Membrane Stability Index Research Articles

Physiological and Biochemical Evaluations for Identification of Drought Tolerance Potential in Doum Palms (Hyphaene Compressa) under Water Deficit Treatment

There is an increasing concern over global warming, which has changed climate and weather patterns resulting in adverse abiotic situations such as drought stress to crop plants and the general vegetation area. This has posed a threat to food security and ecosystem structure, thus it's needed to identify resistant cultivars that can survive the propagation stress. Three (3) varieties (H1, H2, and H3) of Doum palms were subjected to water regimes: sufficiently irrigated, moderate, and severe water shortage conditions for 65 days to assess the drought adaptation ability. Findings revealed that the water status of the plant was noticeably affected by water shortage in all the studied genotypes. Drought stress imposed for 65 days significantly reduced (P ≤0.05) the physiological and biochemical characteristics of the experimental Doum plant, such as relative leaf water content (RLWC), membrane stability index (MSI), starch content, and a relative decrease in chlorophyll content. Water stress induced a significant (P ≤0.05) increase in leaf proline, total soluble sugar (TSS), total free amino acid (TFAA), and glycine betaine. The findings, therefore, present the first step in understanding how doum palms react to harsh water conditions. Physiological and biochemical characteristics such as RLWC, MSI, leaf proline, TSS, TFAA, glycine betaine, and starch content are indicators when prospecting for drought tolerance doum palms.

Genome-wide identification of plasma-membrane intrinsic proteins in pumpkin and functional characterization of CmoPIP1-4 under salinity stress

Plasma membrane intrinsic proteins ( PIPs ) play a crucial role in the salinity and drought tolerance of plants. PIPs operate as vital water conduits for regulating water homeostasis during salt stress. Pumpkin is an important Cucurbitaceae crop, and no research on PIPs in pumpkin has been carried out. The current study, presents the first genome-wide characterization of the PIP gene family and functional characterization of CmoPIP1–4 with knockout mutants in pumpkin. According to their phylogeny, 21 CmoPIP genes have been identified and divided into 2 subgroups: CmoPIP1s and CmoPIP2s . Functional studies on their NPA motifs, ar/R filter, and Froger's positions predicted that these CmoPIP proteins would be substrate specific. The CmoPIP1s expression was found to be responsive to salt stress in leaves and roots. CmoPIP1–4 plays an important role in the salt stress tolerance of pumpkin, and the overexpression of CmoPIP1–4 confers salinity tolerance to yeast. However, hyper sensitivity to salt was observed in CmoPIP1–4 CRISPR plants phenotypically (weaker health, lower relative water contents and reduced photosynthetic activities), physiologically (higher Na + /K + ratios, malondialdehyde, ROS and membrane stability index, lower the contents of proline, glycine betaine and also decreased antioxidative enzyme activities), and molecularly (lower expression levels of salt-associated genes CmoSOS1 , CmoHKT1;1 , CmoNHX4 , and a lower expression levels antioxidative genes CmoSOD1/2, CmoPOD1/2 and CmoCAT1/2 ). This study highlights that CmoPIP1–4 is a key player in the stress-signaling pathway in pumpkin plants and could be valuable for developing stress-resistant cucurbit crops in the future. • Twenty-one plasma membrane intrinsic proteins ( PIPs ) were genome-wide characterized in Cucurbita moschata . • Salinity stress decreases the expression of most CmoPIPs . • Overexpression of CmoPIP1-4 conferred salt tolerance in yeast. • A salt-sensitive phenotype was observed after the CmoPIP1-4 knockout in pumpkin roots.

Methyl Jasmonate Alleviates the Deleterious Effects of Salinity Stress by Augmenting Antioxidant Enzyme Activity and Ion Homeostasis in Rice (Oryza sativa L.)

