Mohammad Hossein Sheikh Mohammadi; Nematollah Etemadi; Ali Nikbakht; Mostafa Arab; Mohammad Mehdi Majidi
Abstract
Introduction: Drought and salinity are the most detrimental abiotic stresses for turfgrass growth across a wide range of geographic locations. Most cool season grass species are not well adapted to extended periods of drought and salinity stress. The decline in turf quality caused by drought and salinity ...
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Introduction: Drought and salinity are the most detrimental abiotic stresses for turfgrass growth across a wide range of geographic locations. Most cool season grass species are not well adapted to extended periods of drought and salinity stress. The decline in turf quality caused by drought and salinity stresses is a major concern in turfgrass cultivation and management. Therefore, developing management practices for improving drought and salinity resistance of turfgrasses has become imperative in arid and semiarid regions. Grass genotypes differ in their responses to drought and salinity stresses, which involve changes in morphological and physiological aspects. Understanding of relative involvement of each morphological and physiological characteristic in drought and salinity tolerance is important in selecting grass genotypes to facilitate breeding of drought and salinity-tolerant genotypes. The purposes of this research were to make selections of genotypes tolerant to drought and salinity stress for turfgrass management program.
Materials and Methods: To study some morphological and physiological responses of six Iranian crested wheatgrasses (Agropyron cristatum L.) under drought and salinity, an experiment was conducted in the greenhouse of College of Abureyhan, University of Tehran, Iran. Six Iranian Agropyron cristatum genotypes were collected from six locations in Iran. Agropyron cristatum genotypes were planted in polyvinyl chloride tubes and kept in the greenhouse. Pots were filled with sandy loam soil which had been sterilized in an oven at 160ºC for 6 h. Irrigation was applied as needed to prevent any visible stress during grass establishment. Grasses were watered three times weekly to maintain plants under well-watered conditions and soil moisture at field capacity. The experiment consisted of three treatments: 1) well-watered plants were irrigated three times per week with distilled water (control), 2) Drought stress was imposed by withholding irrigation for 45 days (drought stress), and 3) plants were irrigated daily with 100 mL of 9 dS.m–1 NaCl solution (salinity stress). To avoid primary salinity shock, the soil in each pot was drenched with 100 mL NaCl solution at incremental electrical conductivity (EC) by 3 dS.m–1 per day until the final EC reached 9 dS.m–1. Data were subjected to analysis based on a split-plot design with water treatments as main-plots and genotypes as sub-plots. Irrigation treatment as the main factor in three levels (control, drought, and salinity) and crested wheatgrass at six levels were considered as sub-plots. Studied characteristics such as height, turf quality, chlorophyll content, soluble carbohydrates, relative water content, electrolyte leakage, root penetration, and effective root depth were recorded. Statistical significance was tested using the analysis of variance procedure in SAS 9.1 (SAS Institute Inc., Cary, NC). Differences between the means were determined using the Fisher’s protected LSD test at the 5% probability level.
Results and Discussion: The results of this study showed that drought and salinity stress decreased the quality of crested wheatgrass masses, and reduced the level of quality varied among the masses. Throughout the experiment, ‘Sabzevar’ and ‘Damavand’ under drought conditions and ‘Sabzevar’, ‘Arak’ and ‘Damavand’ under salinity conditions maintained higher Turf quality compared with other genotypes. Total chlorophyll content of ‘Sabzevar’ and ‘Damavand’ were higher than other genotypes under drought and salinity conditions. The maintenance of higher chlorophyll content has been associated with better drought and salinity tolerance in plant. The soluble sugar content of ‘Sabzevar’ and ‘Damavand’ under drought conditions and ‘Sabzevar’, ‘Arak’ and ‘Damavand’ under salinity conditions were higher than other genotypes during the experiment. Soluble sugar content is an important compatible osmolyte in plants. Increased accumulation of soluble sugar content in stressed plants may be an adaptation process and resistance strategy to abiotic stresses in plants. Throughout the experiment, ‘AEKQI’, ‘Sabzevar’ and ‘Damavand’ genotypes under drought conditions and ‘Sabzevar’ genotypes under salinity conditions maintained higher relative water content in compared with other genotypes. Higher RWC indicates the ability of the leaf to maintain its higher water content under stress conditions with the simultaneous capability of the root system to take up adequate water. Based on morphological and physiological analysis for drought and salinity tolerance in investigated genotypes, the tolerance ranking would appear to be ‘Sabzevar’ > ‘Damavand’ > ‘Arak’ > ‘Urmia’ = Takestan > ‘Hashtgerd’ under drought stress and ‘Sabzevar’> ‘Arak’ > ‘Damavand’ > ‘Takestan’ = ‘Hashtgerd’> ‘Urmia’ under salinity stress. The results of this study showed that ‘Sabzevar’ and ‘Damavand’ genotypes had good tolerance to drought stress, and ‘Sabzevar’ and ‘Arak’ genotypes had good tolerance to salt stress than other Iranian crested wheatgrass genotypes.
