جستجوی مقالات مرتبط با کلیدواژه « Chlorophyll content » در نشریات گروه « زیست شناسی »

An approach to overcome drought stress is using growth-promoting bacteria. This study was carried out to investigate the effect of Azospirillum growth-promoting bacteria under drought stress on yield and biochemical characteristics of Nigella sativa L. in the crop year 2019-2020 in Servak village of Yasouj province in Kohgiluyeh and Boyer-Ahmad province. The experiment was performed as a factorial split plot in a randomized complete block design with three replications. The main factor was irrigation in three levels (irrigation after using 30% soil moisture (control), irrigation after using 60% soil moisture, and irrigation after using 90% soil moisture) and the sub-factor of Azospirillum growth-promoting bacteria in two levels (no inoculation and inoculation of seeds with bacteria). Results showed that inoculation of growth-promoting bacteria increased yield and carbohydrate under moderate stress conditions. In high stress conditions, carotenoid and malondialdehyde had significant changes. Chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids had significant changes under both moderate and severe stress. On the other hand, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids had significant changes in both moderate and high stress. The highest concentrations of total chlorophyll (1.01 mg / g fresh weight) and carotenoids (0.77 mg / g fresh weight) were observed in irrigation after consuming 30% soil moisture and inoculation with bacteria. The highest yield (1072 kg / ha) was observed under consuming 30% soil moisture and bacteria. Measuring the rate of plant growth is suggested at different stages to determine the effect of stress in each period to get a perfect interpretation of the effect of stress on the plant.

Soil application of farmyard manures and moisture-absorbing materials such as natural zeolite is considered a simple and cheap way to conserve soil moisture in arid areas and light soils. To study the effect of two soil amendments on the physiological properties of “Bidaneh Sefid” grapevines under drought stress, an experiment was conducted in factorial based on a randomized block design in the research vineyard of Malayer University, Hamadan, Iran during the 2022 and 2023 growing seasons. The treatments included two levels of irrigation cycle (7 and 21 d intervals) and four levels of soil amendments (control, 12 kg zeolite vine-1, 15 kg sheep manure vine-1, a combination of 12 kg zeolite + 15 kg sheep manure vine-1). Results showed that the drought stress led to a decrease in chlorophyll content, leaf relative water content, and leaf water potential. Drought stress also led to an increase in electrolyte leakage and the activity of antioxidant enzymes. Application of farmyard manure and zeolite moderated all the investigated indicators, due to their ability to absorb and retain water in the soil. The results of the study showed that it is possible to mitigate the adverse effects of drought stress on grapevine by retaining the moisture of light soils by the application of natural zeolite, alone or in combination with farmyard manure.

The purpose of this study, allelopathic potential assessment of aqueous extract of root, stem, leaf and flower organ of Fumaria parviflora weed on morpho-physiological and biochemical characteractics of Lolium rigidum seedling in hydroponic culture. First, 5% suspension was prepared separately from the organs with help of distilled water and then the resulting suspension solution (extract) was applied on 7 day old of seedlings of Lolium rigidum. Based on the results, various organs of Fumaria parviflora had significant inhibitory effect on growth indices of root length and seedling dry weight, content of chlorophyll b and carotenoids of Lolium rigidum. In most cases, the most inhibitory effect was related to leaf and flower organ extract. But content of prolin, soluble sugar and phenolic compounds were increased compared to control. The greatest increase in these compounds were obtained under leaf and flower organs of Fumaria parviflora. Therefore, by identifying the components of Fumaria parviflora and experiment on other species, maybe be a candidate for production of natural herbicide or proposed a model for the synthesis of herbicides.

Water limitation is the most severe stress factor limiting plant growth and crop production in arid and semi-arid regions. Several strategies have been developed in order to decrease water limitation effects caused by the rainfed condition on plant growth. Among them, the use of putrescine and bio-fertilizers such as plant growth promoting rhizobacteria (PGPR) and Mycorrhiza play a significant role in yield improvement. Therefore, to study biofertilizers and putrescine’s effect on biomass and some physiological and biochemical traits of vetch (Vicia villosa) under rainfed conditions, a factorial experiment was conducted based on a randomized complete block design with three replications in a research farm at the University of Mohaghegh Ardabili in 2019. Experimental factors included biofertilizers (no biofertilizer as control, application of Rhizobium, Mycorrhiza, combined application of Mycorrhiza and Rhizobium, Rhizobium and Azotobacter, Mycorrhiza and Azotobacter, Rhizobium with Mycorrhiza and Azotobacter) and foliar application of putrescine in three levels (water as control, 0.5 and 1mM putrescine). The results showed that both application of Azotobacter with Mycorrhiza and Rhizobium and foliar application of 1 mM putrescine increased catalase, peroxidase and polyphenol oxidase enzymes activity )37.08, 37.54 and 34.41% respectively (, maximum fluorescence and anthocyanin content )56.94 and 4.57% respectively( compared to no application of biofertilizers and foliar application of putrescine. Also, both application of Azotobacter with Mycorrhiza and Rhizobium and foliar application of 1 mM putrescine increased total biomass by about 56.9% compared to no application of biofertilizer and putrescine. It seems that the application of biofertilizers and putrescine can increase the total biomass of Vica villosa under rainfed conditions due to improving the physiological and biochemical traits.