Methyl jasmonate (MeJA) is a potent player that fine-tunes growth and developmental activities under salinity stress. In this study, we investigated the influence of MeJA on two rice cultivars (NJ9108 and XD22) subjected to different salinity stresses. Following stress treatment, reduction in the water use efficiency, relative water contents, and membrane stability index in both cultivars were observed, whereas MeJA treatment partially alleviated the negative effects. MeJA treatment significantly increased the maximum photochemical efficiency (Fv/Fm) and electron transfer to photosystem II (Fv/Fo). Under salinity stress, MeJA treatment significantly triggered the H2O2 and APX accumulation, while POD and SOD remained unchanged in both cultivars. Salt stress increased Na+ concentration in the roots and leaves but decreased K+ concentration and the K+/Na+ ratio in both cultivars. However, MeJA-treated plants had the maximum K+ accumulation in both leaves and roots under saline conditions. The differential expression pattern of OsHKT and OsHAK genes implied that ion homeostasis is crucial to growth under salt stress. These findings suggest that the application of MeJA can be an alternative source of reducing salinity without compromising growth and yield.

The Effect of Different Carrier Materials on the Growth and Yield of Spinach under Pot and Field Experimental Conditions

Long-term use of chemical fertilizers is affecting the environment, soil quality, and biodiversity. Organic agriculture is gaining global attention by using microbial-based biofertilizers. Carriers protect microbes by providing nutrition, energy, and suitable conditions for their survival while entering the natural environments. The purpose of this study was to evaluate the ability of different carrier materials to enhance the yield and the quality of spinach and to select the best carrier material for spinach biofertilizer. Three pre-isolated and characterized bacterial strains (AN-35, ZM-27, and ZM-63) were tested for their compatibility and used in this experiment through seed inoculation with organic carriers, i.e., compost, peat, press mud, biochar, and charcoal. A pot experiment and a field experiment were conducted to evaluate the efficacy of different organic carriers. The results of the pot study showed a significant increase in spinach growth, i.e., shoot length (25%), shoot fresh weight (24%), root length (25%), and root fresh weight (29%), spinach nutrition, i.e., nitrogen (18%), phosphorus (22%), potassium (15%), iron (17%), and zinc (14%), spinach physiology, i.e., relative water content (27%), chlorophyll content (9%), and the membrane stability index (28%) under peat coated treatments with 24% more soil microbial populations compared to the control. Similarly, in the field experiment, peat coating significantly enhanced spinach growth, i.e., shoot length (29%), shoot fresh weight (23%), root length (16%), and root fresh weight (24.7%), spinach nutrition, i.e., nitrogen (16%), phosphorus (19%), potassium (15%), iron (17%), and zinc (23%), spinach physiology, i.e., relative water content (28%), chlorophyll content (13%) and the membrane stability index (32%), and spinach yield per hectare (30%), as well as producing 20% higher soil microbial populations. From these results, it is concluded that peat is a good carrier material for biofertilizer production as it not only enhances crop production but also the microbial number, in addition to improving soil quality.

Physiological studies on eggplant (Solanum melongena) grown under drought conditions

Field experiment was conducted during the two growing seasons of 2019 and 2021, at Dokki region, El-Giza Governorate, Egypt, in order to investigate the effect of deficit irrigation (DI) treatments: 100% (control), 70% and 50% of ETo (Reference evapotranspiration) and two irrigation systems: Surface drip irrigation (SDI) and Subsurface irrigation (SSI)porous pipe (20.0cm soil depth) on vegetative growth, chemical constituents, fruit yield and quality of eggplant plants (Cultivars : “Classic” “Swad Eleil”). Results revealed that, DI treatments significantly decreased the vegetative growth, total yield ,marketable yield, leaf relative water content (LRWC) and membrane stability index (MSI) of eggplant plants, compared to control treatment (100% ETₒ). While, water stress treatments improved leaves proline content, alkaloids and irrigation water use efficiency (IWUE). Using SSI (porous pipe) system significantly increased plant height, fresh weight, total yield, marketable fruit yield of eggplant, LRWC and MSI, “Classic” cv had the highest total yield and total marketable yield under the subsurface irrigation system compared to “Swad El-Layl”cv. Regarding, the effect of interaction between DI treatments and irrigation systems, the results illustrated that application of irrigation water with 100% ET0 by SSI system produced the highest significant values of vegetative growth, fruit yield.

