Membrane Stability Index Research Articles

The Combined Effect of Hot Water Treatment and Chitosan Coating on Mango (Mangifera indica L. cv. Kent) Fruits to Control Postharvest Deterioration and Increase Fruit Quality

The synergistic effect of dipping in 55 °C for 5 min of hot water (HW) and 1% chitosan coating during the storage of mango at 13 ± 0.5 °C and 85%–90% relative humidity for 28 days was investigated. The combined treatment significantly suppressed the fruit decay percentage compared with both the single treatment and the control. In addition, the specific activities of key plant defense-related enzymes, including peroxidase (POD) and catalase (CAT), markedly increased. The increase occurred in the pulp of the fruits treated with the combined treatment compared to those treated with HW or chitosan alone. While the control fruits showed the lowest values, the combination of pre-storage HW treatment and chitosan coating maintained higher values of flesh hue angle (h°), vitamin C content, membrane stability index (MSI) percentage, as well as lower weight loss compared with the untreated mango fruits. The combined treatment and chitosan treatment alone delayed fruit ripening by keeping fruit firmness, lessening the continuous increase of total soluble solids (TSS), and slowing the decrease in titratable acidity (TA). The results showed that the combined application of HW treatment and chitosan coating can be used as an effective strategy to suppress postharvest decay and improve the quality of mango fruits.

Small-Sized Nanophosphorus Has a Positive Impact on the Performance of Fenugreek Plants under Soil-Water Deficit Stress: A Case Study under Field Conditions.

Simple SummaryExperiments with fenugreek plants have provided insight into tolerance to deficit irrigation (dI) stress, the way in which fenugreek alters its morpho-physio-biochemical and anatomical responses when nanophosphorus (nP) is administered against dI stress. Foliar nourishing with nP effectively improved biomass, productivity, water use efficiency (WUE), photosynthetic pigments, leaf tissue integrity, and anatomical features in the dI-stressed fenugreek plants. Therefore, nP reduced the negative effects of dI and increased dI stress tolerance, plant growth and productivity by increasing WUE, osmo-regulatory compounds (especially, soluble sugars and proline) and trigonelline, along with the antioxidant (ascorbate, glutathione, phenolics, and flavonoids) activity, which serve as potent defenses to protect plants from dI stress.Phosphorus (P) is an essential macronutrient necessary for plant growth, development, and reproduction. Two field experiments were carried out in 2018/2019 and 2019/2020 on P-deficient soil to evaluate the impact of foliar fertilization with nanophosphorus (nP) on growth, yield, and physio-biochemical indices, as well as trigonelline content of fenugreek plants under deficient irrigation (dI) stress (a deficit of 20 and 40% of crop evapotranspiration; dI-20 and dI-40). The growth and yield traits, leaf integrity (relative water content and membrane stability index), photosynthetic pigment contents, leaf and seed P contents, and stem and leaf anatomical features significantly decreased under dI-20, with greater reductions recorded under dI-40. In contrast, water-use efficiency, osmoprotective compounds, including free amino acids, soluble sugars, proline, and trigonelline, along with antioxidant contents (ascorbate, glutathione, phenolics, and flavonoids) and their activity increased significantly under both dI-20 and dI-40. However, foliar feeding with nano-P considerably increased plant growth and yield traits, leaf integrity, photosynthetic pigments contents, leaf and seed P contents, and anatomical features. Besides, water-use efficiency, osmoprotectant contents, and antioxidant content and activity were further increased under both dI-20 and dI-40. The positive effects were more pronounced with the smaller nP (25 nm) than the larger nP (50 nm). The results of this study backed up the idea of using foliar nourishment with nP, which can be effective in modulating fenugreek plant growth and seed production.

Screening of Onion (Allium cepa L.) Genotypes for Waterlogging Tolerance.

Onion production is severely affected by waterlogging conditions, which are created due to heavy rainfall. Hence, the identification of waterlogging-tolerant onion genotypes is crucial for increasing onion production. In the present study, 100 distinct onion genotypes were screened for waterlogging tolerance under artificial conditions by using the phenotypic approach in the monsoon season of 2017. Based on plant survival and recovery and changes in bulb weight, we identified 19 tolerant, 27 intermediate tolerant, and 54 highly sensitive onion genotypes. The tolerant genotypes exhibited higher plant survival and better recovery and bulb size, whereas sensitive genotypes exhibited higher plant mortality, poor recovery, and small bulb size under waterlogging conditions. Furthermore, a subset of 12 contrasting genotypes was selected for field trials during monsoon seasons 2018 and 2019. Results revealed that considerable variation in the morphological, physiological, and yield characteristics were observed across the genotypes under stress conditions. Waterlogging-tolerant genotypes, namely, Acc. 1666, Acc. 1622, W-355, W-208, KH-M-2, and RGP-5, exhibited higher plant height, leaf number, leaf area, leaf length, chlorophyll content, membrane stability index (MSI), pyruvic acid, antioxidant content, and bulb yield than sensitive genotypes under stress conditions. Furthermore, the principal component analysis biplot revealed a strong association of leaf number, leaf area, chlorophyll content, MSI, and bulb yield with tolerant genotypes under stress conditions. The study indicates that the waterlogging-tolerant onion genotypes with promising stress-adaptive traits can be used in plant breeding programs for developing waterlogging-tolerant onion varieties.

