Levels Of Drought Stress Research Articles

Effects of drought stress on growth and flavonoid accumulation of fish mint (Houttuynia cordata Thumb.)

Fish mint (Houttuynia cordata Thumb.) is a popular medicinal plant grown primarily because of its pharmacological values. Drought stress has on the relationship between growth and physio-biochemical changes, especially flavonoid content. The impacts of various drought stress conditions on the fish mint development were investigated, including 85% of field capacity (FC), 75% FC, 65% FC and 55% FC in 14, 21 and 28 days. Agronomic, physiological and biochemical parameters during the growth of fish mint plants under drought stress conditions were assessed. According to the results of variance analysis, drought stress results in a considerable drop in the measured parameters (shoot height, leaf number, leaf area and fresh weight). Similarly, all of the above-mentioned parameters were also decreased with increasing the number of drought days. Furthermore, drought period and level caused a drop in respiration, photosynthetic rate, chlorophyll and starch content. The concentration of carotenoids and flavonoids, on the other hand, increased dramatically as drought stress periods and levels increased. In comparison to the control, the drought treatment (65% FC) in 7 days maintained the growth rate and increased flavonoid accumulation from 2.42 mg to 3.04 mg. These findings might give a scientific foundation for growing fish mint plants under drought stress to boost flavonoid content.

Effects of post-silking drought stress degree on grain yield and quality of waxy maize.

Drought stress (DS) induced by post-silking have a major impact on the yield and quality of maize. In this study, the effects of different degrees of DS after pollination on grain filling, starch and protein metabolism, and functional properties were investigated using two waxy maize cultivars as materials. The levels of DS that were investigated were 'mild water stress' (WS1), 'moderate water stressed' (WS2), and 'severewaterstressed' (WS3). Drought stressdecreased grain fresh weight, dry weight, and moisture content in both cultivars during grain filling, and reduced kernel number, kernel weight, and grain yield at maturity. The effect on grain development and yield formation gradually increased with drought aggravation. The water stress (WS) treatment downregulated the enzymatic activities related to starch biosynthesis during grain-filling process, accompanied by a decrease in soluble sugar and starch deposition. The WS treatment increased the enzymatic activities involved in protein synthesis during grain-filling process, thereby increasing the protein content of grains. On average, WS2 and WS3 treatments reduced the pasting viscosities and increased the gelatinization temperatures of grains, with WS3 having the greatest effect. However, the changes of setback viscosity, gelatinization enthalpy, retrogradation enthalpy, and retrogradation percentage under WS treatment were inconsistent in both cultivars. Pearson correlation analysis showed that starch content was negatively correlated with gelatinization temperatures and positively correlated with pasting viscosities in both cultivars. However, grain pasting and gelatinization propertieshave opposite correlations with protein content and starch content. These findings suggest that post-silking DS regulated the grain-filling process and starch and protein biosynthesis, which influenced grain yield and quality. © 2022 Society of Chemical Industry.

Nitrification inhibitor application at stem elongation stage increases soil nitrogen availability and wheat nitrogen use efficiency under drought stress

ABSTRACT One of the practices which could mitigate the negative effects of drought stress is ammonium nutrition. Nitrification inhibitor (DMPP) can keep ammonium concentrations high in the soil for several weeks. Although there are contradictory reports regarding the priority of NH4 + uptake and its toxicity effects on wheat, it is necessary to understand better how to apply DMPP to increase drought tolerance without any negative effects. The field experiment was conducted using 15N trace technology. The fertilizers treatment included (15NH4)2SO4 and (15NH4)2SO4 with DMPP at four drought stress levels. Available soil mineral nitrogen was measured, as well as yield components and 15N recovery. The results showed that DMPP application at full irrigation and moderate drought stress caused an increase in grain yield of 13% and 10%, respectively. DMPP application at full irrigation, moderate and severe drought stress caused a significant increase in nitrogen use efficiency of 19%, 11%, and 17%, respectively. It seems DMPP application at the stem elongation stage, promoted NH4 + assimilation and transfer to the shoots, which has created relative resistance to drought stress conditions. In conclusion, it is recommended that farmers use DMPP at stem elongation to avoid wheat yield reduction and nitrogen recovery under drought stress.