A Novel Plant Growth–Promoting Agent Mitigates Salt Toxicity in Barley (Hordeum vulgare L.) by Activating Photosynthetic, Antioxidant Defense, and Methylglyoxal Detoxification Machineries

Developing and applying a novel plant growth–promoting agent (PGPA; a micronutrient-amino acid chelated compound developed from autolysis yeast cells) in alleviating salt stress toxicity can be the best alternative option environmentally and economically. High-performance liquid chromatography (HPLC) showed that the assembled PGPA is rich in nucleobases than yeast extract (> 56-fold). This study, as a first investigation, was aimed to evaluate PGPA’s potential role in reducing oxidative injury induced by salt stress. Barley (Hordeum vulgare L. cv. Giza 123) plants were grown under non-saline or saline conditions (6.0 and 12.0 dS m−1) with and without PGPA foliar application. The PGPA application mitigated salt-induced oxidative stress by enhancing the activity of superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, glutathione peroxidase, and glutathione S-transferase, as well as the content of ascorbate, glutathione, proline, and glycinebetaine. Moreover, PGPA protected salt-stressed plants from the deleterious effects of methylglyoxal by up-regulating the glyoxalase enzymes activity. The PGPA alleviated membrane damage by decreasing reactive oxygen species (ROS) accumulation, lipid peroxidation, protein oxidation, electrolyte leakage, and NADP+ content. The protection of photosynthesis by PGPA was closely associated with the improved chlorophyll fluorescence parameters, leaf water content, membrane stability index, and NADPH content. The PGPA-treated plants also exhibited higher stomatal conductivity together with improved transpiration and photosynthetic rates under saline conditions. Overall, PGPA regulated the antioxidant machinery, glyoxalase system, and photosynthetic capacity, implying that it plays a critical role in salt stress mitigation. Therefore, it could be a useful agent to alleviate the harmful effects of salinity stress.

Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress

Being sessile organisms, plants cannot escape unwanted changes in the environment. The rapid human population explosion caused significant environmental problems. Heavy metals produced through various sources can cause severe damage to living organisms. The study was planned to evaluate four grass species’ morpho-physiological growth characteristics and phytoremediation capabilities under chromium (Cr) and lead stress (Pb) in the arid climate. Typha angustifolia, Tragus roxburghii, Aeluropus logopoides, and Cenchrus ciliaris grass species were used for the study. One-year-old stubbles from the Cholistan desert were used for the experiment. Cr treatments in the form of K2Cr2O7 were applied at 0, 20, 40, and 80 mg L–1, whereas Pb was applied as PbCl2 at 0, 50, 200, and 500 mg L–1 as control, low, moderate and high-stress, respectively. After 6 weeks of heavy metals treatments, plants were harvested and analyzed for growth performance and phytoremediation capabilities. Results depicted that, regarding morphological attributes, T. angustifolia performed better, followed by C. ciliaris; no clear pattern was observed for T. roxburghii and A. logopoides. The CO2 assimilation rate (Co2d) and water use efficiency (WUE) increased as the heavy metal stress increased in all species under both metals. In contrast, total chlorophyll content was higher under low stress. Other physiological parameters, such as relative humidity (RHd), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), leaf internal CO2 concentration (Ci) and membrane stability index (MSI) gradually decreased as the Cr, and Pb stress levels increased among all the species. Moreover, Cr and Pb absorption contents of T. angustifolia were higher than the other three species at each stress level. Overall, T. angustifolia thrived against heavy metals stress and showed higher biomass, maximum photosynthetic measurements, WUE and higher metal absorption among all the selected species. Results concluded that although all the selected species behaved fine under stress conditions, T. angustifolia performance was better; thus, it can be used to remediate the soil near industrial estates.

The NADP-malate dehydrogenase (SmNADP-mdh), a C4 pathway gene from Suaeda monoica enhanced photosynthesis and biomass yield in C3 plants

