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Showing 7 results for Chlorophyll

Mehdi Aghighi Shahverdi, Heshmat Omidi, Sayed Esmail Mousavi,
Volume 3, Issue 2 (2-2017)
Abstract

For the purpose of evaluating the effect of chitosan on seed germination and some biochemical characteristics of the milk thistle herb in the conditions of salinity, an experiment was conducted as factorial in a completely randomized design (CRD) with three replications in the Laboratory of Seed Science and Technology of Shahed University, Tehran in 2015. Experimental factors comprised salinity levels (0, 4, 8 and 12 dS.m-1) and different levels of Chitosan (0, 0.25, 0.5, 0.75 and 1 percent). The results showed that salt stress reduced germination percentage, germination coefficient, germination speed, weight and length vigor index, radical, plumule and seedling length and total biomass and increased mean germination time. Seed priming with chitosan up to 0.5% concentration increased germination coefficient, weighted index vigor and plumule length. The highest amounts of total chlorophyll and total protein were obtained in seed priming with 0.5% chitosan levels in zero salinity level (control). By increasing salinity levels, the activity level of catalase and peroxidase increased, so that the highest level of the activity of these two enzymes was obtained in the salinity level of 12 dS.m-1 in pre-treatment with 0.5% Chitosan. The results showed that seed priming with chitosan of 0.5% could reduce harmful effects of salt stress on some traits of milk thistle seedlings and could even improve their growth.
 


Ali Mansouri, Heshmat Omidi,
Volume 5, Issue 1 (9-2018)
Abstract

Extended abstract
Introduction: Quinoa, with the scientific name (Chenopodium quinoa Willd), belongs to the Spencer family. Seeds vigor can be improved with a variety of seed priming methods. In this method, the seeds are soaked in water or various osmotic solutions and then dried to the original moisture. After priming treatment, seeds are stored and cultivated as untreated seeds. Potassium nitrate is the most frequently used chemical for the purpose of increasing seed germination and is recommended by the Society of Official Seed Specialists and the International Association of Seed Testing for germination experiments of many species. In recent years, the use of nanoscale materials has been of great interest to researchers. Chitin, one of the most abundant polysaccharides in nature, is a polymer chain of N-acetyl glucosamine and is associated with other proteins and other organic compounds, and numerous industrial, pharmaceutical and agricultural applications have been reported for it. The present study was carried out to investigate the effects of chitosan nanoparticles and potassium nitrate on some morphological characteristics, germination characteristics, chlorophyll content and relative humidity of quinoa plant.
Materials and Methods: In order to investigate the effect of pretreatment of quinoa seeds with chitosan nanoparticles and potassium nitrate solution on the early stages of germination, a factorial experiment was conducted in a completely randomized design with four replications in Seed Processing Laboratory, Faculty of Agricultural Sciences and Natural Resources, Shahed University, Tehran, Iran. Experimental treatments consisted of priming with chitosan nanoparticles in 4 levels (no primers, 0.01, 0.20 and 0.04% w / v) and potassium nitrate in 3 levels (no primers, 0.2 and 0.5% Weight percent) and hydroperime for 2 hours at 25° C. For each replicate of every treatment 100 seeds, using standard priming methods, were treated with the materials mentioned above and were dried in a petri dish on Watman paper No. 1 at 20 ± 1 ° C and relative humidity of 70% and 16 hours of daylight and 8 hours of darkness to make germination work. After that, germination percentage, root length, shoot length, germination coefficient, Allometric coefficient, relative water content, chlorophyll content a and b were measured, using standard methods.
Results: Seed treatment with 0.2% potassium nitrate solution increased germination by 9% and treatment with chitosan 0.01% increased germination by 14%, compared with the non-primer treatment. The priming treatment with a 0.5% solution of potassium nitrate and 0.01% chitosan increased germination by 36%, compared to the non-primer treatment. Potassium nitrate increased root length by 25% and shoot length by 10%. In addition, chitosan 0.01% increased the root length by 6%, and seeds with chitosan 0.02% and potassium nitrate 0.2% increased the root length by 32%. The effects of potassium nitrate, chitosan and their interaction on chlorophyll a and b were significant at 1% probability level. The highest levels of chlorophyll a were obtained in 0.02% chitosan and 0.2% potassium nitrate. This formulation increased the chlorophyll a content by 33%. The highest amount of chlorophyll b was obtained by applying 0.01% chitosan and 0.5% potassium nitrate.
Conclusion: The results of this study showed that treatment with 0.01% w/v chitosan and 0.5% w/v potassium nitrate resulted in the highest germination percentage, chlorophyll content a and b, relative water content, and stem length. Treatment with 0.02% chitosan and 0.2% potassium nitrate resulted in the highest allometric coefficient and root length.
 
