scholarly journals Polyamine Application Effects on Gibberellic Acid Content in Creeping Bentgrass during Drought Stress

2017 ◽  
Vol 142 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Sanalkumar Krishnan ◽  
Emily B. Merewitz
Keyword(s):  
Drought Stress ◽  
Gibberellic Acid ◽  
Abiotic Stress Tolerance ◽  
Photochemical Efficiency ◽  
Canopy Temperature ◽  
Creeping Bentgrass ◽  
Relative Water ◽  
Consistent Basis ◽  
Chamber Studies ◽  
Growth Chamber Studies

Polyamines (PAs), spermine (Spm), and spermidine (Spd) may enhance the abiotic stress tolerance and growth of creeping bentgrass (Agrostis stolonifera). Growth chamber studies were conducted to investigate the effect of PA application on the physiological response and hormone content in creeping bentgrass ‘Penn-G2’ under drought. Spm (1 mm) and Spd (5 mm) were applied exogenously under drought or well-watered conditions. PA-treated plants maintained significantly higher turf quality (TQ), relative water content (RWC), photochemical efficiency, and membrane health while maintaining lower canopy temperature. Spm at the 1-mm rate had a 2.46-fold higher osmotic adjustment (OA) at 10 d compared with control plants. A greater content of gibberellic acid (GA) isoforms (GA1, GA4, and GA20) were observed compared with controls during both studies for PA-treated plants under drought. After 7 days of drought stress in Expt.1, GA1 levels were 3.26 higher for Spm 1-mm-treated plants compared with drought controls. GA4 contents were 69% and 65% higher compared with drought-stressed-untreated plants for Spd 5-mm application after 9 and 11 days. Higher levels of GA20 were observed at 10 days (Spd 5 mm, 108.9% higher) due to PA treatment compared with drought controls. In addition to differential regulation of GA isoforms, we observed enhanced abscisic acid (ABA) due to PA application; however, not on a consistent basis. This study showed that PA application may play a role in GA1, GA4, and ABA accumulation in creeping bentgrass ‘Penn G-2’ under drought stress.

scholarly journals Creeping Bentgrass Responses to Drought Stress and Polyamine Application

2015 ◽  
Vol 140 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Vijaya Shukla ◽  
Yingmei Ma ◽  
Emily Merewitz
Keyword(s):  
Drought Stress ◽  
Photochemical Efficiency ◽  
Creeping Bentgrass ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Major Effect ◽  
Abiotic Stress Response ◽  
Low Concentrations ◽  
Malondialdehyde Content ◽  
Relative Water

Polyamines (PAs) such as spermidine (Spd), spermine (Spm), and putrescine are involved in various biological functions including abiotic stress response. Whether PAs play an important role in cool-season turfgrass tolerance of drought stress is not well investigated. We have conducted a series of growth chamber (GC) studies including one hydroponic and two soil-based GC studies with creeping bentgrass (Agrostis stolonifera) ‘Penncross’ and ‘Penn-G2’ to determine whether exogenous application of PAs may affect plant growth and stress tolerance. Application of relatively low concentrations of Spd (500 or 750 μM) or Spm (500 μM) promoted tillering rates under optimal growth conditions in hydroponics. The same levels of PA treatments moderated the damages associated with drought stress in the soil-based GC studies. The most notable differences in drought response associated with PA treatment were increased membrane health. This was observed as greater photochemical efficiency, higher quantum yield, less electrolyte leakage, and less lipid peroxidation (malondialdehyde content) in PA-treated plants compared with control plants. The relatively low level of exogenous PAs used in this study did not have a major effect on plant water relations under drought stress. Canopy temperatures and soil moisture content were unaffected by any PA treatment; however, on some days during early drought stress, relative water content was significantly higher in PA-treated plants compared with controls. PA could play a major role in protecting photosynthetic and cellular membranes during drought stress of creeping bentgrass.

scholarly journals Evaluation of Drought Tolerance and Avoidance Traits for Six Creeping Bentgrass Cultivars

