Effect of Three Water Regimes on the Physiological and Anatomical Structure of Stem and Leaves of Different Citrus Rootstocks with Distinct Degrees of Tolerance to Drought Stress

Citrus is grown globally throughout the subtropics and semi-arid to humid tropics. Abiotic stresses such as soil water deficit negatively affect plant growth, physiology, biochemistry, and anatomy. Herein, we investigated the effect(s) of three water regimes (control, moderate drought, and severe drought) on the physiological and anatomical structure of 10 different citrus rootstocks with different degrees of tolerance to drought stress. Brazilian sour orange and Gadha dahi performed well by avoiding desiccation and maintaining plant growth, plant water status, and biochemical characters, while Rangpur Poona nucellar (C. limonia) and Sunki × bentake were the most sensitive rootstocks at all stress conditions. At severe water stress, the highest root length (24.33 ± 0.58), shoot length (17.00 ± 1.00), root moisture content (57.67 ± 1.53), shoot moisture content (64.59 ± 1.71), and plant water potential (−1.57 ± 0.03) was observed in tolerant genotype, Brazilian sour orange. Likewise, chlorophyll a (2.70 ± 0.06), chlorophyll b (0.87 ± 0.06) and carotenoids (0.69 ± 0.08) were higher in the same genotype. The lowest H2O2 content (77.00 ± 1.00) and highest proline content (0.51 ± 0.06) were also recorded by Brazilian sour orange. The tolerance mechanism of tolerant genotypes was elucidated by modification in anatomical structures. Stem anatomy at severe drought, 27.5% increase in epidermal cell thickness, 25.4% in vascular bundle length, 30.5% in xylem thickness, 27.7% in the phloem cell area, 8% in the pith cell area, and 43.4% in cortical thickness were also observed in tolerant genotypes. Likewise, leaf anatomy showed an increase of 27.9% in epidermal cell thickness, 11.4% in vascular bundle length, 21% in xylem thickness, and 15% in phloem cell area in tolerant genotypes compared with sensitive ones. These modifications in tolerant genotypes enabled them to maintain steady nutrient transport while reducing the risk of embolisms, increasing water-flow resistance, and constant transport of nutrients across.

Download Full-text

Enhancement of drought tolerance in diverse Vicia faba cultivars by inoculation with plant growth-promoting rhizobacteria under newly reclaimed soil conditions

Scientific Reports ◽

10.1038/s41598-021-02847-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Elsayed Mansour ◽

Hany A. M. Mahgoub ◽

Samir A. Mahgoub ◽

El-Sayed E. A. El-Sobky ◽

Mohamed I. Abdul-Hamid ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Severe Drought ◽

Drought Conditions ◽

Moderate Drought ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Effects Of Drought

AbstractWater deficit has devastating impacts on legume production, particularly with the current abrupt climate changes in arid environments. The application of plant growth-promoting rhizobacteria (PGPR) is an effective approach for producing natural nitrogen and attenuating the detrimental effects of drought stress. This study investigated the influence of inoculation with the PGPR Rhizobium leguminosarum biovar viciae (USDA 2435) and Pseudomonas putida (RA MTCC5279) solely or in combination on the physio-biochemical and agronomic traits of five diverse Vicia faba cultivars under well-watered (100% crop evapotranspiration [ETc]), moderate drought (75% ETc), and severe drought (50% ETc) conditions in newly reclaimed poor-fertility sandy soil. Drought stress substantially reduced the expression of photosynthetic pigments and water relation parameters. In contrast, antioxidant enzyme activities and osmoprotectants were considerably increased in plants under drought stress compared with those in well-watered plants. These adverse effects of drought stress reduced crop water productivity (CWP) and seed yield‐related traits. However, the application of PGPR, particularly a consortium of both strains, improved these parameters and increased seed yield and CWP. The evaluated cultivars displayed varied tolerance to drought stress: Giza-843 and Giza-716 had the highest tolerance under well-watered and moderate drought conditions, whereas Giza-843 and Sakha-4 were more tolerant under severe drought conditions. Thus, co-inoculation of drought-tolerant cultivars with R. leguminosarum and P. putida enhanced their tolerance and increased their yield and CWP under water-deficit stress conditions. This study showed for the first time that the combined use of R. leguminosarum and P. putida is a promising and ecofriendly strategy for increasing drought tolerance in legume crops.