Mohammad Hossein Sheikh Mohammadi; Nematollah Etemadi; Ali Nikbakht
Abstract
Introduction: Drought is one of the most detrimental abiotic stresses for turfgrass growth across a wide range of geographic locations. Most cool-season grass species are not well adapted to extended periods of drought, particularly during summer months. Decline in turf quality caused by drought stress ...
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Introduction: Drought is one of the most detrimental abiotic stresses for turfgrass growth across a wide range of geographic locations. Most cool-season grass species are not well adapted to extended periods of drought, particularly during summer months. Decline in turf quality caused by drought stress is a major concern in turfgrass culture. Therefore, developing management practices for improving drought resistance of turfgrasses has become essential in arid and semi-arid regions, especially during water use restriction. One strategy to improve plant drought resistance is to promote drought avoidance by reducing water loss during drought, which may be achieved by slowing growth rate of shoots and lowering leaf area canopy to reduce demand for water. Application of growth regulators is one of the methods for increasing resistance of plants to biotic and abiotic stresses. Trinexapac-ethyl (TE) is one of the most widely used PGRs in the management of cool-season and warm-season turfgrass species. TE absorbed quickly by foliage and slow cell elongation through inhibiting of converting one form of gibberellic acid (GA20) to another (GA1). Most studies conducted under non-stressed conditions found that TE application increased chlorophyll content, turf quality, turf density and reduced shoot extension rate. We hypothesized that TE may influence plant tolerance to drought stress. Limited available data─ as reported in the above referred studies─ suggest that TE application may be beneficial for plant tolerance to stresses, but the effectiveness varies with turfgrass species, dose and duration of TE treatment, and type of stress. The main aim of this research is to evaluate the effect of Trinexapac-ethyl on increased resistance to drought stress in wheatgrass.
Materials and Methods: Wheatgrass (Agropyron desertorum L.) was used in this study. This study was conducted in field conditions at Isfahan University of Technology, Isfahan, Iran.. Wheatgrass native seeds (Agropyron desertorum L.), collected from the turfgrass research farm at Fereydan, Isfahan, which were cultivated hand broadcast in plots (3m × 2m) with seeding rates of 30 gm–2. A factorial experiment based on randomized complete block design (RCBD) with three replications was conducted for TE (Primo Maxx; Syngenta Crop Protection, Inc., Greensboro, NC) and drought stress. Treatments involved three levels of Trinexapac-ethyl growth regulator (0, 0.25 and 0.5 kg/h) and two levels of drought stress (with irrigation and without irrigation). After planting, the plots were irrigated to maintain soil moisture at 80% field capacity or higher. Irrigation was applied as required to prevent any drought stress during grass establishment. Turfgrass species were maintained at cutting height of 4 cm and were mowed once a week using a reel-type mower. All data were subjected to analysis of variance using SAS 9.1 (SAS Institute Inc., Cary, NC) and Fisher’s protected LSD test was employed at the 5% probability level..
