL), reactive oxygen species (ROS) accumulation, and malondialdehyde (MDA) content. Additionally, nSe improved stomatal characteristics and mesophyll cell ultrastructure, further mitigating the adverse effects of drought stress. These findings suggest the potential of nSe as an effective strategy to enhance soybean tolerance and potentially improve crop yields under drought conditions.

GA3 and BAP phytohormone seed priming enhances germination and PEG induced drought stress tolerance in soybean by triggering the expression of osmolytes, antioxidant enzymes and related genes at the early seedling growth stages

Drought stress strongly affects seed germination and seedling development during the early stages of plant growth in soybean (Glycine max L.). Seed priming with phytohormone (PH) is known to regulate various physiological and biochemical processes that govern plant growth and yield under optimal and stress conditions. In the present study, the effects of seed priming with Gibberellic acid (GA3) (0.28 mM), 6-Benzyl aminopurine (BAP) (20 mM) and Methyl Jasmonate (MJ) (2.5 mM) was studied during germination and at early seedling growth stages in JS-335 (drought sensitive) and MAUS-71 (moderately drought tolerant) soybean varieties under PFG induced drought stress conditions. The seed priming effects were studied in terms of germination percentage and rate (Timson Index), accumulation of osmolytes (proline and glycine betaine), antioxidant enzymes activity (superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT)), and the relative expression of genes viz., Cu/Zn-superoxide dismutase copper chaperone (SOD-CCS) , iron-superoxide dismutase (SODB2) , betaine aldehyde dehydrogenase (BADH2) and dehydration-responsive element binding protein (DREB2A). The germination percentage of non-primed soybean seeds decreased under drought stress but significantly increased upon GA3 and BAP priming. Interestingly, seed priming with MJ completely inhibited the germination in both the varieties. GA3 and BAP seed priming increased proline and glycine betaine accumulation under PEG induced drought stress in both the soybean varieties. The results showed that the activities of SOD, APX and CAT were significantly enhanced in the leaves of seedlings raised from GA3 and BAP-primed seeds, as compared to the non-primed seeds under the drought stress conditions. Isozyme profiling of SOD and APX revealed that the GA3 and BAP seed priming treatments enhanced the drought-inducible expression of SOD isozymes rather than inducing novel isoforms. In case of APX isozymes, GA3 seed priming appears to preserve APX isozyme diversity in both varieties, and BAP seed priming elevated the expression of APX isoforms in both soybean varieties under the drought conditions. In response to the drought stress, relative expression of the genes associated with superoxide dismutase and glycine betaine viz., SOD CCS, SODB2, BADH2 and DREB2A was markedly upregulated in the leaves of seedlings raised from the GA3 and BAP primed seeds in both the soybean varieties. The global correlation analysis designated that the osmolyte Proline, antioxidant enzyme APX and CAT, and SOD CCS, SODB2, BADH2 and DREB2A genes were potent regulator for drought stress tolerance mechanism in soybean. This study illuminates the intricate interplay of GA3 and BAP hormonal seed priming during the germination and early seedling stages in soybean plants under the drought stress. This finding emphasizes the critical consideration of genotype specific reactions to the hormonal seed priming under PEG induced drought stress conditions.

Exploring the Correlation between Yield Components and Nutrient Content in Foxtail Millet [Setaria italica (L.) Beauv.] Genotypes Subjected to Drought Stress Condition