Wild Vicia Species Possess a Drought Tolerance System for Faba Bean Improvement.

Faba bean (Vicia faba L.), a drought-sensitive crop, is drastically affected by drought stresses compromising its growth and yield. However, wild relatives of faba bean are considered a reservoir of potential genetic resources for tolerance against abiotic stresses. This study was conducted to characterize wild relatives of faba bean for identification of a specific tolerance system required for its improvement against drought stress. The study focused on physiological, biochemical, and anatomical responses of wild Vicia species under drought stress conditions. The experiment was carried out under various levels of drought stress imposed through different field capacities (FC) which included 80% FC ie (well-watered condition), 55% FC (moderate stress), and 30% FC (severe stress). When compared to plants grown in a control environment, drought stress significantly reduced the studied physiological attributes including soluble sugars (21.3% and 15.8%), protein contents (14.7 and 14.6%), and chlorophyll (8.4 and 28.6%) under moderate (55% FC) and severe drought stress (30% FC), respectively. However, proline content increased by 20.5% and 27.6%, peroxidase activity by 48.5% and 57.1%, and superoxide dismutase activity by 72.6% and 64.8% under moderate and severe stress, respectively. The studied anatomical attributes were also affected under drought stress treatments, including diameter of stem xylem vessels (9.1% and 13.7%), leaf lower epidermal thickness (8.05% and 13.34%), and leaf phloem width (5.3% and 10.1%) under moderate and severe stress, respectively. Wild Vicia spp. showed better tolerance to water-deficit conditions as compared to cultivated Vicia L. The observed potential diversity for drought tolerance in wild Vicia spp. may assist in improvement of faba bean and may also help in understanding the mechanisms of adaptations in drought-prone environments.

A Comparison of the Effects of Rhizophagus Intraradices, Serendipita Indica, and Pseudomonas Fluorescens on Soil and Zea Maize L. Properties under Drought Stress Condition

Drought is one of the most critical environmental stresses that reduce agricultural production. This study aimed to examine the effects of individual and simultaneous inoculation of Rhizophagus intraradices, Serendipita indica, and Pseudomonas fluorescens on the physical properties of soil and the growth parameters of single cross 704 maize under three levels of drought stress (80%, 50%, and 25% available water). It was found that Rhizophagus intraradices significantly increased soil hydrophobicity at all levels of drought stress, as did Serendipita indica at the second and third levels. Pseudomonas fluorescens, on the other hand, decreased soil hydrophobicity at all drought levels. At the optimum moisture level, individual inoculations of the investigated microorganisms did not significantly affect mean weight diameter, but all studied microorganisms increased mean weight diameter as drought stress increased. Additionally, inoculating plants with Rhizophagus intraradices at all levels of drought stress significantly increased the dry and fresh weight of shoots. Nevertheless, inoculating plants with Rhizophagus intraradices and Pseudomonas fluorescens at all levels of drought stress led to a significant increase in plant shoot height. Plant shoot potassium concentrations were significantly reduced by individual inoculation of Pseudomonas fluorescens and Serendipita indica under drought stress at the first and third levels. However, at all drought stress levels, inoculating plants with Rhizophagus intraradices significantly increased phosphorus concentrations in the shoots. Based on the results of this study, simultaneous insemination of maize with Rhizophagus intraradices and Serendipita indica was the most effective microorganism treatment for reducing the harmful effects of drought stress and improving soil properties.

Effects of drought stress on flowering soybean physiology under different soil conditions

Soybean is highly sensitive to drought stress during its flowering period. Heinong84 (HN84) and Hefeng46 (HF46) were planted in clay loam, silty loam, and sandy clay. We studied the effects of drought stress on the content of membrane lipid peroxides in flowering soybean leaves, the activity of antioxidant enzymes, and the activity of key enzymes of nitrogen metabolism under different soil conditions. Our results showed that soybean had clear physiological responses to drought stress. With increasing drought stress, the malondialdehyde, glutathione reductase, and glutathione peroxidase levels in soybean leaves increased continuously. Superoxide dismutase, peroxidase, glutamine synthase, and glutamate synthase levels increased with drought stress, reaching a maximum under moderate drought stress and then decreased; nitrate reductase activity decreased continuously. Under the condition of sufficient water, the performance of soybean in the three soils is almost the same, but there are differences under drought stress; particularly, soybean grown in clay loam shows the strongest drought resistance. In summary, the physiological state of soybean is easily affected by drought stress, which varies greatly among different cultivars and in different soil types.

