scholarly journals Ultraviolet-B Radiation Damage on Kentucky Bluegrass. I. Antioxidant and Colorant Effects

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1465-1470 ◽  
Author(s):  
Erik H. Ervin ◽  
Xunzhong Zhang ◽  
John H. Fike
Keyword(s):  
Ascorbic Acid ◽  
Poa Pratensis ◽  
Stratospheric Ozone ◽  
Photochemical Efficiency ◽  
Visual Quality ◽  
Kentucky Bluegrass ◽  
Ultraviolet B ◽  
Alpha Tocopherol ◽  
Antioxidant Enzyme Activities ◽  
Antioxidant Defense Systems

High ultraviolet-B (UV-B; 290-320nm wavelength) may significantly contribute to kentucky bluegrass (Poa pratensis L.) sod death at harvest and transplanting. As terrestrial UV-B levels continue to increase due to a depletion of the stratospheric ozone layer this problem may worsen. Epidermal attenuation from pigments and detoxification of reactive oxygen species by antioxidant metabolites and enzymes are involved in plant defense against oxidative stress caused by UV-B. Our objective was to determine whether the attenuation and detoxification systems of kentucky bluegrass could be artificially boosted by exogenous applications of ascorbic acid (AA), alpha-tocopherol (AT), or a colorant before exposure to high levels of UV-B. Ascorbic acid, AT, and the colorant Green Lawnger (GL), were applied to plugs of mature kentucky bluegrass alone or in combination, and then subjected to artificial, continuous UV-B exposure (70 μmol·m-2·s-1); three greenhouse experiments were conducted. By 3 to 5 days after UV-B initiation, visual quality and photochemical efficiency, as measured by chlorophyll fluorescence were significantly reduced. However, in Expt. 1, AA alleviated decline of visual quality, delayed loss of photochemical efficiency, and increased recovery relative to the control. In Expt. 3, decreased endogenous AT and antioxidant enzyme activities were measured due to UV-B stress. Application of AA, AA + AT, or GL partially alleviated photochemical efficiency decline from 4 to 12 days after initiation of UV-B. In addition, application of the chemical treatments increased leaf tissue AT concentrations by 32% to 42%, increased SOD activity by 30% to 33% and increased catalase activity by 37% to 59%, relative to the control as measured 10 days after UV-B initiation. Greater AT concentration and SOD and catalase activities were associated with greater visual quality under UV-B stress. The results of these studies indicate that kentucky bluegrass UV-B tolerance may be increased by supplementing its pigment and antioxidant defense systems with foliar applications of AA, AT or GL.

scholarly journals Ultraviolet-B Radiation Damage on Kentucky Bluegrass. III. Cultivar Effects

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1475-1477 ◽  
Author(s):  
Erik H. Ervin ◽  
Xunzhong Zhang ◽  
John H. Fike
Keyword(s):  
Chlorophyll A ◽  
Defense Mechanisms ◽  
Poa Pratensis ◽  
Photochemical Efficiency ◽  
Correlation Coefficients ◽  
Kentucky Bluegrass ◽  
Ultraviolet B ◽  
Antioxidant Systems ◽  
Turf Quality ◽  
Antioxidant Defense Systems

Plants possess various constitutive and inducible defense mechanisms such as pigment and antioxidant systems for protection against stresses such as ultraviolet-B (UV-B; 290 to 320 nm) radiation. Our previous research has indicated that higher chlorophyll, carotenoid, and anthocyanin concentrations were associated with greater tolerance of UV-B stress by `Georgetown' kentucky bluegrass (Poa pratensis L.). The objectives of this study were to determine if kentucky bluegrass cultivars with darker leaf color possessed greater pigment and antioxidant defense systems and if such increases were associated with greater resistance to UV-B. Eight cultivars exhibiting a range of green color intensity (`Apollo', `Brilliant', `Julius', Limerick', `Midnight', `Moonlight', `Nuglade', and `Total Eclipse') were selected and subjected to continuous, artificial UV-B radiation (70 μmol·m-2·s-1). UV-B irradiation reduced turf quality (55% to 62%) and photochemical efficiency (37% to 70%) when measured 5 days after initiation of UV-B exposure. Significant differences in turf color, photochemical efficiency, chlorophyll a, chlorophyll b, chlorophyll a+b, and carotenoids were found among the cultivars. `Moonlight' had greatest photochemical efficiency, chlorophyll, carotenoids, and turf quality. Positive correlations of pigment concentration with photochemical efficiency and turf color were observed under UV-B radiation stress, with correlation coefficients ranging from 0.49 to 0.62. The results of this study suggests that selecting cultivars with higher concentrations of chlorophyll and carotenoids and photochemical efficiency may be an effective way for turfgrass managers and sod producers to improve sod establishment and quality in environments with higher UV-B radiation.