The study evaluated 30 genotypes of foxtail millet at Millets Research Station Dholi, RPCAU, Pusa, during Kharif 2021. A randomized block design with three replications was used. Before selecting genotypes based on micronutrient content (Fe and Zn) for nutritional quality traits, it's crucial to understand their potential impact on yield. The study examined the relationships between quality traits and yield attributes in foxtail millet genotypes using a diverse range of genotypes. Correlation analysis under normal condition revealed positive relationships, particularly between panicle girth and number of productive tillers per plant, grain yield per plant and days to maturity, days to 50% flowering and iron content and days to 50% flowering and zinc content, with correlation coefficients ranging from 0.307 to 0.333. This indicates that these traits collectively enhance plant productivity under favorable conditions. However, under drought conditions, the relationships shift. Grain yield per plant showed significant positive correlation only with days to 50% lowering and number of productive tillers per plant with panicle girth, with correlation coefficients of 0.315 and 0.314, respectively. Further, significantly negative correlation of days to maturity with number of productive tillers per plant, panicle girth and zinc content was observed. Similarly, days to 50% flowering was found negatively correlated with panicle girth. This suggests that under water stress, fewer traits positively influence yield, with panicle girth becoming a crucial factor in maintaining grain yield. This analysis highlights how environmental conditions affect the relationships between plant traits. Under normal conditions, a broader set of traits, including micronutrient levels, contribute to productivity. In contrast, under drought stress, the focus shifts to key traits like panicle girth, essential for resilience and yield stability. These insights can improve and speed up breeding programs aiming to enhance drought tolerance in crops, by prioritizing traits that significantly impact yield under adverse conditions.

Genetic analysis of yield and fiber quality traits in cotton (Gossypium hirsutum L.) under full and deficit irrigation conditions using full diallel method

The aim of the study was to assess the genetic structure and quantitative heritability of cotton yield, yield components and fiber quality parameters under well-watered (100%) and deficit (50%) irrigation conditions using a complete full diallel cross method with six cotton genotypes. The F1 and F2 generations were obtained to study the effect of irrigation conditions on genotypic variation and maternal effects on the traits studied. Parental, F1 and F2 generations were growed under full and deficit irrigation conditions and selected agronomic and fiber quality traits were measured. The data were analysed using various methods, including Griffing Method I, Model I analysis of variance, full diallel table analysis of variance, Jinks-Hayman diallel hybrid analysis. The Jinks-Hayman analysis of variance showed that dominant effects were more important in the inheritance of all traits, as indicated by the negative value of the difference between the additive variance and the dominance variance (D-H1). In addition, the average degree of dominance (H1/D)1/2 was greater than 1, indicating the predominance of dominant gene action in inheritance. The study concluded that starting selection in the F5–F6 generation is appropriate for drought resistant cotton breeding studies. It also emphasised the importance of conducting drought resistant cotton breeding under drought conditions due to the differences in gene movement between well-watered irrigation and drought stress conditions. The study highlighted the importance of population selection, environmental factors, data collection and analysis interpretation in breeding studies. It suggested that the Griffing diallel analysis method is suitable for hybrid breeding studies, while the Jinks-Hayman type analysis method is suitable for studying the genetic structures of populations.

Multigenerational Drought Reveals a Stable Wheat Seed Fungal Community

Wheat ( Triticum spp.) is a staple food crop, providing a fifth of the world's protein and caloric needs. Our research examines the impact of multigeneration postflowering drought stress on the wheat seed endophytic fungal community. Understanding how wheat seed fungal communities respond to drought stress over several generations can improve our knowledge of legacy drought stress. In this article, we aim to identify seed-associated fungi that play critical roles within the wheat seed under drought stress conditions. We examined the endophytic seed fungal communities of three winter wheat cultivars, Catawba, Shirley, and USG 3640. Moderate drought was imposed on a subset of plants immediately after flowering, with plants relieved from drought stress after 1 week. Seeds harvested from generation 1 were planted for a second generation of drought experiments. When examining the postflowering drought impact on wheat physiology, drought-exposed plants consistently exhibited lower daily transpiration rates, chlorophyll-a values, and seed yield compared with control plants, indicating that drought implementation was successful. Internal transcribed spacer 1 metabarcoding revealed that wheat seed fungal community species richness decreased during postanthesis drought stress across both generations. We also observed that generation accounted for variation in fungal species richness and community structure, independent of drought treatment. The most abundant taxa recovered across all cultivars, treatments, and generations included Cladosporium, Penicillium, Alternaria, and Epicoccum. These results support our hypothesis that postanthesis drought shapes the wheat seed fungal community.

