Leaf morphology, photochemistry and water status changes in resprouting Quercus ilex during drought

2005 ◽  
Vol 32 (2) ◽  
pp. 117 ◽  
Author(s):  
Karen Peña-Rojas ◽  
Xavier Aranda ◽  
Richard Joffre ◽  
Isabel Fleck
Keyword(s):  
Drought Stress ◽  
Quercus Ilex ◽  
Structural Characteristics ◽  
Water Status ◽  
Stomatal Closure ◽  
Severe Drought ◽  
Clear Cut ◽  
Leaf Mass Area ◽  
Relative Water ◽  
Moderate Drought

Functional and morphological (structural) characteristics of Quercus ilex L. leaves under drought stress were studied in the forest and in a nursery. We compared undisturbed individuals (controls) with resprouts emerging after clear-cut or excision. When soil water availability was high, gas-exchange was similar in resprouts and controls, despite higher midday leaf water potential, midday leaf hydration and relative water content (RWC). In moderate drought, stomatal closure was found to limit photosynthesis in controls, and in severe drought non-stomatal limitations of photosynthesis were also greater than in resprouts. Leaf structure and chemical composition changed under drought stress. Leaves tended to be smaller in controls with increasing drought, and resprouts had larger leaves and lower leaf mass area (LMA). The relationship between nitrogen (N) content and LMA implied lower N investment in photosynthetic components in controls, which could be responsible for their increased non-stomatal limitation of photosynthesis. Changes were more apparent in leaf density (D) and thickness (T), components of LMA. Decreases in D were related to reductions in cell wall components: hemicellulose, cellulose and lignin. In resprouts, reduced D and leaf T accounted for the higher mesophyll conductance (gmes) to CO2 measured.

scholarly journals DEHYDRIN PROFILES OF SOME IRANIAN MELON VARIETIES (Cucumis melo L. Merr) UNDER DROUGHT STRE SS CONDITIONS

2019 ◽  
Vol 18 (6) ◽  
pp. 75-84
Author(s):  
Alireza Motallebi-Azar ◽  
István Papp ◽  
Anita Szegő
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Water Content ◽  
Water Status ◽  
Field Capacity ◽  
Total Protein Content ◽  
Severe Drought ◽  
Molecular Weights ◽  
Potential Marker ◽  
Relative Water

Dehydrins are proteins that play a role in the mechanism of drought tolerance. This study aimed at establishing dehydrin profile and accumulation in four local melon varieties of Iran: Mino, Dargazi, Saveii, and Semsori, as well as in a commercial variety Honeydew. Plants were treated with drought stress by adjusting the soil water content to 75, 50, 40, 30 and 20% of field capacity (FC) by withholding water. Water status of plants was monitored based on the seedling fresh weight (FW) and relative water content of leaves (RWC). Total protein content was extracted, then heat-stable protein (HSP) fraction was isolated for each variety and water stress treatment. After SDS-PAGE of HSP, Western blotting analysis was carried out with Anti-dehydrin rabbit (primary) and Goat anti rabbit (secondary) antibodies. ANOVA results showed that with decreasing FC below 75%, FW and RWC decreased, but these changes significantly varied among genotypes. On the basis of FW and RWC data under different drought stress treatments, the following drought-tolerant ranking was established: Mino > Dargazi > Saveii and Honeydew > Semsori, from tolerant to sensitive order. Results of Western blot analysis showed that expression of some proteins with molecular weights of 19–52 kDa was induced in the studied varieties under drought stress (% FC). Expression level of the dehydrin proteins in different varieties was variable and also depending on the drought stress level applied. However, dehydrin proteins (45 and 50 kDa) showed strong expression levels in all varieties under severe drought stress (20% FC). The abundance of dehydrin proteins was higher in tolerant varieties (Mino and Dargazi) than in moderate and drought sensitive genotypes. Consequently, dehydrins represent a potential marker for selection of genotypes with enhanced drought tolerance.

scholarly journals Water Relations of Well-watered Citrus Exposed to Cold-acclimating Temperatures