Salinity is one of the environmental factors limiting cultivation of ornamental violet (Viola wittrickiana cv. Queen Yellow Bee). This study was conducted as a factorial experiment in a completely randomized design with four replications at Islamic Azad University, Science and Research Branch in 2019. Studied factors were sodium selenate (0, 0.002, 0.004 and 0.008 mg/L), sodium selenate application (foliar application and soil application) and salinity stress (0 (control), 3 and 6 dS/m). The results showed that salinity significantly reduced flower height, flower number, stem diameter, flower diameter, fresh and dry flower weight, fresh and dry root weight, chlorophyll a and b. At salinity of 6 dS / m, the application of sodium selenate in soil increased the fresh and dry weight of flower by 11.34% and 10.39%, respectively, while the foliar application of sodium selenate increased fresh and dry weight of viola flowers by 25.10% and 25.41%, respectively. Chlorophyll a increased by 12.93%. in salinity of 6 dS / m with application of sodium selenate at 0.008 mg / l compared to control. In salinity stress of 6 dS / m superoxide dismutase enzyme reduced by 26.13%. when sodium selenate was used at 0.008 mg / l in comparison with control. Salinity stress increased the amount of chlorine and sodium in shoots and roots and decreased potassium. Foliar application of sodium selenate  at 0.008 mg / L improved the growth of ornamental violet.

Iran, is classified as arid and semi-arid regions of the world. Therefore, it is important to identify and planting of drought tolerant plants such as quinoa (Chenopodium quinoa Willd.). Zinc is involved in vital processes of the plant therefore; the supply of this element to the plant has a major impact on the quantity and quality of production. This study was conducted as a pot experiment to investigate the effect of zinc sulfate on quinoa under drought stress in a factorial randomized complete design with three replications. Drought stress was prepared with PEG 6000 at four levels (0, -3, -6 and -9 bar) and zinc element from zinc sulfate source with four levels (2 (control), 4, 6, and 8 μM) and in the four-leaf stage, the treatments were applied simultaneously to Hoglandchr('39')s nutrient solution for two weeks. According to the results, an increase in drought stress caused a 68% increase in catalase compared to the control. Maximum leaf soluble protein at -6 bar level with 8 μM zinc sulfate level, highest total soluble sugars and leaf proline at the highest level of drought and 6 μM zinc sulfate were observed. With increasing drought, chlorophyll a (34%), chlorophyll b (187%) and leaf carotenoid increased two-fold but decreased shoot dry weight (38%) and leaf area (37%) compared to control. In general, the use of zinc reduced the damage caused by drought stress by improving the level of osmolytics, and to alleviate the effect of drought stress, the use of 6 μM zinc sulfate in nutrient solutions is recommended.

In order to investigate the effect of drought stress and nano-TiO2 and salicylic acid foliar application on some physiological traits of Echinaceae purpurea under water, an experiment was conducted in split plot factorial based on RCBD in three replications at the Research Station of the Islamic Azad University, Tabriz Branch, during growing seasons of 2017-2018. The main factors were water deficit stress at three levels of 50, 75, and 100% filed capacity, thefactorial combination of nano-TiO2 (n-TiO2) foliar application at two levels (0.02 and 0.04%) and salicylic acid foliar application at two levels (0.02 and 0.04%), and also distilled water foliar application as control treatment. Findingsshowed a significant effect of water deficit stress on relative water content (RWC) and proline (p≤0.01). Also, interaction of the effects of water deficit stress and nano-TiO2 and salicylic acid foliar application on Chl. b, total Chl., and hydrogen peroxide contents was significant (p≤0.01). Application of water deficit stress treatment up to 50% FC increased proline content by 40% and reduced RWC by 10% compared to complete irrigation (100% FC). Furthermore, 0.04% n-TiO2 and 0.04% SA foliar application increased hydrogen peroxide content by 50% compared to complete irrigation group and the control. The maximum total Chl. Contents of leaves was obtained under 100% FC irrigation and and 0.04% n-TiO2 and 0.02% SA foliar application showing 79.52% increase compared to 100% FC irrigation and no foliar application.

