This document discusses the effects of drought and salinity stress on seed germination in 13 cultivars of three Tagetes species. It conducted experiments exposing seeds to polyethylene glycol (PEG) and NaCl solutions to simulate osmotic and ionic stress, respectively. The key findings were:
1) Germination percentages and rates were generally reduced under stress conditions compared to the control for most cultivars.
2) Responses to osmotic stress from PEG were similar across cultivars, but significant differences were found under salt (NaCl) treatments.
3) T. erecta cultivars tended to be more tolerant of salt stress than T. patula and T. tenu
Bacteria of tomatoes managed with well water and pond water: Impact of agricu...Agriculture Journal IJOEAR
Abstract— We know that contamination of crops by human pathogens can occur in agricultural settings but we still do not understand precisely which environmental sources represent the highest risks. Human pathogens maybe introduced by wind, worker hygiene, plant mediated factors, insects, water sources, or any combination of these factors. To safeguard against risks to consumers from agricultural waters, FSMA regulations for U.S. crop production require the use of water with an average of less than 126 CFU per 100 ml for applications that come in direct contact with a crop. Due to availability/scarcity however, water from other sources such as agricultural ponds is commonly used. To better understand risks that may be associated with the use of “surface”(often higher microbial load) water sources, we described the bacterial microbiota associated with an agricultural pond, an agricultural well and the corresponding microbiota of tomato carpospheres managed with each water source (also described as phyllosphere). 16S rRNA gene amplicons were used for bacterial profiling of waters and tomato surfaces at four time points over a growing season. Microbial profiles differentiated surface and ground water samples throughout the season, however no significant influence on tomato fruit surfaces could be correlated to either water source. These results suggest that in certain cases, environmental pressures such as wind, dust or other airborne factors may have a more significant impact on the surface microbiology of field crops than irrigation or management water sources do.
Keynote address at the InterDroughtIV Conference (2-6 Sep 2013) delivered on 2nd September 2013 by Jean-Marcel Ribaut, GCP Director, in Perth, Australia
Impact of Compost Prepared from Invasive Alien Species in Alleviating Water S...YogeshIJTSRD
Invasive alien plant species are major thread to biodiversity, climate change and environmental sustainability. Management of these invasive alien plant species become a typical task at global level. Composting can be an efficient and environment friendly solution for management of these invasive alien species. The aim of present study was to evaluate the effect of compost prepared from three invasive alien species Cuscutareflexa, Eupatorium adenophorum and Lantana camaraon the tomato plant vigour, antioxidant and nutrient content under water deficit and irrigated well watered conditions. The results revealed that Cuscutareflexa CR compost treatment gave highest shoot length 23.0 , 23.7 , root length 30.0 , 21.4 , shoot fresh weight 47.9 , 52.2 , shoot dry weight 71.0 , 49.4 and root dry weight 66.7 , 51.5 , under water stressand irrigated conditions, respectively. The application of compostCR under water stress has enhanced chlorophyll and prolinecontent over control. Similarly, antioxidant enzymes analysis showed the increased superoxide dismutase 1.33 2.17fold , peroxidase 1.38 1.82fold and catalase 1.06 1.73fold activity under water deficit condition. Nutrient content such as nitrogen, phosphorus, potassium and sodiumin tomato leaf were higher under both water stress and irrigated conditions compared to their respective control. It can be concluded from above outcomes that compost prepared from invasive alien species have potential to ameliorate the negative effects of water stress and enhance the tomato growth. Sandhya Bind | A. K. Sharma "Impact of Compost Prepared from Invasive Alien Species in Alleviating Water Stress in Tomato (Solanum Lycopersicum L.)" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-3 , April 2021, URL: https://www.ijtsrd.com/papers/ijtsrd39961.pdf Paper URL: https://www.ijtsrd.com/biological-science/botany/39961/impact-of-compost-prepared-from-invasive-alien-species-in-alleviating-water-stress-in-tomato-solanum-lycopersicum-l/sandhya-bind
Bacteria of tomatoes managed with well water and pond water: Impact of agricu...Agriculture Journal IJOEAR
Abstract— We know that contamination of crops by human pathogens can occur in agricultural settings but we still do not understand precisely which environmental sources represent the highest risks. Human pathogens maybe introduced by wind, worker hygiene, plant mediated factors, insects, water sources, or any combination of these factors. To safeguard against risks to consumers from agricultural waters, FSMA regulations for U.S. crop production require the use of water with an average of less than 126 CFU per 100 ml for applications that come in direct contact with a crop. Due to availability/scarcity however, water from other sources such as agricultural ponds is commonly used. To better understand risks that may be associated with the use of “surface”(often higher microbial load) water sources, we described the bacterial microbiota associated with an agricultural pond, an agricultural well and the corresponding microbiota of tomato carpospheres managed with each water source (also described as phyllosphere). 16S rRNA gene amplicons were used for bacterial profiling of waters and tomato surfaces at four time points over a growing season. Microbial profiles differentiated surface and ground water samples throughout the season, however no significant influence on tomato fruit surfaces could be correlated to either water source. These results suggest that in certain cases, environmental pressures such as wind, dust or other airborne factors may have a more significant impact on the surface microbiology of field crops than irrigation or management water sources do.
Keynote address at the InterDroughtIV Conference (2-6 Sep 2013) delivered on 2nd September 2013 by Jean-Marcel Ribaut, GCP Director, in Perth, Australia
Impact of Compost Prepared from Invasive Alien Species in Alleviating Water S...YogeshIJTSRD
Invasive alien plant species are major thread to biodiversity, climate change and environmental sustainability. Management of these invasive alien plant species become a typical task at global level. Composting can be an efficient and environment friendly solution for management of these invasive alien species. The aim of present study was to evaluate the effect of compost prepared from three invasive alien species Cuscutareflexa, Eupatorium adenophorum and Lantana camaraon the tomato plant vigour, antioxidant and nutrient content under water deficit and irrigated well watered conditions. The results revealed that Cuscutareflexa CR compost treatment gave highest shoot length 23.0 , 23.7 , root length 30.0 , 21.4 , shoot fresh weight 47.9 , 52.2 , shoot dry weight 71.0 , 49.4 and root dry weight 66.7 , 51.5 , under water stressand irrigated conditions, respectively. The application of compostCR under water stress has enhanced chlorophyll and prolinecontent over control. Similarly, antioxidant enzymes analysis showed the increased superoxide dismutase 1.33 2.17fold , peroxidase 1.38 1.82fold and catalase 1.06 1.73fold activity under water deficit condition. Nutrient content such as nitrogen, phosphorus, potassium and sodiumin tomato leaf were higher under both water stress and irrigated conditions compared to their respective control. It can be concluded from above outcomes that compost prepared from invasive alien species have potential to ameliorate the negative effects of water stress and enhance the tomato growth. Sandhya Bind | A. K. Sharma "Impact of Compost Prepared from Invasive Alien Species in Alleviating Water Stress in Tomato (Solanum Lycopersicum L.)" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-3 , April 2021, URL: https://www.ijtsrd.com/papers/ijtsrd39961.pdf Paper URL: https://www.ijtsrd.com/biological-science/botany/39961/impact-of-compost-prepared-from-invasive-alien-species-in-alleviating-water-stress-in-tomato-solanum-lycopersicum-l/sandhya-bind
1. Microbes are everywhere!
There are more microbes in a teaspoon of soil than there are people on earth. In fact, according to this Ohio State article, “Soils contain about 8-to-15 tons of bacteria, fungi, protozoa, nematodes, earthworms and arthropods.
2. Losing Soils
President D. Roosevelt once said, “a nation that destroys its soils destroys itself. Forests are the lungs of our land, purifying the air and giving fresh strength to our people.” Yet despite its importance, we have lost about half of the topsoil on the planet over the last 150 years. According to University of Sydney Scientific Director, Dr. John Crawford in an interview in Time Magazine, “a rough calculation of current rates of soil degradation suggests we have about 60 years of topsoil left. Some 40% of soil used for agriculture around the world is classed as either degraded or seriously degraded.”