Potassium and Salicylic Acid Fertilization Effects on Productive and Qualitative Traits of Cyamopsis Tetragonoloba Under Drought Stress

Drought is one of the main factors of abiotic stress in the agricultural world. The purpose of this study was to assess the impact of drought on Guar (Cyamopsis tetragonoloba (L.) Taub.) Plant and finally improve the productivity of the grain yield and the qualitative characteristics in case of high dryness by spraying salicylic acid and potassium. This experiment was performed as a plot divided into strips in a randomized complete block with three replicates over two years in Kerman, Iran. Experimental treatments include drought stress at three levels, salicylic acid (three levels) by foliar application, and potassium (two levels). Guar is resistant to high drought stress and has had a significantly improved yield. Applying 100 kg/ha of potassium in combination with a foliar spray with salicylic acid produced the highest potassium and cereal protein content. The results clearly demonstrated that potassium and salicylic acid application at all levels of drought stress and dry conditions had a positive effect on cereal yield and quality features.

Salicylic Acid Spraying Affects Secondary Metabolites and Radical Scavenging Capacity of Drought-Stressed Eriocephalus africanus L.

Drought is among the most common abiotic stresses that significantly influence plants’ growth and metabolic activities. In this study, Eriocephalus africanus L. (Asteraceae) was exposed to three levels of drought stress (irrigation with 75, 50, and 25% field capacity), together with foliar spraying of a plant hormone, salicylic acid (1, 2, and 3 mM SA), to observe the effect of drought stress and SA on its secondary metabolites. These growing conditions efficiently affected its total flavonoid and polyphenol contents (TFC and TPC, respectively). TFC and TPC increased by 53% and 35%, respectively, in stressed plants. Consequently, the radical scavenging activity improved by 140%. UPLC-ESI-MS/MS profiles of the extracts of control and stressed plants were assessed. Among identified polyphenols, 3,4-dicaffeoylquinic acid predominated in both samples, although it was detected in a greater percentage of stressed plants. Essential oils hydro-distilled from the plants showed a higher yield (1.05 ± 0.03% v/w) in stressed plants. Artemisia ketone prevailed in all oil samples’ GC/MS chromatograms, with a higher yield (42%) recorded in stressed plants. In conclusion, drought stress and SA spraying triggered the production of phenolic and essential oil components and increased the radical scavenging activity of E. africanus. Thus, agricultural conditions are optimized to provide a continuous supply of plant materials with appropriate amounts of bioactive constituents for economic industrialization.

Uncoupling differential water usage from drought resistance in a dwarf Arabidopsis mutant.

Understanding the molecular and physiological mechanisms of how plants respond to drought is paramount to breeding more drought-resistant crops. Certain mutations or allelic variations result in plants with altered water-use requirements. To correctly identify genetic differences which confer a drought phenotype, plants with different genotypes must be subjected to equal levels of drought stress. Many reports of advantageous mutations conferring drought resistance do not control for soil water content (SWC) variations across genotypes and may therefore need to be re-examined. Here, we reassessed the drought phenotype of the Arabidopsis (Arabidopsis thaliana) dwarf mutant, chiquita1-1 (chiq1-1, also called constitutively stressed 1 (cost1)), by growing mutant seedlings together with the wild-type to ensure uniform soil water availability across genotypes. Our results demonstrate that the dwarf phenotype conferred by loss of CHIQ1 function results in constitutively lower water usage per plant, but not increased drought resistance. Our study provides an easily reproducible, low-cost method to measure and control for SWC and to compare drought-resistant genotypes more accurately.