scholarly journals Ultraviolet-B Radiation Damage on Kentucky Bluegrass II: Hormone Supplement Effects

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1471-1474 ◽  
Author(s):  
Erik H. Ervin ◽  
Xunzhong Zhang ◽  
John H. Fike
Keyword(s):  
Plant Defense ◽  
Catalase Activity ◽  
Foliar Application ◽  
Poa Pratensis ◽  
Photochemical Efficiency ◽  
Kentucky Bluegrass ◽  
Ultraviolet B ◽  
Alpha Tocopherol ◽  
Anthocyanin Content ◽  
Turf Quality

High ultraviolet-B (UV-B; 290-320 nm wavelength) radiation may significantly contribute to the quality decline and death of kentucky bluegrass (Poa pratensis L.) sod during summer transplanting. Antioxidants and protective pigments may be involved in plant defense against oxidative stress caused by UV-B. Selected exogenous hormones may alleviate UV-B damage by upregulating plant defense systems. The objectives of this study were to determine if exogenous hormone or hormone-like substances could alleviate UV-B damage to `Georgetown' kentucky bluegrass (Poa pratensis L.) under greenhouse conditions. The hormone salicylic acid at 150 mg·m-2 and the hormone-containing substances, humic acid (HA) at 150 mg·m-2 and seaweed extract (SWE) at 50 mg·m-2, were applied to plugs of kentucky bluegrass and then subjected to UV-B radiation (70 μmol·m-2·s-1). The UV-B irradiation stress reduced turf quality by 51% to 66% and photochemical efficiency by 63% to 68% when measured 10 or 12 days after initiation of UV-B. Endogenous alpha-tocopherol (AT) and antioxidant enzymes (superoxide dismutase (SOD) and catalase) were reduced by UV-B stress. Anthocyanin content was increased from day 1 to 5 and then decreased from day 5 to 10 of continuous UV-B irradiation. Application of SA and HA + SWE enhanced photochemical efficiency by 86% and 82%, respectively, when measured 10 or 12 days after UV-B initiation. In addition, application of the hormonal supplements increased AT concentration, SOD, catalase activity, and anthocyanin content when compared to the control at 10 days after UV-B initiation. Bluegrass with greater AT concentration and SOD and catalase activity exhibited better visual quality under UV-B stress. The results of this study suggest that foliar application of SA and HA + SWE may alleviate decline of photochemical efficiency and turf quality associated with increased UV-B light levels during summer.

scholarly journals Physiological Assessment of Cool-season Turfgrasses Under Ultraviolet-B Stress

HortScience ◽  
2009 ◽  
Vol 44 (6) ◽  
pp. 1785-1789 ◽  
Author(s):  
Xunzhong Zhang ◽  
Erik H. Ervin
Keyword(s):  
Festuca Arundinacea ◽  
Poa Pratensis ◽  
Photochemical Efficiency ◽  
Kentucky Bluegrass ◽  
Physiological Parameters ◽  
Ultraviolet B ◽  
Cool Season ◽  
Sod Activity ◽  
Ultraviolet B Radiation ◽  
Tolerant Species