HortScience ◽  
2013 ◽  
Vol 48 (10) ◽  
pp. 1309-1312 ◽  
Author(s):  
Smita Barkataky ◽  
Robert C. Ebel ◽  
Kelly T. Morgan ◽  
Keri Dansereau
Keyword(s):  
Drought Stress ◽  
Cold Acclimation ◽  
Water Relations ◽  
Water Status ◽  
Stomatal Closure ◽  
Irrigation Scheduling ◽  
Stem Water Potential ◽  
Cold Temperatures ◽  
Relative Water ◽  
Leaf Relative Water Content

This study was conducted on well-watered citrus to determine changes in water relations during cold acclimation independent of drought stress. Potted sweet orange and Satsuma mandarin trees were exposed to progressively lower, non-freezing temperatures down to 10/4 °C, light/dark temperatures, respectively, for 9 weeks in environmental growth chambers to promote cold acclimation. The trees were watered twice daily and three times on the day water relations data were collected to minimize drought stress. Although soil moisture was higher and non-limiting for plants in the cold than in the warm chamber, cold temperatures promoted stomatal closure, higher root resistance, lower stem water potential (Ψstem), lower transpiration, and lower leaf ψS. Leaf relative water content (RWC) was not different for cold-acclimated trees compared with the controls. Cold acclimation promoted stomatal closure at levels only observed in severely drought-stressed plants exposed to warm temperatures and where Ψstem and RWC are typically much lower than what was found in this study. Ψstem continued to decline the last 4 weeks of the experiment although air temperature, leaf ψS, RWC, stomatal conductance (gS), and transpiration were constant. The results of this experiment indicate that water relations of citrus during cold acclimation vary from those known to occur as a result of drought stress, which have implications for using traditional measures of plant water status in irrigation scheduling during winter.

scholarly journals Cavitation Limits the Recovery of Gas Exchange after Severe Drought Stress in Holm Oak (Quercus ilex L.)

Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 443 ◽  
Author(s):  
José Peguero-Pina ◽  
Óscar Mendoza-Herrer ◽  
Eustaquio Gil-Pelegrín ◽  
Domingo Sancho-Knapik
Keyword(s):  
Drought Stress ◽  
Quercus Ilex ◽  
Stomatal Closure ◽  
Maximum Velocity ◽  
Holm Oak ◽  
Severe Drought ◽  
Summer Drought ◽  
Co2 Uptake ◽  
Partial Recovery ◽  
Xylem Embolism

Holm oak (Quercus ilex L.) is a Mediterranean species that can withstand intense summer drought through a high resistance to cavitation far beyond the stomatal closure. Besides stomatal limitations, both mesophyll and biochemical limitations to CO2 uptake could increase in holm oak under drought. However, no studies have addressed how hydraulic and non-hydraulic factors may limit the recovery of photosynthesis when re-watering after inducing 50% loss of hydraulic conductivity. We measured photosynthetic traits, xylem embolism, and abscisic acid (ABA) in holm oak with increasing levels of drought stress and seven days after plant re-watering. Drought stress caused a sharp decrease in net CO2 assimilation (AN), stomatal and mesophyll conductance (gs and gm), and maximum velocity of carboxylation (Vcmax). The stomatal closure could be mediated by the rapid increase found in ABA. The high level of xylem embolism explained the strong down-regulation of gs even after re-watering. Therefore, only a partial recovery of AN was observed, in spite of non-hydraulic factors not limiting the recovery of AN, because i/ABA strongly decreased after re-watering, and ii/gm and Vcmax recovered their original values. Therefore, the hydraulic-stomatal limitation model would be involved in the partial recovery of AN, in order to prevent extensive xylem embolism under subsequent drought events that could compromise holm oak survival.

scholarly journals Physiological responses of mungbean (Vigna radiata) varieties to drought stress