Integration of landscape-level remote sensing and tree-level ecophysiology reveals drought refugia for a rare endemic, bigcone Douglas-fir

For forest species, areas buffered from the rapidly increasing climate stressors and patterns of disturbance — i.e., climate change refugia — are important targets for conservation and protection. Here, we present a novel field survey and remote sensing approach to identification of fine-scalefunctional drought refugiafor bigcone Douglas-fir (Pseudotsuga macrocarpa)-dominated forests. This rare species has been exposed to climate change-exacerbated drought conditions over the past two decades; yet, little is known about its responses to recent drought and how these drought responses vary across local environmental gradients and interact with recent record wildfire seasons. We combined a remote sensing analysis of vegetation condition with field surveys and physiological measurements to better understand bigcone Douglas-fir responses to recent climate trends. We also identified 444 stands exhibiting relatively low response and high resilience to drought — i.e., potential drought refugia. We found that low elevation stands and those in south-facing aspects generally experienced greater levels of seasonal and interannual drought stress. This trend was more pronounced for stands that experienced fire (2007 Zaca Fire) prior to the drought, suggesting that wildfire can increase the importance of topographic mediation of climate conditions in bigcone Douglas-fir forests. Elevation and aspect also interacted to affect physiological acclimation to seasonal drought conditions, with low elevation north-facing sites in particular experiencing a favorable combination of greater climate buffering and greater drought resilience, suggesting that these sites may be important refugia for bigcone Douglas-fir at low elevations. Furthermore, we found that the relationships between topography and drought response were weaker in more coastal sites, possibly due to maritime climate buffering in these sites. Altogether, these results illustrate how topographic mediation of regional drought conditions is critical for the persistence of this rare species in drought and fire-prone landscapes, and offer important insights for the conservation and restoration of this iconic species.

Effect of metal oxide nanoparticles on the activity of glutathione reductase, catalase, peroxidase and superoxide dismutase in plants under drought

AbstractThere is no accurate information on the effect of metal oxide nanoparticles (MO NPs) on plant enzymatic activities (EAs) under drought stress (DS). The aim of this work was to study the effect of MO NPs on the EAs of Agropyron cristatum (L.) Gaertn and Sanguisorba officinalis L. under DS. Foliar spray of silver oxide (AgO), iron oxide (FeO), zinc oxide (ZnO) and cadmium oxide (CdO) at levels of 30, 60, 90 and 120 mg L−1 were used on plant aerial parts under DS levels of 25–100% field capacity (FC). Glutathione reductase (GR), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) were measured after 2 weeks of the experiment. The EAs changes varied depending on the plant species, levels of DS, types and levels of NPs. Application of 30–60 mg L−1 MO NPs under 25–50% FC significantly reduced EAs, especially in S. officinalis (P < 0.01). Higher concentrations of MO NPs significantly increased EAs. Decreases in CAT (20.90%, 18.80%), POD (21.30%, 17.67%) and SOD (23.14%, 16.88%) were observed using 60 mg L−1 ZnO NPs under 25–50% FC in S. officinalis and A. cristatum, respectively. High concentrations of CdO NPs (90–120 mg L−1) increased EAs (max. = 24.0%) in both species under 25% FC.

The evaluation of drought-tolerance rice genetic resources

About 70% of the rice consumed in Ghana is imported. The state of self-insufficiency in rice production can be attributed to the lack of adequate or continuous water supply. Rice, being an aquatic plant, is not tolerant to drought, which is known as the most threatening abiotic factor causing as much as 64% yield reduction. Therefore, this study was conducted to identify drought-tolerance genotypes among 24 rice collections and to estimate their heritability. A total of 24 traits were assessed in this study, and three treatments were applied, including stress free, mild stress, and severe stress, each of which involved three replications. The results showed that most of the parameters under investigation, including panicle length, fertile panicle rate, shoot, and root dry weight, and maximum root depth, decreased considerably as the level of drought stress increased. In addition, five of the accessions showed considerable tolerance to drought, eight accessions were high yielding, and eight accessions combined high yields and drought tolerance. The study concluded that 80% of the rice accessions offer promising lines to be used as parents in the development of drought-tolerant varieties and in genetic improvement programs aimed at such a purpose. The study recommended that molecular studies and morphological characterization should be done on the collections to understand their genetic makeup, similarities, and differences.