Antioxidant defence system induced by seed priming with nanoparticles to restrain Fusarium wilt in cumin (Cuminum cyminum L.)

An experiment comprising of persuade of seed priming with plant growth promoting rhizobacteria (PGPR) and nanoparticles was conducted to restrain fusarium wilt in cumin. Biochemical changes (chlorophyll stability index, membrane stability index, free amino acid, soluble protein, total phenols) and antioxidant enzymes (superoxide dismutase, guaiacol peroxidase, polyphenol oxidase and catalase) were determined during disease development stages and influenced by nanoparticle treatments. The chlorophyll stability index, free amino acids, soluble proteins, guaiacol peroxidase, polyphenol oxidase and catalase were found higher in seedling tissues of cumin treated with PGPR + chitosan nanoparticles. Membrane stability index, total phenol and superoxide dismutase enzyme activities were enhanced in chitosan nanoparticles + green silver nanoparticles treatment. Antioxidant enzymes activities were increased during disease development stages. The combination of chitosan nanoparticles either with green silver nanoparticles or PGPR for seed priming would be found better for boosting up the antioxidant/defence system to restrain Fusarium wilt infection in cumin.

Response of wheat cultivars on physiological attributes to irrigation scheduling under different sowing windows

A field experiment was conducted under loamy sand soil during two consecutive Rabi seasons of 2016-17 and 2017-18 at Research Farm, Rajasthan Agricultural Research Institute, Sri Karan Narendra Agriculture University, Durgapura, Jobner. The experiment comprises four irrigation scheduling treatments (Irrigation at 0.6 ETc, 0.8 ETc, 1.0 ETc and 1.2 ETc), three cultivars (Raj 4120, Raj 4079 and Raj 4238) and three dates of sowing (15th November, 30th November and 15th December) assigned, respectively to main plot, sub plot and sub-sub plots were replicated three times in split plot design. Results of experiment showed that the irrigation applied at 1.2 Etc significantly influenced and recorded maximum value for the relative water content, membrane stability index and Chlorophyll content. Further results show that cultivar Raj 4079 recorded highest value for the same. By date of sowing maximum value of physiological attributes obtained with crop sown on 15th November.

Polyamines effectively mitigate senescence in persistent leaves of Berginia ciliata - a novel model system.

Plant leaves provide a unique insight into the changes that occur in organs, tissues and cells as they approach senescence. As part of the parental outlay, plants instigate leaf senescence to reallocate resources from older tissues to new organs towards the termination of the growing season. The aim of crop breeding initiatives is to optimize senescence for specific species. Considering hormonal regulation and their crosstalk during leaf senescence through integration of developmental signals, this work examines the efficacy of polyamines (PAs) in modulating several biochemical and physiological aspects with an ultimate aim to delay leaf senescence in leaf discs of Berginia ciliata (Haw.) sternb. Leaf discs were treated with putrescine (Put), spermidine (Spd) and spermine (Spm) at 20μM, 20μM and 15μM concentration, respectively. A set of leaf discs kept in distilled water served as the control. Leaf discs treated with PAs were green and fresh by about 4 days compared to the control, thus exhibited delayed senescence. This delayed leaf senescence corroborated with the maintenance of high activity of reactive oxygen species (ROS) scavenging antioxidant enzymes viz , superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and higher content of chlorophylls. A marked increase was also observed in membrane stability and soluble proteins in leaf discs treated with PAs. Exogenous PAs reduced oxidative stress in the leaf discs, as revealed by lower malondialdehyde (MDA) level, which is manifested as reduced lipid peroxidation (LPO). Improved membrane stability was proportional to lower LPO, as measured by the membrane stability index (MSI).

