جستجوی مقالات مرتبط با کلیدواژه « تنش های محیطی » در نشریات گروه « باغبانی »

Fenugreek (Trigonalla foenum-graecum L.), an annual herbaceous plant belonging to the Coleoidea (Fabaceae) family, has numerous medicinal properties such as decreasing blood glucose, laxative, appetizer, mucus, antipyretic and increasing the amount of milk during lactation . Among the most important problems in arid and semi-arid regions, drought stress or water shortage will have negative effects on plant growth. Drought stress occurs mostly because of reducing water availability in the soil. This may be due to excessive water loss or absorption problems, or both of them. One of the major factors limiting germination, which occurs in more arid and semi-arid regions, is salt stress. The study was done to evaluate germination of four Iranian population of fenugreek (Amol, Tabriz, Sari and Mashhad) under drought and salinity stresses.
To investigate the effect of salinity and drought stresses on germination and seedling growth characteristics of native landrace fenugreek, two separate experiments were conducted in a Completely Randomized Design with three replications in Seed Laboratory of University of Mashhad in 2014. The experiment treatments consisted of four levels of salinity (0, 60, 120, 180 mM) that was induced by different concentrations of sodium chloride and drought stress induced by polyethylene glycol 600 (PEG 6000) at four levels (0, -3, -6 and -9 Bar) with three replications. The drought stress levels were simulation by polyethylene glycol 6000 and using the Michel and Kaufmann formula. Distilled water was applied as control. Iranian seed population of fenugreek were purchased from the city of Amol, Tabriz, Sari and Mashhad then the seeds were washed with sodium hypochlorite (3 % v/v) for two minutes for disinfestation and washed three times with distilled water. On the twelfth day of experiment, seedling traits such as plumule and root length and weight in Petri dishes were measured.
The results of ANOVA showed that salinity and drought stress significantly (p≤0.01) affect germination process. The results of the means comparison confirmed that fenugreek germination in all seed population was reduced by increasing salinity levels. The lowest germination was detected under 180 mM salt stress in “Tabriz” population (12.04%), while the highest germination (95/26%) was calculated in “Mashhad” population at control. Seeds of “Mashhad” population in comparison to other population showed higher germination at other salinity levels. Germination rate also was significantly affected by salinity (p≤0.01). Decreasing of germination rate in fenugreek population of Amol, Tabriz, Sari and Mashhad under 180 mM salinity stress in comparison to control (0 mM) were 84/62, 87/80, 85/93, 82/59, respectively. Mashhad and Amol (second order) populations showed more germination rate stability after changes in salinity levels. The results of analysis of variance from this study showed that interaction effect of salinity and population significantly (p≤0.05) affect root length of the fenugreek. The root length of Mashhad and Amol populations were more stable at high level of salinity. Other researcher also reported that the root length decreased after salinity treatments (10, 13). Salinity stress affect water absorption by seed and decreasing Amylase and lipase activity caused degradation of stored material in seeds and then decreasing root length 23). Salinity, population and interaction between these factors significantly (p≤0.01) affected length of plumule. The results showed that Mashhad population had the highest and Tabriz revealed the lowest length of plumule. Interaction effects of treatments on seedling dry weight showed significant (p≤0.01) differences. Mashhad in comparison to the other populations had the highest seedling dry weight as 9.26, 8.10, 7.22 and 3.6 mg/seedling at different salinity treatments (0, 60, 120, 180 mM), respectively. Interaction effects of drought stress and population on germination percentage was significant (p≤0.01). Mashhad and Amol (second order) populations were the best populations. At the highest level of drought stress (-9 Bar), these two populations had the lowest decrease in germination percentage. The mechanism of the results was the same as salinity which explained in above. According to the results of analysis of variance (ANOVA), all treatments and all interaction had significant effect (p≤0.01) on germination rate. The Mashhad and Sari populations were more tolerant than other populations against drought stress examined as germination rate as concerned. Analysis of variance showed that the simple effects of drought stress and population on root length were significant at one percent but interaction effect of drought stress and population was not significant statistically. The root length was in the range of 26.78 to 50.29 mm in the tested population. Mashhad population was more tolerant against drought stress in comparison to the other tested populations. Analysis of variance showed that simple effect of drought and population were significant (p≤0.01) on this trait but their interaction was not significant. Length of plumule mean comparison showed that the traite was in the range of 21.74 to 43.31 mm in Tabriz and Mashhad populations, respectively.Acoording to the length of plumule,Mashhad population in comparison to other tested populations under drought stress was tolerant . The water potential (drought stress), population and interaction between them showed significant effect (p 0.01) on seedling dry weight. Among the evaluated population the Mashhad population was tolerant to drought stress when seedling dry weight was concerned. The highest correlation coefficient (r=0.96) was detected between germination percentage and root length and in second order the correlation coefficient between germination percentage and seedling dry weight was 0.93. The lowest correlation coefficient (0.61) was observed between germination rates and seedling dry weight.
The decline in germination percentage, germination rate, root length, shoot length and dry weight of seedlings with increased water osmotic potential in Mashhad population was less than other evaluated populations. Seed germination rate was more sensitive than seed germination percentage in both salt and drought stress therefore this trait is a suitable criterion for screening of tolerant population for future breeding purpose. The order for tolerance to salinity and drought stress in evaluated population was Mashhad, Tabriz, Sari and Amol.