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 519-524 ◽  
Author(s):  
Stephen E. McCann ◽  
Bingru Huang
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Water Use ◽  
Photochemical Efficiency ◽  
Creeping Bentgrass ◽  
Root Production ◽  
Drought Avoidance ◽  
Relative Water ◽  
Leaf Relative Water Content ◽  
Use Efficiency

The objectives of this study were: 1) to compare drought responses between the more recently developed creeping bentgrass cultivars to standard cultivars and 2) to determine differential drought tolerance and avoidance characteristics associated with cultivar variation in drought resistance. Six cultivars of creeping bentgrass (Agrostis stoloniferia) (‘Penn A-4’, ‘Independence’, ‘Declaration’, ‘L-93’, ‘Penncross’, and ‘Putter’) were maintained in growth chambers at 20 °C day/15 °C night either well-watered or exposed to drought stress by withholding water for 17 days. Cultivars varied in turf performance and physiological responses (leaf relative water content and photochemical efficiency) to drought stress, which was reflected in their differences in drought tolerance (osmotic adjustment) and drought avoidance traits (water use rate and efficiency, root viability, root length, and number). ‘Penn A-4,’ ‘Independence,’ and ‘L-93’ generally performed better than other three cultivars under drought conditions, mainly through maintaining higher water use efficiency, root viability, root elongation, or root production. The majority of physiological parameters evaluated suggested that of the six creeping bentgrass cultivars examined in this study, the three cultivars with better ability to survive drought stress used mainly avoidance traits related to water use and water uptake.

scholarly journals Effects of SAG12-ipt and HSP18.2-ipt Expression on Cytokinin Production, Root Growth, and Leaf Senescence in Creeping Bentgrass Exposed to Drought Stress

2010 ◽  
Vol 135 (3) ◽  
pp. 230-239 ◽  
Author(s):  
Emily B. Merewitz ◽  
Thomas Gianfagna ◽  
Bingru Huang
Keyword(s):  
Drought Stress ◽  
Root Growth ◽  
Leaf Senescence ◽  
Photochemical Efficiency ◽  
Creeping Bentgrass ◽  
Growth Responses ◽  
Turf Quality ◽  
Relative Water ◽  
Transgenic Lines ◽  
Leaf Relative Water Content

Drought stress is a widespread abiotic stress that causes a decline in plant growth. Drought injury symptoms have been associated with an inhibition in cytokinin (CK) synthesis. The objectives of this study were to investigate whether expression of a gene (ipt) encoding the enzyme adenine isopentenyl phosphotransferase for CK synthesis ligated to a senescence-activated promoter (SAG12) or a heat shock promoter (HSP18.2) would improve drought tolerance in creeping bentgrass (Agrostis stolonifera) and to examine shoot and root growth responses to drought stress associated with changes in endogenous production of CK, and the proportional change in CK and abscisic acid (ABA) due to ipt transformation. Most SAG12-ipt and HSP18.2-ipt transgenic lines exhibited significantly higher turf quality, photochemical efficiency, chlorophyll content, leaf relative water content, and root:shoot ratio under drought stress than the null transformant or the wild-type ‘Penncross’ plants. Transgenic lines that had better growth and turf performance generally had higher CK content and a higher CK-to-ABA ratio, although the direct correlation of CK and ABA content with individual physiological parameters in individual lines was not clear. Our results demonstrated that expressing ipt resulted in the improvement of turf performance under drought stress in creeping bentgrass in some of the transgenic plants with SAG12-ipt or HSP18.2-ipt, which could be associated with the suppression of leaf senescence and promoting root growth relative to shoot growth due to the maintenance of higher CK level and a higher ratio of CK to ABA.

scholarly journals Polyamine Content Changes in Creeping Bentgrass Exposed to Salt Stress

2016 ◽  
Vol 141 (5) ◽  
pp. 498-506 ◽  
Author(s):  
Yingmei Ma ◽  
Emily Merewitz
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Canopy Temperature ◽  
Leaf Tissue ◽  
Creeping Bentgrass ◽  
Extraction Process ◽  
Canopy Temperature Depression ◽  
Polyamine Content ◽  
Chamber Studies ◽  
Growth Chamber Studies