Download Full-text

Elevated CO2 Modulates Plant Hydraulic Conductance Through Regulation of PIPs Under Progressive Soil Drying in Tomato Plants

Frontiers in Plant Science ◽

10.3389/fpls.2021.666066 ◽

2021 ◽

Vol 12 ◽

Author(s):

Shenglan Li ◽

Liang Fang ◽

Josefine Nymark Hegelund ◽

Fulai Liu

Keyword(s):

Drought Stress ◽

Hydraulic Conductance ◽

Water Relation ◽

Severe Drought ◽

Soil Drying ◽

Plant Water ◽

Transcriptional Responses ◽

Plant Water Use ◽

Use Efficiency ◽

Plasma Membrane Intrinsic Proteins

Increasing atmospheric CO2 concentrations accompanied by abiotic stresses challenge food production worldwide. Elevated CO2 (e[CO2]) affects plant water relations via multiple mechanisms involving abscisic acid (ABA). Here, two tomato (Solanum lycopersicum) genotypes, Ailsa Craig (AC) and its ABA-deficient mutant (flacca), were used to investigate the responses of plant hydraulic conductance to e[CO2] and drought stress. Results showed that e[CO2] decreased transpiration rate (E) increased plant water use efficiency only in AC, whereas it increased daily plant water consumption and osmotic adjustment in both genotypes. Compared to growth at ambient [CO2], AC leaf and root hydraulic conductance (Kleaf and Kroot) decreased at e[CO2], which coincided with the transcriptional regulations of genes of plasma membrane intrinsic proteins (PIPs) and OPEN STOMATA 1 (OST1), and these effects were attenuated in flacca during soil drying. Severe drought stress could override the effects of e[CO2] on plant water relation characteristics. In both genotypes, drought stress resulted in decreased E, Kleaf, and Kroot accompanied by transcriptional responses of PIPs and OST1. However, under conditions combining e[CO2] and drought, some PIPs were not responsive to drought in AC, indicating that e[CO2] might disturb ABA-mediated drought responses. These results provide some new insights into mechanisms of plant hydraulic response to drought stress in a future CO2-enriched environment.

Download Full-text

Foliar Application of Saudi Desert Plants Extract Improved Some Mungbean Agronomic Traits Under Drought Stress

Journal of King Abdulaziz University-Meteorology Environment and Arid Land Agriculture Sciences ◽

10.4197/met.27-2.3 ◽

2018 ◽

Vol 27 (2) ◽

pp. 21-29

Author(s):

Fahad Mohammed Alghabari Fahad Mohammed Alghabari

Keyword(s):