Soil salinity and compaction are probably the most prevailed limitations for crop growth and production. Their mitigation and control may be important crop management keys that can ensure yield sustainability and optimum use of land and water. This research was performed to investigate the combined effect of soil salinity and soil compaction on some growth characteristics of corn (Zea mays L.) root. For this purpose, a factorial pot experiment on the basis of completely randomized blocks design with three replications was performed. The experimental factors were three levels of soil salinity (electrical conductivity of saturated paste extract of 1.5, 2.5 and 4.5 dS/m) and three levels of soil compaction (bulk density of 1.3, 1.55 and 1.75 g/cm3). For salinity treatments, different amounts of NaCl was dissolved in the required volume of distilled water to have soil water content to 16% and then were added to the soil. For soil compaction treatments, a 4.5 kg solid cylinder was allowed to fall freely from 45 cm height over the soil surface in the pots. During the 3 months of experimental period, the pots were irrigated with distilled water through regular weighing. Results showed that the main effects of soil salinity and compaction at 1% probability level and their combined effects at 5% probability level led to significant reduction in root dry weight, root volume, root length, root mean diameter and ratio of root weight to soil weight. Combined effects of soil salinity and compaction reduced growth characteristics of the corn roots 20% more than their individual effect. Therefore, it can be concluded that soil salinity and compaction intensify their negative effects and suppress growth and development of corn roots.