Nanoscale Zerovalent Iron Based Moderation of Chromium Stress in Tomato Seedlings is Related with Induced Antioxidants and Suppressed Cr Uptake

The nanoscale zerovalent iron (nZVI) has been widely used in remediation of environmental pollutants from the aqueous as well as soil media. The present study was conducted to evaluate the role of nZVI as a soil amendment in amelioration of chromium (Cr) toxicity in tomato seedlings. Three weeks exposure with low (10 mg kg-1) and high (100 mg kg-1) Cr(VI) was given to tomato seedlings grown in soil medium supplemented with or without 500 mg kg-1 nZVI in corresponding soils. The Cr exposure greatly reduced the biomass with high Cr(VI) lowering the plant height, root length, shoot and root biomass by 34, 24, 33 and 49%, respectively. However, nZVI significantly restored the growth retardation by increasing these parameters by 17, 14, 19 and 33%, respectively. The nZVI also lowered the Cr-induced MDA content, improved membrane stability index and increased relative water contents. The nZVI was also effective in improving the chlorophyll pigments and carotenoids contents. The antioxidant enzymes (viz. SOD, POD, CAT and APX) were slightly increased by Cr stress. The nZVI application together with Cr stressed soil further enhanced these enzyme activities. Application of nZVI further lowered the significant amount of Cr(VI) in shoots and roots tissues. The nZVI-induced tissue Cr concentration was lowered by 35% in shoots in case of low Cr exposure and 29% in roots by high Cr treatments. The amelioration of Cr-induced toxicity in tomato seedlings by nZVI application in soil seems to be the result of suppression of Cr uptake and enhancement in antioxidant enzyme system.

Growth and physiological response of rice ‘Inpari 35’ under salinity stress and application of silicate fertilizer

Rice is an important staple food in Indonesia. Crop areas can be expanded to boost productivity by utilizing marginal lands, which are saline. This study aims to study the growth and physiological response of rice ‘Inpari 35’ to the application of silicate fertilizer under salinity stress conditions. This study used a completely randomized design (CRD) with two factors. The first factor is the difference in NaCl salt concentration consisting of N0: 0 mM; N1: 37.5 mM; N2: 50 mM, while the second factor is the difference in the concentration of silicate fertilizer (CaSiO3) consisting of S0: 0 mM; S1: 1 mM and S2: 2 mM. Each treatment combination was repeated three times. Observed data were analyzed by analysis of variance (ANOVA). A significant difference between treatments is continued with Duncan's multiple distance test at a 95% confidence level. The results showed that NaCl treatment significantly (p<0.05) inhibited the growth of rice ‘Inpari 35’, which was indicated by a decrease in the plant height and number of leaves. The NaCl treatment caused a reduction in the levels of chlorophyll, carotenoids, proline, membrane stability index (MSI), and relative water content (RWC). The interaction between NaCl treatment and CaSiO3 showed significant differences in physiological parameters by increasing the levels of chlorophyll, carotenoid, proline, membrane stability index, and relative water content.

Biochar promotes arsenic (As) immobilization in contaminated soils and alleviates the As-toxicity in soybean (Glycine max (L.) Merr.)

Pot experiments were carried out to examine the biochar application and its alleviating effect on arsenic (As) toxicity in soybean plants. The data showed that As inhibits the growth indices and it increased with enhanced As-concentration in the substrate. The growth indices declined by more than 40% and the osmolyte concentration, photosynthetic pigments and antioxidant enzymes were decreased significantly among As-stressed plants. However, biochar application effectively mitigated the inhibitory effects of As on the soybean growth and the mitigation effect of treatment is more prevalent to the plants subjected to higher As-treatment. Biochar significantly reduced the As-uptake as revealed by the translocation factor (<1), indicating more As is restrained in the roots. The reduction in the total chlorophyll and carotenoid content was found less in the As-treated soybean plants upon biochar application. Similarly, the osmolytes comprising proline, sugar and protein increased upon application of biochar. The biomarkers viz., membrane stability index (MSI), hydrogen peroxide and malondialdehyde (MDA) content significantly decreased at higher As-levels upon biochar application as was also supported by the heatmap analysis. Moreover, the antioxidative enzymes also showed a significant increase upon addition of biochar. Our data showed that biochar amendment effectively alleviates the As-stress by enhancing the sorption of As in the substrate thus, significantly declining the As concentration in plant leaves, and thus the results of the current study depicting the role of biochar as a promising, cost-effective and eco-friendly amendment to decontaminate the As-polluted soils.

Exploration of physiological and biochemical processes of canola with exogenously applied fertilizers and plant growth regulators under drought stress.