3. Fertilizer Factories & Shields
“Microbes are like mini Fertilizer factories,” explains Dr. Robert Neidermyer, Holganix Director of Plant & Soil Science. For example, microbes like Nitrogen Fixing Bacteria and Phosphorus Solubilizing Bacteria release nutrients locked in the soil and make them available to the plant. Fungi like Mycorrhizae, travel across large swaths of soil to hunt down nutrients and water for plants. Further, having a diverse amount of bacteria and fungi allow the microbes to help protect plants from harmful pathogens.
4. Largest Organism On Earth
Mycorrhizae Fungi form synergistic relationships with trees. In exchange for sugars excreted by the plant, mycorrhizae produce thousands of linear miles of “hyphae” in soil to mine nutrients and water for plants. In fact, the largest organism on earth is a 2.5 mile-wide Honey Mushroom (Armillarea ostoyae).
5. We Are More Bacteria Than Human
Humans are about 95% bacteria and 5% human. The consortium of all microbes that live on and within humans is called our MicroBiome.
Studies on the Bacteriological quality of vegetable crops irrigated with dome...Premier Publishers
The bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria was analysed. The vegetable samples were collected during October 2013 and September 2014 in Aliero town in a period of three months across the two seasons (i.e., the dry and rainy seasons). After the analysis, the following bacterial spp were isolated from the vegetable crops irrigated with domestic wastewater water; Salmonella spp (14.0%), Pseudomonas aeruginosa (13.2%), Klebsiella spp (16.0%), Shigella spp (19.2%), Escherichia coli (41.6%), Citrobacter spp (25.2%), Proteus spp (15.6%) and Campylobacter spp (6.8%). The bacterial spp isolated from vegetables irrigated with tube well water was Staphylococcus aureus (26.8%), Escherichia coli (14.0%), Pseudomonas aeruginosa (8.8%), Diplococcus spp (12.0%) and Corynebacteria spp (1.2%). Escherichia coli and Citrobacter spp were recorded to have the highest number of occurrence in vegetables irrigated with domestic wastewater, with the percentage of 41.6% and 22.2% respectively. While Staphylococcus aureus and Escherichia coli have the highest occurrence of 26.8% and 14.0% respectively in vegetables irrigated with tube well water. This study highlights the health risk associated with the consumption of these vegetables particularly those consumed raw.
Improvement of Horticultural Crops for Abiotic Stress ToleranceEtalesh Goutam
This presentation was being presented by Etalesh Goutam (M.Sc. Horticulture; 2018-2020) in the master seminar at Department of Horticulture, H.N.B. Garhwal University, Srinagar (Garhwal) Uttarakhand- 246174
Effect of salinity on seedling growth in early vegetative phase of riceSohel Rana
The aim of this investigation was to analyze genotypic variations of salt tolerance of rice varieties at germination and seedling growth of early vegetative phase of rice.
Effect of nitrogen and phosphorus amendment on the yield of a Chlorella sp. s...Agriculture Journal IJOEAR
Abstract— A strain of microalgae was isolated from phytoplankton samples collected from the sea coast of Amsheet, North Lebanon. Molecular diagnosis based on ribosomal RNA genes showed it to be most closely related to Chlorella sp. (GenBank accession KC188335.1) with over 90 % nucleotide identity. It was then evaluated whether N and P amendments of seawater fertilized with Guillard’s f/2 medium would improve algal growth and production. Addition of nitrogen (30 ppm) and/or phosphorus (2 ppm) to microalgae grown under laboratory conditions in 3L bioreactors resulted in improved biomass yield (mg dry matter/ L) by approximately 48%, and increased protein yield by approximately 56%, from 19.5% to 30.6% of DM content. Total protein yield/L of culture medium was therefore increased by approximately 83%. Total lipid content and carotenoid levels of the microalgal culture were not affected by the N+P amendement, whereas chlorophyll content was almost doubled. When lower levels of N+P supplementations, 10 and 20 ppm N, were tried, the biomass yield was also improved. The experiment was repeated in 20 L bioreactors in a plastic greenhouse, under normal environmental conditions, with an average temperature of 28°C and a maximum temperature of 36°C. At these relatively high temperatures, the growth rate was slowed down, but N supplementations at 10 and 20 ppm resulted in improved dry matter yield by 25 and 45% respectively, and protein content by 17 and 35%, respectively. Knowledge of the optimal culturing conditions of this local Chlorella strain is essential for its efficient production and is expected to serve future environmental and biotechnological purposes.
1. Microbes are everywhere!
There are more microbes in a teaspoon of soil than there are people on earth. In fact, according to this Ohio State article, “Soils contain about 8-to-15 tons of bacteria, fungi, protozoa, nematodes, earthworms and arthropods.
2. Losing Soils
President D. Roosevelt once said, “a nation that destroys its soils destroys itself. Forests are the lungs of our land, purifying the air and giving fresh strength to our people.” Yet despite its importance, we have lost about half of the topsoil on the planet over the last 150 years. According to University of Sydney Scientific Director, Dr. John Crawford in an interview in Time Magazine, “a rough calculation of current rates of soil degradation suggests we have about 60 years of topsoil left. Some 40% of soil used for agriculture around the world is classed as either degraded or seriously degraded.”
3. Fertilizer Factories & Shields
“Microbes are like mini Fertilizer factories,” explains Dr. Robert Neidermyer, Holganix Director of Plant & Soil Science. For example, microbes like Nitrogen Fixing Bacteria and Phosphorus Solubilizing Bacteria release nutrients locked in the soil and make them available to the plant. Fungi like Mycorrhizae, travel across large swaths of soil to hunt down nutrients and water for plants. Further, having a diverse amount of bacteria and fungi allow the microbes to help protect plants from harmful pathogens.
4. Largest Organism On Earth
Mycorrhizae Fungi form synergistic relationships with trees. In exchange for sugars excreted by the plant, mycorrhizae produce thousands of linear miles of “hyphae” in soil to mine nutrients and water for plants. In fact, the largest organism on earth is a 2.5 mile-wide Honey Mushroom (Armillarea ostoyae).
5. We Are More Bacteria Than Human
Humans are about 95% bacteria and 5% human. The consortium of all microbes that live on and within humans is called our MicroBiome.
Studies on the Bacteriological quality of vegetable crops irrigated with dome...Premier Publishers
The bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria was analysed. The vegetable samples were collected during October 2013 and September 2014 in Aliero town in a period of three months across the two seasons (i.e., the dry and rainy seasons). After the analysis, the following bacterial spp were isolated from the vegetable crops irrigated with domestic wastewater water; Salmonella spp (14.0%), Pseudomonas aeruginosa (13.2%), Klebsiella spp (16.0%), Shigella spp (19.2%), Escherichia coli (41.6%), Citrobacter spp (25.2%), Proteus spp (15.6%) and Campylobacter spp (6.8%). The bacterial spp isolated from vegetables irrigated with tube well water was Staphylococcus aureus (26.8%), Escherichia coli (14.0%), Pseudomonas aeruginosa (8.8%), Diplococcus spp (12.0%) and Corynebacteria spp (1.2%). Escherichia coli and Citrobacter spp were recorded to have the highest number of occurrence in vegetables irrigated with domestic wastewater, with the percentage of 41.6% and 22.2% respectively. While Staphylococcus aureus and Escherichia coli have the highest occurrence of 26.8% and 14.0% respectively in vegetables irrigated with tube well water. This study highlights the health risk associated with the consumption of these vegetables particularly those consumed raw.
Improvement of Horticultural Crops for Abiotic Stress ToleranceEtalesh Goutam
This presentation was being presented by Etalesh Goutam (M.Sc. Horticulture; 2018-2020) in the master seminar at Department of Horticulture, H.N.B. Garhwal University, Srinagar (Garhwal) Uttarakhand- 246174
Effect of salinity on seedling growth in early vegetative phase of riceSohel Rana
The aim of this investigation was to analyze genotypic variations of salt tolerance of rice varieties at germination and seedling growth of early vegetative phase of rice.