Use of Biofertilizers as an Effective Management Strategy to Improve the Photosynthetic Apparatus, Yield, and Tolerance to Drought Stress of Drip-Irrigated Wheat in Semi-Arid Environments

Irrigation scheduling, coupled with the use of biofertilizers, constitutes an effective management strategy to overcome soil drought. This study aimed to assess the individual and combined effects of three selected biofertilizers—(R) Bacillus sp. and Bacillus subtilis, (M) native arbuscular mycorrhizal fungi, and (C) compost—on Triticum durum L. The agro-physiological and biochemical traits, along with the soil properties, were evaluated under two different water regimes, 100% crop evapotranspiration (ETc) for the well-watered regime and 30% ETc for the drought-stressed regime under field conditions, using a drip irrigation system. Drought stress (DS) led to significant reductions in the biomass, physiological parameters, and biochemical markers. Furthermore, the application of CM and MR significantly boosted the shoot and root dry weight by 137% and 72%, respectively, under DS compared to the control. Moreover, CM and R resulted in a notable increase of 167% and 130% in the grain and straw yield, respectively, under the same conditions. The normalized difference vegetation index showed improved values in the plants inoculated with MR and CMR, respectively, under DS conditions. Additionally, the soil quality was positively influenced by the application of M and/or R and/or C biofertilizers. These findings provide valuable insights into the intricate soil–plant interactions and the beneficial effects of combined biofertilizers in enhancing wheat’s resilience to drought stress.

Functional Characterization of the Soybean Glycine max Actin Depolymerization Factor GmADF13 for Plant Resistance to Drought Stress.

Abiotic stress significantly affects plant growth and has devastating effects on crop production. Drought stress is one of the main abiotic stressors. Actin is a major component of the cytoskeleton, and actin-depolymerizing factors (ADFs) are conserved actin-binding proteins in eukaryotes that play critical roles in plant responses to various stresses. In this study, we found that GmADF13, an ADF gene from the soybean Glycine max, showed drastic upregulation under drought stress. Subcellular localization experiments in tobacco epidermal cells and tobacco protoplasts showed that GmADF13 was localized in the nucleus and cytoplasm. We characterized its biological function in transgenic Arabidopsis and hairy root composite soybean plants. Arabidopsis plants transformed with GmADF13 displayed a more robust drought tolerance than wild-type plants, including having a higher seed germination rate, longer roots, and healthy leaves under drought conditions. Similarly, GmADF13-overexpressing (OE) soybean plants generated via the Agrobacterium rhizogenes-mediated transformation of the hairy roots showed an improved drought tolerance. Leaves from OE plants showed higher relative water, chlorophyll, and proline contents, had a higher antioxidant enzyme activity, and had decreased malondialdehyde, hydrogen peroxide, and superoxide anion levels compared to those of control plants. Furthermore, under drought stress, GmADF13 OE activated the transcription of several drought-stress-related genes, such as GmbZIP1, GmDREB1A, GmDREB2, GmWRKY13, and GmANK114. Thus, GmADF13 is a positive regulator of the drought stress response, and it may play an essential role in plant growth under drought stress conditions. These results provide new insights into the functional elucidation of soybean ADFs. They may be helpful for breeding new soybean cultivars with a strong drought tolerance and further understanding how ADFs help plants adapt to abiotic stress.