In order to investigate the effect of drought stress and nitrogen application on growth and some physiological characteristics of sorghum genotypes, an experiment was conducted in a split-split plot with randomized complete block design in three replications at Research farm of collage of agriculture, Isfahan University of Technology. Experimental treatments consisted of two irrigation regimes (50% and 85% depletion of available soil water), two levels of nitrogen fertilizer (available rate, 121.5 kg ha-1, nitrogen from Urea fertilizer, N= 45%) and 15 sorghum genotypes (Pegah, Sepideh, GS4, GS5 , GS24, GS25, GS26, GS28, KGS29, KGS33, MGS1, MGS5, SF001, SF002, SF003). The results showed that drought stress significantly decreased biological yield by decreasing plant leaf area, plant height, quantum efficiency of photosystem II and chlorophyll content. In contrast, the activity of antioxidant enzymes including catalase, ascorbate peroxidase and peroxidase was significantly increased under drought stress conditions. Application of nitrogen under normal irrigation and drought stress increased all the above traits except chlorophyll a/b ratio and ascorbate peroxidase activity, however, this increase was less in drought condition. Therefore, application of nitrogen fertilizer under drought stress can modulate the effect of stress and increase yield. Among the studied genotypes, SF001, SF002 and MGS5 genotypes had the highest response to nitrogen and the least sensitivity to drought stress. Therefore, they can be used in areas of water scarcity.

Hypericum perforatum L. (St. John's wort) is a perennial herb which contains precious metabolites such as hypericin, pseudo-hypericin and hyporforin widely used in the treatment of mild to moderate depression.  In order to evaluate light density (three levels including full light condition, 75% and 50% of full light intensities) on plant height, gland number per leaf, stomata number, chlorophyll content, fresh and dry weight, as well as hypericin production of Topaz cultivar and Mishu ecotype of H. perforatum under hydroponic conditions in the greenhouse, an experiment was carried out as split plots based on randomized complete blocks design with three replications at the University of Tabriz in 2017. The chlorophyll and hypericin contents were used by spectrophotometry. The results showed that the light density significantly affected on fresh and dry weight, plant height, gland number per leaf, chlorophylls a and b, photosynthesis and total hypericin content in the H. perforatum. The highest fresh and dry weight, gland number per leaf, stomata number, photosynthesis and total hypericin content were belonged to the full light conditions (100% light). The highest plant height, chlorophyll a and b were belonged to the 50% of prevalent light intensity. The results indicated that Topaz cultivar is better than Mishu ecotype. In conclusion, increasing hypericin content in Hypericum perforatum by managing of light intensity is possible

In order to investigate the effects of arbuscular mycorrhizae on some physiological characteristics of maize (SC704) under water deficit condition, a factorial experiment based on randomized complete design with three replications was conducted at the physiology laboratory of Islamic Azad University Branch Ardabili, during 2015. Studied factors were: water potential in four levels (Zero, -4, -8 and -12 MPa) and Seed pre-treatment with mycorrhizal fungus in four levels (no inoculation, Seed pre-treatment with Funneliformis mosseae, Rhizoglomus fasciculatum and Claroideoglomu etanicatum. The results showed that increasing water stress decreased chlorophyll a, b, total chlorophyll, carotenoid, relative water content and increased soluble carbohydrates and proline compounds followed, The seeds were inoculated with rhizoglomus fasciculatum of increasing traits in comparison with non-inoculated, respectively. The results of the comparison of mean interactions of drought stress and mycorrhiza showed that The highest content of chlorophyll a (85.23 mg/g fresh weight), total chlorophyll (35.33 mg/g fresh weight) and leaf water content (45.8%) related to stress-free treatment and inoculated plants with rhizoglomus fasciculatum. In general, the application of arbuscular mycorrhizal fungi increased the tolerance to water deficit stress through its effect on some physiological characteristics of corn.