Comparative Physiology and Antioxidant Response of Grasspea (Lathyrus sativus L.) Seedlings under the Iso-osmotic Potential of Salinity and Drought Stress

Aims: This study's objective was to determine how early-stage grass pea seedlings will respond to salinity and drought stress with iso-osmotic potential, emphasising ROS-scavenging enzymes.
 Study Design: Completely randomized design.
 Place and Duration of Study: Laboratory studies on the grass pea varieties BK-14 and Pratik were carried out in the academic years 2017–2018 and 2018–2019 at the Department of Plant Physiology, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India.
 Methodology: Sodium chloride and PEG 6000 solutions with iso-osmotic potentials of -0.2, -0.4, and -0.8 MPa were used to study salinity's effects and drought stress. The experiment was conducted in sand culture using modified Hoagland solution under diffused light, at a temperature of 22°C and an approximate relative humidity (R.H.) of 80±1%.
 Results: Results indicated that drought stress was found to produce more adverse effects on seedling dry weight and lipid peroxidation in comparison with iso-osmotic potential of salinity stress. Variety BK-14 was found to be more tolerant than Pratik for seedling dry weight at the highest intensity of drought stress. The data further indicated that drought- induced more accumulation of phenol in the leaf as well than iso-osmotic salinity stress. The activities of four ROS scavenging enzymes (viz, superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and catalase) in leaves mostly showed a sigmoidal pattern of changes under varying levels of both stresses. Comparative analysis indicated that Pratik registered higher activities of two peroxidases, viz, GPOX and APX, under higher levels of drought stress while BK 14 registered higher activities under salinity stress. However, BK-14 was found to register a higher increase in SOD activity at the most intense level of salinity and drought stress as compared to Pratik.
 Conclusion: In the present experiment, it was discovered that BK-14 was generally more tolerant than Pratik for seedling growth under the utmost level of stress. This may be explained by the stronger antioxidative mechanism it exhibited in the present experiment under the conditions of the maximum stress, as generated by both enzymatic and non-enzymatic components.

Effect of PEG-simulated Drought Stress on Seed Germination of Three Medicinal Liquorice (Glycyrrhiza) Species

Background: Glycyrrhiza is an important medicinal plant that has been in shortage in recent years because of high demand and exhaustive harvesting. Investigating the drought tolerance of liquorice species can inform the artificial cultivation of liquorice under different water conditions and help address the shortage. Methods: Seeds of G. uralensis, G. glabra and G. inflata were treated with different concentrations of polyethylene glycol (PEG)-6000 solutions to simulate different levels of drought stress. The germination process germination rate, germination index, vigour index, stress tolerance index and recovery germination percentage of seeds were measured. Drought tolerance was evaluated using the membership function. Result: Low concentrations of PEG promoted the seed germination of G. glabra and G. inflata, whereas high concentrations inhibited the seed germination of all three plants. The degree of inhibition increased with increasing PEG concentration. Under mild PEG stress, the drought tolerance of G. uralensis was highest and that of G. glabra was the lowest. However, under severe PEG stress, the drought tolerance of G. glabra was the highest and that of G. uralensis was the lowest. Therefore, seeds of G. uralensis should be sown in relatively moist soil and those of G. glabra in relatively arid soil.

Efficacy of biological agents and fillers seed coating in improving drought stress in anise.

Many plants, including anise, have tiny, non-uniform seeds with low and light nutrient reserves. The seeds also show a weak establishment, especially under stressful conditions where their accurate planting in the soil and optimal yield are tough. This study sought to improve anise seeds’ physical and physiological characteristics under drought stress. To this end, two factorial experiments under laboratory and greenhouse conditions were performed in a completely randomized design with 4 and 3 replications, respectively. Five levels of seed inoculation (inoculation with T36 and T43 of Trichoderma harzianum, and CHA0 and B52 of Pseudomonas fluorescent, and non-inoculation which means that control seeds were not treated with microbial inoculant), three levels of coating (K10P20, K10P10V5, and non-coating), and three levels of drought stress (0, –3, and –6 bars) were considered as the factorial experiment [vermiculite (V), kaolin (K), and perlite (P) numbers refer to the amount of material used in grams]. The laboratory experiment revealed that the combined treatments of bio-agents with coating increased the physical and germination characteristics of anise seeds compared to the control treatment. The greenhouse experiment showed that drought stress reduced the initial growth indices. Still, the combination treatments of biological agents and coating (fillers) could alleviate the destructive effects of drought stress to some extent and improve these indices. The best treatment was provided by T36 and K10P20 in both experiments, which significantly increased morphological indices.