Enhanced photosynthesis and biomass have been achieved in C 3 plants by over-expressing NADP dependent malate dehydrogenase ( SmNADP-mdh ), a C 4 pathway gene from Suaeda monoica . Over-expression of the SmNADP-mdh improved seed germination, seedling growth and accumulation of pigments, sugar, starch and C H N S elements in transgenic tobacco under in vitro conditions. Transgenic tobacco exhibited higher NADP-MDH activity, membrane stability index, photosynthesis efficiency, improved stomatal conductance, carboxylation efficiency, photosystem II (PSII) operating efficiency, electron transfer rate, photochemical quenching and better accumulation of sugar and starch at elevated (1200 ppm) CO 2 (eCO 2 ). Chlorophyll a fluorescence analysis showed improved pool size, electron transfer, water-splitting activity, photosynthetic performance indexes and efficient working of PSII at eCO 2 in transgenic tobacco over-expressing SmNADP-mdh . The higher expression of antioxidant defence genes indicated better scavenging and lesser accumulation of ROS at eCO 2 . Results suggest the potential of a single-cell C 4 halophytic NADP-mdh gene in the development of smart agriculture to improve the photosynthetic efficiency and biomass yield in C 3 plants. • The SmNADP-mdh transgenic tobacco exhibited higher NADP-mdh activity. • SmNADP-mdh gene improved seed germination and seedling growth. • Transgenic tobacco exhibited higher sugar contents under in vitro conditions. • Transgenic tobacco showed higher photosynthesis and carboxylation efficiency. • Transgenic tobacco showed higher contents of pigments and sugar at eCO 2 .

Polyamines and ethylene action blocker (STS) effectively augment longevity and postharvest attributes in isolated flowers of Digitalis purpurea L.

The present investigation focused on the study of the exogenous inclusion of anti-senescence biogenic polyamines (putrescine, spermidine and spermine) and ethylene antagonist silver thiosulphate on flower longevity and postharvest performance in excised flowers of Digitalis purpurea L. At one day before anthesis stage, isolated buds of Digitalis purpurea were transported to the laboratory in distilled water. The samples were divided into five sets with one set of flower buds (i.e., control) held in distilled water. The remaining four sets were respectively supplied with 0.5, 1 and 1.5 mM of putrescine (PUT), 0.1, 0.2 and 0.3 mM of spermidine (SPD), 0.2, 0.4 and 0.6 mM of spermine (SPM), 0.1, 0.2 and 0.3 mM of silver thiosulphate (STS). The inclusion of polyamines and STS in holding solutions enhanced the flower longevity of D. purpurea significantly compared to the control. The results indicated that the flower longevity of 14 days was recorded in 0.4 mM of spermine, followed by 13 days in 1 mM PUT, 12.5 days in 0.2 mM SPD and 12 days in 0.2 mM STS. This enhanced flower longevity corroborated with the higher values of soluble proteins, total sugars, floral diameter and membrane stability index. The improved flower longevity was also found to be positively associated with increased activities of various antioxidant enzymes viz., superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) and reduced activity of lipoxygenase (LOX). The flowers supplemented with different treatments retained a lower phenolic content than the control. This research concluded that polyamines and STS have a profound impact on the flower longevity of Digitalis flowers. SPM was found to be a more potential polyamine in augmenting the postharvest performance in isolated flowers of D. purpurea.

Foliar salicylic acid application to mitigate the effect of drought stress on isabgol (Plantago ovata forssk)

The aim of this study was to identify the effect of drought stress on physiological and biochemical characteristics of isabgol and to clarify whether the foliar application of salicylic acid is able to mitigate the stress impacts. This study was carried out as a factorial field experiments at Gonbad Kavous, north-eastern Iran during the growing seasons of 2016 and 2017.The treatments were 3 regimes of irrigation, namely irrigation every week throughout the growth period based on field capacity (Non stress = NS), cut-off the irrigation at the seed filling stage for 60 days (Moderate stress = MS) and at the flowering stage for 50 days (Severe stress = SS). Salicylic acid (SA) application with three levels, 0 (distilled water spray), 0.4 and 0.8 mM SA per 5 m−2were assigned as the subplot treatments. Foliar application of salicylic acid was performed simultaneously with cut-off irrigation treatments (in three times).The studied traits included: membrane stability index, catalase activity, proline content, soluble sugars content, total phenol contents in plant leaves and seed yield. According to the results of the two-year experiment, the highest seed yield was obtained by foliar spraying of 0.8 mM salicylic acid at the moderate stress condition. Application of salicylic acid at a concentration of 0.8 mM improved the cell membrane stability from 71 to 98%, water productivity by 53–99 m3 ha−1, water used efficiency from 2 to 4 m3 ha−1the soluble sugar content from 62 to 125 mg g−1 DW and the total phenol content from 2 to 10 mg g−1 DW. In both years of the study, the highest catalase activity was recorded for the normal irrigation treatment under foliar application of 0.4 and 0.8 mM salicylic acid. Application of SA at 0.8 mM under MS and SS conditions increased seed yield, cell membrane stability, catalase activity and proline concentration compared to NS, which indicates the positive effect of this compound.