Effect of nitrogen and phosphorus amendment on the yield of a Chlorella sp. s...Agriculture Journal IJOEAR
Abstract— A strain of microalgae was isolated from phytoplankton samples collected from the sea coast of Amsheet, North Lebanon. Molecular diagnosis based on ribosomal RNA genes showed it to be most closely related to Chlorella sp. (GenBank accession KC188335.1) with over 90 % nucleotide identity. It was then evaluated whether N and P amendments of seawater fertilized with Guillard’s f/2 medium would improve algal growth and production. Addition of nitrogen (30 ppm) and/or phosphorus (2 ppm) to microalgae grown under laboratory conditions in 3L bioreactors resulted in improved biomass yield (mg dry matter/ L) by approximately 48%, and increased protein yield by approximately 56%, from 19.5% to 30.6% of DM content. Total protein yield/L of culture medium was therefore increased by approximately 83%. Total lipid content and carotenoid levels of the microalgal culture were not affected by the N+P amendement, whereas chlorophyll content was almost doubled. When lower levels of N+P supplementations, 10 and 20 ppm N, were tried, the biomass yield was also improved. The experiment was repeated in 20 L bioreactors in a plastic greenhouse, under normal environmental conditions, with an average temperature of 28°C and a maximum temperature of 36°C. At these relatively high temperatures, the growth rate was slowed down, but N supplementations at 10 and 20 ppm resulted in improved dry matter yield by 25 and 45% respectively, and protein content by 17 and 35%, respectively. Knowledge of the optimal culturing conditions of this local Chlorella strain is essential for its efficient production and is expected to serve future environmental and biotechnological purposes.
Regulation of Seed Germination and the Role of Aquaporins under Abiotic StressIJEAB
Aquaporins play a major role in governing the movement of water between neighboring cells during seed germination and are major players in response to abiotic stress conditions that affect water availability. Seeds of pea (Pisum sativum L. cv. Arkel) were used for studying cell growth, expression and function of aquaporins during seed imbibition, radicle emergence and growth.Water channel functioning checked by inhibitory test with mercuric chloride showed closed water channels prior to growth initiation. Addition of mercury scavenging agents dithiothreitol and β-mercaptoethanol along with the HgCl2 overcame the observed inhibitory effects in terms of moisture content. The presence of aquaporin inhibitors (HgCl2 and ZnCl2) and NaCl reduced seedling growth. Here we studied expression of a plasma membrane intrinsic protein (PsPIP1;2) and a tonoplast intrinsic protein (PsTIP1;1) by using the semi quantitative RT-PCR in the germinated seedlings exposed to different abiotic stresses. Treatment with NaCl, HgCl2 and ZnCl2 differentially regulated gene expression in radicle, cotyledon and plumule. NaCl and Hg, upregulated expression of PsPIP1;2 and PsTIP1;1 in radicle and expression of PsTIP1;1 was significantly upregulated in radicle and suppressed in cotyledon by Zn. A possible role for aquaporins in germinating seeds and seedling response to abiotic stresses is discussed.
Drought stress is one of the major abiotic factors affecting seed germination and plant growth especially in arid and semi-arid regions. In this study, we investigated the effects of drought stress on seed germination and seedling growth of five varieties of rapeseed. Seven drought stress levels of zero (control), -3, -5, -7, -9, -11 and -13 bars were performed using polyethylene glycol-6000 (PEG-6000). A completely randomized design with three replications was used for this experiment. Germination percentage (GP), germination rate (GR), mean germination time (MGT), root length (RL) and shoot length (SL) were measured to evaluate the varieties response to PEG-induced drought stress. Drought stress, variety and the interaction drought × variety had a significant effect on all studied parameters. GP and GR decreased with the increase in stress level, while MGT increased. There were no seeds germinated for all varieties at -11 bars and -13 bars. Shoot length decreased with increasing drought stress but different varieties show different performance under stress environment. Root length decreased with increasing level of severe drought stress. However, the presence of moderate drought stress could even improve the root growth of the investigated varieties. The varieties ‘INRA-CZH2’ and ‘INRA-CZH3’ exhibited the highest germination percentage and the best early seedling growth. Thus, they could be recommended for environments with early cropping cycle drought.
Effect of the exposure period to different water salt levels on the morpholog...AI Publications
The increasing salinity of water and soil is one of the environmental factors that most threatens the sustainability of olive cultivation systems in the Mediterranean basin. The identification of plant material with high tolerance to this stress would be one of the ways to solve this challenge, but it is generally a slow and expensive process. The selection of the most reliably parameters involved in the response of the plant to salinity and that are easy to evaluate, could help to speed up the identification of the most tolerant genotypes. The objective of this study is to determine the most interesting morphological characters which could be used in future as early criteria in the selection process of olive tolerant genotypes. For that, young plants, three-month-old, were exposed to salinity (0, 4 and 8 g/L NaCl) during different periods of time (30, 50 and 70 days), and several morphological parameters were assessed. The obtained results showed that most of the parameters were affected by the concentration 8 g/L of NaCl after a treatment period of 50 days. The most affected parameters by this level of salinity were the plant height, the leaf number and the number of lateral shoots. The PCA analysis showed that the number of lateral shoots was poorly correlated with the other parameters, but the height and the leaf number were highly correlated with each other.
Effect of different levels of salinity on germination and early seedling grow...Premier Publishers
An incubation experiment was conducted at the Department of Soil Science, Patuakhali Science and Technology University during Rabi season 2015 to investigate the salinity effect on germination and early seedling growth of sunflower. There were ten treatments consisting different concentrations of salinity viz. 0, 20, 40, 80, 120, 160, 200, 240, 280 and 320 mM NaCl. The germination experiment was conducted in petri dish lined with a layer of cotton consisting ten ml of each test solution. Germination percentage gradually decreased with the increase of concentration of salt. Up to 80 mM NaCl was identified as safe for sunflower seed germination. Salinity cause delay in germination. Highest seedling height was found at 40 mM NaCl concentration (13.09 cm) and root length (14.1 cm) in 20 mM NaCl concentration. In 320 mM NaCl concentration roots were abnormal, deformed and twisted. The 0 to 80 mM NaCl concentration gave statistically similar shoot fresh weight. Compared to control treatment 20 and 40 mM NaCl concentration gave 0.57 and 4.65 % higher fresh weight, respectively which indicates that lower concentration of salt favor plant growth. The 80 mM NaCl concentration could be identified as safe for germination and early seedling growth of sunflower.
Alleviation of Salinity Effects by Poultry Manure and Gibberellin Application...IJEAB
Capsicum is one of the most widely consumed vegetables and is also used as a spice for its pungency. Many species of Capsicum are being cultivated worldwide. Capsicum is considered as a commercial crop for their economic value. However, the yield of the crop suffers severely due to salt stress, Soil salinity reduces water availability of plant roots via negative (low) osmosis potential, as well as decrease of germination dynamics of plant seeds by ionic toxicity of Na and Cl , Significant differences in fruit-set, yield, photo synthetic rates, stomata conductance, total chlorophyll content, proline, In general, salinity affects almost every aspect of the physiology and biochemistry of plants. The aim of this study was to determine the salt tolerance of pepper (Capsicum annuum L) under salinity stress by saline irrigation water, Poultry and gibberellins applications were used to alleviated the negative effects on growth parameters and yield of Pepper under salinity stress. The water salinity levels led to a significant elevation in the values of electrical conductivity of the soil with the peroxidase activity, and Sodium and proline contents in leaves, while resulting in decrease in growth parameters and leave contents of ( NPK),The poultry and gibberellins applications increased the growth parameters ( Dry weight of shoot and root &fruit weight) and (NPK) contents in leaves with slight dropping of peroxidase activity in leaves while a clear dropping of sodium and proline contents in leave. That possible to mitigation the negative affect of salt stress by some application like exogenous hormones and Decomposed organic matter to solve the disruption of endohormons and lack of available nutrients under salt stress, and elevation of osmotic stress in soil solution in roots area. The GA & poultry application improved the growth and it has increased the Pepper tolerance to the abiotic stress which was exerted by saline irrigation water.
Stressful environments such as salinity and drought was assessed on photosynthesis, the most fundamental and intricate physiological process of three oil plants canola (BrassicanapusL.), safflower (Carthamustinctorius L.) and sunflower (Helianthus annusL) grown in different sites in Egypt (Suez road; North Coastal area; El-Kantra East) , is also severely affected in all its phases by such stresses .