ABA-receptor agonist iSB09 decreases soil water consumption and increases tomato CO2 assimilation and water use efficiency under drought stress

Climate change can alter precipitation patterns, disrupting the natural water cycle and generating drought periods that negatively impact crop yield or plant survival. Novel biotechnological approaches are being developed to face water deficits. Specifically, molecular knowledge of the plant hormone abscisic acid (ABA) can be harnessed to develop genetic and chemical approaches to cope with abiotic stress. ABA receptor agonists are promising molecules that activate ABA signaling on demand and show long-lasting effects, in contrast to the exogenous application of ABA, which has a short half-life. In this work, we studied the effect of the iSB09 agonist on tomato plants grown under drought stress or well-watered conditions. iSB09 treatment induced stomatal closure in tomato through activation of PYL1-like and PYL4-like ABA receptors. Additionally, RNA-seq analyses reveal coordinated upregulation by ABA or iSB09 of the genes encoding enzymes involved in the synthesis of the osmoprotective galactinol and raffinose family of oligosaccharides. Foliar spraying of iSB09 under drought conditions anticipated the regulation of transpiration, promoted drought avoidance and increased water use efficiency in tomato plants. Physiological analysis of agonist-treated plants reveals increased CO2 assimilation and effective quantum yield of the photosystem II under drought conditions in iSB09-treated plants compared to mock-treated. Faster regulation of transpiration at the start of the drought period was achieved by iSB09 treatment, and, as a result, water consumption was reduced compared to mock-treated plants. Overall, the agonist treatment mounts the genome-wide transcriptional response to stress and increases water use efficiency under drought conditions and plant protection.

Performance of ACCase-Resistant and ACCase-Susceptible Phenotypes of Sterile Oat Avena sterilis subsp. ludoviciana (Durieu) Nyman under Drought Conditions in the Greenhouse

Climate change might benefit water-stress-adapted weeds, further impairing their management. To evaluate the impact of soil moisture regimes on the growth and reproductive behaviour of ACCase-resistant and ACCase-susceptible phenotypes of sterile oat (Avena sterilis subsp. ludoviciana (Durieu) Nyman), a greenhouse experiment was carried out in 2020 and 2021. The factors were soil moisture regimes (100% field capacity (FC) as well-watered, 75% FC, 50% FC, and 25% FC) and ACCase-resistant and ACCase-susceptible phenotypes of sterile oat. Increased drought stress conditions reduced the number of tillers per plant by 34, 55, and 83% and the number of seeds per plant by 36, 61, and 89% in the 75% FC, 50% FC, and 25% FC conditions, respectively, compared to the well-watered treatment. Notably, both phenotypes reacted similarly to water stress, with no interactions between the two factors. Regardless of water stress, the resistant phenotypes produced fewer seeds per plant, indicating fitness costs. However, due to their high plasticity, both phenotypes will still produce seeds even when facing severe water stress conditions. Thus, sterile oat is expected to continue infesting crop fields in the near future, but with ACCase-resistant phenotypes being less successful than susceptible ones in the absence of herbicide application.

Physiological and biochemical characteristics of milk thistle (Silybum marianum (L.) Gaertn) as affected by some plant growth regulators.

Milk thistle (Silybum marianum (L.) Gaertn) is a globally and widely used medicinal plant that contains silymarin. This plant has antioxidant, antimicrobial, anticancer, hepatoprotective, cardiovascular-protective, and neuroprotective effects. Plant quality, yield, and phytochemicals, especially silymarin content, change under various conditions like drought stress. Therefore, this research studied plant growth regulators (PGRs) like salicylic acid, spermidine, and brassinosteroid to increase plant tolerance to drought stress. Experimental treatments include different levels of irrigation (25%, 50%, 75%, and 90% field capacity), and foliar spraying including salicylic acid (75 and 150 mg/L), spermine (70 and 140 mg/L), and brassinosteroid (1 and 1.2 μM), separately, and water as a control and a secondary factor. The results revealed that the highest amount of leaf phenolic compounds was observed in the highest drought stress level (25%) and 75 mg/L salicylic acid application. Furthermore, brassinosteroid at different concentrations and salicylic acid (75 mg/L) increased leaf flavonoid content compared to other treatments. In 50% field capacity, foliar application of salicylic acid (150 mg/L) significantly increased seed yield by approximately 75% compared to control under the same stress level. Brassinosteroid application (1 μM) under 75% field capacity significantly increased the seed's taxifolin amount by 159%. Additionally, salicylic acid noticeably increased the silychristin concentration. The concentration of silydianin in the seed has also been increased under drought stress and foliar spraying with PGRs. Compared to the control, using spermidine below 75% field capacity caused an increase in its concentrations by over seven times. The highest silybin A amount was obtained in 50% field capacity and foliar150 mg/L salicylic acid. Taxifolin, silychristin, silydianin, silybinin B, iso-silybinin A, and iso-silybinin B compounds were identified in the seed extract. Generally, foliar spraying using plant growth regulators increased the number of silymarin compounds under drought stress conditions and field cultivation conditions.