Conferring of drought tolerance in wheat (Triticum aestivum L.) genotypes using seedling indices.

Wheat is the most widely grown and consumed crop because of its economic and social benefits. This crop is more important globally for food and feed, and its productivity is particularly vulnerable to abiotic factors. In this study, 40 wheat genotypes were studied to access the drought tolerance level using completely randomized design (CRD) in 250 ml disposable cups through morpho–physiological attributes at seedling stage. The wheat germplasm was tested under normal and two drought stress level D1 (50% field capacity) and D2 (75% field capacity) for different seedling attributes such as germination percentage (GP), chlorophyll content (CC), shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), seedling fresh weight (SDFW), shoot dry weight (SDW), root dry weight (RDW), relative water content (RWC), root/shoot ratio (RS), and seedling dry weight (SeDW). The results of analysis of variance (ANOVA) and spider analysis indicate that significant amount of genetic variation was present and behavior of studied germplasm showed different behavior in different environment. The correlation analysis showed that root length has significantly positive association with root/shoot ratio, dry weight, and fresh weight while negatively correlated with shoot length and relative water content. Based on the positively associated traits, the studied genetic material would improve genetic gain for drought tolerance. The multivariate analysis showed that out 13 principal components only five PCs were significant and has eigenvalue > 1, cumulatively showed 82.33, 83.07, and 97.34% of total variation under normal, D1 and D2 conditions, respectively. Significantly, the result of spider graph and multivariate analysis showed that genotypes G47, G48, G65, G68, and G80 performed well in all drought stress conditions and considered as drought-tolerant genotypes. The best performing genotypes can be used in future breeding programs. The selection on the bases of studied attributes is effective for development of drought-tolerant and high-yielding varieties for sustainable food security.

Response of Bermudagrass Grown in Different Soil Media to Drought Stress

Bermudagrass is one of the most commonly used warm-season turfgrasses worldwide. In the present study, the tolerance to drought stress by applying farmyard manure and biological seed coating preparations containing Trichoderma harzianum, Bacillus subtilis and Bacillus megaterium in bermudagrass were assessed. Seeds of Gobi (registered cultivar) were used as plant material. Gobi were planted in 2 different growing media (A = garden soil + river sand + peat, B = garden soil + river sand + farmyard manure). Uncoated grass seeds were sown in the A group growing medium, while coated seeds were sown in the B group growing medium. As the coating material, which is a new generation seed coating preparation containing Trichoderma harzianum, Bacillus subtilis and Bacillus megaterium, was preferred. To create drought stress [T0 (0), T1 (25%), T2 (50%) and T3 (75%)], 4 doses of irrigation regimes were determined. The traits of clipping yield, shoot dry weight, root dry weight, leaf burning and turfgrass quality were all affected by levels of drought stress. However, farmyard manure and seed coating mitigated the adverse effects of drought stress.

FOLIAR SUPPLEMENTATION OF PROLINE AND GLYCINE BETAINE IMPROVES DROUGHT TOLERANCE IN MEDICINAL PLANTS (Lavandula dentata and Plantago ovata)