2019 ◽  
Vol 44 (1) ◽  
pp. 1-11 ◽  
Author(s):  
A Nazran ◽  
JU Ahmed ◽  
AJMS Karim ◽  
TK Ghosh
Keyword(s):  
Drought Stress ◽  
Physiological Responses ◽  
Field Capacity ◽  
Water Relation ◽  
Severe Drought ◽  
Water Regimes ◽  
Randomized Design ◽  
Physiological Adaptations ◽  
Relative Water ◽  
Moderate Drought

A pot experiment under polyshed condition was carried out at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during the period from 27 March 2017 to 5 May 2017 to study the physiological responses of mungbean varieties to drought stress under varying water regimes. The treatments consisted of four mungbean varieties, namely BARI Mung-5, BARI Mung-6, BUmug 2, BUmug 4 and three water regimes viz., 50 to 60% field capacity (FC), 70 to 80% FC and 90 to100% FC which were considered as severe drought stress, moderate drought stress and non-stress, respectively. The experiment was laid out in a completely randomized design with factorial arrangement having four replications. Results indicated that BARI Mung-6 maintained significantly the highest relative water content, leaf water potential, proline content, shoot dry matter and lower rate of electrolyte leakage at 50 to 60% FC (severe drought stress). BUmug 2 showed the lowest performance in terms of all the water relation and physiological characters which indicates its higher sensitivity to severe drought stress. Variety BARI Mung-6 was relatively water stress tolerant than others in respect of physiological adaptations. So, BARI Mung-6 can be a potential variety for cultivation under drought condition where irrigation facility is limited. Bangladesh J. Agril. Res. 44(1): 1-11, March 2019

scholarly journals Licorice (Glycyrrhiza glabra)—Growth and Phytochemical Compound Secretion in Degraded Lands under Drought Stress

2021 ◽  
Vol 13 (5) ◽  
pp. 2923
Author(s):  
Botir Khaitov ◽  
Munisa Urmonova ◽  
Aziz Karimov ◽  
Botirjon Sulaymonov ◽  
Kholik Allanov ◽  
...  
Keyword(s):  
Drought Stress ◽  
Water Deficit ◽  
Background Field ◽  
Field Trials ◽  
Glycyrrhiza Glabra ◽  
Agricultural System ◽  
Positive Effects ◽  
Relative Water ◽  
Moderate Drought ◽  
Four Levels

Water deficiency restricts plant productivity, while excessive soil moisture may also have an adverse impact. In light of this background, field trials were conducted in secondary saline soil (EC 6.5 dS m−1) at the experimental station of Tashkent State Agrarian University (TSAU), Uzbekistan to determine drought tolerance of licorice (Glycyrrhiza glabra) by exposure to four levels of water deficit, namely control (70–80%), moderate (50–60%), strong (30–40%) and intense (10–20%) relative water content (WC) in the soil. The moderate drought stress exhibited positive effects on the morphological and physiological parameters of licorice, and was considered to be the most suitable water regime for licorice cultivation. Plant growth under the 50–60% WC treatment was slightly higher as compared to 70–80% WC treatment, exhibiting weak water deficit promotes licorice growth, root yield and secondary metabolite production. In particular, secondary metabolites i.e., ash, glycyrrhizic acid, extractive compounds and flavonoids, tended to increase under moderate water deficit, however further drought intensification brought a sharp decline of these values. These results contribute to the development of licorice cultivation technologies in arid regions and the most important consideration is the restoration of ecological and economical functions of the dryland agricultural system.

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

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.

Phedimus Aizoon L. Responds to Drought Stress: Growth, Physiological Changes and Mechanism of Drought Resistance

2020 ◽  
Author(s):  
Yuhang Liu ◽  
Zhongqun He ◽  
Yongdong Xie ◽  
Lihong Su ◽  
Ruijie Zhang ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Resistance ◽  
Soluble Sugar ◽  
Severe Drought ◽  
Physiological Changes ◽  
Moderate Drought ◽  
Negative Effect ◽  
Mda Content ◽  
Maximum Water ◽  
Mild Drought