Drought Stress ◽

Plant Growth ◽

Azadirachta Indica ◽

Eucalyptus Globulus ◽

Field Capacity ◽

Severe Drought ◽

Simmondsia Chinensis ◽

Desert Plants ◽

Natural Plant ◽

Ambrosia Dumosa

To evaluate Saudi desert plants potential to promote mungbean growth under drought stress, a pot experiment was performed at field experimental station, King Abdulaziz University during 2016/2017 season. Drought stress was imposed by application of 40% and 60% field capacity (FC) levels. Pots with 100% field capacity were also maintained as control. Natural plant extracts of ten desert plants (Eucalyptus globulus, Azadirachta indica, Moringa oleifera Lam, Moringa peregrine Forssk., Tetraena simplex L., Simmondsia chinensis, Indigofera tinctoria, Dianella ensata, Emex spinosa, Ambrosia dumosa) were foliar applied prior to stress treatment application. Tap water treatment was used as control. Data for mungbean growth and pod characteristics were recorded. Drought stress decreased mungbean growth and severity of impact increased with lowering field capacity. The natural plant extract (NPE); NPE 9 (Dianella ensata) and NPE 11 (Ambrosia dumosa) favoured both plant growth 33% and pod characteristics 11%. The effect of NPE 6 (Tetraena simplex L.) and NPE 7 (Simmondsia chinensis) were significant for plant growth 21-24 cm while non-significant for pod characteristics under severe drought stress. On contrary, NPE 2 (Eucalyptus globulus) and NPE 3 (Azadirachta indica) effect was significant for mungbean pod characteristics 60% and non-significant for growth traits. The rest of the applied NPEs were non-significant for both growth and yield traits. The combination of NPE9 × FC-2, NPE6 × FC-2, NPE11 × FC-1 and NPE7 × FC-1 produced tallest plants (29.33 cm), maximum fresh biomass (8.54 g), dry biomass (6.71 g) and number of branches per plant (6.8). The combination of NPE2 × FC-2, NPE3 × FC-1, NPE9 × FC-1 and NPE11 × FC-3 produced maximum pods per plant (4.2), pod length (7 cm), pod fresh weight (5.4 g) and dry weight (4.5 g) respectively. It’s clear from the statistical analysis that mungbean performed better under medium stress level (FC-2) while NPE6, NPE7, NPE9 and NPE11 significantly stimulated plant growth under stressed environment. In conclusion, by application of Dianella ensata and Ambrosia dumosa, mungbean can be successfully grown under medium drought stress conditions.

Download Full-text

Whole-plant Photosynthesis of Containerized Hydrangeas and Abelias as Affected by Substrate Moisture Content

HortScience ◽

10.21273/hortsci.40.4.1111d ◽

2005 ◽

Vol 40 (4) ◽

pp. 1111D-1111 ◽

Cited By ~ 1

Author(s):

Marc W. van Iersel ◽

Sue Dove

Keyword(s):

Growth Rate ◽

Drought Stress ◽

Moisture Content ◽

Water Potential ◽

Photosynthetic Rate ◽

Severe Drought ◽

Whole Plant ◽

Growing Medium ◽

Plant Photosynthesis ◽

Substrate Moisture

Efficient water use in nurseries is increasingly important. In recent years, new soil moisture sensors (ECH2O probes) have become available, making it possible to monitor the moisture content of the growing medium in containers. One piece of information that is lacking for fully-automated irrigation systems is how much water actually needs to be present in the growing medium to prevent detrimental effects of drought on plants. We determined the effect of substrate moisture on photosynthesis and plant water relations of hydrangea and abelia. Growth rates of these species were measured during two subsequent drying cycles to determine how drought affects the growth rate of these species. Whole-plant photosynthesis, an indicator of growth rate, of both species remained stable as the volumetric moisture content of the substrate dropped from 25% to 15%, with pronounced decreases in photosynthesis at lower substrate moisture levels. Abelias and hydrangeas wilted when the substrate moisture level dropped to 6.3% and 8.3%, respectively. At wilting, abelias had lower leaf water potential (–3.7 MPa) than hydrangeas (–1.8 MPa). After the plants were watered at the end of the first drying cycle, the photosynthesis of the plants did not recover to pre-stress rates, indicating that the drought stress caused a long-term reduction in photosynthesis. Despite the more severe drought stress in the abelias (both a lower substrate water content and lower water potential at wilting), abelias recovered better from drought than hydrangeas. After the plants were watered at the end of the first drying cycle, the photosynthetic rate of abelias recovered to ≈70%, while the photosynthetic rate of the hydrangeas recovered to only 62% of the pre-stress rate.