One of the most common environmental constraints with adverse impacts is the drought stress which is rapidly increasing due to the intensive usage of water resources. It has been reported to affect and limit plant growth and development. A pot experiment was conducted at Botanical garden University of Balochistan, Quetta to explore the impact of foliar application of Osmoprotectant i.e., Proline (PRO; 2 mM), Glycine Betaine (GB; 1 µM) in mitigating the drought stress in Plantago ovata and Lavandula dentata. Fifteen days seedlings were subjected to three levels of drought stress i.e., Quarter Field Capacity (QFC), Half Field Capacity (HFC) and Full Field Capacity (FFC) and after 10 days of drought plants were foliarly supplemented with Pro and GB. Plants were harvested after 1 week of foliar treatment and analyzed for the accumulation of essential nutrients i.e., (Nitrate, Calcium, Potassium, Zinc and Magnesium) under drought stress. Foliar supplementation of GB and Pro, improved nutrient status under drought stress thereby improving plants tolerance to drought stress. Therefore, foliar supplementation of GB and Pro can be recommended to plants especially medicinal plants to withstand and mitigate the impacts of drought stress effectively.

Morpho-physiological responses of iaa9 tomato mutants to different levels of PEG simulated drought stress

Abstract. Suminar E, Budiarto R, Nuraini A, Mubarok S, Ezura H. 2022. Morpho-physiologicalresponsesof iaa9 tomato mutants to different levels of PEG simulated drought stress. Biodiversitas 23: 3115-3126.This study aimed to analyze the morphological and physiological responses of iaa9 mutants and its WT-MT to different levels of drought stress in in vitro growing medium. This study applied a completely randomized design with two factors, i.e., tomato genotypes and polyethylene glycol (PEG) - induced drought stress levels. The factor of varieties consisted of three levels, i.e., WT-MT as control (G1), iaa9-3(G2), and iaa9-5 (G3). The factor of PEG-induced drought stress also consisted of four levels, i.e., 0% PEG as control (PEG0), 5% PEG (PEG5), 10% PEG (PEG10), and 15% PEG (PEG15). The results observed 12 weeks after culture showed the variations of the morpho-physiological response of WT-MT and mutant genotypes to PEG-induced in vitro drought stress. The WT-MT showed a higher reduction in plantlet height, root number, and root length than mutants under severe drought conditions. The plantlet fresh and dry weight of iaa9-3and iaa9-5were higher than its WT-MT under no drought conditions. The total chlorophyll content of WT-MT was lower than iaa9-5due to the significant gain of chlorophyll-b on that mutant rather than its WT-MT. However, the analysis of principal components and correlation revealed the reduction of morphological size and leaf pigment content in response to drought stress, irrespective of genotype factor. These results suggest that in vitro selection techniques using PEG is useful for the initial screening of drought-tolerant tomato.

Arbuscular mycorrhiza and vermicompost alleviate drought stress and enhance yield, total flavonoid concentration, rutin content, and antioxidant activity of buckwheat (Fagopyrum esculentum Moench)

The use of root symbionts and vermicompost as powerful natural tools is advised in stress conditions. To study the effect of vermicompost and mycorrhizal fungi on some phytochemicals and functional traits of buckwheat under drought stress, a greenhouse experiment was conducted. Three levels of drought stress: D0 (100% Field Capacity: FC), D1 (75% FC), and D2 (50% FC), two levels of mycorrhizal inoculation: M0 (without) and M1(with), and two levels of vermicompost V0 (without) and V1 (with) were used. Vermicompost significantly enhanced seed yield and aerial parts biomass. The highest grain yield (4.97 g dry weight per pot) and aerial parts biomass (40.3 g fresh weight per pot) were obtained in D0V1. The use of mycorrhiza was mainly effective on phytochemical parameters. Moderate levels of drought stress (D1: 75% FC) increased total phenols (33.6 mg gallic acid/g dry weight) and flavonoids (38.3 mg rutin/g Dry weight). Rutin content ranged from 16.24 to 32.5 mg/g dry weight that the highest content being in D1V1M0. Phenolic, flavonoid, and rutin content are correlated with higher antioxidant properties. This increase showed that mycorrhiza and vermicompost act as moderators and elicit to produce metabolites. Simultaneous use of M and V increased nitrogen, phosphorus, and potassium uptake. Cluster analysis classified the treatments into three groups with a higher impact of drought stress. According to Principal component analysis (PCA) FWH, Rutin, TFC, TPC, SS, and IC50 were affecting dimensions. The results showed that drought stress up to 75% FC (D1) can be used in buckwheat.