 
Highlights:
  1. Chitosan nano particle and potassium nitrate increase quinoa germination.
  2. Chitosan nano particle and potassium nitrate increase the content of chlorophyll a and b.

Elnaz Mohamadian, Hormozdyar Kianmehr, Hojjat Ataei Somagh, Neda Azad Nafas Mahjor, Fatemeh Safari, Arezo Safarzadeh,
Volume 5, Issue 1 (9-2018)
Abstract

Extended abstract
 Introduction: Stevia is a perennial short day plant, belonging to the Asteraceae family. It is also called sugar leaf. Poor germination of this plant serves as a barrier for its planation on a large scale, which contributes to its scarcity and expensivenss as a medicinal herb. In many plants, seed germination is sensitive to salinity, which determines the survival of the plants in saline soils. High levels of soil salinity can significantly reduce germination and seedling growth due to the effects of high osmotic potential and ion toxicity. Jasmonates represent new plant growth regulators that play an important role in increasing the resistance of plants to environmental stresses, including salinity stress. Therefore, this experiment was conducted to study the effect of pre-treatment of seed with methyl jasmonate on germination indices and biochemical traits of stevia, as a medicinal herb, under salinity stress.
Materials and Methods: They study was conducted, adopting a completely randomized design with three replications in the year 2016 in the Professor Hassabi’s Laboratory of Plant Biology, Islamic Azad University, Islamshahr Branch. The factors were pre-treatment of methyl jasmonate in 5 levels (0, 2.5, 5, 10 and 15 μM) and salinity stress at 4 levels (0, 3, 6 and 9 dS m-1). At the end of the experiment, germination traits percentage and germination rate, mean germination time, germination value, seedling length, seedling index, total chlorophyll, proline, activity of the enzyme catalase, peroxidase and superoxide dismutase were measured.
Results: The results of the study showed that effects of salinity stress, methyl jasmonate and interaction between salinity and methyl jasmonate were significant on the germination percentage and germination rate, mean germination time, germination value, seedling index, total chlorophyll, proline and catalase enzyme activity. Seed priming with 5 μM methyl jasmonate at salinity level with electrical conductivity of zero ds/m, had the highest germination percentage and rate, germination value, seed vigor index, and total chlorophyll content. Increases in salt stress and methyl jasmonate increased the activity of catalase enzyme. Salinity reduced germination index and seedling stoichiation and increased activity of peroxidase and superoxide dismutase enzymes. However, seed priming with methyl jasmonate improved seed germination through germination percentage, germination rate and seed vigor index and moderated the effects of salt stress.
Conclusions: Given the results of this study, it could be said that methyl jasmonate, as a potent inhibitor, can reduce the negative effects of salinity and by increasing germination indices such as germination percentage and germination rate, it can be effective in improving the growth of Stevia. Of course, further research can produce more definitive results.
 
 
Highlights:
  1. Salinity had a negative effect whereas methyl jasmonate had a positive effect on germination indices and activity of antioxidant enzymes of Stevia seeds.
  2. Application of 5 μM of methyl jasmonate, as a pre-treatment, can be effective in improving the growth of the stevia plant and reducing the negative effects of salinity.