Download Full-text

Legume Plant Growth at Various Levels of Drought Stress Treatment

Indonesian Journal of Agricultural Research ◽

10.32734/injar.v1i1.182 ◽

2018 ◽

Vol 1 (1) ◽

pp. 9-19 ◽

Cited By ~ 1

Author(s):

Veronica Sinamo ◽

Nevy Diana Hanafi ◽

Tri Hesty Wahyuni

Keyword(s):

Drought Stress ◽

Plant Growth ◽

Crop Production ◽

Animal Feed ◽

Field Capacity ◽

Severe Drought ◽

Fresh Matter ◽

Dry Land ◽

Stress Treatment ◽

Matter Production

A strategic alternative step for the development of cultivation of feed crops is to optimize the use of dry land that has the potential for agricultural and livestock business. One of the forage plants that has good adaptation to less good soil condition and is a pioneer plant, Pueraria javanica legume, so it can be considered as a potential alternative forage as animal feed. The research aims at determining the effect of various levels of drought stress treatment on the plant hight, fresh matter production, dry matter production and root biomass of Pueraria javanica legume. The experiment was conducted in the Greenhouse of the Agriculture Faculty of Universitas Sumatera Utara. The experiment was carried out using a completely randomized design (CRD) with 3 treatments and 4 replications. The treatments were A1 (25% field capacity (FC)=144 ml/polybag, A2 (50% FC)=288 ml/polybag and A3 (100% FC)=576 ml/polybag. The results show that Pueraria javanica legume can survive and grow up to severe drought stress (25% FC) but the crop production does not increase when compared to the field capacity condition; besides, the legume cannot survive longer in drought condition. The volume of water supplied corresponding to the field capacity makes the plant growth better.

Download Full-text

Poly-γ-glutamic acid enhanced the drought resistance of maize by improving photosynthesis and affecting the rhizosphere microbial community

BMC Plant Biology ◽

10.1186/s12870-021-03392-w ◽

2022 ◽

Vol 22 (1) ◽

Author(s):

Haizhen Ma ◽

Panpan Li ◽

Xingwang Liu ◽

Can Li ◽

Shengkui Zhang ◽

...

Keyword(s):

Microbial Community ◽

Drought Stress ◽

Plant Growth ◽

Glutamic Acid ◽

Root Development ◽

Drought Resistance ◽

Severe Drought ◽

Plant Growth Promoting Bacteria ◽

Exogenous Application ◽

Rhizosphere Microbial Community

Abstract Background Compared with other abiotic stresses, drought stress causes serious crop yield reductions. Poly-γ-glutamic acid (γ-PGA), as an environmentally friendly biomacromolecule, plays an important role in plant growth and regulation. Results In this project, the effect of exogenous application of γ-PGA on drought tolerance of maize (Zea mays. L) and its mechanism were studied. Drought dramatically inhibited the growth and development of maize, but the exogenous application of γ-PGA significantly increased the dry weight of maize, the contents of ABA, soluble sugar, proline, and chlorophyll, and the photosynthetic rate under severe drought stress. RNA-seq data showed that γ-PGA may enhance drought resistance in maize by affecting the expression of ABA biosynthesis, signal transduction, and photosynthesis-related genes and other stress-responsive genes, which was also confirmed by RT–PCR and promoter motif analysis. In addition, diversity and structure analysis of the rhizosphere soil bacterial community demonstrated that γ-PGA enriched plant growth promoting bacteria such as Actinobacteria, Chloroflexi, Firmicutes, Alphaproteobacteria and Deltaproteobacteria. Moreover, γ-PGA significantly improved root development, urease activity and the ABA contents of maize rhizospheric soil under drought stress. This study emphasized the possibility of using γ-PGA to improve crop drought resistance and the soil environment under drought conditions and revealed its preliminary mechanism. Conclusions Exogenous application of poly-γ-glutamic acid could significantly enhance the drought resistance of maize by improving photosynthesis, and root development and affecting the rhizosphere microbial community.

