Ornamental plants
T. Oraee; M. Shoor; A. Tehranifar; S.H. Nemati; A. Oraee
Abstract
Introduction Climate change predictions indicate that drought and extreme heatwaves will become more frequent and extreme in many regions. Drought is the main abiotic stress that severely reduces plant yield across the globe. Thus, this may have negative consequences for the agricultural soils, ...
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Introduction Climate change predictions indicate that drought and extreme heatwaves will become more frequent and extreme in many regions. Drought is the main abiotic stress that severely reduces plant yield across the globe. Thus, this may have negative consequences for the agricultural soils, as it limits the availability of water and nutrients to soil microorganisms and plants that develop on these soils. To cope with this situation, the use of organic amendments is the best option. Recent studies have shown that the application of organic fertilizers can affect soil moisture and thus, mitigate the negative effect of climate change on that parameter. Organic amendments increase soil organic matter content thus improving soil physical, chemical, and biological properties, and therefore, can confer drought resistance to soils. The application of organic residues has been presented as a great strategy against soil degradation in semiarid environments. However, the interactions between organic amendments and drought in hollyhock plants are not fully known. Here, we evaluate whether the organic amendment influences the physiological traits of hollyhocks and soil properties under drought conditions. Materials and Methods The experiment was conducted in the research field at Ferdowsi University of Mashhad, Iran. The experiment consisted of three factors (cultivars, organic amendments, and drought) with organic amendments and drought having four and three levels, respectively. Drought treatments were controlled by a TDR at 80, 60, and 40% FC. The three sources of organic amendments were used cow manure, rice hull and wheat straw. Seeds were planted in cocopeat, perlite, and peat mixture trays in the greenhouse with an average temperature of 20 °C and under a photoperiod of 14 hours of light and 10 hours of darkness with a light intensity of 400 μmol-1 m2. In the 5-6 leaf stage, seedlings were transferred in pots (18 cm high and 8 cm in diameter) containing field soil. The plants were transferred to the field with four different substrates (field soil, field soil + manure, field soil + rice hull, and field soil + wheat straw) and were exposed to drought stress for one month during the flowering stage. This analysis examined both the physical and chemical properties of the soil, including changes in the macroelements nitrogen, phosphorus, and potassium. Results and Discussion Soil nitrogen changes were significantly affected by the interactions of ecotype with drought, ecotype with the medium, and drought stress with medium. The highest nitrogen changes were recorded in Mashhad ecotype under 80% FC. Nitrogen content in amended soil had an increasing trend during the experiment, but the amount of nitrogen had a decreasing trend in soil. In all media under stress, the amount of soil phosphorus was increased and the highest amount of phosphorus was observed in soil + manure at all irrigation regimes. The highest amount of potassium in both ecotypes was observed in soil + manure. The amount of potassium in amended soils under stress significantly increased, but in all organic amendments with increasing drought stress from 80 to 40% FC, the potassium content decreased. In both ecotypes, soil salinity was increased in all culture media. Han et al. (2016) stated that the amount of nitrogen, phosphorus, and potassium in the amended soil was higher than the substrates containing chemical fertilizer. The medium EC was alkaline at the end of the experiment and the salinity of the culture medium increased compared to the control. This study revealed a negative correlation between electrolyte leakage and dry weight in hollyhock plants. Furthermore, all measured physiological and growth parameters were significantly affected by the treatments. Notably, the Mashhad ecotype grown in soil supplemented with animal manure at 80% field capacity (FC) exhibited the highest levels of physiological traits (SPAD and relative water content) and growth index (dry weight).The application of manure + soil by providing macro elements reduces the negative effects of drought stress. Conclusion The type of crops grown in arid and semi-arid regions should be reconsidered. Also, some plants with high water requirements should be replaced with plants with low and unexpected water requirements. Because hollyhocks are low-expected plants that grow well in drought areas, so they can be considered as suitable species for cultivation in low-input systems and can tolerate drought situations by 40% FC in amended soil.
Growing vegetables
M. Sajedimehr; M. Haghighi; M. Mehnatkesh
Abstract
Introduction
Drought stress is one of the most important factors limiting plant growth and production and leads to a reduction of more than 50% in the average production of most crops worldwide. Drought stress due to increased soil osmotic potential, especially in greenhouses where fertilizer consumption ...
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Introduction
Drought stress is one of the most important factors limiting plant growth and production and leads to a reduction of more than 50% in the average production of most crops worldwide. Drought stress due to increased soil osmotic potential, especially in greenhouses where fertilizer consumption is high, is one of the greenhouse crop problems.