Environmental stresses may alter the nutritional profile and economic value of crops. Chemical fertilizers and phytohormones are major sources which can enhance the canola production under stressful conditions. Physio-biochemical responses of canola altered remarkably with the use of nitrogen/phosphorus/potassium (N/P/K) fertilizers and plant growth regulators (PGRs) under drought stress. The major aim of current study was to evaluate nutritional quality and physio-biochemical modulation in canola (Brassica napus L.) from early growth to seed stage with NPK and PGRs in different water regimes. To monitor biochemical and physiological processes in canola, two season field experiment was conducted as spilt plot under randomized complete block design (RCBD) with four treatments (Control, Chemical fertilizers [N (90 kg/ha), P and K (45 kg ha-1)], PGRs; indole acetic acid (IAA) 15g ha-1, gibberellic acid (GA3) 15g ha-1 and the combination of NPK and PGRs] under different irrigations regimes (60, 100, 120, 150 mm evaporations). Water stress enhanced peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), polyphenol oxidase (PPO), soluble sugar, malondialdehyde (MDA), proline contents as well as leaf temperature while substantially reduced leaf water contents (21%), stomatal conductance (50%), chlorophyll contents (10-67%), membrane stability index (24%) and grain yield (30%) of canola. However, the combined application of NPK and PGR further increased the enzymatic antioxidant pool, soluble sugars, along with recovery of leaf water contents, chlorophyll contents, stomatal conductance and membrane stability index but decreased the proline contents and leaf temperature at different rate of evaporation. There is positive interaction of applied elicitors to the water stress in canola except leaf area. The outcomes depicted that the combination of NPK with PGRs improved the various morpho-physiological as well as biochemical parameters and reduced the pressure of chemical fertilizers cost about 60%. It had also reduced the deleterious effect of water limitation on the physiology and grain yield and oil contents of canola in field experiments.

Exogenous salicylic acid-induced drought stress tolerance in wheat (Triticum aestivum L.) grown under hydroponic culture.

Wheat is an important cereal crop, which is adversely affected by water deficit stress. The effect of induced stress can be reduced by the application of salicylic acid (SA). With the objective to combat drought stress in wheat, an experiment was conducted in greenhouse under hydroponic conditions. The treatments consisted of (a) no drought (DD0 = 0 MPa), mild drought (DD1 = -0.40 MPa) and severe drought (DD2 = -0.60 MPa) by applying PEG-8000, (b) two contrasting wheat varieties Barani-17 (drought tolerant) and Anaj-17 (drought-sensitive), and (c) foliar treatments of salicylic acid (0, 50 mM, 75 mM, and 100 mM). Evaluation of wheat plants regarding biochemical, physiological, and morphological attributes were rendered after harvesting of plants. Statistically, maximum shoot and root fresh and dry weights (18.77, 11.15 and 1.99, 1.81 g, respectively) were recorded in cultivar Barani-17 under no drought condition with the application of SA (100 mM). While, minimum shoot and root fresh and dry weights (6.65, 3.14 and 0.73, 0.61 g, respectively) were recorded in cultivar Anaj-2017 under mild drought stress without SA application. The maximum shoot length (68.0 cm) was observed in cultivar Barani-2017 under no drought condition with the application of SA (100 mM). While, maximum root length (59.67 cm) was recorded in cultivar Anaj-17 under moderate drought stress without application of SA. Further, minimum shoot length (28.67 cm) was recorded in Anaj-17 under moderate drought stress without SA application. Minimum root length (38.67 cm) was recorded in cultivar Barani-17 under no drought condition without SA application. Furthermore, maximum physio-biochemical traits, including membrane stability index (MSI), chlorophyl content, photosynthetic rates, stomatal conductance, antioxidant enzymatic activities and relative water content (RWC) were found highest in cultivar Barani-17 under no drought stress and SA application at 100 mM. However, minimum values of these traits were recorded in cultivar Anaj-17 under severe drought stress without SA application. Our results also demonstrated that under severe drought, application of SA at 100 mM significantly increased leaf nitrogen (N), phosphrus (P) and potassium (K) contents and cultivar Barani-17 demonstrated significantly higher values than Anaj-17. The obtained results also indicated that the cultivation of wheat under drought stress conditions noticeably declines the morphological, physiological, and biochemical attributes of the plants. However, the exogenous application of SA had a positive impact on wheat crop for enhancing its productivity.