Download Full-text

Role of Ascorbic acid, Glutathione and Proline Applied as Singly or in Sequence Combination in Improving Chickpea Plant through Physiological Change and Antioxidant Defense under Different Levels of Irrigation Intervals

Molecules ◽

10.3390/molecules25071702 ◽

2020 ◽

Vol 25 (7) ◽

pp. 1702 ◽

Cited By ~ 10

Author(s):

Hossam S. El-Beltagi ◽

Heba I. Mohamed ◽

Mahmoud R. Sofy

Keyword(s):

Ascorbic Acid ◽

Drought Stress ◽

Plant Growth ◽

Antioxidant Defense ◽

Harmful Effect ◽

Antioxidant Defense System ◽

Severe Drought ◽

Chickpea Plant ◽

Moderate Drought ◽

Effects Of Drought

In recent years, the harmful effects of drought stress have been be mitigated by using bioactive compounds such as antioxidants and osmolytes. In this research, pot experiments were carried out to investigate the effects of ascorbic acid, glutathione and proline on alleviating the harmful effect of drought stress in chickpea plants during season 2017. Chickpea plant seeds were soaked in ascorbic acid (0.75 mM), glutathione (0.75 mM), proline (0.75 mM) singly and/or in sequence combinations for 4 h and then planted in pots. The pots were irrigated with water after seven days (to serve as control), after 14 days (moderate drought stress) and after 28 days (severe drought stress). The sequence combination of antioxidants and proline under drought stress has not been studied yet. The results showed significantly decreased in plant growth, yielding characteristics, photosynthetic pigments and soluble protein content in response to moderate and severe drought stress. Moreover, treatment with antioxidants caused increment the antioxidant enzyme activity, non-enzymatic antioxidant (ascorbic acid and glutathione) contents and endogenous proline in stressed and unstressed plants. In conclusion, The sequence combination of antioxidants and proline caused improvement in plant growth under drought stress by up-regulating the antioxidant defense system and osmolyte synthesis.

Download Full-text

Assessing photosynthetic performance of fennel (Foeniculum vulgare Mill) influenced by plant growth regulators and drought stress imposed at vegetative and reproductive stages

Italian Journal of Agronomy ◽

10.4081/ija.2019.1319 ◽

2019 ◽

Vol 14 (2) ◽

pp. 93-100 ◽

Cited By ~ 2

Author(s):

Ghasem Parmoon ◽

Ali Ebadi ◽

Soodabeh Jahanbakhsh ◽

Masoud Hashemi ◽

Seyed Amir Moosavi

Keyword(s):

Drought Stress ◽

Plant Growth ◽

Plant Growth Regulators ◽

Growth Regulators ◽

Crop Productivity ◽

Photosynthetic Performance ◽

Photosynthetic Parameters ◽

Severe Drought ◽

Mild Stress ◽

Foeniculum Vulgare

Maintaining crop productivity under limited irrigation water requires some new strategies. This study investigated the influence of drought stress and the application of plant growth regulators (PGRs) including jasmonic acid, brassinosteroids, and putrescine on photosynthetic performance of fennel (Foeniculum vulgare Mill). The results indicated that fennel exhibited active osmoregulation which prevented a sharp decrease in relative water content. Fennel successfully maintained high leaf chlorophyll index, Net photosynthesis rate, and transpiration under mild stress, however, severe stress reduced the photosynthetic parameters by 22%, 24%, and 50%, respectively. Drought stress increased chlorophyll a fluorescence when fennel plants exposed to the stress condition. Vk and Wk parameters related to the donor side of photoinhibition of photosystem II (PSII) increased by 44% when severe drought stress imposed at the vegetative stage and 34% when occurred during the flowering. The elevation of Vk and Wk indicated a failure in water splitting in PSII. The VJ and VI parameters of acceptor sides increased by 16% and 22%, respectively when drought stress imposed at the vegetative phase and to 19% and 30%, when drought stress occurred during reproductive phase. Using PGRs resulted in reduced VJ, VI, Vk, and Wk, suggesting that some degree of recovery of damages occurred. All three PGRs stimulated biomass production and on average, plants yielded roughly 1.6 fold higher than the control plants. The influences of PGRs were mainly independent of drought stress level.