Improvement of Yield and Quality of Peanut (Arachis hypogaea L.), Some Enzymatic and Non-Enzymatic Antioxidants Activity in Response to Zn-Nano Fertilizer in Different Irrigation Regimes

ABSTRACT Peanut, as an oilseed, have high nutritional value for humans and livestock and poultry. The seed yield (SY) of peanut decreases under drought stress conditions, and the zinc (Zn) nano-fertilizer can reduce the negative impacts of water deficiency on peanut plants and improves its SY. This experiment carried out as split plot based on randomized complete block design with three replications in Astara, Iran, during the 2018 and 2019 cropping seasons. Three irrigation regimes at 50 mm (IR50), 75 mm (IR75) and 100 mm (IR100) evaporation from class A evaporation pan in main plot and three levels of Zn nano-chelate, including 0.5 g. l−1; (Zn0.5), 1 g. l−1; (Zn1) and 1.5 g. l−1; (Zn1.5) in sub plot, comprised experimental treatments. The results indicated that the highest pod yield (PY), SY, oil yield (OY) and protein yield (PRY) of peanut (3633, 2900, 1582 and 826 kg. ha−1, respectively) were obtained in response to Zn nano-chelate with a dose of 1.0 g. l−1 in IR50 treatment. Nonetheless, under foliar spraying of Zn1 and severe drought stress conditions (IR100) were observed the highest proline (14.84 µmol g−1 FW), superoxide dismutase (53.42 Unit mg−1 proteinmin−1), catalase (72.87 nmol mg−1 proteinmin−1), peroxidase (64.17 nmol mg−1 protein min−1), soluble sugar content (172.04 mg g−1 FW), soluble protein content (114.16 mg g−1 DW) and anthocyanin pigments (11.20 µmol g−1 FW). Generally, application of Zn1 treatment, through increasing antioxidant enzymes activity and non-enzymatic antioxidants, improved peanut SY. Hence, foliar application of Zn nano-chelate could be recommended to enhance peanut yield.

Adaptation of Drought Stress by use of Silicon Element in Wheat (Triticum aestivum L.)

Drought stress is a menacing type of abiotic stress caused by low rainfall, high temperature, etc., where water sparsity condition occurs in soil, affecting the process of plant growth and development. Drought stress has become a serious issue that must be considered before it becomes a significant threat to agricultural production. Wheat is India's second most crucial cereal crop; even its production is affected due to prevailing drought conditions in the fields, which causes many physiological, morphological & biochemical changes in the plant, indirectly affecting yield. Many methods are adopted to improve wheat crop efficiency even under drought-stress conditions, such as releasing resistant varieties, following advanced agronomic practices, using elements, etc. Still, the most recent method is to use the silicon element to mitigate the drought stress conditions in wheat crops. Silicon had not been regarded as an essential plant element; However, when applied to plants, it still promotes proper root growth, provides resistance against many diseases, decreases the abiotic stress effect on plants & increases the crop's growth and yield. So, in recent times, many research experiments have been performed in pots & laboratories where silicon is applied to wheat crops in the form of priming, fertilization & foliar spray in different stages of the crop to know its efficiency. Even silicon is also supplied to wheat crops in the form of nanoparticles. In the end, though, the silicon can be sprayed in any form and prevents the harm that drought stress does to wheat crops. Ultimately, Silicon is helping the wheat crop mitigate drought stress and produce better yields by enhancing its growth.

