scholarly journals Elongation of Hibiscus acetosella Under Well-watered and Drought-stressed Conditions

HortScience ◽  
2016 ◽  
Vol 51 (11) ◽  
pp. 1384-1388 ◽  
Author(s):  
Amanda Bayer ◽  
John Ruter ◽  
Marc W. van Iersel
Keyword(s):  
Drought Stress ◽  
Average Length ◽  
Stem Elongation ◽  
Ornamental Plants ◽  
Leaf Size ◽  
Dry Weight ◽  
Time Lapse ◽  
Plant Quality ◽  
Shoot Dry Weight ◽  
Diurnal Patterns

Controlling the elongation of ornamental plants is commonly needed for shipping and aesthetic purposes. Drought stress can be used to limit elongation, and is an environmentally friendly alternative to plant growth regulators (PGRs). However, growers can be reluctant to expose plants to drought stress because they do not want to negatively affect overall plant quality and marketability. Knowing how and when stem elongation is affected by water availability will help to increase our understanding of how elongation can be controlled without reducing plant quality. Rooted Hibiscus acetosella Welw. ex Hiern. cuttings were grown in a growth chamber set to a 12-hour photoperiod at 25 °C. Two plants of similar size were used for each replication of the study to compare growth under well-watered and drought-stressed conditions. Time lapse photography was used to determine the diurnal patterns of elongation over the course of the replications. Evapotranspiration was measured using load cells. Well-watered and drought-stressed plants had similar diurnal patterns of elongation and evapotranspiration, demonstrating that both follow circadian rhythms and are not just responding to environmental conditions. Stem elongation was greatest at night and coincided with evapotranspiration decreases, with greatest elongation shortly after the onset of darkness. Elongation was minimal between 800 and 1000 hr when evapotranspiration increases. During the drought-stress portion of the replications, elongation of drought-stressed plants was 44% less than well-watered plants. Final plant height and shoot dry weight for the drought-stressed plants were 21% and 30% less than well-watered plants, respectively. Total leaf area, number of leaves, and number of new visible internodes were greater for well-watered plants than drought-stressed plants. Average length of visible internodes and leaf size were similar for drought-stressed and well-watered plants. If growers want to use drought stress for elongation control, they should ensure that plants are drought stressed before the onset of and during the dark period, when most elongation occurs.

scholarly journals Growth Retardants Affect Landscape Performance of Zinnia, Impatiens, and Marigold

HortScience ◽  
1991 ◽  
Vol 26 (5) ◽  
pp. 557-560 ◽  
Author(s):  
Joyce G. Latimer
Keyword(s):  
Weight Gain ◽  
Plant Height ◽  
Stem Elongation ◽  
Dry Weight ◽  
Plant Quality ◽  
Subjective Rating ◽  
Growth Retardants ◽  
Shoot Dry Weight ◽  
Landscape Performance ◽  
Bedding Plant

Various spray rates of paclobutrazol, 5000 ppm daminozide, 200 ppm ancymidol, or drought imposition (visible wilt symptoms for up to 2 hours daily) were applied to three bedding plant species to determine effects on growth in the greenhouse and the subsequent growth and performance of treated plants in the landscape. Seedlings of Zinnia efegans Jacq. `Peter Pan Scarlet' responded to all growth retardants (paclobutrazol at 40 and 90 ppm) and the drought treatment in the greenhouse. However, zinnias treated with paclobutrazol or ancymidol still exhibited reductions in plant height 5 and 7 weeks after transplanting to the landscape, and in plant quality (subjective rating of plant appearance with emphasis on flower cover) at 5 weeks after transplanting. Daminozide or drought controlled zinnia growth in the greenhouse but had no carry-over effect in the landscape. Stem elongation of Impatiens wallerana Hook `Accent Red' seedlings was moderately controlled by 20 ppm paclobutrazol in the greenhouse. There were no other treatment effects in the greenhouse. Paclobutrazol (20 ppm) reduced final plant height and quality (7 weeks postplanting). Treatment with daminozide or drought reduced plant width and quality after 5 and 7 weeks in the landscape. Ancymidol had no effect on landscape performance of impatiens. Shoot dry weight gain and stem elongation of Tagetes erects L. `Papaya Crush' seedlings were reduced by ancymidol or 40 ppm paclobutrazol in the greenhouse. Shoot dry weight gain of marigold seedlings was inhibited during the first week of landscape establishment by prior treatment with daminozide, ancymidol, or drought. Final plant height and width in the landscape were not affected by any treatment; however, 40 ppm paclobutrazol, daminozide, or ancymidol decreased final plant quality. Chemical names used: α -cyclopropylα -(4-methoxyphenyl) -5-pyrimidinemethanol (ancymidol); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); β -[(4-chlorophenyl) methyl] - β - (1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

scholarly journals Drought Stress Reduces Stem Elongation and Alters Gibberellin-related Gene Expression during Vegetative Growth of Tomato