In order to investigate effects of Azomite application in reducing salinity stress in basil herb, a pot factorial experiment based on completely randomized design with three replications was conducted in the research greenhouse of Agriculture Faculty, Ferdowsi University of Mashhad. Treatments were consisted of salinity stress at three levels (0, 50 and 100 mM) as the first factor and the application of Azomite mixed with soil before cultivation at four levels (0, 3, 6 and 9 g per kg of soil) as the second factor. Vegetative traits such as plant height, number of branches, inflorescence length, leaf length and leaf fresh and dry weight were significantly decreased with increasing salinity stress. Application of 9 g/kg Azomite at high levels of salinity stress improved these traits compared to control plants (non-application of Azomite). Also, the highest chlorophyll a content was obtained in control plants (non-salinity stress) and 50 mM salinity stress treatments with application of 9 g/kg Azomite which were 8.33 and 7.48 mg/g.FW, respectively. The highest antioxidant activity (90%), total phenol (0.93 mg/g.FW) and proline (0.4 mg/g.DW) was observed in 100 mM salinity stress treatment and application 9 g/kg Azomite. The highest relative water content (RWC) was obtained under non salinity stress conditions (control) and application of 9 g/kg Azomite. In general, it could be concluded that using of Azomit as a natural substance consistent with sustainable agriculture under salt stress conditions can increase plant growth and improve Basil's biochemical traits.

Compost produced from municipal waste and has suitable chemical and physical properties, which plays an important role in reducing the negative effects of environmental stress in plants. In order to evaluate the effects of compost fertilizer on photosynthetic parameters of phonological stages of lentil under drought stress, a factorial experiment in completely randomized design was conducted with three replications (p≤0.05). Experiment were carried out with five ratios of compost to soil, i.e., 0:100, 5:95, 15:85, 25:75 and 35:65, and three levels of drought stress including non-stress, moderate and severe drought stress (100, 75, and 25% of field capacity, respectively). Results showed that,adding 25 and 35% compost to the soil at seedling stage under moderate stress, led to significant increase of total chlorophyll content (12 and 15%), intercellular CO2 (8 and 8%), net-photosynthesis (16 and 17%) and efficiency of PSII (4 and 4%), compared with the control. However, under severe stress, it was effective levels of 35% compared with other levels. At flowering stage, 25 and 35% compost levels under moderate and severe stress led to significant increase in all parameters compared with control group. According to the results, this study suggests that compost plays an important role in reducing the negative effects of stress on photosynthetic performance of lentil, especially in the early stages of growth.

In order to investigating the effects of composts containing the natural zeolite- and the Mg-modified zeolites- (CNZ and CMZ, respectively) on some morphological and physiological traits, greenhouse experiments as a completely randomized design with eight treatments and three replications were performed. The results showed that the using compost especially containing Mg-modified zeolites increased plant diameter, plant height, root volume, root dry weight; stem dry weight, leaf dry weight in comparison to the compost free zeolite. With using CMZ amended soils, shoot dry weight increased 11.8% in comparison to the CNZ amended soils. The amount of nitrogen from CNZ- and CMZ-amended soils was approximately 34.68% and 54.47% higher, respectively than that of the free zeolite compost. Chlorophyll a, Chlorophyll b, total Chlorophyll and Carotenoids in CNZ- amended soil increased by 29.22, 44.29, 32.14 and 19.77% respectively, in comparison to the free zeolite compost. While in CMZ, they increased by 34.88, 76.45, 42.94 and 29.58%, respectively. Chlorophyll a, b and total Chlorophyll of leaves increases as the N supply increases. Correlation between nitrogen and chlorophyll content was about 80%. Overall, the use of MSW compost containing modified zeolite would be an efficient method to improve some morphological and physiological traits of corn plant.

Chlorophyll fluorescence parameters and chlorophyll content are the most important factors for determining photosynthetic capacity in plant. For this purpose, an experiment was conducted to compare the resistance to different levels of drought stress, to evaluate the most important physiological indices and assess the function of photocysteine II using chlorophyll fluorescence parameters, chlorophyll content (chlorophyll a, b and a + b) and carotenoids of two bean cultivars in three levels of water deficiency including 30, 60 and 100% crop capacity (FC) in factorial arrangement in a randomized complete design with three replications in the greenhouse of the University of Guilan. Comparison of mean values showed that severe drought stress reduced the amount of chlorophyll content, Fv / Fm, Fv and, in contrast, increased the amount of fluorescence and Y (NPQ). The highest Fv/Fm ratio was observed in the control plants, while the highest reduction in Fv/Fm ratio in severe stress was obtained for the 18-G cultivar. In general, the interaction of drought cultivar was significant for all traits except Y (II), PAR and Fv/Fm. Also, Pearson correlation between total chlorophyll and Fv/Fm showed a positive and significant correlation (R = 0.86 **) in Ghaffar cultivar, but was not significant in G-18. Therefore, it can be concluded that Ghaffar cultivar can tolerate relatively high levels of drought by making changes in some physiological characteristics with better performance.

