Effect of Salinity Stress on Coriander ( Coriandrum sativum ) Seeds Germination and Plant Growth

A pot experiment was carried out to study the effect of salinity stress on seeds germination and plants growth of Coriander (Coriandrum sativum L.) by the selection method. For this purpose, four treatments of different concentrations of NaCl were used, namely, 0, 1000, 2000, 3000, and 4000 ppm of NaCl. The following parameters of: seeds germination, roots number and length, plant strength, number of leaves, plant length, shoot tip necrosis, and the percentage of survivals were recorded. The Obtained results showed that all growth parameters were reduced by increasing the NaCl concentration except for the percentage of shoot tip necrosis which was increased with a significant difference among all treatments. Coriander plants were found to resist salinity up to the concentration of 3000 ppm NaCl only.


INTRODUCTION
Coriander (Coriandrum sativum) which belongs to family Apiaceae (Umbelliferae), is a herb which possesses nutritional and medicinal properties, besides, it is one of the most commonly used spices.The first medicinal uses of the plant were reported by the ancient Egyptians.Both leaves and seeds of the plant are used for medicinal purpose.Coriander contains many active principles primarily monoterpenes, & pinene, limpene, ý-terpinene, p-Cymene, borenol, Citronellol, camphor, geraniol, coriandrin, dihydrocoriandrin, coriandrons A-E, flavonoids, and essential oils.Coriandrum sativum has been reported to have several pharmacological effects such as antifertility, antihyperglycemic, antihyperlipidemic, antioxidant, antiproliferative, hypotensive, and digestive stimulant.Coriander is also used in detox diet.It helps to remove toxic mineral residue, such as mercury and lead and excretes them in the urine or faces, (Leena et al., 2012).
Salinity is one of the most serious and widely spread agricultural problem resulting to the loss of yield and arable land.One strategy available to cope with the saline soil is to choose salt-tolerant crops or to select salt-tolerant cultivars within a crop, (Morpurgo, 1991).
Salt stress is one of the most serious limiting factors for crop growth and production in the arid regions.About 23% of the world's cultivated lands is saline and 37% is sodic (Khan and Duke, 2001).Selection and breeding of salt tolerant plants is becoming an option to minimize the negative impact of salinity (Epstein et al., 1980).Considerable research work has been conducted on the effect of salinity on different growth characters of different crops worldwide (Boyer, 1982;Hanson and Hitz, 1982;Munns and Termatt, 1986;Munns, 2005;Munns, 1993;Khavari-Nejad and Mostofi, 1998;Essa, 2002;FAO, 2002;Maghsoud et al., 2008;Ashraf, 2009;Cha-um et al., 2011;Nasser, 2012;Moradi and Zauareh, 2013;and Zeinoalbedin, 2012).
The aim of this study was to detect the effect of salinity stress on seeds germination and plants growth of Coriander (Coriandrum sativum) and to evaluate its tolerance to salinity levels.

MATERIALS AND METHODS
In this experiment, the effect of salinity stress using sodium chloride (NaCl) on both Coriander (Coriandrum sativum) seeds germination and growth in vivo was studied.Five treatments of NaCl were used.The different concentrations of NaCl were added to distilled water, these concentrations are: 0, 1000, 2000, 3000, and 4000 ppm NaCl, respectively.Coriander seeds (Figure 1) were grown in pots (size 25 cm) and 2-3 cm depth, filled with peat moss and sand (2:1).The seeds were irrigated with the last NaCl concentrations.Irrigation with the previous concentrations continued for 21 days from seeds germination until plants collecting.Data were recorded including: seeds germination, roots number and length, plant strength, number of leaves, plant length, shoot tip necrosis, and the percentage of survivals.
For both plants strength and shoot tip necrosis, degrees were given to the plants using the method described by Klein and Livingston (1982).In this method, the plants were rated from culture on 0 to 5 relative growth scale as shown in Table (1).
Table 1: Descriptive grades used for determination of the in vitro relative growth of potato explants (Klein and Living, 1982).Rating Description 0 The cultures turned brown and appeared to be invisible. 1 The culture stills green, showed no readily observable growth and development differentiation from the initially excised tissue. 2 One or two leaves were evident.3 More than two leaves were evident.4 The culture showed evidence of shoot formation and development.5 Both shoots and roots have been developed.After 21 days, data were recorded including seeds germination and all growth parameters of all treatments of coriander plants (Figure 2).
The experimental design consisted of five salinity levels replicated five times in a completely randomized plot design.
Data of Coriander seeds germination and growth characters were statistically analyzed and the means were compared using L.S.D. according to the method described by SAS (1990).

RESULTS AND DISCUSSION
Data in Table (2) and in Histogram (Figure 3) showed that Sodium chloride (NaCl) reduced all the studied parameters including: seeds germination, plant length, number of leaves, plant strength, roots number, root length, and percentage of survivals, with a significant difference among all treatments.So, increasing NaCl concentration leads to more reduction in seeds germination percentage and plant growth rate, also, it leads to a decreasing in the percentage of survivals.While the percentages of shoot tip necrosis is increased by the increase of NaCl concentration.In case of the NaCl concentration 5000 ppm, there is no any germination occurred.In general, the adverse effect of salinity linearly increased with the increase in its concentration.These results are in harmony with El-Barkouki (2000) who mentioned that sodium chloride reduced the percentage of survivals.However, Levy et al., (1988), after working with potato reported that salinity tended to lower water and osmotic potentials of leaves and tubers while increasing the content of total soluble solids and proline.It also increased the content of dry matter and reduced (tuber) yields.Zhang and Donnelley, (1997), also after working with potato found that plantlet growth parameters were not affected by 40 mM NaCl, while 80 and 120 mM NaCl significantly reduced all plantlet growth parameters compared with the control (0mM) and with each other, the only exception to this was root length which was similarly affected by 80 and 120 mM NaCl and less affected by salinity than the other growth parameters.It was also noticed that shoot tip necrosis increased by the increase of NaCl concentration in the medium, its scale was (2.6 in case of control treatment, and3.3, 3.7, 4.2, and4.7 in case of NaCl concentrations (1462, 2924, 5848, and11696 ppm, respectively), this may be due to that Ca content that was decreased in NaCl-salt tolerant cells.There is a significant difference between treatment 1(control) and all treatments except treatment 2 (1462 ppm NaCl) (Piqueras et al., 1996).(5) 0 e 0 e 0 e 0 e 0.0 e 0.0 e 0 d 0 e *1= control (0 ppm), 2= 1000 ppm, 3=2000 ppm, 4= 3000 ppm, 5= 4000 ppm.** different at p= 0.05.according to L.S.D.Means followed by the same letter in each column for each factor are not significantly.

Table 2 :
Effect of salinity stress on Coriander (Coriandrum sativum) seeds germination and growth.