Download Full-text

Effect of plant growth promoting rhizobacteria (PGPR) and water stress on phytohormones and polyamines of soybean

Indian Journal of Agricultural Research ◽

10.18805/ijare.v49i5.5805 ◽

2015 ◽

Vol 49 (5) ◽

Cited By ~ 3

Author(s):

Hossein Zahedi ◽

Samira Abbasi

Keyword(s):

Abscisic Acid ◽

Drought Stress ◽

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Control Treatment ◽

Rhizobium Japonicum ◽

Severe Drought ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Soybean Plants

The effect of inoculation of three plant growth promoting rhizobacteria (PGPR) that is <italic>Rhizobium japonicum</italic>, <italic>Azotobacter chroococcum</italic> and <italic>Azospirillum brasilense</italic> and mixture of them on phytohormones and polyamines of soybean under different irrigation regimes was investigated. Drought stress induced by irrigation withholding until 40, 80 and 120 mm evaporation from evaporation pan. However seed bacterization of soybean was accompanied with 20 kg ha−1 nitrogen. In addition, 20 and 100 kg ha−1 nitrogen were considered as control treatments. The results showed that drought stress significantly decreased cytokinin, gibberellin and auxin accumulation in plant tissues. By contrast, drought stress led to increase in abscisic acid accumulation in soybean plants. Polyamines that are putrescine and spermidine increased due to drought stress and then decreased under severe drought stress. PGPR application had positive effect on growth promoting phytohormones compared to control treatment. However the highest accumulation of cytokinin, gibberellin and auxin was related to 100 kg ha−1 nitrogen treatment. In case of abscisic acid PGPR application decreased its accumulation. Asignificant decrease as observed on polyamines accumulation when PGPRs were applied on stressed soybean plants.

Download Full-text

Poly-γ-glutamic acid enhanced drought resistance of maize by improving photosynthesis and affecting rhizosphere microbial community

10.21203/rs.3.rs-846088/v1 ◽

2021 ◽

Author(s):

Haizhen Ma ◽

Xingwang Liu ◽

Panpan Li ◽

Can Li ◽

Shengkui Zhang ◽

...

Keyword(s):

Microbial Community ◽

Drought Stress ◽

Plant Growth ◽

Glutamic Acid ◽

Drought Resistance ◽

Yield Reduction ◽

Severe Drought ◽

Plant Growth Promoting Bacteria ◽

Exogenous Application ◽

Rhizosphere Microbial Community

Abstract Background Compared with other abiotic stresses, drought stress is a serious causal factor leading to crop yield reduction. Poly-γ-glutamic acid (γ-PGA), as an environmentally friendly biomacromolecule, plays an important role in plant growth and regulation. Results In this project, the effect of exogenous application of γ-PGA on drought tolerance of maize (Zea mays. L) and its mechanism were studied. Drought dramatically inhibited the growth and development of maize, but the exogenous application of γ-PGA significantly increased the dry weight of maize and the contents of ABA, soluble sugar, proline, chlorophyll and the photosynthetic rate under severe drought stress. RNAseq data showed that γ-PGA may enhance drought resistance of maize by affecting the expression of ABA biosynthesis and signal transduction related genes, photosynthesis-related genes and other stress-responsive genes, which were also confirmed by RT-PCR and promoter motif analysis. In addition, diversity and structure analysis of rhizosphere soil bacterial community demonstrated that γ-PGA enriched the plant growth promoting bacteria such as Actinobacteria, Chloroflexi, Firmicutes, Alphaproteobacteria and Deltaproteobacteria. Meanwhile, γ-PGA significantly improved roots development, urease activity and ABA contents of maize rhizospheric soil under drought stress. This study emphasized the possibility of using γ-PGA to improve crop drought resistance and soil environment under drought condition and revealed its preliminary mechanism. Conclusions Exogenous application of poly-γ-glutamic acid could significantly enhance the drought resistance of maize by improving photosynthesis, root development and affecting rhizosphere microbial community.

Download Full-text