Yaser Alizadeh, Ehsan Zeidali, Hamid Hassaneian Khoshro,
Volume 5, Issue 2 (3-2019)
Abstract



Extended abstract
Introduction: Crop rotations are practiced to eliminate the effect of monoculture, but the succeeding crop may be influenced by the phytotoxins released by the preceding crop. Among plants, Brassica species contain allelochemical compounds as glucosinolate that is, under special conditions, released to environment and affects seed germination and plant growth. Wild mustard (Sinapis arvensis L.) as a weed of 30 crops in 52 countries which has a series of allelopathic effects that prevent germination of other plants. Products of glucosinolate- like ionic thiocyanate (SCN-) inhibited the root or shoot growth of many crop species. Also volatile compounds like isoprenoid and benzenoid released from Brassica tissue degradation may suppress many crops growth. It was also found in many studies that allelochemicals, which inhibited the growth of some species at certain concentrations, might stimulate the growth of same or different species at lower concentrations. The present research was conducted to evaluate the effects of aqueous extract concentration of various mustard parts on barley seed germination and seedling growth.
Materials and Methods: In order to evaluate the allelopathic effect of mustard in agro ecosystems, a factorial experiment based on completely randomized design with three replications was carried out in botany laboratory of agriculture faculty, Illam University in 2014. Experimental treatments included five concentrations of mustards foliage and root aqueous extract (0, 10, 30, 50, and 70 percent) that were studied at germination and early growth stage of barley (cv. Abidar) in two separate experiments. In the seed germination section, the effects of aqueous extract of mustard on germination rate and germination percentage of barley seed were measured. In the study of the effect of aqueous extract of mustard on barley seedlings, weight and length of root and shoot, leaf chlorophyll content, proline and soluble sugars content were measured.
Results: Results showed that the highest amount of barley seed germination percentage and germination rate (100 and 19.5, respectively) were observed in control and the lowest amount (40 and 9.5, respectively) belonged to mustard root aqueous treatment with 70 percent concentration. The most decrease in barley seedlings length and weight were observed at the highest concentration of aqueous extract. The amount of chlorophyll a decreased from 2.39 in control to 1.66 mg per fresh weight in 70 percent concentration of aqueous extract treatment. The highest amount of proline (66.8 μM per fresh weight) in barley foliage was observed in 70 percent aqueous extract treatment. The results from this study showed that mustard allelopathic effect may be a possible mechanism controlling the barley germination and early growth stage in agro ecosystems.
Conclusion: Generally, we were able to demonstrate short term auto toxicity and possible short-term allelopathy due to mustard has harmful effects on barley including reduced seed germination and emergence of barley seedling. Depending on the concentrations of Mustard extract, allelopathic activity will vary Mustard. Further investigations are also needed to determine the influence of cultivar variations, and to identify the active compounds involved in mustard auto toxicity and Allelopathy.
  
Highlights:
1-Mustards aqueous extract reduced seed germination percentage and plant growth in barley.
2-Mustards aqueous extract increased proline and soluble sugars in barley, but it reduced amount of chlorophyll in this plant.


Vahdat Rajaee, Ebrahim Gholamalipour Alamdari, Zeinab Avarseji, Masoumeh Naeemi,
Volume 5, Issue 2 (3-2019)
Abstract