Interactive Effects of Organic Fertilizers and Drought Stress on Growth and Nutrient Content of Brassica juncea at Vegetative Stage

With the ongoing climate change scenario and alarmingly increased land degradation, understanding complex interactions of drought stress and organic fertilizers on morpho-physiological traits and dynamics of nutrient concentration is pivotal for sustainable production leafy vegetables such as mustard (Brassica juncea). Thus, this study evaluated the effect of drought stress and organic fertilizers on B. juncea growth, physiology, and dynamics of nutrient concentration at the vegetative stage. The plants were exposed to three water stress levels (well-watered (100% field capacity, FC), mild (50% FC), and severe (25% FC) supplemented with three organic fertilizers (chitosan, ultra green, and home-grown natural vegetable foods) either individually or in combination during the vegetative growth stage. Water stress had a negative effect on growth and physiological traits, and macro- and micronutrients of mustard. However, the ameliorative effects of fertilizer application were revealed by improved plant height, leaf area, relative water content, membrane stability index, and chlorophyll content from 9.7% to 26.9%, 28% to 32.72%, 7.97% to 39.51%, 7.93% to 39.66%, and 29.68% to 56.53%, respectively. Analysis of variance revealed a significant effect of soil moisture level, fertilizer type and their interaction on content of macronutrients (Ca, K, P, N, C, S, Na, Mg) and micronutrients (Fe, Zn) in mustard leaves. However, there was no significant effect detected for Cu across all factors as well the interaction effect on Mn. Overall, our results indicated that application of organic fertilizers enables mustard plant to withstand the deleterious effect of drought stress, resulting in improved growth and physiological traits as well as leaf nutrient content.

6-Benzylaminopurine Alleviates the Impact of Cu2+ Toxicity on Photosynthetic Performance of Ricinus communis L. Seedlings.

Copper (Cu) is an essential element involved in various metabolic processes in plants, but at concentrations above the threshold level, it becomes a potential stress factor. The effects of two different cytokinins, kinetin (KIN) and 6-benzylaminopurine (BAP), on chlorophyll a fluorescence parameters, stomatal responses and antioxidation mechanisms in castor (Ricinus communis L.) under Cu2+ toxicity was investigated. Ricinus communis plants were exposed to 80 and 160 μM CuSO4 added to the growth medium. Foliar spraying of 15 μM KIN and BAP was carried out on these seedlings. The application of these cytokinins enhanced the tissue water status, chlorophyll contents, stomatal opening and photosynthetic efficiency in the castor plants subjected to Cu2+ stress. The fluorescence parameters, such as Fm, Fv/Fo, Sm, photochemical and non-photochemical quantum yields, energy absorbed, energy trapped and electron transport per cross-sections, were more efficiently modulated by BAP application than KIN under Cu2+ toxicity. There was also effective alleviation of reactive oxygen species by enzymatic and non-enzymatic antioxidation systems, reducing the membrane lipid peroxidation, which brought about a relative enhancement in the membrane stability index. Of the various treatments, 80 µM CuSO4 + BAP recorded the highest increase in photosynthetic efficiency compared to other cytokinin treatments. Therefore, it can be concluded that BAP could effectively alleviate the detrimental effects of Cu2+toxicity in cotyledonary leaves of R. communis by effectively modulating stomatal responses and antioxidation mechanisms, thereby enhancing the photosynthetic apparatus’ functioning.

Morpho-physiological and Biochemical Characterization of Chrysanthemum Varieties For Early Flowering under Heat Stress

• Being a SD plant, photoperiodic manipulation is imperative to maintain year round availability of chrysanthemum. • The early planting treatment with application of artificial SDs contributed to early flower bud initiation and flower maturation. • However, because of early planting and blackout treatment, plants faced heat stress and the development from buds to flower was slower. • The variety Yellow Delight overcame heat stress, flowered in August and proved to be heat tolerant while the others viz. Reagan Emperor, Reagan White, Shova and Punjab Shyamli were found to be heat sensitive. Cluster analysis also grouped Yellow Delight in separate cluster than others on the basis of morpho physiological and biochemical parameters. • Hence, Yellow Delight could be used for the off- season flower production with artificial SD treatment in sub tropical region. Chrysanthemum morifolium Ramat. is a short day plant, with commercial significance in floriculture industry. Using photoperiod as a tool, flowering can be regulated throughout the year. The present study evaluated five spray varieties (Yellow Delight, Reagan Emperor, Reagan White, Shova and Punjab Shyamli) under different planting treatments [Early Planting (P 1 ), Early Planting treated with artificial short days (P 2 ) and Normal Planting (P 3 )] for morpho-physiological and biochemical characterization of flowering under heat stress. The plants of all varieties took least days to bud initiation and flowering under normal planting whereas plants under early planting took maximum days for bud initiation and flowering. The plants treated with artificial SDs initiated buds earlier than early planting but due to sub-optimal temperature further development of buds to flower was slower. The plants of all varieties under early planting exhibited maximum vegetative growth as they took more days to bud initiation. Yellow Delight exhibited optimum vegetative growth, minimum days to bud initiation (87.98 days) and flower maturation (141.93 days) under P 2 . The membrane stability index, relative water content, total soluble sugars, total soluble proteins, sucrose and proline content, along with peroxidase activity supported early bud initiation, heat tolerance and flower development in Yellow Delight. The varieties Reagan Emperor, Reagan White, Shova and Punjab Shyamli were found to be heat sensitive. Further, the cluster analysis supported our results as Yellow Delight under early planting with SDs was in cluster II, all varieties under P 1 along with Reagan Emperor, Reagan White, Shova and Punjab Shyamli under P 2 were in Cluster I and all varieties under P 3 were in cluster III. Hence, Yellow Delight could be used for the off- season flower production with artificial SD treatment in Punjab region.