Silicon and Seaweed Extract Injection into Olive Tree (Olea europaea L.) Trunks Results in the Tree’s Drought Stress Resistance

ABSTRACT Trunk injection applies more nutrients in the correct volume and composition, delivering ideal results with fewer fertilizer treatments under drought-stress conditions. We used a completely randomized block design to examine the effects of trunk injection therapy on the development of drought stress tolerance in olive trees in arid climates. Treatments included seaweed extract (SWE), potassium amino acid chelate (PAC), calcium silicate (CS), and potassium silicate (PS) at five different concentrations: 0.25, 0.5, 1, 2, and 4% for each treatment. Each treatment consisted of four replications – four dry replications for each treatment and four irrigation controls – each receiving weekly irrigation. The findings showed that, in comparison to drought control, trunk injection of PAC at a concentration of 2% enhances the relative water content of leaf and proline and decreases electrolyte leakage (EL) and malondialdehyde (MDA) content. Chlorophyll a, carotenoids, and proline content are all significantly higher in the trunk after CS injection at a 4% concentration than in the control treatment. MDA and EL were also reduced. Injecting PS leads to an increase in proline and photosynthetic pigments. The SWE treatment improved the proline, relative leaf water content, and photosynthetic pigments. To sum up, trunk injection treatments under drought conditions improved plant photosynthetic pigments, increased proline content, prevented relative water content reduction, and prevented an increase in MDA and EL. In conclusion, among the several treatments, the use of 2% PS was the most effective at reducing the adverse effects of drought stress on olive plants.

Cultivating Pharmaceutical Potential: Optimising Triacontanol Application to Enhance Linseed’s Attributes under Drought Stress

Background: Triacontanol (TRIA) has been identified as a potent plant growth regulator, demonstrating significant benefits under various stress conditions. However, its specific impact on Linum usitatissimum L. (flax) under drought stress conditions remains underexplored. This study investigates the effects of TRIA on the growth, physiology, and biochemistry of two flax genotypes subjected to drought stress, aiming to enhance our understanding of its potential as a biostimulant for improving crop resilience and productivity. Objective: The primary objective of this study was to evaluate the effects of different concentrations of TRIA on the growth, physiological, and biochemical responses of two flax genotypes under drought stress conditions. We aimed to determine whether TRIA application could mitigate the adverse effects of drought and enhance plant performance. Methods: This study was conducted using two flax genotypes, G-20888 and G-22186. Plants were grown under controlled conditions and subjected to drought stress by maintaining soil moisture at 50% field capacity. TRIA was applied in three concentrations: 0 M (control), 10^-6 M, and 10^-7 M. A completely randomized design was used with three replications for each treatment. Plant growth parameters, including root length, shoot length, plant height, and shoot fresh weight, were measured. Physiological parameters such as chlorophyll content, relative water content (RWC), and electrolyte leakage were assessed. Biochemical analyses included the estimation of antioxidant enzyme activities (superoxide dismutase, catalase, and peroxidase). Data were statistically analyzed using SPSS version 25.0. Results: TRIA application significantly improved root length, shoot length, plant height, and shoot fresh weight in both flax genotypes under drought stress. For genotype G-20888, root length increased from 5.1 cm (control) to 6.8 cm (TRIA 10^-7 M). Shoot length showed a similar trend, with increases from 8.3 cm (control) to 10.1 cm (TRIA 10^-7 M). In G-22186, plant height increased from 70 cm (control) to 82 cm (TRIA 10^-7 M). Chlorophyll content increased by 15%, and RWC by 18% in TRIA-treated plants compared to controls. Antioxidant enzyme activities were also enhanced, with catalase activity increasing by 25% and peroxidase by 30%. Conclusion: TRIA application significantly mitigated the adverse effects of drought stress on flax genotypes by enhancing growth, physiological, and biochemical parameters. The findings suggest that TRIA could be an effective biostimulant for improving drought tolerance in flax, potentially leading to better crop resilience and productivity.