2016 ◽  
Vol 141 (6) ◽  
pp. 591-597 ◽  
Author(s):  
Alexander G. Litvin ◽  
Marc W. van Iersel ◽  
Anish Malladi
Keyword(s):  
Drought Stress ◽  
Cell Expansion ◽  
Stem Elongation ◽  
Feedback Regulation ◽  
Dry Weight ◽  
Data Logger ◽  
Transcript Accumulation ◽  
Stress Effects ◽  
Shoot Dry Weight ◽  
Wall Loosening

Drought stress reduces stem elongation and cell expansion. Since gibberellins (GAs) play an important role in controlling cell elongation, the objective of this study was to determine if the reduction in growth under drought stress is associated with altered GA metabolism or signaling. We exposed ‘Moneymaker’ tomato (Solanum lycopersicum) to drought stress to observe the effects on growth. Irrigation was automated using a data logger, which maintained volumetric water contents (VWC) of 0.35 and 0.15 m3·m−3 for well-watered and drought-stressed conditions, respectively. To further investigate the effect of GAs on elongation, paclobutrazol (PAC), a GA biosynthesis inhibitor, was applied to reduce endogenous GA production. Drought stress and PAC treatment reduced plant height. Internode length, cell size, and shoot dry weight displayed an interaction between the VWC and PAC treatments. The transcript levels of SlGA20ox1, -2, -3, and -4, SlGA3ox2, and SlGA2ox2, -4, and -5, corresponding to enzymes in GA metabolism, and LeEXP1, and -2, encoding expansin enzymes related to cell wall loosening necessary for cell expansion, were analyzed. Downregulation of transcript accumulation due to drought stress was observed for SlGA20ox4, SlGA2ox5, and LeEXP1, but not for any of the other genes. PAC increased expression of SlGA20ox-3, and SlGA3ox2, potentially through feedback regulation. These findings suggest that drought stress effects on elongation are at least partly mediated by altered GA metabolism.

scholarly journals Foliar applications of bio-fabricated selenium nanoparticles to improve the growth of wheat plants under drought stress

2020 ◽  
Vol 9 (1) ◽  
pp. 706-714
Author(s):  
Muhammad Ikram ◽  
Naveed Iqbal Raja ◽  
Bilal Javed ◽  
Zia-ur-Rehman Mashwani ◽  
Mubashir Hussain ◽  
...  
Keyword(s):  
Drought Stress ◽  
Field Capacity ◽  
Dry Weight ◽  
Positive Control ◽  
Morphological Characterization ◽  
Leaf Length ◽  
Selenium Nanoparticles ◽  
Fresh Weight ◽  
Wheat Varieties ◽  
Shoot Dry Weight

AbstractThe present study was aimed to biosynthesize selenium nanoparticles (SeNPs) and assess their foliar applications to improve the growth of wheat plants under controlled irrigation and drought stress. Bud aqueous extract of Allium sativum L. was used as a reducing and stabilizing agent of SeNPs followed by their optical and morphological characterization by using ultraviolet-visible spectroscopy, scanning electron microscopy, Fourier-transform infrared, and energy dispersive X-ray analysis. Various concentrations of SeNPs (10, 20, 30, and 40 mg/L) were applied exogenously to drought-tolerant (V1) and drought-susceptible (V2) wheat varieties at the trifoliate stage. Under the positive control conditions, plants were irrigated with 450 mL of water/pot (100% field capacity); and under water-deficit environment, plants were irrigated with 160 mL of water/pot (35% field capacity). Remarkable increase in plant height, shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, leaf area, leaf number, and leaf length has been observed when 30 mg/L concentration of SeNPs was used. However, the plant morphological parameters decreased gradually at higher concentrations (40 mg/L) in both selected wheat varieties. Therefore, 30 mg/L concentration of SeNPs was found most preferable to enhance the growth of selected wheat varieties under normal and water-deficient conditions.

scholarly journals Evaluation of a Substrate-applied Humectant to Mitigate Drought Stress in Young, Container-grown Plants