Tissue culture and influence of salt stress on growth and nutrient acquisition
Raluca_163-72_2015
1. 63
Propagation of Ornamental Plants
Vol. 15, № 2, 2015: 63-72
Received: April 2, 2015 Accepted: May 25, 2015
Introduction
Drought and salinity are the abiotic factors that have
the most devastating effects on horticulture. Insufficient
rainfall induces a progressive reduction of the amount
of water available for plants in the soil, which further
affects their growth and development, and the produc-
tivity of crops (Jabeen and Ahmad 2011). Irrigation
is required to mitigate drought stress, but prolonged
irrigation causes secondary soil salinisation, which is
responsible for the yearly loss of more than 10 mil-
lion ha of arable land (Owens 2001). These losses are
expected to increase in the years ahead because of the
foreseeable effects of climate change, which could re-
duce agricultural yields by more than 50% in the next
two decades (Lobell et al. 2008). For this reason, there
is an urgent need to use new strategies for cultivation of
plants, including ornamental species. Besides applying
water-saving techniques, the use of alternative irrigation
water sources should be considered for certain species
(Valdez-Aguilar et al. 2009). As this will generally
imply the use of water with a higher salt content such
as sewage, industrial and agricultural waste water, or
brackish water from saline aquifers the selection of
more stress tolerant cultivars is getting considerable
attention.
Simulation of drought or salinity in open-air field
conditions may be difficult, whereas in vitro experi-
ments avoid technical difficulties and allow the screen-
ing of a larger number of varieties. One of the most
easily achieved and reliable testing for plant stress
tolerance can be carried out at the seed germination
Comparative analysis of osmotic and ionic stress effects on seed
germination in Tagetes (Asteraceae) cultivars
Raluca Cicevan1
, Mohamad Al Hassan2
, Adriana Sestras1
, Monica Boscaiu3
*, Adrian Zaharia1
,
Oscar Vicente2
, and Radu Sestras1
1
University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca,
3-5 Manastur str., 400372 Cluj-Napoca, Romania
2
Institute of Plant Molecular and Cellular Biology (IBMCP, UPV-CSIC), Polytechnic University of Valencia,
CPI, Building 8E, Camino de Vera s/n, 46022 Valencia, Spain
3
Mediterranean Agroforestry Institute (IAM, UPV), Polytechnic University of Valencia, CPI, Building 8E,
Camino de Vera s/n, 46022 Valencia, Spain,
*Fax: + 34-96-387 92 69, *E-mail: mobosnea@eaf.upv.es
Abstract
Drought and salinity are the most adverse environmental factors affecting crop productivity worldwide. The
increasing scarcity of fresh, high-quality irrigation water is forcing the use of alternative water sources-such
as sewage, waste water or brackish water in agriculture, in general, and also in floriculture. Seed germination
is the first and the most important stage in a plant’s life cycle, but it is also the most sensitive to environmental
conditions, representing a bottleneck in plant development. Checking for stress tolerance at the germination
stage is a reliable approach for the rapid screening of a large number of plant cultivars. The aim of the present
study was to analyze the responses to osmotic and ionic stress, induced by isotonic solutions of polyethylene
glycol (PEG) and NaCl, in 13 cultivars of Tagetes patula, T. tenuifolia, and T. erecta at the germination stage.
Germination percentages and rates, and radicle, hypocotyls, and cotyledon lengths were determined after
seven days of treatment. Responses to osmotic stress induced by PEG were similar in all selected cultivars,
but significant differences were detected upon the salt treatments. In general, T. erecta responded better to salt
stress than the other two species, but a large variability among cultivars within each species was observed. The
most stress-tolerant cultivars of T. patula were ‘Orion’and ‘Robuszta’, and those of T. tenuifolia were ‘Luna
Gold’, ‘Luna Rot’ and ‘Luna Orange’.
Key words: genotypes, osmotic stress, salt stress, Tagetes erecta, T. patula, T. tenuifolia
2. 64
stage (Richards 1978). Germination is the first and
most important phase in the plant life cycle, which is
decisive for survival, but it is also the most sensitive
to environmental stressful conditions. Germination in-
volves a complex series of physiological events, which
starts with the uptake of water by seeds and terminates
with the elongation of the embryonic axis (Bewley
1997). Water availability plays a major role in germi-
nation, as water is necessary for enzymatic reactions,
solubilisation and transport of metabolites, and also
as a reagent in the hydrolytic biochemical processes
that occur during germination (Muscolo et al. 2014).
Inadequate levels of soil moisture at sowing may not
only completely prevent seed germination, but can also
induce an irregular seedling emergence with negative
effects on further plant development (Passioura 2002).
Among the many environmental factors that in-
fluence seed germination, this process is extremely
sensitive to soil salinity. Even for most halophyte spe-
cies that naturally grow in highly saline habitats seed
germination is optimal under non-saline conditions,
and it is strongly affected even by salt concentrations
much lower than those tolerated by adult plants (Ungar
1995). Seed of halophytes usually develop the abil-
ity of dormancy during the periods of stress and are
ready to germinate when salinity is alleviated and the
environmental conditions are appropriate for seedling
growth (Gul et al. 2013). In glycophyte salt-sensitive
plants germination is often inhibited by very low salt
concentrations. Salinity has two major effects of plants:
osmotic stress and ion toxicity. The osmotic component
results from dehydration and loss of turgor induced by
external solutes. This effect is not specific for high soil
salinity, but it is also induced by other abiotic stresses
such as drought, cold or high temperatures (Greenway
and Munns 1980). The second component of salt stress,
ion toxicity, occurs at high intracellular concentrations
of Na+
and Cl-
, which inhibit the activity of many en-
zymatic systems and some fundamental cellular proc-
esses, such as protein synthesis or mRNA processing
(Zhu 2001, Forment et al. 2002). Salinity also affects
plant nutrition by competition of Na+
with the uptake
of essential cations, especially K+
and Ca2+
(Zhu 2001).
Among additional deleterious effects, NaCl also modi-
fies the contents of plant growth regulators, including
an increase in abscisic acid (ABA). This could partially
explain the high sensitivity of seed germination to salt
stress, as ABA inhibits germination (Zhu 2001).
The aims of the present study were: (a) to determine
the germination response of 13 marigold cultivars to
stress in the presence of NaCl and PEG, differentiat-
ing the osmotic effect from ion toxicity, (b) to evaluate
the effects of NaCl and PEG on the lengths of radicle,
hypocotyl, and cotyledons at early seedling stages, and
(c) to select the most tolerant cultivars, which will prob-
ably grow better under water and salt stress conditions.
Materials and Methods
Plant material
Seeds of 13 cultivars belonging to three different
Tagetes species were used in this study: French mari-
gold, Tagetes patula (‘Orion’, ‘Robuszta’, ‘Bolero’,
‘Orange Flame’, and ‘Szinkeverek’); golden or signet
marigold, Tagetes tenuifolia (‘Sarga’, ‘Luna Gold’,
‘Luna Lemon’, ‘Luna Rot’, and ‘Luna Orange’); and
African marigold, Tagetes erecta (‘Magas Citromsarga’,
‘Cupid Golden Yellow’, and ‘Alacsony Citromsarga’).
Seed germination
Seed germination was conducted in Petri dishes
(diameter 9 cm) on double filter paper discs and cotton
moistened with 15 ml of distilled water (for the con-
trols) or the PEG and NaCl solutions, and sealed with
parafilm to prevent evaporation. Seeds were germinated
under different osmotic potentials, –0.25 MPa, –0.5
MPa, and –1 MPa, induced either by PEG (6000) or
by NaCl. Distilled water was used as control (0 MPa).
PEG concentrations were calculated according to the
equation of Michel and Kaufmann (1973):
Ψh = – (1.18 × 10-2
) × C – (1.18 × 10-4
) × C2
+ (2.67 ×
10-4
) × CT + (8.39 × l0- 7
) × C2
T,
where Ψh: water potential (MPa); T: temperature in
°C; and C: PEG-6000 concentration in the solution (g l-1
).