Screening of Big Onion Varieties for Sodicity Tolerance at Cauvery Delta Zone in South India

Sodicity is a major factor affects crop growth and productivity at global level. Out of 1.5 billion ha of cultivable land at global level, 23% are affected due to salinity and 37% by sodicity. Fourteen Big onion varieties were screened by employing germination test in an osmatic solution of Na2CO3 (Sodium bicarbonate).Simultaneously, all the varieties were allowed to germinate in distilled water (control).Three Replications of 20 seeds of each variety were counted and distributed over two layers of paper towel (21x21 cm) previously moistened with water equivalent to three times the dry weight of the paper and tied both ends with rubber band and kept in a plastic tray with different concentrations ( 0, 25mM, 50mM, 75mM, 100 M ) of Na2CO3. At the end of the 21st day, final germination percent, root length, shoot length, root dry weight, shoot weight, Relative water content and membrane stability index, were recorded in Na2CO3 solution as against the distilled water was calculated. The experiment was designed as a completely randomized design with two factors. As a result a decline in all onion growth paramers, with increasing sodicity stress has been recorded. Significant differences were observed between the varieties and different Na2CO3 concentrations. Irrespective of Na2CO3 concentrations, Bhima Safed recorded significantly maximum stress tolerant index compared to other varieties and minimum stress tolerant index value recorded bhima red variety. Based on stress tolerant index, Bhima safed variety tolerant to sodicity stress and Bhima red variety sensitive to sodicity stress.

Effects of Funneliformis mosseae and Potassium Silicate on Morphological and Biochemical Traits of Onion Cultivated under Water Stress

Water stress negatively impacts the physiology of plants, affecting their growth and development. It is considered among the most important environmental factors responsible for reduced crop production. In this regard, biofertilizers may be considered significant for their reparative properties to increase stress tolerance in crop plants. We studied the effects of water stress on the morphological and biochemical characteristics of onion plants with AMF (Funneliformis mosseae) and potassium silicate application. The water stress significantly affected all the studied traits, each with minimum recorded levels. Plants that received combined treatments of AMF and potassium silicate showed maximum percent increments in all the studied characteristics, e.g., plant height (156.7%), weight of bulb (416.8%), antioxidant activity (224.0%), membrane stability index (74.5%), relative water content (87.3%), and total soluble solids (63.71%). Therefore, the study demonstrated that all the investigated variables were affected negatively by water stress. However, bio-fortification of onion plants with silicates and AMF inoculation may be considered useful for functional food production, with numerous health promoting properties.

PGPR improve physiological and yield attributes in mustard under different regimes of water supply

ABSTRACT Study was aimed to evaluate the effect of rhizobacteria on physiological attributes, agro-morphological-traits and yield of mustard under rainfed, one irrigation and two irrigation, at two different agro-climatic locations. At both locations, plant height, yield and physiological attributes – relative water content, membrane stability index and chlorophyll content – were adversely affected under rainfed condition; single irrigation had beneficial effect on these parameters. Two irrigations did not have similar impact at both locations. Inoculation with all the rhizobacteria improved yield, yield components and most of the assayed physiological attributes. The highest seed yield at Location I (2410 kg ha−1) and Location II (2130 kg ha−1) was obtained due to the inoculation with rhizobacteria Bacillus casamancensis MKS 6 and Bacillus sp. MRD 17, respectively; there was an increase in mustard seed yield by 650 kg ha−1 and 430 kg ha−1 compared with uninoculated treatment at Locations I and II, respectively. Correlation analysis indicated strong positive correlation between most of the plant biometric traits and plant physiological attributes. Hence, due to the application of rhizobacteria, plantphysiological attributes were improved, as a result, crop growth and yield were enhanced. Thus, these rhizobacterial strains can be used as bioinoculants to alleviate the adverse effects of drought and improve crop productivity.