2015 ◽  
Vol 33 (3) ◽  
pp. 137-141
Author(s):  
Bruce R. Roberts ◽  
Chris Wolverton ◽  
Samantha West
Keyword(s):  
Drought Stress ◽  
Root Growth ◽  
Shoot Growth ◽  
Dry Weight ◽  
Root:Shoot Ratio ◽  
Xylem Water Potential ◽  
Bedding Plants ◽  
Shoot Dry Weight ◽  
Soilless Substrate ◽  
Absorbing Roots

The efficacy of treating soilless substrate with a commercial humectant was tested as a means of suppressing drought stress in 4-week-old container-grown Zinnia elegans Jacq. ‘Thumbelina’. The humectant was applied as a substrate amendment at concentrations of 0.0, 0.8, 1.6 and 3.2% by volume prior to withholding irrigation. An untreated, well-watered control was also included. The substrate of treated plants was allowed to dry until the foliage wilted, at which time the plants were harvested and the following measurements taken: number of days to wilt (DTW), xylem water potential (ψx), shoot growth (shoot dry weight, leaf area) and root growth (length, diameter, surface area, volume, dry weight). For drought-stressed plants grown in humectant-treated substrate at concentrations of 1.6 and 3.2%, DTW increased 25 and 33%, respectively. A linear decrease in ψx was observed as the concentration of humectant increased from 0.0 to 3.2%. Linear trends were also noted for both volumetric moisture content (positive) and evapotranspiration (negative) as the concentration of humectant increased. For non-irrigated, untreated plants, stress inhibited shoot growth more than root growth, resulting in a lower root:shoot ratio. For non-irrigated, humectant-treated plants, the length of fine, water-absorbing roots increased linearly as humectant concentration increased from 0.0 to 3.2%. Using humectant-amended substrates may be a management option for mitigating the symptoms of drought stress during the production of container-grown bedding plants such as Z. elegans.

scholarly journals Plant Growth and Leachate Electrical Conductivity and pH as Influenced by Controlled-release Fertilizer Blends and Coating Technologies

2017 ◽  
Vol 27 (5) ◽  
pp. 639-643 ◽  
Author(s):  
Carey Grable ◽  
Joshua Knight ◽  
Dewayne L. Ingram
Keyword(s):  
Trace Elements ◽  
Controlled Release ◽  
Polymer Coating ◽  
Ornamental Plants ◽  
Nutrient Release ◽  
Dry Weight ◽  
Polymer Coatings ◽  
Release Rates ◽  
Shoot Dry Weight ◽  
Controlled Release Fertilizers

Although controlled-release fertilizers (CRFs) have been used in container-grown ornamental plants for decades, new coating technologies and blends of fertilizers coated for specific release rates are being employed to customize fertility for specific environments and crops. A study was conducted in the transitional climate of Kentucky to determine the nutrient release rates of three controlled-release blends of 8- to 9-month release and growth response of ‘Double Play Pink’ japanese spirea (Spiraea japonica) and ‘Smaragd’ arbovitae (Thuja occidentalis). Fertilizer 1 (16N–3.5P–8.3K–1.8Mg + trace elements) and Fertilizer 2 (18N–3.1P–8.3K–1.8Mg + trace elements) were prototype blends with different experimental polymer coatings. Fertilizer 3 was a blend of 18N–2.2P–6.6K–1.1Ca–1.4Mg–5.8S + trace elements, which combined 100% resin-coated prills with a polymer coating. Fertilizer 4 was commercially available 15N–3.9P–10K–1.3Mg–6S + trace elements. Fertilizer 3 released its nutrients earlier in the 12-week study than the other three fertilizers and resulted in lower shoot dry weight in both species. The new polymer coating technologies show promise for delivering a predicted release rate and are appropriate for container production of these woody shrubs in Kentucky. An interesting side note of this experiment was that leachate pH measurements across treatments averaged 1.2 units lower for arbovitae (6.3) than for japanese spirea (7.5) at week 12. It was assumed that chemical and/or biological reactions at the root/substrate interface in arbovitae moderated pH increases over the study.

Integration among ramets of Trifolium repens

1991 ◽  
Vol 69 (1) ◽  
pp. 226-228 ◽  
Author(s):  
Roy Turkington ◽  
Elena Klein
Keyword(s):  
Key Words ◽  
Trifolium Repens ◽  
Leaf Size ◽  
Dry Weight ◽  
Leaf Number ◽  
Subsequent Growth ◽  
Shoot Dry Weight ◽  
Neighbour Effects ◽  
Stolon Length