Ultraviolet-B (280–320 nm) radiation is one of the major factors causing quality decline of transplanted turfgrass sod. Information on physiological parameters for assessing turfgrass tolerance to ultraviolet-B stress is lacking. The objective of this study was to evaluate ultraviolet-B tolerance of four cool-season turfgrass species and varieties using selected physiological parameters under artificial ultraviolet-B radiation stress. The physiological performance of 18 varieties of tall fescue (TF; Festuca arundinacea Schreb.), chewings fescue (CF; Festuca rubra L. ssp. commutata Gaud.), perennial ryegrass (PRG; Lolium perenne L.), and kentucky bluegrass (KBG; Poa pratensis L.) were subjected to continuous, artificial ultraviolet-B radiation (70 μmol·m−2·s−1) for 10 days. Visual quality ratings of TF, CF, PRG, and KBG measured at Day 10 were reduced by 49%, 18%, 51%, and 74%, respectively, relative to that at trial initiation. Ultraviolet-B tolerance in CF was the greatest, KBG was the least, and TF and PRG were intermediate. ‘Ebony’ was the most ultraviolet-B-tolerant TF variety, whereas ‘BlueTastic’, ‘BlueRiffic’, and ‘747’ had greater ultraviolet-B tolerance than the other four KBG varieties. No differences were observed in ultraviolet-B tolerance between varieties in either CF or PRG. The ultraviolet-B-tolerant species had less electrolyte leakage (EL), greater canopy photochemical efficiency (PEc), and relatively smaller and slower upregulation in antioxidant superoxide dismutase (SOD) activity relative to ultraviolet-B-sensitive ones. The results suggest that EL, PEc, and SOD may be used as physiological parameters in selecting ultraviolet-B-tolerant species and varieties for sod production and lawn establishment.

scholarly journals The Role of Leaf Pigment and Antioxidant Levels in UV-B Resistance of Dark- and Light-green Kentucky Bluegrass Cultivars

2005 ◽  
Vol 130 (6) ◽  
pp. 836-841 ◽  
Author(s):  
Xunzhong Zhang ◽  
E.H. Ervin ◽  
R.E. Schmidt
Keyword(s):  
Poa Pratensis ◽  
Plant Stress ◽  
Photochemical Efficiency ◽  
Kentucky Bluegrass ◽  
Ultraviolet B ◽  
Turf Quality ◽  
Dark Green ◽  
Major Factors ◽  
Artificial Uv ◽  
Light Green

Ultraviolet-B [UV-B (280-320 nm)] radiation is one of the major factors causing quality decline of transplanted sod. Pigments and antioxidants are associated with plant stress resistance, but their roles in turfgrass tolerance to UV-B damage are not well understood. The objectives of this study were to determine if kentucky bluegrass (Poa pratensis L.) cultivars with darker green genetic leaf color possessed greater pigment and antioxidant defense capacities and if such characteristics were associated with greater resistance to UV-B. Two cultivars, `Moonlight' (dark green) and `Limerick' (light green), were selected and subjected to continuous, artificial UV-B radiation (70 μmol·m-2·s-1). UV-B irradiation reduced turf quality by 58% (`Moonlight') and 77% (`Limerick') relative to day 1 when measured 10 days after initiation of UV-B exposure. Higher canopy photochemical efficiency (PEc) was found in `Moonlight' relative to `Limerick' under UV-B stress and during recovery. `Moonlight' contained greater levels of chlorophyll (1.5 to1.6-fold), carotenoids (1.3-fold), superoxide dismutase [SOD (1.0-fold)] and catalase [CAT (1.5-fold)] than `Limerick' when measured at 10 days after UV-B initiation. Turfgrass quality and PEc were positively correlated with pigments (chlorophyll and carotenoids) and antioxidant enzymes (SOD and CAT), and negatively correlated with lipid peroxidation. The results suggest that selecting dark-green cultivars with greater pigment content and antioxidant activity may be an effective approach for turfgrass breeders and sod producers to improve tolerance of newly transplanted sod to environments with higher UV-B radiation.

scholarly journals Effects of Abscisic Acid on Drought Responses of Kentucky Bluegrass

