299-303/ 31 March, 2014 ISSN 2322-4134 ©2014 IJFAS

The Effects of Salinity Stress on Seed Germination and Seedling Growth of Three Medicinal Plants

Saba Siadat Jamian1, Sadegh Mehrani1, Kamal Sadat Asilan1*, Avishan Taherkhanchi Tabrizi2 and Alireza Goharian1

1-Department of Agricultural Sciences (Agronomy Engineering), Payame Noor University, Karaj, Iran 2-Department of Agronomy and Plant Breeding, Aboureyhan Campus, University of Tehran, Iran

Corresponding author: Kamal Sadat Asilan

ABSTRACT: Plants in natural and agricultural conditions are continuously exposed to several biotic and abiotic stresses such as drought, salinity. Salinity is one of the important problem affecting seed germination and plant growth especially in many area of the world. Seed germination is the most sensitive stage to abiotic stresses in medicinal plants which are negatively affected by environmental conditions like salinity. This study was performed to study the effects of salinity stress at critical stage of plant life (seed germination). The effect of salinity stress in form of NaCl at three levels of zero, 5.3, and 8.48 gL-1 on germination and seedling growth of three important medicinal plants. Germination rate and percentage, root length, shoot length, root to shoot length and, root to shoot dry weight ratios, root fresh weight and shoot fresh weight were estimated. Obtained results indicated that salinity decreased germination rate and percentage at the severe salinity level, but increase in these traits were observed in moderate salinity level. We observed different trends in other traits in these three plants. In general, marshmallow has the highest level of drought tolerance in comparison to other plants, especially at moderate NaCl level. In general, it has been concluded medicinal plants studied in this experiment have higher tolerance compared to crop plants at moderate salt levels.

Keywords: Psyllium, Marshmallow, Fennel flower, Salinity stress, Germination

INTRODUCTION

Salinity is one of the most important environmental factors that has a critical influence on the seed germination and seedling establishment. Salinity affects seed imbibition, seed germination and root growth. Seeds are the main way through that plants propagate, and a seed contains all of the genetic material of the plant. As seed germination is the first stage of the plant growth, seedling emergence is critical for plant growth (Khan and Gulzar, 2003). The effect of salinity stress has been carried out on many agricultural crops. However, little work has been done for exploring the possibility of saline soils for the cultivation of medicinal plants. Plantago psyllium L. commonly known as Psyllium has reported as herbal medicine around the world due to its medicinal properties. Recently it has obtained agricultural importance because of its wide use in pharmaceutical and food grade industries worldwide (Li, 2005). Morphologically psyllium is a bushy herb growing in sandy, salty soil, is believed to be native to Asia, the Mediterranean region and North Africa. Psyllium seeds have characteristic of mucilage formation on catching humidity (Li, 2005). Psyllium is cool, laxative, antidiuretic, soothing, harmless, antiacidic, emollient, demulesent and stabilizer. Due to these properties it is largely used in pharmaceutical industry, food preparations, ayurvedic medicine, preparation of crude drugs, etc (Li, 2005). Marshmallow (Althaea officinalis) is a species that originates from Africa, which is used as a medicinal and ornamental plant (Elmastas, 2004). The leaves, flowers and the root of A. officinalis all have medicinal properties. Intl J Farm and Alli Sci. Vol., 3 (3): 299-303, 2014

Marshmallow is traditionally used as a treatment for the irritation of mucous membranes, including use as a gargle for mouth and throat ulcers, and gastric ulcers (Elmastas, 2004). Fennel flower (Nigella sativa) is an annual flowering plant, native to south and southwest Asia. Nigella sativa oil contains an abundance of conjugated linoleic (18:2) acid, thymoquinone, nigellone (dithymoquinone), melanthin, nigilline, damascenine, and tannins (Al-Ghamdi, 2001). Thymoquinone, found in the seed oil extract of N. sativa, has been shown to have anti-neoplastic effects in rats and in cultured human cells from several types of cancer, including pancreatic ductal adenocarcinoma (Al- Ghamdi, 2001). eeds production and technology is an alternative method of industrial propagation and is being used widely for the commercial propagation of a large number of plant species, including many medicinal plants (Ashraf, 1986). The environmental stress such as, salinity are serious obstacles for medical plants and field crops in many areas of the world, especially arid and semiarid regions. Salt stress leads to suppression of plant growth and establishment, however, depending upon plant types, certain stages such as germination, seedling or flowering stage could be the most critical stages for salts stress. Seed germination is first critical and the most sensitive stage in plant growth (Ahmad, 2009) and the seeds exposed to unfavorable conditions like salinity may have to compromise the seedlings establishment (Albuquerque and Carvalho, 2003). The aim of this study was to evaluate the effects of salinity stress in form of NaCl on the germination parameters and seedling growth of three important medicinal plants.