Abstract A pot experiment was conducted to investigate the growth, physiological changes and mechanism of drought resistance of Phedimus aizoon L. under different levels of water content .CK: 75% ~ 80% of the MWHC (maximum water holding capacity), Mild drought: 55% ~ 60%, Moderate drought: 40% ~ 45%, Severe drought: 20% ~ 25%.We observed that the plants grew normally in the first two treatments, even the mild drought promoted the growth of the roots. In the last two treatments, drought stress had a significant negative effect on plant growth, at the same time, Phedimus aizoon L. also made positive physiological response to cope with the drought: The aboveground part of the plant (leaf, plant height, stem diameter) was smaller, the waxy layer of the leaves was thickened, the stomata of the leaves were closed during the day, and only a few stomata were opened at night, which proved that the dark reaction cycle metabolism mode of the plant was transformed from C3 cycle to CAM pathway. The activity of antioxidant enzymes (SOD, POD and CAT) was continuously increased to alleviate the damage caused by drought. To ensure the relative stability of osmotic potential, the contents of osmoregulation substances such as proline, soluble sugar, soluble protein and trehalose increased correspondingly. But plants have limited regulatory power, with aggravation of drought stress degree and extension of stress time, the MDA content and electrolyte leakage of leaves increased continuously. Observed under electron microscope,the morphology of chloroplast and mitochondria changed and the membrane structure was destroyed. The plant's photosynthetic and respiratory mechanisms are destroyed and the plant gradually die.

scholarly journals Isolation, purification and characterization of an ascorbate peroxidase from celery and overexpression of the AgAPX1 gene enhanced ascorbate content and drought tolerance in Arabidopsis

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jie-Xia Liu ◽  
Kai Feng ◽  
Ao-Qi Duan ◽  
Hui Li ◽  
Qing-Qing Yang ◽  
...  
Keyword(s):  
Drought Stress ◽  
Ascorbate Peroxidase ◽  
Drought Resistance ◽  
Stomatal Closure ◽  
High Survival ◽  
Gene Encoding ◽  
Sds Page ◽  
Relative Water ◽  
New Evidence

Abstract Background Celery is a widely cultivated vegetable abundant in ascorbate (AsA), a natural plant antioxidant capable of scavenging free radicals generated by abiotic stress in plants. Ascorbate peroxidase (APX) is a plant antioxidant enzyme that is important in the synthesis of AsA and scavenging of excess hydrogen peroxide. However, the characteristics and functions of APX in celery remain unclear to date. Results In this study, a gene encoding APX was cloned from celery and named AgAPX1. The transcription level of the AgAPX1 gene was significantly upregulated under drought stress. AgAPX1 was expressed in Escherichia coli BL21 (DE3) and purified. The predicted molecular mass of rAgAPX1 was 33.16 kDa, which was verified by SDS-PAGE assay. The optimum pH and temperature for rAgAPX1 were 7.0 and 55 °C, respectively. Transgenic Arabidopsis hosting the AgAPX1 gene showed elevated AsA content, antioxidant capacity and drought resistance. Less decrease in net photosynthetic rate, chlorophyll content, and relative water content contributed to the high survival rate of transgenic Arabidopsis lines after drought. Conclusions The characteristics of APX in celery were different from that in other species. The enhanced drought resistance of overexpressing AgAPX1 in Arabidopsis may be achieved by increasing the accumulation of AsA, enhancing the activities of various antioxidant enzymes, and promoting stomatal closure. Our work provides new evidence to understand APX and its response mechanisms to drought stress in celery.