2003 ◽  
Vol 128 (1) ◽  
pp. 36-41 ◽  
Author(s):  
Zhaolong Wang ◽  
Bingru Huang ◽  
Qingzhang Xu
Keyword(s):  
Abscisic Acid ◽  
Drought Stress ◽  
Osmotic Adjustment ◽  
Foliar Application ◽  
Poa Pratensis ◽  
Turgor Pressure ◽  
Photochemical Efficiency ◽  
Kentucky Bluegrass ◽  
Exogenous Aba ◽  
Turf Quality

Abscisic acid (ABA) is an important hormone regulating plant response to drought stress. The objective of this study was to investigate effects of exogenous ABA application on turf performance and physiological activities of kentucky bluegrass (Poa pratensis L.) in response to drought stress. Plants of two kentucky bluegrass cultivars, `Brilliant' (drought susceptible) and `Midnight' (drought tolerant), were treated with ABA (100 μm) or water by foliar application and then grown under drought stress (no irrigation) or well-watered (irrigation on alternate days) conditions in a growth chamber. The two cultivars responded similarly to ABA application under both watering regimes. Foliar application of ABA had no effects on turf quality or physiological parameters under well-watered conditions. ABA application, however, helped maintain higher turf quality and delayed the quality decline during drought stress, compared to the untreated control. ABA-treated plants exposed to drought stress had higher cell membrane stability, as indicated by less electrolyte leakage of leaves, and higher photochemical efficiency, expressed as Fv/Fm, compared to untreated plants. Leaf water potential was not significantly affected, whereas leaf turgor pressure increased with ABA application after 9 and 12 d of drought. Osmotic adjustment increased with ABA application, and was sustained for a longer period of drought in `Midnight' than in `Brilliant'. The results suggested that exogenous ABA application improved turf performance during drought in both drought-sensitive and tolerant cultivars of kentucky bluegrass. This positive effect of ABA could be related to increased osmotic adjustment, cell turgor maintenance, and reduced damage to cell membranes and the photosynthetic system.

Choline-Mediated Lipid Reprogramming as a Dominant Salt Tolerance Mechanism in Grass Species Lacking Glycine Betaine

2020 ◽  
Author(s):  
Kun Zhang ◽  
Weiting Lyu ◽  
Yanli Gao ◽  
Xiaxiang Zhang ◽  
Yan Sun ◽  
...  
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Glycine Betaine ◽  
Metabolic Pathways ◽  
Poa Pratensis ◽  
Choline Chloride ◽  
Photochemical Efficiency ◽  
Kentucky Bluegrass ◽  
Grass Species ◽  
Tolerance Mechanism

Abstract Choline, as a precursor of glycine betaine (GB) and phospholipids, is known to play roles in plant tolerance to salt stress, but the downstream metabolic pathways regulated by choline conferring salt tolerance are still unclear for non-GB-accumulating species. The objectives were to examine how choline affects salt tolerance in a non-GB-accumulating grass species and to determine major metabolic pathways of choline regulating salt tolerance involving GB or lipid metabolism. Kentucky bluegrass (Poa pratensis) plants were subjected to salt stress (100 mM NaCl) with or without foliar application of choline chloride (1 mM) in a growth chamber. Choline or GB alone and the combined application increased leaf photochemical efficiency, relative water content and osmotic adjustment and reduced leaf electrolyte leakage. Choline application had no effects on the endogenous GB content and GB synthesis genes did not show responses to choline under nonstress and salt stress conditions. GB was not detected in Kentucky bluegrass leaves. Lipidomic analysis revealed an increase in the content of monogalactosyl diacylglycerol, phosphatidylcholine and phosphatidylethanolamine and a decrease in the phosphatidic acid content by choline application in plants exposed to salt stress. Choline-mediated lipid reprogramming could function as a dominant salt tolerance mechanism in non-GB-accumulating grass species.