Cuttings of Trifolium repens were grown in pots without neighbours. When individual interconnected stolons from these cuttings were directed into adjacent pots so that daughter ramets were growing with different grass neighbours, these neighbouring grasses had dissimilar effects on leaf number, leaf size, percent branching of nodes, stolon length, and shoot dry weight. When the T. repens cuttings were grown in pots with neighbours, the effects of different grass neighbours on subsequent growth of stolons and ramets evened out. Key words: integration, clone, ramet, neighbour effects, Trifolium repens.

scholarly journals Screening of Mungbean Genotypes under Polyethylene Glycol (PEG) Induced Drought Stress Condition

2020 ◽  
pp. 1-12
Author(s):  
Abdullah All Imtiaz ◽  
Saleh Ahmed Shahriar ◽  
Md. Abdullahil Baque ◽  
Most. Nurjahan Khatun Eaty ◽  
Maliha Rahman Falguni
Keyword(s):  
Drought Stress ◽  
Water Retention ◽  
Stress Condition ◽  
Dry Weight ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Shoot Dry Weight ◽  
Root Shoot Ratio ◽  
Relative Water ◽  
Drought Stress Condition

Sixteen advance genotypes of mungbeans under 5 different concentrations of Polyethylene Glycol (PEG) were studied to find out the better cultivar against drought stress condition. The experiment results revealed that germination, seedling production and water-related behavior of mungbean genotypes differed significantly under different PEG (drought inducer) concentrations. The mungbean genotype BINA Mung-6 (V8) is proved as highly tolerant against drought stress condition among all other tested genotypes. The results of the investigation revealed that BINA Mung-6 (V8) genotype consistently scored the highest value for all parameters except for the root shoot ratio and water retention capacity that was statistically comparable to genotypes BARI Mung-4 (V2) and BINA Mung-5 (V7). Consistently poor performance were recorded from IPM-02-03 (V16) genotype which is statistically similar as genotypes BMXK1-09015-2 (V13) and BMXK1-09015-6 (V10). The maximum percentage of germination (98.12%), shoot length (139.40 mm), root length (99.07 mm), shoot dry weight (22.32 mg), root dry weight (6.88 mg), relative water content (94.78), water retention capacity (24.98), germination co-efficient (22.27) and vigor index (233.90) were reported from BINA Mung-6 (V8) at a concentration of 0 percent PEG. The minimum percentage of germination (28.22 percent), shoot length (31.17 mm), root length (16.50 mm), shoot dry weight (2.21 mg), root dry weight (0.97 mg), relative water content (25.55), water retention capacity (3.08), germination co-efficient (6.06) and vigor index (13.45) were reported from IPM-02-03 (V16) mungbean advance lines at 0 percent PEG. Maximum (0.92) root shoot ratio was recorded from both BARI Mung-8 (V6) and BMX-08011-2 (V11) mungbean genotypes at 20 percent PEG concentration and minimum (0.22) at 0 percent PEG concentration from BARI Mung-5 (V3) genotype. Maximum water retention capacity (74.45) was recorded at 20 per cent PEG concentration from IPM-02-03 (V16) genotype and minimum (5.22) was at 0 per cent PEG concentration from BINA Mung-6 (V8) genotype.

scholarly journals Automated Irrigation Control for Improved Growth and Quality of Gardenia jasminoides ‘Radicans’ and ‘August Beauty’

HortScience ◽  
2015 ◽  
Vol 50 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Amanda Bayer ◽  
John Ruter ◽  
Marc W. van Iersel
Keyword(s):  
Soil Moisture ◽  
Sustainable Use ◽  
Leaf Size ◽  
Dry Weight ◽  
Plant Production ◽  
Moisture Sensor ◽  
Soil Moisture Sensor ◽  
Shoot Dry Weight ◽  
Gardenia Jasminoides ◽  
Irrigation Volume