Salt stress is a major problem in turfgrass management. Investigation of metabolites, such as polyamines (PAs) that may improve salt tolerance of turfgrass species, is needed. Two independent growth chamber studies were conducted to evaluate physiological characteristics and changes in PAs, such as putrescine (Put), spermidine (Spd), and spermine (Spm), in response to salt stress in ‘Penncross’ and ‘PsgSLTZ’ creeping bentgrass (Agrostis stolonifera). The study also aimed to determine a method of PA extraction to improve PA yields from creeping bentgrass. Salt solutions were drench applied to plants growing in pure sand daily in a stepwise manner for ≈70 days in both studies. For both cultivars, salt stress caused an increase in leaf Na+ content, percent of electrolyte leakage (EL), and canopy temperature depression (CTD) while it caused a decrease in turf quality (TQ), osmotic potential (Ψs), and K+ and Ca2+ content compared with controls. In the early stages of salt stress, Put content increased in salt-stressed plants compared with controls. Spd content did not change significantly while a transient increase in Spm was observed in the later stage of salt stress. The PA quantification method used in this study included using formic acid during the extraction process, which exhibited enhanced quantification of PAs from creeping bentgrass compared with other methods previously published. Salinity stress upregulated the content of Put and Spm in leaf tissue, which may be involved in salinity tolerance in creeping bentgrass, while Spd accumulation may not be a major salt tolerance mechanism; supplementation with these biochemical compounds could be an alternative to improve creeping bentgrass salt tolerance.

scholarly journals 278 Gas Exchange and Water Relations of Diverse Tall Fescue Cultivars in Response to Drought Stress

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 490C-490
Author(s):  
Bingru Huang ◽  
Hongwen Gao
Keyword(s):  
Drought Stress ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Physiological Factors ◽  
Relative Water

To investigate shoot physiological responses to drought stress of six tall fescue (Festuca arundinacea) cultivars representing several generations of turfgrass improvement, forage-type `Kentucky-31', turf-type `Phoenix', `Phoenix', and `Houndog V', and dwarf-type `Rebel Jr` and `Bonsai' were grown in well-watered or drying soil for 35 days in a greenhouse. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), relative water content (RWC), and photochemical efficiency (Fv/Fm) declined during drought progression in all cultivars, but the time and the severity of reductions varied with cultivars and physiological factors. Pn, RWC, gs, and Tr decreased significantly for `Rebel Jr', `Bonsai', and `Phoenix' when soil water content declined to 20% after 9 days of treatment (DOT) and for `Falcon II', `Houndog V', and `Kentucky-31' when soil water content dropped to 10% at 15 DOT. A significant decrease in Fv/Fm was not observed in drought-stressed plants until 21 DOT for `Rebel Jr', `Bonsai', and `Phoenix' and 28 DOT for `Houndog V', `Kentucky-31', and `Falcon II'. The decline in Pn was due mostly to internal water deficit and stomatal closure under short-term or mild drought-stress conditions. After a prolonged period of drought (35 DOT), higher Pn in `Falcon II', `Houndog V', and `Kentucky-31' could be attributed to their higher Fv/Fm.

scholarly journals Changes in Antioxidant Enzyme Activities and Lipid Peroxidation for Bentgrass Species in Response to Drought Stress

2007 ◽  
Vol 132 (3) ◽  
pp. 319-326 ◽  
Author(s):  
Michelle DaCosta ◽  
Bingru Huang
Keyword(s):  
Lipid Peroxidation ◽  
Drought Stress ◽  
Antioxidant Enzyme ◽  
Drought Resistance ◽  
Enzyme Activities ◽  
Photochemical Efficiency ◽  
Creeping Bentgrass ◽  
Antioxidant Enzyme Activities ◽  
Species Variation ◽  
General Decline