Physiological and biochemical responses of Sorghum vulgare plants to supplemental ultraviolet-B radiation

1998 ◽  
Vol 76 (7) ◽  
pp. 1290-1294 ◽  
Author(s):  
Navin Kumar Ambasht ◽  
Madhoolika Agrawal
Keyword(s):  
Ascorbic Acid ◽  
Gas Exchange ◽  
Peroxidase Activity ◽  
Plant Biomass ◽  
Stratospheric Ozone ◽  
Ascorbic Acid Content ◽  
Ultraviolet B ◽  
Sorghum Vulgare ◽  
Ultraviolet B Radiation ◽  
Physiological And Biochemical

Sorghum (Sorghum vulgare (Pers.) cv. MSH 51) plants were grown in the field under ambient and supplemental levels of ultraviolet-B radiation (UV-B; supplemental daily dose corresponding to a 20% reduction in the stratospheric ozone column). Gas exchange characteristics, biomass, and levels of photosynthetic pigments, flavonoids, catalase, peroxidase activity, and ascorbic acid were determined to evaluate the changes induced by enhanced levels of UV-B irradiation. Gas exchange analysis indicated that one of the reasons for the decline in photosynthesis is stomatal limitation. Enhanced UV-B also caused reductions in chlorophyll and carotenoid pigments after 60 days of exposure. Concentrations of UV-B absorbing pigments increased linearly with age. UV-B irradiation also increased phenolic compounds. Catalase activity decreased, while peroxidase activity increased in response to elevated UV-B. There was a decrease in total plant biomass and ascorbic acid content of plants exposed to UV-B. Thus, an enhanced level of UV-B irradiation over a long period has a cumulative unfavourable effect on a number of physiological and biochemical processes, leading to a reduction in dry matter production.Key words: UV-B radiation, Sorghum vulgare, photosynthesis, stomatal resistance, flavonoids, peroxidase.

scholarly journals Antioxidant Enzyme Activities and Gene Expression Patterns in Leaves of Kentucky Bluegrass in Response to Drought and Post-drought Recovery

2011 ◽  
Vol 136 (4) ◽  
pp. 247-255 ◽  
Author(s):  
Lixin Xu ◽  
Liebao Han ◽  
Bingru Huang
Keyword(s):  
Gene Expression ◽  
Drought Stress ◽  
Antioxidant Enzyme ◽  
Water Deficit ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Grass Species ◽  
Antioxidant Enzyme Activities ◽  
Guaiacol Peroxidase ◽  
Drought Recovery

The objectives of this study were to examine antioxidant enzyme responses to drought stress and rewatering at both enzymatic activity and transcript levels and to determine the major antioxidant processes associated with drought tolerance and post-drought recovery for a perennial grass species, kentucky bluegrass (Poa pratensis). Antioxidant enzyme responses to drought and rewatering in a drought-tolerant cultivar (Midnight) and a drought-sensitive cultivar (Brilliant) were compared in a growth chamber. Plants were exposed to 22 days of drought stress for ‘Midnight’ and 18 days for ‘Brilliant’ before rewatering to allow the leaf relative water content (RWC) of both cultivars to drop to the same level. ‘Midnight’ exhibited higher photochemical efficiency (Fv/Fm) and lower electrolyte leakage compared with ‘Brilliant’ when at the same water deficit status (26% to 28% RWC). After 6 days of rewatering, all physiological parameters returned to the control level for ‘Midnight’, but only Fv/Fm fully recovered for ‘Brilliant’. The transcript level of cytosolic copper/zinc superoxide dismutase (cyt Cu/Zn SOD) and ascorbate peroxidase (APX) was significantly higher in ‘Midnight’ than in ‘Brilliant’ when exposed to the same level of water deficit (26% to 28% RWC), suggesting that SOD and APX could be involved in scavenging oxidative stress-induced reactive oxygen species in kentucky bluegrass through changes in the level of gene expression. Significantly higher activities of APX, monodehydroascorbate reductase, glutathione reductase, and dehydroascorbate reductase as well as lower lipid peroxidation levels were observed in ‘Midnight’ versus ‘Brilliant’ when exposed to drought. However, the activities of SOD, catalase (CAT), and guaiacol peroxidase (POD) did not differ between the two cultivars. After 6 days of rewatering, ‘Midnight’ displayed significantly higher activity levels of CAT, POD, and APX compared with ‘Brilliant’. The enzyme activity results indicate that enzymes involved in the ascorbate–glutathine cycle may play important roles in antioxidant protection to drought damage, whereas CAT, POD, and APX could be associated with better post-drought recovery in kentucky bluegrass.