For the salt-stress treatments, NaCl concentrations
of equivalent osmotic pressure to those with PEG were
calculated based on the Van’t Hoff’s equation (Ben-Gal
et al. 2009), which resulted in the following salt con-
centration: 57.2 mM NaCl (equivalent to –0.25 MPa),
114.6 mMNaCl (equivalent to –0.5 MPa), and 227.8
mM NaCl (equivalent to –1 MPa).
Four replicates of 25 seeds were used for each treat-
ment and each cultivar. Germination was performed in
a germination chamber at 23°C, with 16 hours photope-
riod. The number of germinated seeds was recorded
daily, and seeds were considered as germinated if the
radicle protruded at last 2 mm. Germination capacity
(%) was determined after seven days and the germina-
tion rate was calculated as MGT (mean germination
time) according to the formula provided below (Ellis
and Roberts 1981):
MGT= Σ D n/Σn,
Where "D" is the days from the beginning of the
germination test, and "n" is the number of seeds newly
germinated on day "D".
Analysis of seedling growth
On the seventh day from the beginning of ex-
periment, radicle, hypocotyl, and cotyledonary leaves
lengths were measured after scanning the seedlings,
using ‘imageJ’software (Rasband 1997-2012). The re-
duction of seedling length was calculated as percentages
Raluca Cicevan et al. Effect of PEG and NaCl on seed germination in Tagetes
3. 65
with respect to the values registered in the correspond-
ing control, for each cultivar (Table 1). Seedling vigour
index (SVI) was calculated by the following formula
(Abdul-Baki and Anderson 1973):
SVI = Germination (%) × [Mean root length (mm)
+ Mean hypocotyl length (mm)].
Statistical analysis
The statistical analysis was performed using the
SPSS 16 statistical programme. Prior to analysis of vari-
ance, germination percentages were arcsine transformed
and reduction of radicle, hypocotyl, and cotyledon was
calculated in percentages, considering as 100% their
length in control treatments. The post hoc Duncan test
was applied to identify the homogenous groups when
the ANOVA null hypothesis was rejected (p < 0.05).
Results
The germination was higher than 80% (Figs. 1 and
2) and was completed within seven days (Figs. 3 and 4)
Fig. 1. Seed germination (%) of different cultivars of three Tagetes species in the presence of PEG (polyethylene glycol) at
the indicated osmotic potentials.
Means ± standard deviation (SD) followed by the same lowercase letter were not significantly different among treatments, and
means followed by the same capital letter were not significantly different among cultivars, according to the Duncan’s test (p < 0.05).
Cultivar abbreviations: Or - ‘Orion’, Ro - ‘Robuszta’, Bo - ‘Bolero’, Of - ‘Orange Flame’, and Sz - ‘Szinkeverek’ (Tagetes
patula); Sa - ‘Sarga’, Lg - ‘Luna Gold’, Ll - ‘Luna Lemon’, Lr - ‘Luna Rot’, and Lo - ‘Luna Orange’ (T. tenuifolia); Mc -
‘Magas Citromsarga’, Cg - ‘Cupid Golden Yellow’, and Ac - ‘Alacsony Citromsarga’ (T. erecta).
T. patula
aAB aAB
bB
aB
aA
aAB aB aB
aA
aB aA cA
aAaBC
aA
bC
aABC
aAB
aAB
aAB
aB
aA
aB aB
bcA
aB
aAB
aA
aAB
aAB aB
aA
aA
aA
aA
aA
aB
bA
aB
aABC
aA
bC
aBC
aAB
aA
aA aA
aA aA
aB
aA
aB
0
20
40
60
80
100
120
Or Ro Bo Of Sz Sa Lg Ll Lr Lo Cg Al Mc
Control -0.25 Mpa -0.5 Mpa -1Mpa
T. patula T. tenuifolia T. erectaT. tenuifolia T. erecta
Germination(%)
Fig. 2. Seed germination (%) of different cultivars of three Tagetes species in the presence of the indicated concentrations on NaCl.
Means ± standard deviation (SD) followed by the same lowercase letter were not significantly different among treatments, and
means followed by the same capital letter were not significantly different among cultivars, according to the Duncan’s test (p < 0.05).
Cultivar abbreviations: Or - ‘Orion’, Ro - ‘Robuszta’, Bo - ‘Bolero’, Of - ‘Orange Flame’, and Sz - ‘Szinkeverek’ (Tagetes
patula); Sa - ‘Sarga’, Lg - ‘Luna Gold’, Ll - ‘Luna Lemon’, Lr - ‘Luna Rot’, and Lo - ‘Luna Orange’ (T. tenuifolia); Mc -
‘Magas Citromsarga’, Cg - ‘Cupid Golden Yellow’, and Ac - ‘Alacsony Citromsarga’ (T. erecta).
cAB cAB
cB
cB
bA
cAB cB cB
cA
cB
bA
cA
cA
cAB
cAB
cC
bcBC
bA
bA
cBC cC
bcAB
bcBC
bA
bcA cA
bB
bA
bB
bB
aA
abA
bA
bA
bA
bA
bB
bA
bA
aAB
aA
aB
aAB
aB
aAB
aAB
aA
aAB
aB
aA
aA
0
20
40
60
80
100
120
Or Ro Bo Of Sz Sa Lg Ll Lr Lo Cg Al Mc
Control 57.2 mM NaCl 114.4 mM NaCl 228.8 mM NaCl
T. patula T. tenuifolia T. erectaT. patula T. tenuifolia T. erecta
Germination(%)
Propagation of Ornamental Plants
Vol. 15, № 2, 2015: 63-72
4. 66
in all cultivars in the control treatment. The highest ger-
mination percentage (100%) was recordered in T. erecta
‘Cupid Golden Yellow’ and ‘Alacsony Citromsarga’,
and the lowest (72.5%) in T. patula ‘Szinkeverek’. Op-
timal germination in the T. patula and T. erecta cultivars
was recorded in control treatments in the absence of
stress, and the presence of PEG resulted in lower mean
germination percentages. The situation was somewhat
different for the T. tenuifolia cultivars (except ‘Luna
Orange’), in which the highest mean germination per-
centages were observed in seeds exposed to the highest
PEG concentration tested (Fig. 1). The effect of NaCl
on seed germination (Fig. 2) was clearly stronger than
that of PEG. Under the highest concentration of NaCl
tested, less than half of the seeds germinated, with the
exception of ‘Cupid Golden Yellow’ of T. erecta (52%
germination). Even at lower concentrations, NaCl
had a clearly inhibitory effect on germination of most
cultivars, although T. erecta varieties appeared to be
relatively more resistant to salt stress.
MGT increased when seeds were treated with PEG
or with NaCl, in a concentration-dependent manner and
for all tested cultivars; that is, the stress treatments led
to slower germination. This retardation of germination
was relatively stronger in the presence of NaCl than in
the presence of PEG (Figs. 3 and 4).
The effect of the stress treatments on seedling de-
velopment was more evident than on seed germination.
PEG treatments induced a concentration-dependent
reduction on radicle and hypocotyl lengths, in all cul-
tivars under study (Tables 2 to 4), although this effect
was relatively weaker in the case of T. erecta cultivars
Fig. 3. Seed mean germination time (MGT) of different cultivars of three Tagetes species in the presence of PEG at the indi-
cated osmotic potentials
Means ± standard deviation (SD) followed by the same lowercase letter were not significantly different among treatments, and
means followed by the same capital letter were not significantly different among cultivars, according to the Duncan’s test (p < 0.05).
Cultivar abbreviations: Or - ‘Orion’, Ro - ‘Robuszta’, Bo - ‘Bolero’, Of - ‘Orange Flame’, and Sz - ‘Szinkeverek’ (Tagetes
patula); Sa - ‘Sarga’, Lg - ‘Luna Gold’, Ll - ‘Luna Lemon’, Lr - ‘Luna Rot’, and Lo - ‘Luna Orange’ (T. tenuifolia); Mc -
‘Magas Citromsarga’, Cg - ‘Cupid Golden Yellow’, and Ac - ‘Alacsony Citromsarga’ (T. erecta).
Fig. 4. Seed mean germination time (MGT) of different cultivars of three Tagetes species in the presence in the presence of
the indicated concentrations on NaCl
Means ± standard deviation (SD) followed by the same lowercase letter were not significantly different among treatments, and
means followed by the same capital letter were not significantly different among cultivars, according to the Duncan’s test (p < 0.05).