Physiochemical Changes of Mung Bean [Vigna radiata (L.) R. Wilczek] in Responses to Varying Irrigation Regimes

Mungbean is one of the most powerful pulses providing substantial protein for human diets and fixing N to the soil, improving nutritional food security and agricultural sustainability. The production of summer mungbean in the tropics and subtropics is adversely affected by drought due to water scarcity caused by various factors as well as lack of rainfall. Irrigation at different growth phases is not a suitable solution. An environmentally friendly and economically viable answer is a convenient irrigation management option that will be available to farmers together with drought-tolerant genotypes. The study considered to determine the effect of differences between drought-tolerant and drought susceptible genotypes on water productivity response and physiological traits in mung beans. To quantify seed yield-related to irrigation at different growth stages eventually to quickly determine the most appropriate irrigation stage. One water stress tolerant mung bean genotype (BMX-08010-2) and one sensitive genotype (BARI Mung-1) were grown in the field with four different irrigation schedules along with water stress conditions (no irrigation) under rain shelter at Regional Agricultural Research Station, BARI, Ishwardi, Pabna, Bangladesh. The experiment was laid out in split plots with three replications, with irrigation schedules assigned in the main plot and mung bean genotypes assigned in the side plots. Water use efficiency ranged from 3.79 to 4.68 kg ha−1 mm−1 depending on irrigation regime, and mung bean seed yield of mung bean Water stress decreased plant water status, photosynthetic pigment and membrane stability index, and increased proline soluble sugar content. Treatments that received irrigation during two or three phases (I3 or I4) gave significantly higher yields than those that received irrigation during only one stage (I1 and I2) with the lowest yield. While the yield obtained ranged between 1145.44 kg ha−1 with seasonal irrigation of 277 mm (I4) and 555.14 kg ha−1 without irrigation (I0). The flowering stage (I3) was recorded as the most sensitive growth stage with an 18.15% yield reduction compared to the treatment with triple irrigation (I4). Also, depending on the irrigation sources, at least two irrigation phases should be provided at the triple leaf stage (I2, i.e., 20 DAS) and at the flowering stage (I3, i.e., 35 DAS) to achieve the highest yield. Genotypes that maintained the higher performance of physicochemical traits under water stress provided higher seed yield and promoted drought tolerance. Therefore, these parameters can be used as physiological and biochemical markers to identify and develop superior genotypes suitable for drought-prone environments.

Effect of K and Zn Application on Biometric and Physiological Parameters of Different Maize Genotypes

Potassium (K) and zinc (Zn) are mineral nutrients required for adequate plant growth, enzyme activation, water retention and photosynthetic activities. However, Pakistani soils are alkaline and have serious problems regarding Zn deficiency. The current study aims at finding the nutrient–nutrient interaction of K and Zn to affect maize plants’ (i) physiological processes and (ii) productivity. For this purpose, a pot experiment was conducted at the research area of the Department of Soil Science, Faculty of Agricultural Science and Technology, Bahauddin Zakariya University, Multan. Two maize genotypes, DK-6142 (hybrid) and Neelam (non-hybrid), were used with three K fertilizer doses, i.e., 0, 60 and 100 kg ha−1 in all possible combinations with three Zn fertilizer doses, i.e., 0, 16 and 24 kg ha−1. The treatments were replicated under a completely randomized block design. The results elucidated that the combined application of K and Zn with K60 + Zn16 treatment significantly increased agronomic, productive, and physiological attributes. It has improved fresh biomass (89%), dry biomass (94%), membrane stability index (142%), relative water content (200%) and chlorophyll contents (191%) as compared to the control. Moreover, the mineral uptake of K and Zn was significantly improved with their maximum fertilization rate in hybrid genotype compared to non-hybrid and CK.