scholarly journals Improvement of Salt Tolerance in Kentucky Bluegrass by Trinexapac-ethyl

HortScience ◽  
2012 ◽  
Vol 47 (8) ◽  
pp. 1163-1170 ◽  
Author(s):  
Masoud Arghavani ◽  
Mohsen Kafi ◽  
Mesbah Babalar ◽  
Roohangiz Naderi ◽  
Md. Anamul Hoque ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Antioxidant Activities ◽  
Poa Pratensis ◽  
Acid Ethyl Ester ◽  
Kentucky Bluegrass ◽  
Sand Culture ◽  
Antioxidant Enzyme Activities ◽  
Turf Quality ◽  
Salinity Levels ◽  
Ga Biosynthesis

Trinexapac-ethyl (TE) is a popular plant growth regulator in the turfgrass industry that inhibits gibberellic acid (GA) biosynthesis and effectively reduces leaf elongation and subsequent clipping production. This greenhouse sand culture experiment was conducted to determine effects of TE application on kentucky bluegrass (Poa pratensis L.) responses to salinity stress. The five salinity levels (0, 20, 40, 60, and 80 mm NaCl) were applied in nutrient solutions and TE treatments (0, 1, and 1.7 g/100 m2) were applied twice at 4-week intervals. Under non-saline conditions and low level salinity conditions, application of TE at 1 g/100 m2 (TE1) increased turf quality (TQ), leaf total non-structural carbohydrates (TNC), and chlorophyll (Chl) content. In high salinity, TE1 alleviated the decline in TQ, antioxidant enzyme activities, leaf TNC, Chl, and K+ content. In addition, treated turf with TE at 1 g/100 m2 had lower proline, Na+, and malondialdehyde (MDA) contents. However, the adverse effects of high salinities were more pronounced when turf was treated by TE at 1.7 g/100 m2 (TE1.7), suggesting that effects of TE on salt tolerance vary with its dosages and salinity levels. We concluded that moderate inhibition of GA biosynthesis by TE enhances salt tolerance in kentucky bluegrass and suggest that enhancement is the result of the maintenance of antioxidant activities, leading to more root growth and greater levels of TNC and Chl content. Chemical names used: 4-(cyclopropyl-β-hydroxymethylene)-3, 5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl).

scholarly journals Protective mechanism in UV-B treated Crotalaria juncea L. seedlings

2010 ◽  
Vol 41 (No. 3) ◽  
pp. 115-120 ◽  
Author(s):  
V. Balakrishnan ◽  
K. Venkatesan ◽  
K.C. Ravindran ◽  
G. Kulandaivelu
Keyword(s):  
Stratospheric Ozone ◽  
Ultraviolet B ◽  
Atmospheric Pollutants ◽  
Protective Mechanism ◽  
Antioxidant Enzyme Activities ◽  
Crotalaria Juncea ◽  
Antioxidant Defence System ◽  
Phenylalanine Ammonialyase ◽  
Global Reduction

There is concern that some anthropogenic atmospheric pollutants may result in a global reduction of stratospheric ozone. This would undoubtedly increase the level of ultraviolet radiation reaching the surface of the earth, which might have important biological consequences. The antioxidant defence system of a plant consists of a variety of antioxidant molecules and enzymes. The role of antioxidant enzyme activities in <I>Crotalaria juncea</I> under control without UV-B treatment and ultraviolet-B supplemental radiation (UV-B) was investigated. UV-B treatment for 6 h for 4 days resulted in severe inhibition in catalase activity. On the other hand, the activities of peroxidase, polyphenol oxidase, superoxide dismutase and phenylalanine ammonialyase increased after the UV-B treatment when compared to control seedlings. These increases could be an adaptive mechanism to minimise the effects of UV-B radiation.

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