Compost fertilizer because of containing abundant nutrients, high capacity for holding water, plant growth regulators and helpful microorganisms can improve soil physicochemical characteristics and play an effective role in plant growth and development. In order to evaluate the effects of compost fertilizer on morpho-physiological indices of lentil under water deficit stress, a factorial experiment was conducted in a natural environment and with three replications based on a completely randomized design in the Khatam Alanbia University of Behbahan. The experiment treatments consisted of five ratios of compost fertilizer and soil (0:100, 5:95, 15:85, 25:75, and 35:65) and three levels of water stress inclding no stress, moderate stress, and severe stress (irrigation at 25, 50, and %75 of field capacity, respectively). Results showed that there were significant differences in all traits under different compost fertilizer and water stress levels. The findings also showed that under no stress and moderate water stress conditions, application of a mixture of compost and soil at %25 and %35 weight, resulted in a significant increase in the plant height, leaf area, leaf number, root dry weight, root length, root area, and Chlorophyll a and a/b ratio compared to the control levels. Under severe water stress, application of compost at 35% level led to a significant increase in the number of leaves, leaf area, root length, and Chlorophyll a content. Therefore, the use of a mixture of compost and soil (especially 35:65 ratio) is recommended to improve the morpho-physiological characteristics and yield componentsof lentil under moderate (or severe) water stress conditions.

To evaluate the application methods of nitroxin and nitrogen fertilizers on yield and physiological traits of maize (SC 704), a field experiment was carried out in Ahvaz based on a split plot randomized complete block design with three replications during 2013-2014. The treatments included four levels of nitrogen fertilizer (N1:100%, N2: 75%, N3:50%, N4: 25%) pure nitrogen (equivalent to 180 kg per hectare) as the main factor and nitroxin biological fertilizer application method at two levels (seed inoculation B1 and with irrigation water B2) as the secondary factor. The results showed that nitrogen fertilizer significantly increased grain yield and physiological traits. The highest and lowest grain yields were obtained in 75% and 25% nitrogen treatments respectively. The biological fertilizer, nitroxin, had a significant impact on performance, chlorophyll a and b, efficiency, and NAE. The highest grain yield was recorded in B1 (seed treatment). In this study, while method of application of nitroxin showed no significant effect on the traits under study, the combined use of bio-fertilizer with N fertilizer, in addition to producing sufficient crop and improving nitrogen uptake efficiency, could reduce the use of nitrogen fertilizer by 25 percent.

Salinization and alkalization of soils are an agricultural problems in arid and semiarid regions of the world such as Iran. In this experiment the effects of salicylic acid (SA) on resistance of pepper under salt and alkali stresses was investigated. Experimental treatments include 0 and 150 mM of NaCl stress, 0, 50 and 100 mM of Na2Co3/NaHCo3 and 0. 0.75 and 1.5 mM SA. Results showed that salt and alkali stresses imposed negative effects on plant growth and productivity. Reduction in growth and yield in salinity condition was higher than alkaline condition and maximum reduction occurred in mixed stresses. Application of SA in both conditions significantly increased yield, plant growth parameters and chlorophyll content. For most traits, 0.75 mM of SA was more effective than 1.5mM concentration. In general, Salinity and alkalinity have negative effects on growth and yield of pepper plant and these negative effects can be reduced by application of SA.

Study of physiological reactions of recombinant inbreed lines (RILs) to drought stress could help to identify the actual drought tolerance mechanisms. In this view a field experiment was conducted to evaluate the effect of drought stress on chlorophyll content , leaf proline content, leaf length, leaf width, leaf area, peduncle length and plant height using 169 RILs, in the two separate simple Latis design with four replications using two moisture regime f normal and water deficit stress. Irrigation regimes performed based on Class A-pan of 70 and 130 mm evaporation from Class -A -pan and moisture content of soil in effected root depth. The RILs were obtained by crossing between a tolerant and sensitive wheat cultivar. The result of analysis of variance showed a significant difference among RILs. Drought stress caused a decrease in the chlorophyll content, leaf width, leaf length, peduncle length, leaf area and increase in the proline content. Although drought stress increased the proline content and decreased the peduncle length and leaf area in both tolerant and sensitive line groups, but these declines in tolerant lines was lower than sensitive lines. Therefore, It may be possible to use the physiological traits comprising proline amino acid content, peduncle length and leaf area as a selection tool for selecting drought tolerant lines in bread wheat.