Previous investigations identified velvet bentgrass (Agrostis canina L.) as having higher drought resistance among bentgrass species. This study was designed to determine whether species variation in drought resistance for colonial bentgrass (A. capillaris L.), creeping bentgrass (A. stolonifera L.), and velvet bentgrass was associated with differences in antioxidant enzyme levels in response to drought. Plants of ‘Tiger II’ colonial bentgrass, ‘L-93’ creeping bentgrass, and ‘Greenwich’ velvet bentgrass were maintained in a growth chamber under two watering treatments: 1) well-watered control and 2) irrigation completely withheld for 28 d (drought stress). Prolonged drought stress caused oxidative damage in all three bentgrass species as exhibited by a general decline in antioxidant enzyme activities and an increase in lipid peroxidation. Compared among the three species, velvet bentgrass maintained antioxidant enzyme activities for a greater duration of drought treatment compared with both colonial bentgrass and creeping bentgrass. Higher antioxidant enzyme capacity for velvet bentgrass was associated with less lipid peroxidation and higher turf quality, leaf relative water content, and photochemical efficiency for a greater duration of stress compared with colonial bentgrass and creeping bentgrass. These results suggest that bentgrass resistance to drought stress could be associated with higher oxidative scavenging ability, especially for velvet bentgrass.

scholarly journals Differential Physiological Responses and Genetic Variations in Fine Fescue Species for Heat and Drought Stress

2017 ◽  
Vol 142 (5) ◽  
pp. 367-375 ◽  
Author(s):  
Jinyu Wang ◽  
Patrick Burgess ◽  
Stacy A. Bonos ◽  
William A. Meyer ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
Drought Stress ◽  
Drought Tolerance ◽  
Heat Tolerance ◽  
Photochemical Efficiency ◽  
Physiological Parameters ◽  
Festuca Rubra ◽  
Relative Water ◽  
Prolonged Heat ◽  
Fine Fescue

Summer decline is typically characterized by heat and drought stress and is a major concern for fine fescue species (Festuca). The objectives of this study were to examine whether heat or drought stress is more detrimental, and to determine the genotypic variations in heat and drought tolerance for fine fescues. A total of 26 cultivars, including seven hard fescues (Festuca trachyphylla), eight chewings fescues (Festuca rubra ssp. commutate), seven strong creeping red fescues (Festuca rubra ssp. rubra), two sheep fescues (Festuca ovina ssp. hirtula), and two slender creeping red fescues (Festuca rubra ssp. littoralis) were subjected to prolonged heat or drought stress in growth chambers. Several physiological parameters, including turf quality (TQ), electrolyte leakage (EL), photochemical efficiency (Fv/Fm) chlorophyll content (Chl), and relative water content (RWC) were measured in plants exposed to heat or drought stress. The results indicated that heat stress was more detrimental than drought stress for fine fescue species. Based on TQ and major physiological parameters (EL and Fv/Fm) under heat stress, several cultivars with good heat tolerance were selected, including ‘Blue Ray’, ‘Spartan II’, ‘MN-HD1’, ‘Shoreline’, ‘Navigator II’, ‘Azure’, ‘Beacon’, ‘Aurora Gold’, ‘Reliant IV’, ‘Marco Polo’, ‘Garnet’, ‘Wendy Jean’, ‘Razor’, and ‘Cindy Lou’. Based on TQ and major physiological parameters (EL, RWC, and Fv/Fm) under drought stress, several cultivars with good drought tolerance were selected, including ‘Spartan II’, ‘MN-HD1’, ‘Reliant IV’, ‘Garnet’, ‘Azure’, and ‘Aurora Gold’. These cultivars could be used in hot, dry, or both environments and as breeding germplasm for developing heat tolerance, drought tolerance, or both.

scholarly journals Alleviation of drought stress by silicon supplementation in pistachio (Pistacia vera L.) plants

2013 ◽  
Vol 25 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Ghader Habibi ◽  
Roghieh Hajiboland
Keyword(s):  
Drought Stress ◽  
Photochemical Efficiency ◽  
Dry Weight ◽  
Pistacia Vera ◽  
Antioxidant Defence ◽  
Photosynthetic Gas Exchange ◽  
Relative Water ◽  
Effects Of Drought ◽  
Net Assimilation ◽  
Quantum Yield Of Psii