Salinity is a common abiotic stress that seriously affects crop production around the world, particularly in arid and semi-arid regions.The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, specific ion effect (salt stress), or a combination of these factors. Olive is one of the most important fruit crops in Iran and the world. Despite olive has been classified as moderately salt tolerant plant, poor quality of irrigation water in association with salt build-up soils has reduced the yields, especially in arid and semi-arid regions of Iran. The tolerance of the olive to salt is to a great extent depends on the cultivar. Selecting salinity-resistant cultivars is one of the most important strategies used for mitigating salinity effects on olive. Therefore, this study was performed to assess the salt tolerance of four olive cultivars under greenhouse condition.
For this purpose, one-year-old rooted cuttings of Iranian olive cultivars (‘Dakal’, ‘Shiraz’, ‘Zard’) and non-Iranian cultivar ‘Amigdal’ were grown in the research greenhouse of Agricultural College, Isfahan University of Technology of Iran. Plants were grown in plastic pots. The pots were 180 mm in diameter and 20 mm in depth with volume of 7 L. The minimum and maximum temperatures during the experiment period were 19 and 35˚C, respectively. After sticking the cuttings, the pots with uniform plants were subjected to the treatment with 0 (control), 100, 150 or 200 mMNaCl. The electrical conductivities of these solutions were 0.003, 10.52, 15.43 and 19.55 dS m-1, respectively. To avoid osmotic shock, the NaCl concentration was gradually increased. The layout was a 4×4 factorial experiment based oncompletely randomized design, with four replications. The experimental measurements were carried out three months after beginning the salt treatments.
The results showed that salt stress and cultivar hadsignificant effects on all of vegetative and physiological parameters. Injury rating valueof plants wasfound to increase significantly as the salt concentration was raised. Among the cultivars, the highest injury rating value (2.75) belonged to Amigdal cultivar, while the lowest means (2.00) was related to Dakal cultivar. By increasing the salinity level, stem heightincreasing ratesignificantly decreased. The lowest means (18.17%) belonged to 200 mMNaCl treatment, showing 81.83% decrease compared with control. Among the cultivars, Zard showed the highest means of increase in stem height (71.75%). Leaf area influenced significantly by salinity, sothat the lowest means of leaf area (35.05%) was recorded for200 mMNaCl treatment, showing a 69.91% decrease compared with the control. The highest leaf area belonged to Shiraz cultivar, which had a significant difference with Zard and Amigdal cultivars. Compared with the control, salinity caused 50.83% and 54.36% decreases in shoot fresh and dry weight in 200 mMNaCl, respectively. The highest shoot fresh and dry weightswere recorded forZard cultivar. The lowest shoot fresh and dry weights were observed forAmigdal cultivar.Increment of salinity concentration significantly declined root fresh and dry weight. Among the cultivars, the highest means of root fresh weightbelonged to Amigdal cultivar, whereas the lowest was related to Shiraz cultivar. The highest and lowest root dry weightswere observed forDakal and Amigdal cultivars, respectively.Salinity significantly decreased relative water content.The lowest leaf relative water content (66.04%) was recorded in 200 mMNaCl treatment, showing a 23.43% decrease compared with the control.Zard cultivar showed the highestleafrelative water content. Salinity stress decreased chlorophyll fluorescence in leaves of salt-treated olive plants. At 200 mMNaCl, leaf chlorophyll fluorescence was minimal as compared to control and other salt levels. The highest leaf chlorophyll fluorescence ratio (0.74) was recorded forZard cultivar. However, Amigdal cultivar showed the lowest means for this index (0.60).Salinity significantly decreasedleaf chlorophyll content.The lowest leaf chlorophyll content (69.39%) was recorded in 200 mMNaCl, showing a 66.80% decrease compared with the control.Among the cultivars, Zard showed the highest leaf chlorophyll content (170.33). In the present study, the increase in proline content in the NaCl-treated plants was noted, with the highest level being attained with 200 mMNaCl. The highest proline content (1.03 µmol.g-1 F.W.)was observed in Zard cultivar. Salinity stress increased malondialdehyde content in the leaves of salt-treated plants. The highest malondialdehyde content was obtained from leaves of plants treated with 200 mMNaCl. The highest malondialdehyde content was recorded in Amigdal cultivar.Shirazl cultivar showed the lowest malondialdehyde content. In this study, the correlation betweenvegetative and physiological parameters of olive plants subjected to salt stress was analysed. These correlations suggested that salt injury symptoms was negatively correlated with relative water content, leaf chlorophyll fluorescence and leaf chlorophyll content, but positively correlated with proline content and malondialdehyde content.
In overall, this investigation revealed that salt stress had aninhibitory effect on the vegetative growth of olive plants.The responses of olive cultivars to salt stress suggested that Zard and Shiraz cultivars were more tolerant and ‘Amygdal’ was the most sensitive to changes in the salt levels.

The required water for greenhouses in Kishestan, Soume-e-Sara town, Guilan province, Iran, is mainly provided by underground resources that have inappropriate quality. One way to reduce the impact of salinity an plant growth is proper nutrition. This greenhouse research was conducted to evaluate the effect of water salinity and foliar spray of calcium (Ca) and silicon (Si) on growth and vase life of gerbera in a factorial experiment based on compeletly randomized design with two factors. The first factor was salinity of irrigation water at two levels (0 and 1.5 dS/m) and the second factor was foliar spray at seven levels (without spray, twice Ca spray, four times Ca spray, two times Ca spray + once Si spray, twice Ca spray + twice Si spray, four times Ca spray + once Si spray, and four times Ca spray + twice Si spray), each with three replications. Results showed that four times Ca foliar spray led to an increase in stem hight, stem and neck diameter, postharvest life and Ca concentration of shoots. In all spray treatments, number of flowers in zero salinity was more than 1.5 dS/m treatments. In general, in case of using low-quality water (electrical conductivity of 1.5 dS/m), the effects of salinity on dry and fresh weights of gerbera plant and vase life of its flowers can be reduced by foliar application of Ca and Si. Since inappropriate water quality in Rasht Greenhouse Complex, Soume-e-Sara town, is one of the main problems of the farmers, especially in growing the ornamental plants, effects of salinity on plant growth could be alleviated with foliar spray of nutrients, especially Ca and Si. In this respect, four times spray of Ca and also twice spray of Ca + twice spray of Si are recommended.