Salinity Stress Tolerance in Potato Cultivars: Evidence from Physiological and Biochemical Traits.

Salinity stress is a major constraint to sustainable crop production due to its adverse impact on crop growth, physiology, and productivity. As potato is the fourth most important staple food crop, enhancing its productivity is necessary to ensure food security for the ever-increasing population. Identification and cultivation of salt-tolerant potato genotypes are imperative mitigating strategies to cope with stress conditions. For this purpose, fifty-three varieties of potato were screened under control and salt stress conditions for growth and yield-related traits during 2020. Salt stress caused a mean reduction of 14.49%, 8.88%, and 38.75% in plant height, stem numbers, and tuber yield, respectively in comparison to control. Based on percent yield reduction, the genotypes were classified as salt-tolerant (seven genotypes), moderately tolerant (thirty-seven genotypes), and salt-sensitive genotypes (nine genotypes). Seven salt-tolerant and nine salt-sensitive genotypes were further evaluated to study their responses to salinity on targeted physiological, biochemical, and ionic traits during 2021. Salt stress significantly reduced the relative water content (RWC), membrane stability index (MSI), photosynthesis rate (Pn), transpiration rate (E), stomatal conductance, and K+/Na+ ratio in all the sixteen genotypes; however, this reduction was more pronounced in salt-sensitive genotypes compared to salt-tolerant ones. The better performance of salt-tolerant genotypes under salt stress was due to the strong antioxidant defense system as evidenced by greater activity of super oxide dismutase (SOD), peroxidase (POX), catalase (CAT), and ascorbate peroxidase (APX) and better osmotic adjustment (accumulation of proline). The stepwise regression approach identified plant height, stem numbers, relative water content, proline content, H2O2, POX, tuber K+/Na+, and membrane stability index as predominant traits for tuber yield, suggesting their significant role in alleviating salt stress. The identified salt-tolerant genotypes could be used in hybridization programs for the development of new high-yielding and salt-tolerant breeding lines. Further, these genotypes can be used to understand the genetic and molecular mechanism of salt tolerance in potato.

Exogenously Applied Proline Enhances Morph-Physiological Responses and Yield of Drought-Stressed Maize Plants Grown Under Different Irrigation Systems.

The exogenous application of osmoprotectants [e.g., proline (Pro)] is an important approach for alleviating the adverse effects of abiotic stresses on plants. Field trials were conducted during the summers of 2017 and 2018 to determine the effects of deficit irrigation and exogenous application of Pro on the productivity, morph-physiological responses, and yield of maize grown under two irrigation systems [surface irrigation (SI) and drip irrigation (DI)]. Three deficit irrigation levels (I100, I85, and I70, representing 100, 85, and 70% of crop evapotranspiration, respectively) and two concentrations of Pro (Pro1 = 2 mM and Pro2 = 4 mM) were used in this study. The plants exposed to drought stress showed a significant reduction in plant height, dry matter, leaf area, chlorophyll content [soil plant analysis development (SPAD)], quantum efficiency of photosystem II [Fv/Fm, Fv/F0, and performance index (PI)], water status [membrane stability index (MSI) and relative water content (RWC)], and grain yield. The DI system increased crop growth and yield and reduced the irrigation water input by 30% compared with the SI system. The growth, water status, and yield of plants significantly decreased with an increase in the water stress levels under the SI system. Under the irrigation systems tested in this study, Pro1 and Pro2 increased plant height by 16 and 18%, RWC by 7 and 10%, MSI by 6 and 12%, PI by 6 and 19%, chlorophyll fluorescence by 7 and 11%, relative chlorophyll content by 9 and 14%, and grain yield by 10 and 14%, respectively, compared with Pro0 control treatment (no Pro). The interaction of Pro2 at I100 irrigation level in DI resulted in the highest grain yield (8.42 t ha–1). However, under the DI or SI system, exogenously applied Pro2 at I85 irrigation level may be effective in achieving higher water productivity and yield without exerting any harmful effects on the growth or yield of maize under limited water conditions. Our results demonstrated the importance of the application of Pro as a tolerance inducer of drought stress in maize.