Material and Methods
In the present study, two concentrations of polyethylene glycol at three levels of 0 (D1), -1.48 (D2), 4-91 (D3 ds/m to create different levels of drought stress due to osmotic changes in culture medium and application of KCl two levels (0 (K1) and 6 (K2) mmol / l) was used to reduce the possible effects. The experiment was performed as a factorial experiment in a completely randomized design with three replications. To apply drought stress, pot water was measured using a tensiometer, and when the drought reached below the field capacity (FC), irrigation with different concentrations of PEG and once a week spraying with KCl at the desired concentrations was done. Cucumber seeds were planted directly in 5 kg plastic pots containing a mixture of potting soil, including soil + sand + animal manure in the ratio of 1 + 2 + 0.5. The number of seedlings in each pot was 2 to 3 kg, which was reduced to one seedling seventeen days after sowing the seeds in the stage of three to four leaves. KCl spraying and spraying began in the three to the four-leaf stage of the seedlings and lasted for about a month. The plants were kept in the greenhouse during the experiment with an average temperature of 25 ° C and relative humidity of 70%. At the end of the experiment, dry weight, fresh weight, chlorophyll, chlorophyll fluorescence, flavonoids, carotenoids, proline, phenol, total protein, abscisic acid, superoxide, and ascorbate peroxidase, antioxidants, and catalase were measured.
Result
The results showed that the effect of foliar application of potassium in all traits except chlorophyll fluorescence and superoxide dismutase was significant (P <0.01). According to the obtained results, ccontrol treatment increased the amount of antioxidants and catalase, but the application of K2 on most of the measured parameters, including dry weight, fresh weight, chlorophyll, flavonoids, carotenoids, proline, phenol, total protein, abscisic acid, and superoxide disodium showed a positive effect. In D3 with the addition of K2 the highest amount of phenol and protein was observed. Also, the content of abscisic acid in all treatments increased with the addition of K2 and the highest amount was observed in D3 which can be concluded that the use of potassium at a concentration of 6 mM Acceptable cut. According to the results obtained in this study, it can be stated that the plant tries to maintain its osmotic pressure in the face of drought stress, and this is done by increasing osmolites such as proline and antioxidant enzymes that help maintain plant cell pressure and torsion. Potassium application can reduce the adverse effects of drought stress by improving the activity of antioxidant enzymes and preserving chlorophyll. Thus, the cell continues its vital activities and ultimately produces more acceptable performance under these conditions. In other words, increasing the antioxidant activity in drought conditions along with the application of potassium leads to a higher inhibitory capacity of reactive oxygen species and production stability in these conditions. Therefore, to compensate for at least some harmful effects of stress and help the plant to return to normal growth conditions after re-irrigation, foliar application of such elements can be effective in drought resistance of the plant and play a role. Based on the findings of this study, it seems that the application of potassium with a concentration of 6 mM is the most effective.
F. Ghanbari; M. Sayyari
Abstract
Introduction: Due to its low level of calorie and being as an excellent source of C and A vitamins as well as containing lycopene as a powerful antioxidant, Tomato (solanum lycopersicum, 2n=2 x=24), is extensively consumed in the world. According to the statistics presented in 2013, following China, ...
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Introduction: Due to its low level of calorie and being as an excellent source of C and A vitamins as well as containing lycopene as a powerful antioxidant, Tomato (solanum lycopersicum, 2n=2 x=24), is extensively consumed in the world. According to the statistics presented in 2013, following China, United States, Turkey and Egypt, Iran ranked sixth in tomato production (6174182 kg per year) world tomato production. Similar to other tropical crops, tomato is sensitive to chilling stress. The chilling stress is considered as one of the environmental factors influencing growth and development of many plants including tomato. Applying different environmental conditions and cultivation techniques within transplant production can mitigate the chilling stress of seedlings. The seedling hardening is one of the simple technique being employed to physiological characters of plant, so as to induce subsequent stress resistance. This phenomenon is so-called cross tolerance and it means that exposing plants to stressful conditions can induce plant tolerance to upcoming stresses. Therefore, the objective of our study was to investigate the effect of drought hardening and chilling stress on tomato plant growth and productivity in field condition.
Materials and Methods: This experiment was conducted in greenhouse and research laboratories of agricultural college of Bu Ali Sina University. First of all, the seeds of tomato cv. C.H Falat, were sown in pots filled with perlite and vermiculite (ratio 2:1) and then maintained under natural light and at 25±2°C / 18±2°C (day/night). At four-leaf full development stage, seedlings were subjected to seven-day drought stress simulated with polyethylene glycol 6000 (PEG) at three levels: control (0% PEG), moderate drought stress (10 % PEG equaling to 0.18 Mpa osmotic potential) and severe drought stress (20% PEG equaling to 0.57 Mpa osmotic potential). After employing different levels of drought stress and consequently placing them in recovery for 48 h, they were exposed to chilling stress and non-chilling stress condition. For imposing chilling stress, the seedlings were transferred into growth chamber under 3°C for 6 days and 6 h per day. After receiving chilling stress treatments, the produced seedlings, were planted in the field.