Cultivar abbreviations: Or - ‘Orion’, Ro - ‘Robuszta’, Bo - ‘Bolero’, Of - ‘Orange Flame’, and Sz - ‘Szinkeverek’ (Tagetes
patula); Sa - ‘Sarga’, Lg - ‘Luna Gold’, Ll - ‘Luna Lemon’, Lr - ‘Luna Rot’, and Lo - ‘Luna Orange’ (T. tenuifolia); Mc -
‘Magas Citromsarga’, Cg - ‘Cupid Golden Yellow’, and Ac - ‘Alacsony Citromsarga’ (T. erecta).
aB
aAB
aA
aB
aC
bAB
abAB
aA
aB
aA
aA
aA
aB
bB
bBC
abA
bB
aC
abBC
aA
abB
abC
abA
bA
bAB abB
bB abA
abcA
bB
aC
abB
abA abA
bB
abcA
bcA
bcAB
bB
bAB
bB
cA
bAB
aB bB
bA
bA
abAB
cB
cA
cAB
bB
0
1
2
3
4
5
Or Ro Bo Of Sz Sa Lg Ll Lr Lo Cg Al Mc
Control -0.25 Mpa -0.5Mpa -1Mpa
T. patula T. tenuifolia T. erectaT. patula T. tenuifolia T. erecta
Meangerminationtime(days)
aB
aAB
aA
aB
bC
aB
aB
aA
aB
aA
aA
aA
aB
abC
bC
abA
abB
aB
bC
abAB
bA
bB
bA
bA
bA
bB
bC
cD
bA
cB
bB
cC
abcAB
bcAB
cB
bA
bcA cA
bB
bC
bC
cB
bA
bAB
cAB
cB
cAB
cA
cA
dB
cC
0
1
2
3
4
5
Or Ro Bo Of Sz Sa Lg Ll Lr Lo Cg Al Mc
Control 57.2 mM NaCl 114.4 mM NaCl 228.8 mM NaCl
T. patula T. tenuifolia T. erectaT. patula T. tenuifolia T. erecta
Meangerminationtime(days)
Raluca Cicevan et al. Effect of PEG and NaCl on seed germination in Tagetes
5. 67
(Table 4), as compared to the other two species. Re-
garding cotyledons lengths, the decreasing trend in
the presence of PEG was generally maintained, but
the relative reduction was less marked than in the case
of radicle or hypocotyl length. In fact, the differences
between treatments were not statistically significant in
T. erecta cultivars (Tables 2 to 4).
NaCl treatments also induced a reduction of the
seedlings’ radicle and hypocotyls lengths in all tested
cultivars; as in the case of PEG treatments, the cotyle-
don length was not so much affected by salt, at least at
the lowest NaCl concentration. Moreover, here again
a relatively higher resistance was observed in the T.
erecta cultivars than in the other two Tagetes species
Table 1. Mean radicle, hypocotyls, and cotyledon length (mm) in control treatments in the absence of stress.
Species Cultivar Radicle Hypocotyl Cotyledon
T. patula
Orion 4.5 ± 0.3 c 1.4 ± 0.6 b 0.5 ± 0.0 bc
Robuszta 4.0 ± 0.2 bc 1.4 ± 0.1 b 0.5 ± 0.0 c
Bolero 3.9 ± 0.9 bc 1.1 ± 0.1 a 0.4 ± 0.0 a
Orange Flame 4.0 ± 0.5 c 1.1 ± 0.1 a 0.5 ± 0.0 bc
Szinkeverek 3.3 ± 0.3 a 1.3 ± 0.7 b 0.5 ± 0.0 b
T. tenuifolia
Sarga 3.1 ± 0.3 a 0.9 ± 0.0 c 0.3 ± 0.0 b
Luna Gold 2.9 ± 0.2 a 1.1 ± 0.1 c 0.3 ± 0.0 a
Luna Lemon 3.2 ± 0.2 a 0.8 ± 0.1 b 0.3 ± 0.0 a
Luna Rot 3.6 ± 0.3 a 0.6 ± 0.1 a 0.3 ± 0.1 a
Luna Orange 3.5 ± 0.2 a 0.8 ± 0.0 b 0.3 ± 0.0 a
T. erecta
Cupid Golden Yellow 2.6 ± 0.2 a 0.6 ± 0.0 a 0.5 ± 0.0 a
Alacsony Citromsarga 3.0 ± 0.2 b 0.7 ± 0.0 a 0.4 ± 0.0 a
Magas Citromsarga 3.6 ± 0.2 c 1.0 ± 0.1 b 0.5 ± 0.0 b
Means ± standard deviation (SD) followed by the same letter in each column did not differ significantly, according to the Duncan’s
test (p < 0.05).
Table 2. Effects of isotonic PEG and NaCl solutions on young seedlings of Tagetes patula.
Radicle length (% of control)
Cultivar
–0.25 MPa –0.5 MPa –1 MPa·
PEG NaCl PEG NaCl PEG NaCl
Orion 70.5 ± 3.2 e AB 25.5 ± 2.4 c B 66.6 ± 3.2 e B 8.3 ± 0.3 b B 52.3 ± 4.2 d C 0 a A
Robuszta 57.0 ± 5.3 e A 24.1 ± 1.1 c B 52.3 ± 4.6 e A 13.1 ± 0.5 b C 39.2 ± 3.6 d AB 0 a A
Bolero 76.6 ± 3.3 c B 14.7 ± 0.1 a A 72.9 ± 4.9 c B 0.0 ± 0.0 a A 31.3 ± 3.8 b A 0 a A
Orange Flame 63.8 ± 3.2 e AB 14.4 ± 1.0 b A 54.2 ± 3.5 d A 0.0 ± 0.0 a A 47.4 ± 2.0 c BC 0 a A
Szinkeverek 77.8 ± 7.3 e B 22.8 ± 1.9 b B 62.3 ± 3.4 d AB 0.0 ± 0.0 a A 46.4 ± 3.2 c BC 0 a A
Hypocotyl length (% of control)
Orion 92.5 ± 2.7 e B 76.0 ± 5.0 c B 87.1 ± 3.6 de B 31.0 ± 1.7 b B 82.5 ± 3.7 ed B 0 a A
Robuszta 78.7 ± 4.0 d A 60.6 ± 4.8 c A 72.7 ± 3.4 d A 32.2 ± 3.0 b B 60.4 ± 3.1 c A 0 a A
Bolero 94.8 ± 4.8 c B 80.1 ± 4.2 b B 80.7 ± 5.0 b AB 0.0 ± 0.0 a A 68.9 ± 6.3 b B 0 a A
Orange Flame 94.9 ± 5.8 c B 78.8 ± 5.2 b B 89.3 ± 5.5 bc B 0.0 ± 0.0 a A 85.1 ± 4.0 bc A 0 a A
Szinkeverek 86.3 ± 3.0 c A 77.5 ± 3.7 c B 85.3 ± 3.8 c A 0.0 ± 0.0 a A 64.4 ± 5.2 b A 0 a A
Cotyledon length (% of control)
Orion 96.2 ± 3.0 cd B 113.2 ± 4.8 e A 92.5 ± 2.1 c B 100.9 ± 2.4 d B 82.0 ± 1.4 b B 0 a A
Robuszta 94.0 ± 3.5 c B 103.4 ± 2.6 d A 79.7 ± 2.1 b A 99.9 ± 8.7 d B 79.0 ± 2.7 b AB 0 a A
Bolero 95.4 ± 4.3 c B 135.2 ± 4.8 d B 79.3 ± 2.4 b A 0.0 ± 0.0 a A 73.5 ± 3.3 b A 0 a A
Orange Flame 81.6 ± 2.3 c A 111.8 ± 4.1 c A 75.6 ± 2.7 c A 0.0 ± 0.0 a A 76.3 ± 2.1 c AB 0 a A
Szinkeverek 95.0 ± 3.1 c B 127.3 ± 4.0 d B 95.4 ± 2.7 c B 0.0 ± 0.0 a A 79.7 ± 1.7 b AB 0 a A
Means ± standard deviation (SD) followed by the same lowercase letter in each row were not significantly different among treat-
ments, and means followed by the same capital letter in each column were not significantly different among cultivars, according
to the Duncan’s test (p < 0.05).