Assessment of Various Nanoprimings for Boosting Pea Germination and Early Growth in Both Optimal and Drought-Stressed Environments.

One of the main climate change-related variables limiting agricultural productivity that ultimately leads to food insecurity appears to be drought. With the use of a recently discovered nanopriming technology, seeds can endure various abiotic challenges. To improve seed quality and initial growth of 8-day-old field pea seedlings (cv. NS Junior) under optimal and artificial drought (PEG-induced) laboratory conditions, this study aimed to assess the efficacy of priming with three different nanomaterials: Nanoplant Ultra (Co, Mn, Cu, Fe, Zn, Mo, and Se), Nanoplant Ca-Si (Ca, Si, B, and Fe), and Nanoplant Sulfur (S). The findings indicate that nanopriming seed treatments have a positive impact on seed quality indicators, early plant growth, and drought resilience in field pea plants established in both optimal and drought-stressed conditions. Nevertheless, all treatments showed a positive effect, but their modes of action varied. Nanoplant Ultra proved to be the most effective under optimal conditions, whereas Nanoplant Ca-Si and Nanoplant Sulfur were the most efficient under drought stress. After a field evaluation, the examined comprehensive nanomaterials may be utilized as priming agents for pea seed priming to boost seed germination, initial plant growth, and crop productivity under various environmental conditions.

Selection of Barley Genotypes (Hordeum vulgare L.) with High and Stable Grain Yield in Drought Stress Conditions

Selection of Barley Genotypes (Hordeum vulgare L.) with High and Stable Grain Yield in Drought Stress Conditions

The biochemical properties of Satureja species affected by micronutrients, genotype, and locations in drought stress conditions

Medicinal plants, as important sources of secondary metabolites, are used for treating different diseases. It is accordingly pertinent to find methods, which may improve their growth and quality in different conditions including variable stresses. It was hypothesized micronutrients use and suitable genotypes may improve Satureja growth and quality in drought stress conditions. The objective of this study was to investigate the effects of drought stress (irrigating plants each 3 (A1), 6 (A2) and 9 days (A3)), micronutrients (Mn and Cu at 0 (M1), 20 (M2) and 40 mgL−1 (M3)), and field location (Isfahan (F1) and Golpayegan (cooler) (F2), Isfahan province, Iran) on the biochemical properties of different Satureja species including S. bakhtiarica, S. khuzestanica and S. mutica. The experimental treatments significantly affected the measured parameters including nodule number, essential oil, antioxidant activity, proline, Mn and Cu contents, and relative water content. Although Cu and Mn, enhanced plant biochemical properties, especially in M2, in some cases, the two micronutrients, unfavorably affected plant properties in M3. The responses of genotypes were different in the two research fields and S. bakhtiarica performed better in F2. The highest essential oil was resulted by A2. The two micronutrients improved plant responses in drought stress by increasing nodule number (148 %), and essential oil yield (143 %) and decreasing plant relative water content and conserving plant water. The use of Mn and Cu is recommendable for planting Satureja species in drought stress conditions, as the two nutrients may enhance plant tolerance by increasing proline production and antioxidant activities.

Sunflower grain yield and oil content affected by zinc fertilization and genotype in drought stress conditions