Seed priming with salicylic acid enhances growth, physiological traits, fruit yield, and quality parameters of cantaloupe under water-deficit stress

Cantaloupe is a nutritive and popular commercial fruit crop. Soil moisture deficit could seriously jeopardize the yield and quality of cantaloupe. Salicylic acid (SA) has a proven role in sustainably mitigating environmental stresses in many plants applied through various methods. A factorial experiment consisting of six SA seed priming doses (non-primed control, 100, 200, 300, 400, and 500 ppm) and three soil moisture regimes (50%, 75%, and 100% field capacity [FC]) was conducted to evaluate the performance of cantaloupe in terms of growth, physiological traits, fruit yield, and quality parameters. The results revealed that severe moisture-deficit condition of 50% FC drastically reduced fruit yield (64%), water productivity (48%), total soluble solids (22%), and membrane stability index (43%), while electrolyte leakage was increased by 260% at the same soil moisture regime compared with 100% FC without any SA application. Plants grown from SA primed seeds exhibited significantly better performance in terms of seed germination traits, growth, physiological, and fruit yield parameters than non-primed plants across soil moister regimes. The performance of cantaloupe in terms of germination rate, root and shoot dry matter, fruit yield, water productivity, total soluble solids content, and membrane stability index was better at 300 ppm SA priming dose, which was statistically similar with 400 and 500 ppm SA doses in most cases. A consistent trend of better performance at 300 ppm SA dose, especially at severe soil moisture-deficit of 50% FC, was observed (48%, 59%, 54%, and 153% higher fruit yield, water productivity, membrane stability index, and net photosynthetic rate, respectively, compared with the non-primed control at the same soil moisture regime). There was almost no effect of increasing SA priming dose above 300 ppm; therefore, this could be regarded as an optimum dose for maximizing productivity and economic returns when cantaloupe is grown under soil moisture-deficit conditions.

Microbial amelioration of salinity stress in endangered accessions of Iranian licorice (Glycyrrhiza glabra L.)

BackgroundGlycyrrhiza glabra L. is a medicinal and industrial plant that has gone extinct due to different abiotic stress caused by climate change. To understand how the plant-associated microorganism can support this plant under salinity, we collected sixteen Iranian accessions of G. glabra L., inoculated their rhizomes with Azotobacter sp. (two levels, bacterial treatments, and no-bacterial treatments, and grown them under salinity stress (NaCl levels; 0, and 200 mM).ResultsTwo accessions of Bardsir and Bajgah significantly showed higher resistant to salinity, for example by increasing crown diameter (11.05 and 11 cm, respectively) compared to an average diameter of 9.5 in other accessions. Azotobacter inoculation caused a significant increase in plant height and crown diameter. Among studied accessions, Kashmar (46.21%) and Ilam (44.95%) had the highest rate of membrane stability index (MSI). Evaluation of enzyme activity represented that bacterial application under salinity, increased polyphenol oxidase (PPO) (0.21 U mg−1 protein), peroxidase (POD) (3.09 U mg−1 protein U mg−1 protein), and phenylalanine ammonia-lyase (PAL) (17.85 U mg−1 protein) activity. Darab accession showed the highest increase (6.45%) in antioxidant potential compared with all studied accessions under Azotobacter inoculation. According to principal component analysis (PCA), it was found that the accession of Meshkinshahr showed a more remarkable ability to activate its enzymatic defense system under salt stress. Also, three accessions of Meshkinshahr, Eghlid, and Ilam were categorized in separated clusters than other accessions regarding various studied treatments.ConclusionAnalysis indicated that five accessions of Meshkinshahr, Rabt, Piranshahr, Bardsir, and Kermanshah from the perspective of induced systematic resistance are the accessions that showed a greater morphophysiological and biochemical outcome under salinity. This study suggested that, inoculation of with Azotobacter on selected accession can relieve salt stress and support industrial mass production under abiotic condition.

Plant elicitation and TiO2 nanoparticles application as an effective strategy for improving the growth, biochemical properties, and essential oil of peppermint.