Results and Discussion: In the present study, drought pretreatment reduced the effects of cold stress on fruit yield and quality. Results revealed that, the growth and yield of tomato plants were significantly increased by drought stress pretreatment in field condition. Herein, Seedlings without receiving drought pretreatment slowly grew and gained lower yield than those receiving drought. Some traits such as higher fruit size and shelf life and low number of decayed end blossom fruits were gained by drought application. The highest growth and yield rates were obtained through 10% PEG. These results indicate that drought stress at seedling stage increases the yield of tomato without harmful effects on fruit quality. The results showed that in 0% PEG treatment (control), chilling stress increased the number of days for flowering and fruiting, which indicates the growth retardation in this plant under cold stress condition. Drought pre-treatment using PEG increased the thickness of the pericarp and its post-harvest life, which may indicate the maintenance of the effects of initial stress in all stages of vegetative and reproductive growth. It has been reported that cold stress directly affects the growth potential of plants that interfere with the proper production of plants by disrupting metabolic reactions and indirectly by preventing the absorption of water by plants and oxidative stress (Hussain et al., 2018). In the present study, pre-treatment of drought reduced the destructive effects of chilling stress on fruit size. These results show that pre-treatment of drought (especially 10% PEG) had a significant effect on increasing fruit size and preventing its fruit yield reduction due to cold treatment. Similarly, Paradosi et al. (1987) reported that water stress in tomato plants increased its tolerance to cold and maintained the growth of tomato plants and its yield in cold greenhouse conditions. So far, there have been no reports of interactions between environmental stresses on fruit size, but the effects of drought stress on tomato fruit have been studied.
Conclusion: In general, the results of this experiment showed that the effects of drought pre-treatment on seedling remain in the next stages of tomato growth and can have beneficial effects on growth and yield of tomato in field conditions.
R. Fotouhi Ghazvini; yusuf hamidoghli; R. Hassan Sajedi
Abstract
The production of reactive oxygen species (ROS) in plants under low temperature stress cause damage to plants. In order to evaluate of antioxidant responses of Page mandarin young trees (two years old) on different rootstocks under low temperatures, an experiment was conducted in a factorial plan based ...
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The production of reactive oxygen species (ROS) in plants under low temperature stress cause damage to plants. In order to evaluate of antioxidant responses of Page mandarin young trees (two years old) on different rootstocks under low temperatures, an experiment was conducted in a factorial plan based on completely randomized design. Treatment of temperatures were at seven levels include 9, 6, 3, 0.-3,-6 °C and 25 ± 2 °C (as control) and rootstocks were Sour orange, Citrange and Trifoliate orange. Results showed that, low temperatures increased electrolyte leakage, lipid proxidation, antioxidant capacity, superoxide dismutase, ascorbate peroxidase, catalase and peroxidase enzyme activities (P
M Goldani; yahya selahvarzi; J. Nabati; M. Alirezai
Abstract
Salinity is one of the environmental stresses that have limited influence on the crop growth. Oxidative process is a secondary stress due to salinity. Oregano is enumerated as one of the most important of medicinal plant that its production and development is possible in Iran. In order to study the effect ...
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Salinity is one of the environmental stresses that have limited influence on the crop growth. Oxidative process is a secondary stress due to salinity. Oregano is enumerated as one of the most important of medicinal plant that its production and development is possible in Iran. In order to study the effect of exogenous application of hydrogen peroxide on salt tolerance in oregano (Origanum majorana L.) an experiment was conducted in greenhouse conditions. This study was designed as factorial based on completely randomized design with 3 replications. Different concentration of hydrogen peroxide (0, 2.5 and 5 mM) and four levels of NaCl (0, 50, 10 and 150 mM) were treated in this study. Results showed that foliar application of hydrogen peroxide can improve shoot and root dry weight and alleviate adverse effects of salinity. In the other hand, high concentration of hydrogen peroxide (5mM) increased total chlorophyll and caroteoid content about 46.6 and 100.6 percent comparing to control plant, respectively. Salt stress had no significant effect on cellular hydrogen peroxide, but it increased free proline and reduced K:Na ratio. While hydrogen peroxide content, free proline and K:Na ratio were increased 104.6, 320.7 and 77.8 percent by high level of hydrogen peroxide, respectively. The final result showed that foliar application of hydrogen peroxide decreased salt stress.