ContextDrought stress is a major environmental factor limiting sunflower (Helianthus annus L.) growth and productivity, worldwide. Although there has been research on the use of zinc (Zn) to alleviate drought stress in sunflower, more has yet to be indicated on how Zn may affect sunflower yield and biochemical properties in drought stress conditions as the objective of the present research. MethodsThe field experiment was a split plot on the basis of a complete randomized block design with 18 treatments and 3 replicates conducted in the province of Fars, Iran, in 2018. The experimental treatments of drought (main plots) including irrigating at 70 (control, S1), 105 (mild, S2) and 140 mm (severe, S3) evaporation from the evaporation pan and the sub plots (factorial arrangement) of sunflower genotypes (Shams and Barzegar) and Zn fertilizer (ZnSO4) at 0, 40 and 70 kgha−1 were tested. Different sunflower, growth, yield and biochemical parameters were determined. ResultsStress significantly affected leaf area index (LAI), tray diameter (TD), grain weight (GW), infertile seeds (I), water use efficiency (WUE) and proline (Pr), and genotype was significant on LAI, TD, number of grains per tray (NGT), GW, WUE, and grain protein (PP). However, Zn significantly increased LAI, PP, GW and WUE by 50, 5.9, 35 and 32 %, respectively. ConclusionZn fertilization can alleviate the unfavourable effects of drought stress on sunflower yield and biochemical properties by improving plant growth (LAI), yield (grain weight), and physiology (water use efficiency and protein percentage), and genotype is a determining factor.

Volatile compositions and glandular trichomes of Zataria multiflora in different phenological stages under normal and drought stress conditions

BackgroundZataria multiflora Boiss. is a medicinal and aromatic plant from the Lamiaceae family. It is extensively used in Iranian traditional medicine, mostly as a replacement for Thyme species. This study was focused on the analysis of chemical composition and the distribution and types of trichomes of Z. multiflora grown under different conditions. Equilibrium headspace analysis in combination with GC-FID-MS was used to identify volatile compounds released by aerial parts of Z. multiflora in development stages of 50 and 100% flowering under normal and drought-stress conditions.ResultsThe main constituents were p-cymene (20.06–27.40%), γ-terpinene (12.44–16.93%), and α-pinene (6.91–16.58%) and thymol (8.52–9.99%). The highest content of p-cymene (27.40%) and thymol (9.99%) was observed in the 50% flowering stage at the 90% field capacity, while the maximum γ-terpinene (16.93%) content was recorded in the 100% flowering stage under normal conditions. Using the SEM method, it was found that peltate glandular and non-glandular trichomes are distributed on the surface of the leaf, stem, and outer side of the calyx. However, capitate trichomes only are detected on the stem and calyx in the 100% flowering and beginning of blooming stages, respectively. The type and structure of trichomes do not vary in different development stages, but they differ in density. The highest number of leaf peltate glandular trichomes was observed in the vegetative and beginning of blooming stages at 50% and 90% field capacity, respectively. Non-glandular trichomes of the stem were observed with high density in both normal and stress conditions, which are more densely in 90% field capacity.ConclusionsSince this plant has strong potential to be used in the food and pharmacological industries, this study provides valuable information for its cultivation and harvesting at specific phenological stages, depending on desired compounds and their concentrations.

Characterization of cassava (Manihot esculenta Crantz) resistant to drought stress as a result of selection using PEG 6000

Cassava is a source of carbohydrates that grows in tropical areas. The largest cassava producing province in Indonesia is Lampung, and Central Lampung Regency is the main cassava production center in Lampung Province. Plant responses in response to drought vary, such as plants wilting, stomata closing, and chlorophyll content decreasing. The drought stress inducer used in this research was polyethylene glycol. Drought-sensitive cassava will show reduced growth, while tolerant plants will obtain new genotypes that are resistant to drought stress conditions. The aim of this research was to determine the drought tolerant concentration of PEG 6000; distinguish between chlorophyll a, b, and total; and determine the differences in stomata density and stress tolerance index in cassava treated with PEG 6000 and the control. The PEG 6000 treatment consisted of 5 concentration levels, namely 0%, 10%, 20%, 30%, and 40% with each treatment repeated 5 times. The tolerable concentration of PEG 6000 is 40%. The higher the concentration of PEG 6000, the lower the chlorophyll a, b and total content. As the concentration of PEG 6000 increases, the stomata density increases. The stress tolerance index of cassava is categorized into medium tolerant at concentrations of 10% and 20%, and tolerant at concentrations of 30% and 40%.