MATERIALS AND METHODS

In this experiment, the seeds of Psyllium (Plantago psyllium), Marshmallow (Althaea officinalis) and Fennel flower (Nigella sativa) were used for the germination and seedling growth study under salinity stress in form of NaCl. The seeds had been kindly obtained from the National Seed Gene Bank, Karaj, Iran. Before initiation of the experiment, seeds were sterilized with solution of 3% sodium hypochlorite for five minutes. The incubator prior to use was thoroughly washed with tap water followed by a rinsing with distilled water and then sterilized at 170 ºC for 4 hours. The experimental design arranged in a completely randomized design (CRD) with three replications. Then, all the seeds were subjected to sodium Chloride (NaCl) at zero, 5.3 and 8.48 gL-1 NaCl in a dark room. Thirty seedlings from each treatment were randomly selected for fresh and dry weight determination. Seedlings were dried at 65 ºC for 72 hours. The moisture contents of seedlings were determined on oven dry basis (Hussain, 1992). The number of germinated seeds was recorded daily and in the last day traits such as: root length, shoot length, root to shoot length ratio, root to shoot dry weight ratio, root fresh weight, shoot fresh weight and root to shoot fresh weight ratio were measured using five samples from each replicates. Root and shoot lengths were measured using a ruler. Germination percentage (GP) and germination rate (GR) were calculated using following formulas: Germination percentage (GP) = S/T × 100 Germination rate (GR) = (Σ Ni/Di)/S S: Number of germinated seeds T: Total of number seeds Ni: The number of germinated seeds in Di (day) Analysis of variance was carried out using SAS software, Mean comparison was performed using Duncan’s test at the 5% level of significance (P < 0.05).

RESULTS AND DISCUSSION

Plants indicate great diversity in terms of salinity tolerance. Distribution and survival mainly many plant species depend on the seed ability to complete germination and the seedling ability to establish completely under adversely conditions (Živković, 2007). Most seeds are often located near the soil surface. Salt concentration in the soil surface changes over time. So, the responses of stressed plants must be elucidated. In this study, mean comparisons of germination percentage showed that the highest germination percentage were observed in psyllium independent to stress treatments, but the salinity led to decrease in germination percentage in psyllium and fennel flower seeds (Figure 1). On the other hand, salinity led to more considerable reduction in psyllium when compared to fennel flower plants. The response of marshmallow to salinity was different. So that, application of 5.3 gL-1 decreased the germination percentage, but treatment of seeds with 8.48 gL-1 led to increase germination percentage in marshmallow seeds (Figure 1). Germination rate of these three medicinal plants also showed that the salinity reduced germination rate of psyllium seeds in a dose dependent manner. While, the response of two

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other species was completely different, so that application of 5.3 gL-1 decreased germination rate in marshmallow seeds, but increased this trait in fennel flower seeds. Highest level of salinity also increased germination rate of fennel flower seeds, but increased marshmallow seeds (Figure 1).These results are in agreement with results of Khalesro and Aghaalikhani (2008) about sorghum (Sorghum bicolor L.) and pearl millet (Pennisetum americanum L.). Root and shoot growth reduction depends on salt concentration; while, when salt concentration increase, it can be more considerable reduction of growth (Shannon and Grieve, 1999). A number of studies also showed that salinity led to reduction in germination, growth and dry mater production of plants (Munns and Termaat, 1986; Rawson, 1986; Pessarakli, 1991; Munns and Schachtman, 1993; Hajar, 1996).

Psyllium Marshmallow Fennel flower Psyllium Marshmallow Fennel flower

70 a a 1.2 a 60 a ab 1 a a 50 b b b 0.8 b 40 b 30 0.6 c c 0.4 20 c c c 10 Germinatio rate 0.2 c 0 0

Germination percentage Control 5.3 gL─1 8.48 gL─1 Control 5.3 gL─1 8.48 gL─1

Figure 1. Effect of salinity stress treatments on germination percentage and germination rate of three medicinal plants

Psyllium Marshmallow Fennel flower Psyllium Marshmallow Fennel flower 250

a 250 a 200 200 b 150 150 b 100 100 c c c c cd 50 50 d d cd d d d d Root fresh (g) wight d d

Shoot fresh weight (g) 0 0 Control 5.3 gL─1 8.48 gL─1 Control 5.3 gL─1 8.48 gL─1

Figure 2. Effect of salinity stress treatments on shoot and root fresh weight of three medicinal plants