Extended abstract
Introduction: Nowadays exploitation of hetrotoxic characteristics  of hetrotoxic plants regarding  harmful effects of synthetic herbicides can most important role in weeds management and their control. In fact chemical compounds which is released by root, stem, leaf, flowers, seeds pollen, fruit and seeds can be used as bio herbicides and bio pesticides. The purpose of this srudy was evaluation of hetrotoxicity potential of Datura stramonium L. shoots on germination traits and photosynthetic pigments of wheat cultivars.
Materials and Methods: An experiment was conducted to evaluate hetrotoxicity potential of aqueous extract of different organs of Datura stramonium L. such as stem, leaf, fruit and mixed of them on germination traits and photosynthetic pigments of two cultivars of wheat (Kohdasht and N8720) as factorial experiment based on compeletly randomized design in three replications in Weeds Scince Laboratory of Gonbad-e- Kavous University in 2017. Datura stramonium shoot was collected at fruit formation stage in the Moghan plain and seprated into stem, leaf and fruit firstly. Five ml of studied extracts as well as mixed of them were added on 25 disinfected seeds of studied cultivars separately.
Results: Results showed that wheat cultivars had a different response to organs extract and this difference also were significant for various organs extract as well as interaction effect of cultivars in organs extract. Mean comparison of interaction of cultivars and organs showed that germination percent of Kohdash were decreased under experimental treatments. The highest decrease effect was obtained in the leaf extract about 98.33%. In return, stem, fruit and mixed organs had an increase effect on germination percent of N8720 about 5.72, 5.72 and 1.41% respectively. Result of the germination rate was similar with result of germination percent. Radicle and shoot length of both cultivars under experimental treatments were decreased. Leaf extract had an highest inhibition effect on radicle and shoot length about 96.70 and 89.21% respectively. Content of total chlorophyll of both cultivars of Kohdast and N8720 were increased under aqueous extract of stem (24.64%) and fruit (14.62%). Where as, extract of other organs and mixed of them had a decrease effect on studied trait. The result of carotenoid also was similar with result of total chlorophyll. Persumably, difference in allelochemicals concentration in various organs of Datura stramonium and physiological chracteractics of studied traits in cultivars caused different behavior.
Conclusions: According to the results, use of Datura stramonium biomass esspecially leaf, it is suggested as natural herbicides and strategy of non- chemical management. To accomplish this need to analyze phytochemical compounds of this weed.
 
Highlights:
  1. Extract of different parts of Datura stramonium weed had a different effect on germination traits and content of chlorophyll and carotenoids  of both cultivars of Kohdast and N8720.
  2. Leaf extract of Datura stramonium significantly decrease germination traits and content of chlorophyll and carotenoids of Kohdasht cultivar seedlings.
3- Use of Datura stramonium can be a good option for appearance of natural herbicides.


Ebrahim Gholamalipour Alamdari, Rashid Poornamazi, Abbas Biabani, Fakhtak Taliey,
Volume 6, Issue 1 (9-2019)
Abstract



Extended abstract
Introduction: Interference includes competition for environmental potentials and allelopathy. By releasing chemical compounds, usually of secondary metabolites, in various ways such as root exudation, decomposition, leaching and volatilization, allelopathic weeds may have positive, negative or even neutral effects on crops. Therefore, the purpose of this experiment was to evaluate the hetrotoxic potential of Sorghum halepense, Portulaca oleracea and Centurea depressa in characteristics of germination, chlorophyll content and carotenoid pigments of cress under laboratory conditions.
Materials and methods: For bioassay experiments, various concentrations of 0, 20, 40, 60, 80 and 100% of the weeds such as S. halepense, P. oleracea and C. depressa were prepared with the help of distilled water and were subsequently separately applied on 50 certified seeds of cress. In this experiment, characteristics such as rate and germination percentage, content of chlorophyll a, b, total chlorophyll content and carotenoids were measured based on the chilled acetone method.
Results: Regression model showed that rate and germination percentage of cress significantly decreased at concentrations higher than 80% of S.halepense only. For every unit increase in the concentration, radicle length, seed vigor, content of total chlorophyll and carotenoids of cress decreased about 0.08 cm, 8.68, 0.007 mg/g and 0.007 mg/g, respectively. According to the results, there was an exponential relationship between different concentrations of the P. leracea extract with germination characteristics and photosynthesis pigments of cress so that in most cases, these characteristics up to concentration of 40% had moderate decline, but beyond this concentration, they showed a steep decline. In case of C. depressa, rate and germination percentage, as well as the shoot length of cress decreased about 14.67, 14.67 and 29.81% respectively, using only a concentration of 100%. However, radicle length and seed vigor of cress decreased with increased concentrations of aqueous extract of C. depressa. The most reductive effects were obtained in the treatment of 100%, which were about 52.38 and 55.44% respectively. Amount of total chlorophyll of cress decreased about 14.37, 27.59 and 25.29% respectively in concentrations of 60, 80 and 100% of C. depressa extract, as compared with the control. On the other hand, concentrations of 20 and 40% of C. depressa had no significant effect on the pigment studied. The result of carotenoids content was the same as total chlorophyll.
Conclusions: Based on the results, the weeds studied, especially P. oleracea, with high concentrations, had strong hetrotoxic effect on germination characteristics and photosynthesis pigments. This requires further investigation in a natural environment where targeted plants grow in close proximity.
 