Results Discussion: Results indicated that Trinexapac-ethyl and drought reduced growth, fresh weight and dried above ground organs significantly. Wheatgrass growth in concentrations 0.25 and 0.5 kg/h were 19.20 and 26.90%, respectively. Previous studies reported plants that have slow-growing shoots may survive more extended periods than faster-growing plants in drought conditions. Slow growth may reduce the adverse impact of drought by conserving water and carbon energy, and plants can use limited water to survive drought for an extended period of time. Unlike drought stress, Trinexapac-ethyl improved the quality of plant tissues and their color. Increase in turf quality under TE treatment might occur as a result of improved canopy photosynthesis capacity and single-leaf photochemical efficiency. Drought stress reduced relative water and chlorophyll content, increased proline level and finally led to electrolyte leakage. Trinexapac-ethyl improved wheatgrass in drought stress conditions by increasing relative water content, prolin, chlorophyll and decreasing electrolyte leakage and increased wheatgrass to drought stress resistance. Proline acts as an osmotic regulator in cytoplasm and vacuoles, protects proteins against dehydration, adjusts osmosis; detoxify radical active oxygen species, keeping more stable antioxidant enzymes. Proline immediate increase under drought stress is associated with decreasing leaf water content, in turn, induced drought tolerance. Under drought stress conditions, penetration of root depth and effective root depth has been increased, while Trinexapac-ethyl did not affect root traits significantly. The results of the present study indicated that TE decreased damages on drought stress probably via improving turf quality, chlorophyll concentration, leaf water content, proline content and less electrolyte leakage in Wheatgrass.
Hamed Alipour; Ali Nikbakht; Nematollah Etemadi; Farshid Nourbakhsh; Farhad Rejali
Abstract
Introduction: Drought stress is one of the most important abiotic stresses which significantly reduce yield and growth of most of plants. Plane tree is one of the important trees planted in the urban landscapes of Iran. One of the major limiting factors of landscapes development is providing water for ...
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Introduction: Drought stress is one of the most important abiotic stresses which significantly reduce yield and growth of most of plants. Plane tree is one of the important trees planted in the urban landscapes of Iran. One of the major limiting factors of landscapes development is providing water for plants. Deficit irrigation is a desirable method for saving water use in water deficit conditions and ultimately reducing necessary cost of water securement to landscape plants. Moreover, inoculation of plant root with mycorrhizal fungi can be considered as a method to reduce water demand of plants. In addition, mycorrhiza can increase plant resistance against environmental stress, such as salinity, temperature stress, drought stress and etc. Mycorrhiza can improve drought stress through enhancing water uptake as result of extra radical hyphae and stomatal regulation or transpiration. Increasing P concentration by mycorrhiza inoculation can be another mechansim for drought resistance in plants. The purpose of the present study was to evaluate two Glomus species in combination together on plane tree under water deficit for growth characteristics and nutrients uptake such as P, Fe and Zn concentration.
Materials and Methods: This outdoor experiment was conducted at - Isfahan University of Technology, Isfahan, Iran, with average temperature 14.2 ºC and 27.9 ºC night/day, respectively and relative humidity 35-70% between Mar and Aug 2012 and repeated under the same condition in 2013. This experiment was carried out to evaluate the effect of inoculation with mycorrhizal fungus on plane saplings response to different applicable water levels (50 and 100% of water needs) based on a completely randomized design with 3 replications. The treatments were control (without fertilizer), Germans peat + fertilizer, Germans peat + fertilizer + mycorrhiza in 50% of field capacity and Germans peat + fertilizer + mycorrhizain 100% of field capacity. The Mycorrhiza fungi (mycorrhizal root, soil containing spore and extra radical mycelium) were obtained from Institute of Soil and Water Research (Tehran, Iran). There were inoculums treatments: two AM fungus inoculums (G. intraradices and G. mosseae) with combination of both. The inoculated dosage was approximately 80 spores g-1 for G. intraradices and 80 spores g-1 for G. mosseae, calculated by microscope before the experiment. Plants were irrigated daily base of 100% FC after the confidence of establishing plants about 2 months and then differential irrigations were applied. The amount of 100 and 50% ET was applied for full irrigation, moderate and serve deficit irrigation, respectively. To monitor the soil water content, tensiometry probe tubes were inserted into the soil in control pot around the root. Irrigation was performed whenever 40% of the available water was consumed. In order to calculate the amount of water necessary to bring each soil to FC, soil samples were collected and the water content determined by drying. Photosynthesis rate was measured with a LCI portable photosynthesis system. Soluble sugars measured according to Phenol–Sulfuric Acid method. Extraction of the Leaf chlorophyll pigments using with 100% acetone. The extraction of P, K, Fe, and Zn from the plant tissue material was performed by using dry ashing method. The mean data of two years were analyzed with SAS 9.1 software, the means were compared for significance by the least significant difference (LSD) test at P < 0.05.