Propagation of Ornamental Plants
Vol. 15, № 2, 2015: 63-72
6. 68
(Tables 2 to 4). The inhibition of seedling growth
by NaCl was generally stronger than that observed
in the presence of isoosmotic PEG concentrations.
In fact, under the lowest osmotic potential (-1MPa;
227.8 mM NaCl) and, for several cultivars, also at
the intermediate salt concentration tested (-0.5 MPa,
114.6 mM NaCl), seedlings measurements were not
possible (‘0’ values in Tables 2 to 4) since, although
the radicle emerged in some seeds, seedlings did not
develop further.
The most illustrative deleterious effect of osmotic
and ionic stress was shown by the reduction of the
seedling vigor index (SVI, Figs. 5 and 6). PEG treat-
ments caused a significant, concentration-dependent
reduction of SVI (Fig. 5), and the effect of NaCl, at
the same isoosmotic concentrations, was by far more
Table 3. Effects of isotonic PEG and NaCl solutions on young seedlings of Tagetes tenuifolia.
Radicle length (% of control)
Cultivar
–0.25MPa –0.5MPa –1MPa·
PEG NaCl PEG NaCl PEG NaCl
Sarga 70.7 ± 5.6 c AB 12.8 ± 0.9 a A 67.0 ± 5.5 c A 0.0 ± 0.0 a A 35.7 ± 4.4 b B 0 a A
Luna Gold 88.4 ± 6.8 d C 19.5 ± 1.2 b BC 63.3 ± 6.5 c A 13.4 ± 0.9 b C 58.5 ± 4.9 c C 0 a A
Luna Lemon 66.6 ± 6.0 e AB 15.5 ± 1.3 b AB 51.6 ± 3.8 d A 0.0 ± 0.0 a A 31.7 ± 3.3 c B 0 a A
Luna Rot 52.2 ± 5.2 d A 20.4 ± 1.3 c BC 52.7 ± 5.6 d A 8.6 ± 0.7 b B 18.1 ± 1.2 c A 0 a A
Luna Orange 78.3 ± 5.3 c BC 24.1 ± 2.3 b C 65.7 ± 6.5 d A 7.5 ± 0.5 a B 36.4 ± 2.6 c B 0 a A
Hypocotyl length (% of control)
Sarga 63.0 ± 5.7 c A 42.0 ± 3.2 b A 60.3 ± 9.2 c A 0.0 ± 0.0 a A 61.4 ± 6.2 c A 0 a A
Luna Gold 84.2 ± 6.4 d B 65.0 ± 3.7 c B 81.3 ± 6.0 d B 41.2 ± 2.3 b B 54.4 ± 3.4 c A 0 a A
Luna Lemon 79.0 ± 4.8 b AB 74.3 ± 3.4 b B 73.6 ± 5.8 b AB 0.0 ± 0.0 a A 67.1 ± 5.6 b AB 0 a A
Luna Rot 100.7 ± 7.4 c C 137.7 ± 5.0 d D 103.4 ± 5.3 c C 95.6 ± 7.0 c D 61.5 ± 5.4 b A 0 a A
Luna Orange 84.5 ± 3.5 b B 113.5 ± 8.6 c C 83.1 ± 3.5 b B 73.6 ± 4.5 b C 81.2 ± 4.9 b B 0 a A
Cotyledon length (% of control)
Sarga 94.0 ± 3.1 c AB 134.0 ± 5.1 d B 76.8 ± 3.2 b A 0.0 ± 0.0 a A 78.6 ± 4.5 b A 0 a A
Luna Gold 84.4 ± 3.7 b A 113.7 ± 4.0 c A 78.6 ± 4.1 b AB 124.1 ± 0.0 c B 77.1 ± 3.1 b A 0 a A
Luna Llemon 94.8 ± 2.8 c AB 124.1 ± 4.2 d AB 85.3 ± 2.9 c AB 0.0 ± 0.0 a A 68.8 ± 2.4 b A 0 a A
Luna Rot 98.4 ± 4.5 c B 135.4 ± 4.6 e B 87.4 ± 4.5 c B 119.9 ± 8.8 d B 97.7 ± 3.5 c A 0 a A
Luna Orange 99.6 ± 3.9 d B 114.5 ± 4.1 e A 85.3 ± 2.6 c AB 113.9 ± 4.5 e B 73.0 ± 2.9 b A 0 a A
Means ± standard deviation (SD) followed by the same lowercase letter in each row were not significantly different among treat-
ments, and means followed by the same capital letter in each column were not significantly different among cultivars, according
to the Duncan’s test (p < 0.05).
Fig. 5. Seedling vigour index (SVI) of different cultivars of Tagetes patula, T. tenuifolia, and T. erecta, in the presence of PEG
at the indicated osmotic potentials
Means ± standard deviation (SD) followed by the same lowercase letter were not significantly different among treatments, and
means followed by the same capital letter were not significantly different among cultivars, according to the Duncan’s test (p < 0.05).
Cultivar abbreviations: Or - ‘Orion’, Ro - ‘Robuszta’, Bo - ‘Bolero’, Of - ‘Orange Flame’, and Sz - ‘Szinkeverek’ (Tagetes
patula); Sa - ‘Sarga’, Lg - ‘Luna Gold’, Ll - ‘Luna Lemon’, Lr - ‘Luna Rot’, and Lo - ‘Luna Orange’ (T. tenuifolia); Mc -
‘Magas Citromsarga’, Cg - ‘Cupid Golden Yellow’, and Ac - ‘Alacsony Citromsarga’ (T. erecta).
cB
bAB
cB cB
cA
cB cBC dBC
bA
cC
bB
aA
cCbB
aA
bB
bA bA
bA
bBC
cAB
bA
bC
bB
aA
bB
abC
aA
aBC
abAB bAB
bB
abB
bA
bBC
bC
aB
aA
aB
aD
aA
aCD aBC
aAB
aB
aE
aC
aA
aD
aB
aA
bC
0
1000
2000
3000
4000
5000
6000
Or Ro Bo Of Sz Sa Lg Ll Lr Lo Cg Al Mc
Control -0.25MPa -0.5MPa -1MPa
T. patula T. tenuifolia
T.erectaT. patula T. tenuifolia T. erecta
Seedlingvigourindex
Raluca Cicevan et al. Effect of PEG and NaCl on seed germination in Tagetes
7. 69
pronounced (Fig. 6). All cultivars behaved in a simi-
lar manner, qualitatively, except T. erecta ‘Alacsony
Citromsarga’, which showed anomalous reduced SVI
values in the control, non-treated seedlings.
Table 4. Effects of isotonic PEG and NaCl solutions on young seedlings of Tagetes erecta.
Radicle length (% of control)
Cultivar
–0.25MPa –0.5MPa –1MPa·
PEG NaCl PEG NaCl PEG NaCl
Cupid Golden
Yellow
98.9 ± 7.5 e C 27.4 ± 1.6 c B 80.7 ± 5.8 d B 12.3 ± 0.5 b B 75.7 ± 3.6 d B 0 a A
Alacsony
Citromsarga
76.5 ± 6.7 d B 22.4 ± 0.9 b A 62.0 ± 3.5 c A 12.4 ± 0.8 b B 61.0 ± 1.3 c A 0 a A
Magas
Citromsarga
56.1 ± 3.2 d A 19.8 ± 1.3 c A 55.3 ± 4.8 d A 8.4 ± 0.3 b A 64.6 ± 4.4 e A 0 a A
Hypocotyl length (% of control)
Cupid Golden
Yellow
92.6 ± 5.7 c A 107.9 ± 5.5 d B 84.5 ± 3.9 bc A 73.0 ± 5.8 b B 83.4 ± 3.3 bc AB 0 a A
Alacsony
Citromsarga
104.1 ± 5.2 c A 129.5 ± 4.0 d C 93.2 ± 3.91 c A 66.3 ± 7.3 b B 92.7 ± 3.1 c B 0 a A
Magas
Citromsarga
84.7 ± 6.8 cd A 93.1 ± 4.8 d A 81.0 ± 3.9 cd A 47.9 ± 2.1 b A 73.3 ± 4.4 c A 0 a A
Cotyledon length (% of control)
Cupid Golden
Yellow
102.5 ± 3.9 b B 118.5 ± 4.9 c A 94.0 ± 4.1 b A 102.2 ± 4.2 b B 93.1 ± 3.4 b A 0 a A
Alacsony
Citromsarga
101.6 ± 2.3 c B 132.9 ± 5.2 e A 89.8 ± 2.9 b A 117.3 ± 4.7 d C 110.2 ± 3.0 c dB 0 a A
Magas
Citromsarga
90.9 ± 3.5 b A 120.8 ± 3.8 c A 93.4 ± 3.3 b A 88.1 ± 3.3 b A 89.1 ± 2.6 b A 0 a A
Means ± standard deviation (SD) followed by the same lowercase letter in each row were not significantly different among treat-
ments, and means followed by the same capital letter in each column were not significantly different among cultivars, according
to the Duncan’s test (p < 0.05).