Cattle manure compost and biochar supplementation improve growth of Onobrychis viciifolia in coal-mined spoils under water stress conditions

Surface mining is a critical anthropogenic activity that significantly alters the ecosystem, while the use of appropriate revegetation techniques can be considered an important and feasible strategy in the way to improve the ecosystem services of degraded land. In the present study, we carried out a pot experiment to investigate the effects of three different variables on morpho-physiological and biochemical parameters of Onobrychis viciifolia to assess the capability of this species to be used for restoration purposes. Specifically, the variables studied were: (a) water (W) regime, working at five values as regards field capacity (FC) (i.e., 80% FC = highest, 72% FC = high, 60% FC = moderate, 48% FC = low, and 40% FC = very-low dose); and (b) rates of cattle manure compost (CMC) and wood biochar (BC) (weight/weight ratio), working at five rates (i.e., 4.0% = highest, 3.2% = high, 2.0% = moderate, 0.8% = low, and 0% = either no-CMC or no-BC dose). In addition, soil physical-chemical properties and enzyme activities were also investigated at the end of the experimental period. It was found that morphological growth attributes such as plant height, maximum root length, and dry biomass significantly increased with W, CMC and BC applications. Compared to control, moderate-to-high W, CMC and BC doses (W80CMC2BC2) increased net photosynthesis rate (by 42%), stomatal conductance (by 50%), transpiration rate (by 29%), water use efficiency (by 10%), chlorophyll contents (by 73%), carotenoid content (by 81%), leaf relative water content (by 33%) and leaf membrane stability index (by 30%). Under low-W content, the application of CMC and BC enhanced osmotic adjustments by increasing the content of soluble sugar and the activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, decreasing the oxidative stress, as verified by low levels of hydrogen peroxide, superoxide anion, malondialdehyde and proline contents in leaf tissues. Moreover, application of W, CMC and BC significantly improved soil water holding capacity, available nitrogen, phosphorus and potassium, urease and catalase activities, which facilitate plant growth. These results would aid in designing an appropriate strategy for achieving a successful revegetation of O. viciifolia, providing optimum doses of W (64% field capacity), CMC (2.4%) and BC (1.7%), with the final aim of reaching ecological restoration in arid degraded lands.

Exogenous Application of Alpha-Lipoic Acid Mitigates Salt-Induced Oxidative Damage in Sorghum Plants through Regulation Growth, Leaf Pigments, Ionic Homeostasis, Antioxidant Enzymes, and Expression of Salt Stress Responsive Genes.

In plants, α-Lipoic acid (ALA) is considered a dithiol short-chain fatty acid with several strong antioxidative properties. To date, no data are conclusive regarding its effects as an exogenous application on salt stressed sorghum plants. In this study, we investigated the effect of 20 µM ALA as a foliar application on salt-stressed sorghum plants (0, 75 and 150 mM as NaCl). Under saline conditions, the applied-ALA significantly (p ≤ 0.05) stimulated plant growth, indicated by improving both fresh and dry shoot weights. A similar trend was observed in the photosynthetic pigments, including Chl a, Chl b and carotenoids. This improvement was associated with an obvious increase in the membrane stability index (MSI). At the same time, an obvious decrease in the salt induced oxidative damages was seen when the concentration of H2O2 and malondialdehyde (MDA) was reduced in the salt stressed leaf tissues. Generally, ALA-treated plants demonstrated higher antioxidant enzyme activity than in the ALA-untreated plants. A moderate level of salinity (75 mM) induced the highest activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX). Meanwhile, the highest activity of catalase (CAT) was seen with 150 mM NaCl. Interestingly, applied-ALA led to a substantial decrease in the concentration of both Na and the Na/K ratio. In contrast, K and Ca exhibited a considerable increase in this respect. The role of ALA in the regulation of K+/Na+ selectivity under saline condition was confirmed through a molecular study (RT-PCR). It was found that ALA treatment downregulated the relative gene expression of plasma membrane (SOS1) and vacuolar (NHX1) Na+/H+ antiporters. In contrast, the high-affinity potassium transporter protein (HKT1) was upregulated.

Exogenous Myo-Inositol Alleviates Salt Stress by Enhancing Antioxidants and Membrane Stability via the Upregulation of Stress Responsive Genes in Chenopodium quinoa L.