ABSTRACT The effect of silicon (Si) supplementation (0.35 g Na2SiO3 kg-1 soil, 2.73 mmol Si kg-1 soil) was studied in drought-stressed pistachio (Pistacia vera L. ‘Ahmadaghaii’) plants under field conditions. Silicon treatment significantly increased plant dry weight and relative water content under drought stress. The application of Si for drought-stressed plants improved the maximum quantum yield of PSII. A reduction in the net assimilation rate due to drought stress was alleviated by Si application, accompanied by an increase in stomatal conductance. Silicon treatment resulted in higher catalase and superoxide dismutase activities and lower lipid peroxidation in the leaves of drought-stressed plants. The results suggest that supplementation of water-deficient pistachio plants with Si alleviates the adverse effects of drought due to its enhancement of photochemical efficiency and photosynthetic gas exchange, as well as an activation of the antioxidant defence capacity in this species.

FACTORS INFLUENCING THE DEVELOPMENT OF PRIMARY DORMANCY IN WILD OAT SEEDS

1979 ◽  
Vol 59 (3) ◽  
pp. 777-784 ◽  
Author(s):  
STEVEN G. RICHARDSON
Keyword(s):  
Gibberellic Acid ◽  
Wild Oat ◽  
Night Temperature ◽  
Primary Dormancy ◽  
Factors Influencing ◽  
Seed Maturity ◽  
Oat Seeds ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Mature Seeds

Germination in response to gibberellic acid was used as an assay for wild oat seed dormancy. In growth chamber studies removal of glumes, a 5 °C reduction in night temperature (20 °C day/15 °C night vs. constant 20 °C), and a shorter photoperiod (12 vs. 18 h) during the period following panicle emergence reduced subsequent germination (increased dormancy) of mature seeds. Dormancy of field-grown wild oat seeds increased with increasing seed maturity and was affected by planting location and associated crop.

Pigment dynamics during cold-induced photoinhibition of Acacia melanoxylon

2004 ◽  
Vol 31 (5) ◽  
pp. 481 ◽  
Author(s):  
Tim L. Watson ◽  
Dugald C. Close ◽  
Neil J. Davidson ◽  
Noel W. Davies
Keyword(s):  
Chlorophyll Concentration ◽  
Photochemical Efficiency ◽  
Light Level ◽  
High Light ◽  
Additional Increase ◽  
Acacia Melanoxylon ◽  
Light Intensities ◽  
Growth Chambers ◽  
Chamber Studies ◽  
Growth Chamber Studies

Long-term acclimation of photo- and pigment-chemistry was investigated in a naturally-regenerating stand of Acacia melanoxylon R.Br. ex Ait. A pronounced decrease in photochemical efficiency of A. melanoxylon saplings was observed between autumn and winter in both thinned and unthinned treatments, but the decrease was more severe in the thinned treatment. Associated pigment changes in the unthinned treatment included a decrease in total chlorophyll content and a rise in chlorophyll a : b. Similar acclimation occurred in the thinned treatment with additional increase in zeaxanthin per unit chlorophyll observed. Saplings in the thinned treatment were exposed to lower minimum temperatures, more hours of frost and higher light intensities in the mid- to lower-crown. Growth chamber studies of the short-term acclimation of photo- and pigment-chemistry were conducted in a low / high light and cold / warm temperature factorial experiment. Photochemical efficiency and quantum yield adjusted within one day and then remained constant for 10 d in response to the imposed treatments. Chlorophyll concentration had decreased in all treatments by day 2 in the growth chambers, and subsequently increased in warm, but not in cold, treatments, irrespective of light level by day 10 in the growth chambers. The concentration of lutein-5,6-epoxide decreased in response to the cold-high light treatment and increased in response to other treatments by day 10 in the growth chambers, consistent with a function in sustained photoprotection in leaves of shade-adapted species. Our experiments indicated that A. melanoxylon is susceptible to cold-induced photoinhibition under cool temperatures (2–8°C) and moderate light intensities (450 μmol m–2 s–1).

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