 
Highlights:
  1. Hetrotoxic compounds of Portulaca oleracea, especially in high concentrations significantly decrease seed germination and photosynthetic pigments of cress as compared with Sorghum halepense and Centurea depressa.
  2. Given the evidence for the hetrotoxic effect of aqueous extract of the weeds studied, they could be introduced as candidates for production of bio-herbicides.

Alireza Gorzi, Heshmat Omidi, Abdolamir Bostani,
Volume 6, Issue 2 (3-2020)
Abstract



Extended abstract
Introduction: Stevia (Stevia rebaudiana Bert.) is a herbaceous perennial plant that belongs to the family of Asteraceae. Stevia is a self-incompatible herb and the seeds resulting from this plant have low germination ability. Steviol glycosides found in this plant are 250-300 times sweeter than sucrose and despite their sweet flavor; they are not absorbed by the body. In general, the poor germination capacity of Stevia seeds is a major impediment for its large-scale cultivation. Priming is one of the seed enhancement techniques that could lead to an increase of germination percentage and germination rate under stress conditions. Therefore, the present study was conducted to evaluate the impact of priming with salicylic acid (SA), iron (Fe) and zinc (Zn) on some germination indices, seedling growth as well as the content of photosynthetic pigments in Stevia under normal and drought stress conditions.
Materials and methods: A factorial experiment using a completely randomized design was carried out in the Seed Science and Technology Laboratory of Agricultural College, Shahed University, in 2017. The factors studied comprised four levels of drought stress (0, –0.3, –0.6 and –0.9 MPa) and seven priming combinations with SA, Fe and Zn. Non-primed seeds (dry seeds) were also considered as control. In this experiment, Fe and Zn were supplied by sources of iron (II) sulfate heptahydrate (FeSO4.7H2O, 0.5%) and Zinc sulfate heptahydrate (ZnSO4.7H2O, 0.5%), respectively. The traits examined in this study included germination percentage, radicle length, plumule length, seedling weight vigor index and the content of photosynthetic pigments and carotenoid.
Results: The results of this experiment indicated that the plumule length was more sensitive to drought stress, as compared with the root length. With increased intensity of drought stress from 0 to – 0.9 MPa, the content of photosynthetic pigments in Stevia significantly decreased in all the priming treatments, so that the lowest amounts of chlorophyll a, b and carotenoid were observed at the potential of – 0.9 MPa. Priming with SA + Fe + Zn was found to be more effective than other treatments in improving the germination characteristics and the chlorophyll content of Stevia under normal and drought stress conditions. At the highest level of drought stress, germination percentage, radicle length, plumule length, seedling vigor index and total chlorophyll content increased by 55.7, 50.5, 74.3, 90.3 and 85.5%, compared with the control in the concurrent application of Fe, Zn, and SA.
Conclusion: In general, seed priming by micronutrient elements (Fe and Zn) and salicylic acid, and particularly their integrated application, could be recommended to increase the resistance of Stevia to drought stress in the germination phase.
 
 
Highlights:
  1. Drought stress at the germination stage has a significant effect on the seedling growth and the content of photosynthetic pigments in Stevia.
  2. Seed priming increases drought tolerance of Stevia at the germination stage.
  3. The integrated application of SA, Fe, and Zn is more effective than their separate application to alleviate the drought-induced damaging effects.


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