Results and Discussion: Mycorrhiza inoculation significantly increased fresh and dry weight, chlorophyll content, total sugar, leaf area, photosynthesis rate and P and K concentration as compared to control. As compared to the 100 and 50% FC, total chlorophyll, fresh and dry weight and P concentration significantly was increased in 100% FC (Table 4 & 5). The results showed that inoculation of plants with mycorrhizal fungus significantly increased most growth parameters including leaf area, chlorophyll content and leaf fresh and dry weight of plane saplings. Phosphorus content significantly increased in inoculated plants as compared to non-inoculated plants. It is recommended that in dry regions and water shortage conditions, the deficit irrigation method accompanied with mycorrhizal fungus inoculation to save water.
Conclusion: Our data showed that mycorrhiza inoculations increased most growth parameters including leaf area, chlorophyll content and leaf fresh and dry weight of plane saplings. In conclusion, mycorrhiza inoculations can increase plant tolerance against drought stress by increasing phosphorus concentration, chlorophyll content, and photosynthesis rate. Generally, results of this study revealed that inoculation of plane tress with mycorrhizal fungi, improved plant growth under stress conditions through its positive influence on nutrients uptake, chlorophyll content and other growth parameters.
Amir Sadeghi; Nematollah Etemadi; Mahboobe Shams; Fateme Nyazmand
Abstract
In this study, the effect of drought stress on morphological and physiological characteristics of wheatgrass and tall fescue was investigated in a factorial-split plot in time arrangement based on a completely randomized design with three replications. After turf establishment, half pots were exposed ...
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In this study, the effect of drought stress on morphological and physiological characteristics of wheatgrass and tall fescue was investigated in a factorial-split plot in time arrangement based on a completely randomized design with three replications. After turf establishment, half pots were exposed to drought stress and the half other were completely irrigated. Based on the results tall fescue had higher color and lower percent leaf firing during first 10 days of drought stress, but after this period, the percent leaf firing in tall fescue increased, so that it had higher percent leaf firing and lower color than wheatgrass in the end of experiment. The results showed that under drought stress conditions was not observed the significant difference between two species in leaf relative water content. In wheatgrass, proline content of stressed plants was equal to control plants during first 10 days of drought stress but with prolonged stress treatment, the proline content increased significantly. Despite wheatgrass which had moderate rate for closed stomata percentage during stress period, tall fescue showed a great increased in this index and reached to 89.52% at the end of 20th day. Also in drought stress, the stomata density increased and stomata diameter decreased significantly. Therefore, based on the results in long drought stress, wheatgrass had higher drought resistance than tall fescue.
Mahsa Salehi; Nematollah Etemadi; Naser Honarjoo; Mehrdad Jafarpour
Abstract
In order toa desirable growth, plants need fertile soil which has the availability of nutrient elements in it. Sometimes, in spite of having access to the nutrient elements, decrease yield, due to undesirable physical situation. Stock (Matthiolaincana cv. Column Crimson) is one of the potting flower ...
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In order toa desirable growth, plants need fertile soil which has the availability of nutrient elements in it. Sometimes, in spite of having access to the nutrient elements, decrease yield, due to undesirable physical situation. Stock (Matthiolaincana cv. Column Crimson) is one of the potting flower that its growth medium traditionally including HAWAR soil, basin sediment and untreated waste municipal. Due to decrease reach to mentioned soils, so that, it is necessary to replace a growth medium and surveying the effect of different organic matter in pot stock. Garden soil was used as main source of medium and as control. In this study, treatments including garden soil amendment by 4 and 8 % (w/w) of different organic matter (untreated waste municipal, beet pulp, leaf mold, and municipal compost). Another treatment was traditional growth medium. This research was performed in a randomized complete block design with four replications. Result showed that manure treatments on plant height, floret diameter, carbohydrate content had significant different (p
Maryam Hojjati; Nematollah Etemadi; Bahram Baninasab
Abstract
Abstract
Growth retardants are new chemical organic compounds that increase period of flowering, leave chlorophyll, lateral shoot number, flower number and decrease vegetative growth. They also increase dry, cold and heat tolerance. Paclobutrazol and Cycocel are examples of these compounds. This ...
