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.
H. Nastari Nasrabadi; S.F. Saber Ali
Abstract
Introduction: Melon (Cucumis melo L.) is one of the most important vegetables in Cucurbitaceae family and one of the most important economic crops in the Torbat-e Jam city (Longitude: 60 ̊48', latitude: 35 ̊31', altitude: 928 m). Growth and yield of agricultural crops are affected by biotic ...
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Introduction: Melon (Cucumis melo L.) is one of the most important vegetables in Cucurbitaceae family and one of the most important economic crops in the Torbat-e Jam city (Longitude: 60 ̊48', latitude: 35 ̊31', altitude: 928 m). Growth and yield of agricultural crops are affected by biotic and abiotic environmental stresses. Cold stress can be one of the most important environmental factors reducing crops yield. Cold acclimation in plant is a complex process involving many morphological, physiological and biochemical changes, including a significant reduction in tissue hydration during cold hardening. Melatonin (MEL, N-acetyl-5-methoxytryptamine) is a conserved substance, which has been discovered in all living organisms, from bacteria to mammals. MEL regulates the growth of root, shoot, and explant, activates seed germination and rhizogenesis, and delays leaf senescence. In addition, the most frequently mentioned functions of MEL are related to various abiotic stresses such as drought, radiation, low/high temperature, heavy metals, and salinity stresses. Materials and Methods: In order to investigate the effect of PEG priming and melatonin on cold stress resistance of melon seedlings, a factorial experiment was conducted in a completely randomized design with three replications in Torbat-e-Jam University. In this experiment polyethylene glycol 6000 was used to produce drought stress at three levels (0, 0.18 and 0.58 MPa) and melatonin was used at two levels (0 and 200 μmol). When melon seedlings were at 4 leaf stage, the amount of polyethylene glycol was added to the irrigation solution for a week and to prevent drought stress, drought stress was increased for 3 days and increased one third of the required concentration daily. Recovery was performed for three days after drought stress and during this period melatonin was added to the irrigation solution at the required concentration. Seedlings were then exposed to cold stress (T0: non-stress and T1: cold conditions). Control plants were kept in greenhouse conditions. Results and Discussion: Comparison of the mean results showed that there was an increasing trend in proline production by increasing drought stress. The highest amount of proline (0.80 µmol g-1 FW) was recorded at the highest level of drought pretreatment with no melatonin and without cold stress (D2M0T0), and then a decreasing trend in proline production was observed. The results showed that melatonin significantly increased leaf relative water content compared to the control. Interaction effects of drought pretreatment and temperature showed that there was a trend of decrease in relative water content by increasing drought pretreatment. Ghanbari and Sayyari (8) reported that drought pretreatment stress maintains relative water content of tomato seedlings under cold stress conditions. Drought pretreatment significantly reduced the amount of chlorophyll a and total chlorophyll. The results showed that the highest levels of drought pretreatment stress (D2) and melatonin (M1) maintained chlorophyll a under cold stress conditions. Results showed that the amount of chlorophyll b was decreased by drought pretreatment stress, but it increased by melatonin application in all compounds. Based on the results, it was found that only simple effects of treatments at 1% of probability level had significant effects on soluble sugars content. Comparison of the mean simple effects of drought pretreatment showed that under drought stress the amount of soluble sugars increased significantly and the highest sugar content was recorded at the highest drought stress level. The amount of soluble sugars in plants under cold stress also increased significantly. Melatonin application also significantly increased the amount of soluble sugars. Kabiri et al. (19) reported that the use of melatonin increased soluble sugars in Moldavian balm seedlings under osmotic stress which is similar to this study results. It was found that melatonin significantly increased phenolic compounds under stress conditions and significantly decreased electrolyte leakage.
H. Farhadi; M. Azizi; S.H. Nemati
Abstract
Introduction: Drought is an event that happens due to lack of rainfall in a period of time. The occurrence of drought, reduces available soil water, but water losses through evaporation and transpiration is constantly increasing. The first stage of the plant, which may be faced with drought, is ...
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Introduction: Drought is an event that happens due to lack of rainfall in a period of time. The occurrence of drought, reduces available soil water, but water losses through evaporation and transpiration is constantly increasing. The first stage of the plant, which may be faced with drought, is germinating. Since Germination begins with water uptake, lack of water at this stage in terms of duration and intensity of the stress causes or reduce germination percentage and germination rate. Because of the heterogeneity of soils in the field and lack of control of the environmental factors such as drought, laboratory research on the stress is considered. Some of these methods can be used to study the reaction of the landraces to the solutions from materials polyethylene glycol. This study aimed to investigate the characteristics of the native population of fenugreek germinating rate under drought stress conditions and identify landrace was incurred.
Materials and Methods: To investigate the effect of drought stress on germination and seedling growth characteristics of native landrace fenugreek, an experiment was conducted in a Completely Randomized Design with three replications in Seed Laboratory of University of Mashhad in 2014. The experiment treatments consisted of eight landraces of fenugreek of Esfahan, Tabriz, Hamedan, Sari, Challous, Amol, Mashhad and Yassooj on polyethylene glycol 6000 (PEG 6000) at four levels: (0, 3, 6 and 9 times) were replicated three times. The stress test for the simulation of polyethylene glycol 6000 was used and the amount of material needed to create each of the stress levels using the formula Michel and Kaufmann respectively. To (control) and distilled water was used. Landraces seed of fenugreek the city of Esfahan, Tabriz, Hamedan, Sari, Challous, Amol, Mashhad and Yassooj purchased before the start of the experiment with a three percent solution of hypochlorite for two minutes to disinfect and then were washed three times with distilled water on the twelfth day, seeds and traits such as root length and root out the Petri measure.
Results and Discussion: In the study the interactions between landrace and drought, the rate of decline in most of the traits was related to native populations of fenugreek, Tabriz, Hamadan, Sari, Challous, Amol, Yasuj and Mashhad, respectively (-9 times) compared to control (0 times). As can be seen, the Isfahan landrace was more stable in most of the traits due to changes in drought levels. On the other hand, as the drought stress increased, the percentage and rate of germination of fenugreek seeds decreased. Fenugreek seed germination rate and percentage with increased drought stress the germination rate under drought stress sensitivity was higher than the percentage of germinating. The plants grow in different stages react differently to drought show seed germination and seedling production and a dry condition indicates that the plant is a potential for drought tolerance but that does not mean that the seedlings start to grow in dry conditions, can continue to grow in the same conditions.
hassan Farhadi; majid Azizi; hossein Nemati
Abstract
Introduction: 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 ...
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Introduction: 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.
Materials and methods: 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 6000 (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.
Results and Discussion: 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.
Conclusions: 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.