Sustainable use of water resources is of increasing importance in container plant production as a result of decreasing water availability and an increasing number of laws and regulations regarding nursery runoff. Soil moisture sensor-controlled, automated irrigation can be used to irrigate when substrate volumetric water content (θ) drops below a threshold, improving irrigation efficiency by applying water only as needed. We compared growth of two Gardenia jasminoides cultivars, slow-growing and challenging ‘Radicans’ and easier, fast-growing ‘August Beauty’, at various θ thresholds. Our objective was to determine how irrigation can be applied more efficiently without negatively affecting plant quality, allowing for cultivar-specific guidelines. Soil moisture sensor-controlled, automated irrigation was used to maintain θ thresholds of 0.20, 0.30, 0.40, or 0.50 m3·m−3. Growth of both cultivars was related to θ threshold, and patterns of growth were similar in both Watkinsville and Tifton, GA. High mortality was observed at the 0.20-m3·m−3 threshold with poor root establishment resulting from the low irrigation volume. Height, width, shoot dry weight, root dry weight, and leaf size were greater for the 0.40 and 0.50 m3·m−3 than the 0.20 and 0.30-m3·m−3 θ thresholds. Irrigation volume increased with increasing θ thresholds for both cultivars. For ‘August Beauty’, cumulative irrigation volume ranged from 0.96 to 63.21 L/plant in Tifton and 1.89 to 87.9 L/plant in Watkinsville. For ‘Radicans’, cumulative irrigation volume ranged from 1.32 to 126 L/plant in Tifton and from 1.38 to 261 L/plant in Watkinsville. There was a large irrigation volume difference between the 0.40 and 0.50-m3·m−3 θ thresholds with little additional growth, suggesting that the additional irrigation applied led to overirrigation and leaching. Bud and flower number of ‘Radicans’ were greatest for the 0.40-m3·m−3 θ threshold, indicating that overirrigation can reduce flowering. The results of this study show that growth of the different G. jasminoides cultivars responded similarly to θ threshold at both locations. Similarities in growth and differences in irrigation volume at the 0.40 and 0.50-m3·m−3 θ thresholds show that more efficient irrigation can be used without negatively impacting growth.

scholarly journals Response of Mediterranean Ornamental Plants to Drought Stress

Horticulturae ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 6 ◽  
Author(s):  
Stefania Toscano ◽  
Antonio Ferrante ◽  
Daniela Romano
Keyword(s):  
Drought Stress ◽  
Ornamental Plants ◽  
Leaf Size ◽  
Mediterranean Area ◽  
Negative Effects ◽  
Aesthetic Value ◽  
Root Shoot Ratio ◽  
Adaptive Mechanisms ◽  
Effects Of Drought ◽  
Physiological And Biochemical

Ornamental plants use unique adaptive mechanisms to overcome the negative effects of drought stress. A large number of species grown in the Mediterranean area offer the opportunity to select some for ornamental purposes with the ability to adapt to drought conditions. The plants tolerant to drought stress show different adaptation mechanisms to overcome drought stress, including morphological, physiological, and biochemical modifications. These responses include increasing root/shoot ratio, growth reduction, leaf anatomy change, and reduction of leaf size and total leaf area to limit water loss and guarantee photosynthesis. In this review, the effect of drought stress on photosynthesis and chlorophyll a fluorescence is discussed. Recent information on the mechanisms of signal transduction and the development of drought tolerance in ornamental plants is provided. Finally, drought-induced oxidative stress is analyzed and discussed. The purpose of this review is to deepen our knowledge of how drought may modify the morphological and physiological characteristics of plants and reduce their aesthetic value—that is, the key parameter of assessment of ornamental plants.

scholarly journals Mitigation of Drought Stress Effects on Pepper Seedlings by Exogenous Methylamine Application

2019 ◽  
Vol 76 ◽  
pp. 111-123
Author(s):  
Ertran Yildirim ◽  
Melek Ekinci ◽  
Raziye Kul ◽  
Metin Turan ◽  
Ayla Gür
Keyword(s):  
Drought Stress ◽  
Plant Growth ◽  
Dry Weight ◽  
Stress Effects ◽  
Shoot Dry Weight ◽  
New Synthesis ◽  
Relative Water ◽  
Mda Content ◽  
Irrigation Levels ◽  
Physiological And Biochemical

The study was conducted to determine effects of a new synthesis of methylamine on the plant growth, physiological and biochemical characteristics in pepper.  There were four irrigation levels [full irrigation (100%) (I0), 80% (I1), 60% (I2) and 40% (I3)] and two methylamine (MA) treatments (0, 2.5 mM). At the end of the study, it was observed that there were significant differences between applications and levels. Effects of MA treatments on plant growth (plant height, stem diameter, fresh, dry weight etc.), plant physiological and biochemical parameters [tissue electrical conductivity (TEC), tissue relative water content (TRWC), hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, antioxidant enzyme activity], and plant nutrient element content of pepper seedlings under different irrigation levels were significantly important.  The results of the study showed that the drought stress conditions negatively affected the plant growth, increased the content of TEC, H2O2 and MDA, and decreased the TRWC and  plant mineral content in pepper. However, MA application improved plant growth and decreased TEC, H2O2 and MDA content compared to control in pepper under drought conditions. MA treated plants at I3 had higher shoot fresh weight and shoot dry weight than non-treated plants by 12 and 20%, respectively.  In conclusion, MA application could mitigate the deleterious effects of the drought stress on the pepper seedlings.

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