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Abstract
Growth retardants are new chemical organic compounds that increase period of flowering, leave chlorophyll, lateral shoot number, flower number and decrease vegetative growth. They also increase dry, cold and heat tolerance. Paclobutrazol and Cycocel are examples of these compounds. This study was conducted to evaluate the effect of Paclobutrazol and Cycocel on some quantitative and qualitative traits of Rudbeckia. Plants transplanted at Horticulture Department Farm, College of Agriculture, Isfahan University of Technology. The experiment was conducted based on randomized completed block design with 3 replications. Traits were studied included height, leaf and flower number, lateral shoot number, flower diameter, lateral shoot length, leave chlorophyll, the period of flowering , root fresh and dry weight, leaf area, root number, diameter and length, root and shoot carbohydrate. Results showed that Paclobutrazol 30 ppm reduced leaf number. Cycocel 2000 ppm produced the most leave chlorophyll, the period of the flowering and root diameter. Paclobutrazol 5 ppm and Cycocel 500 ppm reduced flower number. All treatments except Cycocel 500 ppm significantly reduced leaf area. There were no significant difference between treatments related to height, lateral shoot number, lateral shoot length, flower diameter, root fresh and dry weight and root and shoot carbohydrate.
Keywords: Rudbeckia, Paclobutrazol, Cycocel, Vegetative growth, Flowering
Negar Simkeshzadeh; Mostafa Mobli; Nematollah Etemadi; Bahram Baninasab
Abstract
Abstract
Planting of olive (Olea europaea L.) tree due to salt and drought tolerance and ever green habit increasingly is considered in urban landscape in recent years. The low resistance to cold has been a major problem in using this tree in temperate and cold zones. So, determination of frost resistance ...
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Abstract
Planting of olive (Olea europaea L.) tree due to salt and drought tolerance and ever green habit increasingly is considered in urban landscape in recent years. The low resistance to cold has been a major problem in using this tree in temperate and cold zones. So, determination of frost resistance cultivars is one of the important measures for use of this tree in urban landscape. To evaluate frost resistance of 15 olive cultivars and to compare the visual assessment and chlorophyll fluorescence methods, a factorial experiment was carried out using 7- year- old olive trees which were planted in randomized complete block design with 3 replications. In visual method, frost damage of winters 2007 and 2008 to plants (percentage of drying by scoring and percentage of leaf abscission) were measured. Results of this experiment showed that ‘Amphisis’ followed by 'Gorgan' and 'Shengeh' were tolerant and ‘Kroneiki’ and ‘Rashid’ were sensitive cultivars to low temperatures. In method of chlorophyll fluorescence, in July 2008 leave samples of each cultivar was gradually incubated in 0, -5, -10, -15 and -20 ° C for one hour at least. Then Fv/Fm value of each sample was measured with fluorescence spectrometer. Results indicated that 0 and -5 ° C had no damage on samples and all cultivars tolerated these temperatures (Fv/Fm> 0.83). When temperature reduced to -10 and -15 ° C the stress on plants increased and ‘Rashid’ showed the lowest Fv/Fm (0.243 and 0.001 respectively) and was the most frost sensitive. Decreasing temperature to -20 °C had no further significant effect on reduction of Fv/Fm index and showed no difference between cultivars. Based on this method, ‘Shengeh’, ‘Gorgan’ and ‘Amphisis’ were tolerant cultivars and ‘Rashid’, ‘Spain’, ‘Manzanilla’ and ‘Kroneiki’ were sensitive cultivars to low temperatures which confirmed the results of visual assessment.
Keywords: Chlorophyll fluorescence, Frost resistance, Olive, Visual assessment