Myo-inositol has gained a central position in plants due to its vital role in physiology and biochemistry. This experimental work assessed the effects of salinity stress and foliar application of myo-inositol (MYO) on growth, chlorophyll content, photosynthesis, antioxidant system, osmolyte accumulation, and gene expression in quinoa (Chenopodium quinoa L. var. Giza1). Our results show that salinity stress significantly decreased growth parameters such as plant height, fresh and dry weights of shoot and root, leaf area, number of leaves, chlorophyll content, net photosynthesis, stomatal conductance, transpiration, and Fv/Fm, with a more pronounced effect at higher NaCl concentrations. However, the exogenous application of MYO increased the growth and photosynthesis traits and alleviated the stress to a considerable extent. Salinity also significantly reduced the water potential and water use efficiency in plants under saline regime; however, exogenous application of myo-inositol coped with this issue. MYO significantly reduced the accumulation of hydrogen peroxide, superoxide, reduced lipid peroxidation, and electrolyte leakage concomitant with an increase in the membrane stability index. Exogenous application of MYO up-regulated the antioxidant enzymes’ activities and the contents of ascorbate and glutathione, contributing to membrane stability and reduced oxidative damage. The damaging effects of salinity stress on quinoa were further mitigated by increased accumulation of osmolytes such as proline, glycine betaine, free amino acids, and soluble sugars in MYO-treated seedlings. The expression pattern of OSM34, NHX1, SOS1A, SOS1B, BADH, TIP2, NSY, and SDR genes increased significantly due to the application of MYO under both stressed and non-stressed conditions. Our results support the conclusion that exogenous MYO alleviates salt stress by involving antioxidants, enhancing plant growth attributes and membrane stability, and reducing oxidative damage to plants.

Drought Tolerant Enterobacter sp./Leclercia adecarboxylata Secretes Indole-3-acetic Acid and Other Biomolecules and Enhances the Biological Attributes of Vigna radiata (L.) R. Wilczek in Water Deficit Conditions.

Simple SummaryDrought stress is one of the most important factors that significantly affects agricultural lands and reduces the production of various crops. Among bean crops, Vigna radiata (mung bean) is a highly nutritious food crop that provides protein, carbohydrates, several essential minerals, amino acids, vitamins, and antioxidants. To resolve the problem of drought-affected agriculture of mung bean, we focused on finding a novel and sustainable solution by using a drought-tolerant bacterium Enterobacter sp./Leclercia adecarboxylata PAB19 that produces significant amounts of plant growth-promoting bioactive compounds and colonizes the roots of mung bean plants. By performing a series of in vitro and in situ (on field) experiments, we conclude that the bacterium PAB19 holds a great potential to mitigate drought stress. Several agriculturally important parameters were enhanced by the bacterial activity which was suppressed by the drought stress induced by a chemical PEG-6000 without bacterial inoculation. Conclusively, strain PAB19 can be applied to alleviate drought stress by improving the biological attributes of mung bean under water-deficit conditions.Drought or water stress is a limiting factor that hampers the growth and yield of edible crops. Drought-tolerant plant growth-promoting rhizobacteria (PGPR) can mitigate water stress in crops by synthesizing multiple bioactive molecules. Here, strain PAB19 recovered from rhizospheric soil was biochemically and molecularly characterized, and identified as Enterobacter sp./Leclercia adecarboxylata (MT672579.1). Strain PAB19 tolerated an exceptionally high level of drought (18% PEG-6000) and produced indole-3-acetic acid (176.2 ± 5.6 µg mL−1), ACC deaminase (56.6 ± 5.0 µg mL−1), salicylic acid (42.5 ± 3.0 µg mL−1), 2,3-dihydroxy benzoic acid (DHBA) (44.3 ± 2.3 µg mL−1), exopolysaccharide (204 ± 14.7 µg mL−1), alginate (82.3 ± 6.5 µg mL−1), and solubilized tricalcium phosphate (98.3 ± 3.5 µg mL−1), in the presence of 15% polyethylene glycol. Furthermore, strain PAB19 alleviated water stress and significantly (p ≤ 0.05) improved the overall growth and biochemical attributes of Vigna radiata (L.) R. Wilczek. For instance, at 2% PEG stress, PAB19 inoculation maximally increased germination, root dry biomass, leaf carotenoid content, nodule biomass, leghaemoglobin (LHb) content, leaf water potential (ΨL), membrane stability index (MSI), and pod yield by 10%, 7%, 14%, 38%, 9%, 17%, 11%, and 11%, respectively, over un-inoculated plants. Additionally, PAB19 inoculation reduced two stressor metabolites, proline and malondialdehyde, and antioxidant enzymes (POD, SOD, CAT, and GR) levels in V. radiata foliage in water stress conditions. Following inoculation of strain PAB19 with 15% PEG in soil, stomatal conductance, intercellular CO2 concentration, transpiration rate, water vapor deficit, intrinsic water use efficiency, and photosynthetic rate were significantly improved by 12%, 8%, 42%, 10%, 9% and 16%, respectively. Rhizospheric CFU counts of PAB19 were 2.33 and 2.11 log CFU g−1 after treatment with 15% PEG solution and 8.46 and 6.67 log CFU g−1 for untreated controls at 40 and 80 DAS, respectively. Conclusively, this study suggests the potential of Enterobacter sp./L. adecarboxylata PAB19 to alleviate water stress by improving the biological and biochemical features and of V. radiata under water-deficit conditions.