Mint is an important medicinal herb that is cultivated in different parts of the world. In order to investigate the effects of salinity stress on morphological characteristics of spearmint (Mentha spicata L.), an experiment was conducted in 2013, based on complete randomized design, under hydroponic conditions, at Research Greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Treatments were five salinity levels (0, 30, 60, 90 and 120 mM of sodium chloride) with four replications. Growth medium was 2:1 cocopeat to perlite, and complete nutrients solution was used. Supplying plants’ nutrients was twice a week along the irrigation water application. When plants’ height was 30 cm, salinity treatments were applied and were continued till full flowering. At the end of the experiment, morphologic traits including plant height, number of main stems, number of lateral branches, leaf area, specific leaf weight, stem diameter, number of nodes, fourth internode length, and spike length were measured. Results showed that salinity stress had significant effects on leaf area, fresh and dry weights of leaf, stem and root, plant height, number of lateral branches, number of nodes, fourth internode length, and spike length. The highest leaf area, leaf dry weight, plant height and number of lateral branches were observed in control treatment. The lowest leaf area and leaf dry weight were obtained in salinity level of 120 mM, and the lowest plant height and number of lateral branches were observed in salinity levels of 90 mM and 120 mM. Salinity had no significant effect on fresh weight of shoot to root ratio, fresh weight of leaf to root ratio, specific weight of leaves, number of main stems and stem diameter. According to the results, it appears that spearmint is sensitive to salinity stress and it cant tolerate salinity levels higher than 30 mM sodium chloride.

Presence of heavy metals (such as lead, Pb) in plants is one of the major environmental stresses that decrease plant growth. Therefore, it is essential to determine the threshold of the plant's tolerance to these elements. In this regard, to evaluate the effect of different concentrations of Pb on eco-physiological traits of petunia plant, an experiment was carried out in the hydroponics greenhouse of Tabriz University, Tabriz, Iran, as a completely randomized design with 8 treatments and 4 replications. Treatments consisted of different concentrations of Pb (0, 0. 25, 0. 5, 0. 75, 1, 1. 5, 2 and 4 mg/L as Pb(NO3) 2). After applying the treatments, at the end of the growing season, the eco-physiological indices including photosynthesis, transpiration, stomatal conductance, stomatal resistance and leaf temperature were measured. Results showed that concentrations higher than 0. 75 mg/L Pb (NO3) 2 reduced the rate of photosynthesis, transpiration and stomatal conductance as compared to control. The highest stomatal resistance (8. 754 M/m2. s) was observed in 4 mg/L treatment; though it didnt have significant difference with 1. 0, 1. 5 and 2 mg/L treatments. The lowest stomatal resistance (7. 285 M/m2. s) was seen in 0. 25 mg/L treatment, which had no significant difference with control. The highest leaf temperature (33. 26 ْC) was observed in 2 mg/L treatment; though it didnt have significant difference with 1. 5 and 4 mg/L treatments. The lowest leaf temperature (26. 19 ْC) was obtained in the control treatment. After 0. 75 mg/L, the increase in leaf temperature was sensible. Based on the results, it appears that in soils having Pb concentration of ≤ 0. 75 mg/L, petunia plants are recommendable for cultivation in landscapes, accumulation of Pb, and phytoremediation.

In drought stress conditions، besides the inhibition of water uptake، the plant nutrients availability and uptake are also limited. Proper nutrition is known as a management procedure for plant production under different environmental-stress conditions. Generally، the combined effects of drought and deficiency of potassium and zinc on plant water content and some physiological parameters reduce yield quantity and quality. This investigation was conducted to assess the interactive effect of different levels of potassium as KNO3 (0. 6، 3 and 6 mM) and zinc as ZnSO4 (0، 1 and 2 μM)، under drought stress conditions induced with PEG 6000 (0، 55 and 110 g/L PEG 6000) on some water status indices and physiological parameters of tomato in hydroponic culture. The results showed that interaction of drought، potassium and zinc on shoot and root dry weight، leaf chlorophyll and proline content and percentage of root ion leakage was significant. Both potassium and zinc improved water status of the plants; however the effect of zinc on leaf water potential was not significant. Drought stress increased the chlorophyll content and decreased the sulfhydryl groups. Application of a high level of potassium in the nutrient solution increased root ion leakage.