Shoot fresh weight and root fresh weight of these three medicinal plants also changed by salinity treatments. Application of NaCl at the levels of 5.3 gL-1 increased shoot fresh weight in all these three plants, while application of highest level of NaCl increased shoot fresh weight in marshmallow seeds, but decreased shoot fresh weight in two other seed species (Figure 2). Root fresh weight of these three plants showed a different trend in response to NaCl treatments. As shown in Figure 2, NaCl at the moderate level (5.3 gL-1) led to increase in root fresh weight, but it decreased shoot fresh weight at the highest level of NaCl (8.48 gL-1). The results of studies carried out by Penuelas, (1997) on barley and Pessarakli, (1991) on barley and wheat indicated the reduction of shoot length and shoot growth under salt stress. It has been suggested that extra energy consumption for production of organic substances is the major factor that decrease the shoot weights and so had keeping role in osmotic balance with ion uptake (Niu, 1995; Singh and Pal, 2001). Moderate NaCl treatment slightly increased root to shoot length ratio in all these three medicinal plants, but highest NaCl level increased the root to shoot length ratio in marshmallow andfennel flower seedlings, and decreased this trait in psyllium seedlings (Figure 3). However, the responses of the root to shoot dry weight ratio in each of these three plats was obviously different. The root to shoot dry weight ratio does not significantly changed in marshmallow seedlings (Figure 3). Fisrt, it was decreased in moderate NaCl level and then increased at the severe level of NaCl in psyllium plants. Salinity stress also decrease in root to shoot dry weight ratio in a dose 301

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dependent manner in fennel flower plants (Figure 3). Our results are in agreement with those of Hadi, (2007) in Seidlitzia Rosmarinus plants. Shoot dry weight of marshmallow plants decreased by salinity treatments in a dose dependent manner. Salinity at the moderate level increased shoot dry weight and then decreased at the severe NaCl level in psyllium and fennel flower plants (Figure 4). Root dry weight of plants also changed by salinity treatments (Figure 4). Moderate NaCl treatment increased root dry weight and then decreased at higher NaCl level in psyllium and fennel flower plants. However, it increased in marshmallow plants in a dose dependent manner (Figure 4). These results are in agreement with the results of Ashraf and Rasul (1988) on mung bean plants. It has been reported that the reduction in root dry weight is due to disturbing of ionic and osmotic balances that negatively affected under salinity conditions and root is the first organ encountering with stress due to nutrients uptake (Shannon, 1986; Penuelas, 1997).

Psyllium Marshmallow Fennel flower Psyllium Marshmallow Fennel flower

2.5 1.5 a a 2 ab 1 b 1.5 b c 1 c cd cd 0.5 cd 0.5 d d d d d d d d

0 Root DW/ Shoot DW 0 Control 5.3 gL─1 8.48 gL─1 Control 5.3 gL─1 8.48 gL─1

Root length/Shoot length

Figure 3. Effect of salinity stress treatments on root to shoot length and root to shoot dry weight ratio of three medicinal plants

Psyllium Marshmallow Fennel flower Psyllium Marshmallow Fennel flower

30 a 8 a a

a ab 25 b 6 20 b c 15 4 c 10 c c c 2 5 cd

d d Root wight dry (g) d d d Shoot weight dry (g) 0 0 Control 5.3 gL─1 8.48 gL─1 Control 5.3 gL─1 8.48 gL─1

Figure 4. Effect of salinity stress treatments on shoot and root dry weight of three medicinal plants

Shoot length also increased with an increase in the severity of salinity in marshmallow seedlings. But it increased at the moderate NaCl level and then decreased at the severe NaCl treatment, in psyllium and fennel flower plants (Figure 5). Root length of all the plants increased in moderate NaCl treated level, and then decreased at the severe NaCl level (Figure 5). However, it was obvious that root length of severe NaCl treated plats was higher that control plants, although these change were not significant. It has been reported that salinity at germination stage, adversely affects cell membranes, especially cytoplasmic membranes and thus led to increase membrane permeability. When this conditions is continuous, weight loss will be occurred (Niu, 1995; Shabala, 2000).

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Psyllium Marshmallow Fennel flower Psyllium Marshmallow Fennel flower a

5 a 6

4 5 b 4 b 3 b bc b bc bc 3 2 bc 2 c cd 1 d 1 d d

d d Root Length(cm) d Shoot length(cm) 0 0 Control 5.3 gL─1 8.48 gL─1 Control 5.3 gL─1 8.48 gL─1

Figure 5. Effect of salinity stress treatments on shoot and root length of three medicinal plants

Finally, salinity stress in form of NaCl treatment led to decrease in the seed reserves materials hydrolysis and thus decrease the germination and seedling growth in these medicinal plants (Munns and Weir, 1981). It is widely accepted that the effect of salts such as NaCl on plants leads to physiological drought. It can be concluded that salinity reduces the water potential of soil solution, which prevents the efficient water supply to the plants. Therefore, saline habitats receiving large amounts of salts in root cells that limit the germination, seedling growth and establishment.

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