Performance of interior spruce seedlings treated with abscisic acid analogs

1996 ◽  
Vol 26 (12) ◽  
pp. 2061-2070 ◽  
Author(s):  
Steven C. Grossnickle ◽  
Raymund S. Folk ◽  
Suzanne R. Abrams ◽  
David I. Dunstan ◽  
Patricia A. Rose
Keyword(s):  
Environmental Conditions ◽  
Stomatal Closure ◽  
Frozen Storage ◽  
Net Photosynthesis ◽  
Severe Drought ◽  
Bud Break ◽  
Root Temperature ◽  
Interior Spruce ◽  
Moderate Drought ◽  
Aba Analogs

This research examined the performance of interior spruce (Piceaglauca (Moench) Voss × Piceaengelmannii Parry ex Engelm.) seedlings, each group treated with one of nine abscisic acid (ABA) analogs, during the initial stages of seedling establishment under a range of environmental conditions. Interior spruce seedlings were removed from frozen storage, ABA analog treatments were immediately applied, and seedlings were tested under low root temperature or moderate drought cycle conditions. Alternatively, seedlings were removed from frozen storage and held until bud break had occurred before ABA analog treatments were applied. These seedlings were then tested under severe drought or optimum environmental conditions. ABA analog 1, followed by ABA analog 2, had the most consistent performance of the nine tested ABA analogs under all combinations of environmental test conditions. These ABA analogs reduced needle conductance for 7–9 days when seedlings were tested under low root temperature conditions with only a reduction in net photosynthesis on the first day of testing. During three successive moderate drought cycles, seedlings treated with ABA analogs 1 and 2 had partial stomatal closure, thereby increasing mean shoot water potential by around 50%. During a severe drought, ABA analog 1 caused partial stomatal closure, which allowed seedlings to maintain a mean shoot water potential of greater than −3.0 MPa and a positive net photosynthesis up to 8 days longer than control seedlings. Under optimum environmental conditions, ABA analogs 1 and 2 reduced needle conductance for up to 7 days, with net photosynthesis reduced for 1 day. Root growth was not adversely affected in seedlings treated with any of the ABA analogs prior to bud break. However, when seedlings were treated after bud break, all ABA analogs reduced growth of long roots (>4.0 cm) by approximately 60%. ABA analogs 1 and 2 delayed bud break by 4 days, when compared with control seedlings. Results are discussed in reference to the establishment process of spruce seedlings on reforestation sites.

scholarly journals Foliar application of melatonin induces tolerance to drought stress in Moldavian balm plants (Dracocephalum moldavica) through regulating the antioxidant system

2018 ◽  
Vol 30 (1) ◽  
pp. 155-167 ◽  
Author(s):  
Rozita Kabiri ◽  
Ali Hatami ◽  
Hakimeh Oloumi ◽  
Mehdi Naghizadeh ◽  
Fatemeh Nasibi ◽  
...  
Keyword(s):  
Drought Stress ◽  
Foliar Application ◽  
Leaf Length ◽  
Stress Conditions ◽  
Guaiacol Peroxidase ◽  
Severe Drought ◽  
Wide Range ◽  
Significant Difference ◽  
Relative Water ◽  
Leaf Surface Area

Abstract Melatonin, as an indoleamine molecule, regulates a wide range of physiological functions during the growth, morphogenesis and response of plants to biotic and abiotic stresses. In this research, the effect of exogenous application of melatonin (0 (distilled water), 50, 100 and 150 µM) to the leaves of Moldavian balm plants grown under different levels of drought stress (100% (control), 80%, 60% and 40% of field water capacity) was investigated. The results indicate that plants which were treated with 100 µM melatonin showed the greatest leaf surface area, lateral branching, flower length and activities of antioxidant enzymes (superoxide dismutase, guaiacol peroxidase and ascorbate peroxidase). Foliar application of 100 µM melatonin had no significant difference in catalase activity in comparison with the control and other concentrations of melatonin under normal, moderate and severe drought stress conditions. The lowest H2O2 content and lipid peroxidation (electrolyte leakage, concentrations of malondialdehyde and other aldehydes) were obtained at the concentration of 100 µM melatonin under severe drought stress. This concentration also significantly increased the chlorophyll content and enhanced the relative water content; however, foliar application of 100 µM melatonin had no significant effect on leaf length and proline content compared with the control under normal and stress conditions. The obtained results suggested that foliar application of 100 µM melatonin was more effective than the concentrations of 50 and 150 µM melatonin in reducing the adverse effects of moderate and severe drought stress.

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