MenthapiperitaL., which is an abundant source of essential oils (EO) and phenolic acids, is well known for its medicinal significance. The present research aimed to evaluate the impact of various concentrations of methyl jasmonate (MeJA; 0, 0.1, and 0.5mM), titanium dioxide nanoparticles (TiO2 NPs; 0 and 150mg L-1), and salicylic acid (SA; 0, 0.1, and 1mM) on growth, EOs, and phenolic compounds ofM.piperitaL. The results demonstrated that the simultaneous application of SA (0.1mM) and TiO2 NPs (150mg L-1) enhanced shoot dry weight, the shoot length, and membrane stability index of peppermint by 56.17, 19.52, and 36%, respectively, compared to control. Moreover, phenolic content (76%), caffeic acid content (78%), rosmarinic acid content (87%), 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability (78%), and catalase (155%), ascorbate peroxidase activities (95%) were further improved by simultaneously applying MeJA (0.1mM) and TiO2 NPs (150mg L-1) compared to control. The highest menthol production (44.51%) was obtained with exogenous application of MeJA (0.1mM) with 150mg L-1 TiO2 NPs. The findings of the current study presented an ideal combination of TiO2 NPs with plant growth regulators for promoting antioxidant activities and increasing major components of EO in peppermint plants.

The Improvement of Growth, Water Relations, and Oxidative Reduction of Pistachio Rootstock in Drought Stress Conditions with Beta-Aminobutyric Acid Pretreatment

Environmental stresses are inevitable during the plant growth. The β-aminobutyric acid (BABA) induces systemic resistance in plants. The efficiency of BABA pretreatments (0.5 and 10 mM) in inducing drought tolerance in the ‘Akbari’ pistachio rootstock in controlled environmental conditions was investigated. The BABA solutions were sprayed three times every two days on pistachio seedlings at the 15-leaf stage. Subsequently, the irrigation of plants was withheld for 25 days, and the effects of BABA pretreatments on the growth, water relations, and oxidative damage indices in plants were investigated. The BABA pretreatments prevented the reduction of shoot dry and fresh mass under a drought stress by inhibiting the leaf abscission and maintaining the relative water content. Owing to the leaf abscission, leaf water potential and turgidity of drought-stressed plants were similar to the control plants. However, the measurement of osmotic potential indicated that the BABA pretreatments improved turgor potential in leaves of the drought-stressed plants by inducing osmotic regulation. A declined membrane stability index and chlorophylls, as well as the malondialdehyde accumulation in line with the hydrogen peroxide accumulation in the leaves, indicated the development of oxidative damage under drought. Still, the BABA pretreatment restricted the severity of oxidative damages. In this regard, a 5 mM BABA pretreatment was the most effective one in the anti-drought plant protection.

Identification and characterization of drought tolerant rice genotypes using physiological and biochemical traits

The present study was conducted to evaluate the performance of seven rice genotypes using morphological, physiological and biochemical parameters, under induced drought (water stress) conditions at seedling level using PEG6000 in Hoagland's medium. At the end of the stress period sampling was done to record the root and shoot lengths and various physiological parameters viz., total chlorophyll content, cell membrane stability index (MSI), relative water content were estimated. Proline and Malondialdehyde (MDA) content were also estimated as biochemical parameters. The results obtained from the study revealed the existence of significant variation in the seven genotypes studied for different physiological and biochemical parameters. Out of the seven genotypes studied, HT-18 (AC-34973) had performed better than the tolerant check CR-143-2-2 and showed better root and shoot growth, maintained higher total chlorophyll content (2.6 mg/gm FW), relative water content (61.3%) and membrane stability index (MSI) (52.9%), it has also shown higher proline content (20.52 ?moles/gm FW) and lesser MDA content (0.068) under stress. To assess the membrane integrity under osmotic stress, roots from all the genotypes grown in hydroponic culture with 20% PEG were stained with Evan's blue, where the stress effect is directly reflected on the intensity of Evans blue uptake by the cell. Because of more membrane damage, the roots of the susceptible genotype, IR-64, had taken up more stain than the roots of tolerant genotype HT-18. The present study has identified HT-18 as seedling level drought tolerant genotype.