Fig. 6. Seedling vigour index (SVI) of different cultivars of Tagetes patula, T. tenuifolia, and T. erecta, in the presence of the
indicated concentration of NaCl
Means ± standard deviation (SD) followed by the same lowercase letter were not significantly different among treatments, and
means followed by the same capital letter were not significantly different among cultivars, according to the Duncan’s test (p < 0.05).
Cultivar abbreviations: Or - ‘Orion’, Ro - ‘Robuszta’, Bo - ‘Bolero’, Of - ‘Orange Flame’, and Sz - ‘Szinkeverek’ (Tagetes
patula); Sa - ‘Sarga’, Lg - ‘Luna Gold’, Ll - ‘Luna Lemon’, Lr - ‘Luna Rot’, and Lo - ‘Luna Orange’ (T. tenuifolia); Mc -
‘Magas Citromsarga’, Cg - ‘Cupid Golden Yellow’, and Ac - ‘Alacsony Citromsarga’ (T. erecta).
cB
cAB
bB bB
bA
bB cBC bBC
cA
cC
cB
aA
cC
bB
bA aA
aA aA
aA
bB aB bB
bC
bA bAB
bB
aA aA
aA aA
aA aB
aA aA
0
1000
2000
3000
4000
5000
6000
Or Ro Bo Of Sz Sa Lg Ll Lr Lo Cg Al Mc
Control 57.2 mM NaCl 114.4 mM NaCl 228.8 mM NaCl
T. patula T. tenuifolia T. erecta
T. patula T. tenuifolia T. erecta
Seedlingvigourindex
Propagation of Ornamental Plants
Vol. 15, № 2, 2015: 63-72
8. 70
Discussion
Several well-known mechanisms mediate the inhibi-
tory effect of salinity on seed germination and early
seedling development and vigor. As indicated in the
Introduction, among many other deleterious effects, salt
stress includes an osmotic component, altering water
imbibition by seeds, and anion toxicity component,
which inhibits enzymatic activities and basic cellular
processes and directly affects macromolecular struc-
tures (Yupsanis et al. 1994, Dantas et al. 2007).
One of the methods used to mimic drought condi-
tions is the exposure of seeds to PEG 6000, an inert,
non ionic and impermeable compound (Hohl and Peter
1991). Because PEG does not enter the apoplast, water
is withdrawn from the cell and the cell wall. On the other
hand, by using isotonic solutions of PEG and NaCl, the
toxic effect of the salt can be distinguished from its
osmotic component, thus achieving a more complete
analysis of the responses to salt stress.
Most horticultural crops are glycophytes (Greenway
and Munns 1980), plants which grow optimally in the
absence of salt. Even though marigolds are not true
halophytes, they are considered as relatively resistant
to low or moderate salinity. Valdez-Aguilar et al. (2009)
reported that the species T. erecta and T. patula could
withstand soil salinity levels of about EC =3.6 dSm-1
.
Sayyed et al. (2014) showed that T. erecta is moderately
tolerant to salt stress, reporting a significant increase in
plant biomass after two weeks of treatment with 50 or
100 mM NaCl, but a decrease in the presence of higher
(150 mM and 200mM NaCl) salt concentrations. In
gardening, many marigold varieties are also considered
among (relatively) drought tolerant ornamental plants.
Lin et al. (2014) reported that germination rate of spe-
cies Leymus chinensis was significantly affected by pH,
salinity and their interactions. At 200 mM salinity, the
germination percentage was zero.
Results of the in vitro germination assays reported
here support the aforementioned considerations. Seeds
of several of the Tagetes cultivars under study germi-
nated even better than those of the halophyte Plantago
crassifolia under salt stress conditions (Vicente et al.
2004), and better than seeds of two stress-tolerant
Iberian species of the genus Gypsophila (Soriano et
al. 2014) in the presence of both, NaCl and PEG. The
observed inhibitory effects of osmotic and ionic stress
were more pronounced on seedling development than
on the mere fraction of germinated seeds, as reported in
other species (Okçu et al. 2005, Meneses et al. 2011).
Not all seedling structures of the Tagetes cultivars were
affected in the same way by stress, as the inhibitory ef-
fects of PEG and NaCl on early seedling growth were
mostly reflected in a reduction of radicle length. This
has been previously reported in other plant species (Al-
mas et al. 2013) and may be associated to reduced cell
division and elongation during germination (Frazer et
al. 1990).Agreater root lenght confers increased resist-
ance to drought and a better capacity to extract water
from soil. Therefore, the ability to develop extensive
root systems in extremely important and may be used
as a convenient trait to select stress tolerant cultivars
(Muscolo et al. 2014).
Several studies have compared PEG and NaCl treat-
ments of germinating seeds. In Phaseolus mungo (Garg
2010) and Helianthus annuus (Luan et al. 2014) PEG
had a stronger effect than NaCl. In the present experi-
ments, however, NaCl toxicity appeared to inhibit seed
germination and seedling growth to a higher degree
than water stress, mimicked by PEG treatments at the
same isoosmotic concentrations than NaCl. Similar
responses were reported in Agropyron elongatum and
Elymus cinereus (Roundy et al. 1985) and in Atriplex
prostrata and A. patula (Katembe et al. 1998), which
also show higher tolerance to osmotic stress.
Comparing responses to abiotic stresses in a rela-
tively high number of related genotypes represents a
useful strategy in plant breeding. For this reason
selection of plants with improved drought and/or salt
tolerance will be especially important for the future of
agriculture in many areas of the word, considering the
forecasted effects of climate change (Tuberosa and Salvi
2006). The Tagetes cultivars used in this study showed
clear differences in their responses to osmotic and salt
stress during germination, mostly concerning toxicity of
NaCl, as mentioned above. Overall, T. erecta was found
to be the most tolerant of the three selected species, but
a large variability among cultivars within one species
was detected. Thus, ‘Orion’ and ‘Robuszta’ showed
the highest stress tolerance in T. patula, whereas in T.
tenuifolia ‘Luna Gold’, ‘Luna Rot’ and ‘Luna Orange’
were the most tolerant. These results support the useful-
ness of in vitro germination assays and determination
of seedling growth parameters for a rapid selection of
stress tolerant cultivars in floriculture, even though this
tolerance should be confirmed at later developmental
stages. Such cultivars could then be cultivated using
poor-quality, relatively saline water for irrigation, with-
out compromising the economic value of the product,
as already stated for Tagetes (Valdes-Aguilar et al.
2009) and other ornamentals such as Celosia argentea
(Friedman et al. 2007) and Antirrhinum majus (Carter
and Grieve 2008).
Acknowledgements: Raluca Cicevan is PhD
student at the University of Agricultural Sciences and
Veterinary Medicine Cluj-Napoca. This paper was
published according to the PhD study contract no.
14855 from October 1, 2012, and under the frame of
European Social Fund, Human Resources Develop-
ment Operational Programme 2007-2013, project no.
POSDRU/159/1.5/S/132765. MohamadAl Hassan is a
recipient of an Erasmus Mundus pre-doctoral scholar-
Raluca Cicevan et al. Effect of PEG and NaCl on seed germination in Tagetes
9. 71
ship financed by the European Commission (Welcome
Consortium).
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