Effect of calcium and boron on germination of ... · Effect of calcium and boron on germination of...

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261 Khomari and Javadi Int. J. Biosci. 2015 RESEARCH PAPER OPEN ACCESS Effect of calcium and boron on germination of differentially aged oilseed rape seeds under salinity Saeid Khomari * , Ahmad Javadi Department of Agronomy and Plant Breeding, Faculty of Agricultural Science, University of Mohaghegh Ardabili, Ardabil, Iran Key words: Boron, Brassica napus, Calcium, Salinity, Seed vigor. http://dx.doi.org/10.12692/ijb/6.5.261-272 Article published on March 14, 2015 Abstract A soilless culture experiment was carried out at the glasshouse conditions, in order to elucidate the beneficial effect of seed vigor and the possible alleviatory influence of boron and calcium on the salt tolerance capability of Rapeseed. Artificial aging of rapeseed seeds significantly reduced the seedling growth especially under more saline conditions. In spite of promotive effects of application of both boron and calcium on rapeseed germinability and seedling growth, there was a more significant enhancement on emergence rate of seedlings from high vigor seeds. Supplementary concentrations of boron and calcium more significantly reduced the Na + content and increased the K + amount of the seedlings under 100 mM NaCl. Finally, it can be concluded that boron and calcium would improve the salt tolerance capability of rapeseed seedlings from vigorous seeds, at least in the early seedling development. * Corresponding Author: Saeid Khomari [email protected] International Journal of Biosciences | IJB | ISSN: 2220-6655 (Print), 2222-5234 (Online) http://www.innspub.net Vol. 6, No. 5, p. 261-272, 2015

Transcript of Effect of calcium and boron on germination of ... · Effect of calcium and boron on germination of...

261 Khomari and Javadi

Int. J. Biosci. 2015

RESEARCH PAPER OPEN ACCESS

Effect of calcium and boron on germination of differentially

aged oilseed rape seeds under salinity

Saeid Khomari*, Ahmad Javadi

Department of Agronomy and Plant Breeding, Faculty of Agricultural Science, University of

Mohaghegh Ardabili, Ardabil, Iran

Key words: Boron, Brassica napus, Calcium, Salinity, Seed vigor.

http://dx.doi.org/10.12692/ijb/6.5.261-272 Article published on March 14, 2015

Abstract

A soilless culture experiment was carried out at the glasshouse conditions, in order to elucidate the beneficial

effect of seed vigor and the possible alleviatory influence of boron and calcium on the salt tolerance capability of

Rapeseed. Artificial aging of rapeseed seeds significantly reduced the seedling growth especially under more

saline conditions. In spite of promotive effects of application of both boron and calcium on rapeseed

germinability and seedling growth, there was a more significant enhancement on emergence rate of seedlings

from high vigor seeds. Supplementary concentrations of boron and calcium more significantly reduced the Na+

content and increased the K+ amount of the seedlings under 100 mM NaCl. Finally, it can be concluded that

boron and calcium would improve the salt tolerance capability of rapeseed seedlings from vigorous seeds, at least

in the early seedling development.

* Corresponding Author: Saeid Khomari [email protected]

International Journal of Biosciences | IJB |

ISSN: 2220-6655 (Print), 2222-5234 (Online)

http://www.innspub.net

Vol. 6, No. 5, p. 261-272, 2015

262 Khomari and Javadi

Int. J. Biosci. 2015

Introduction

Rapeseed or canola (Brassica napus L.) is today the

world’s third-leading source of both vegetable oil and

oil extraction meal (Friedt and Snowdon 2009).

Today salinity remains a major abiotic stress that

adversely affects crop productivity and quality (Boyer

1982; Yamaguchi and Blumwald 2005). Salt as NaCl

is the predominant salt causing salinization (Munns

and Tester 2008) and is so abundant on our planet

that it is a major constraint to field crops production

especially rapeseed, jeopardizing the capacity of

agriculture to sustain the burgeoning human

population increase (Flowers 2004). It is estimated

that 20% of all cultivated land and nearly half of

irrigated land is salt-affected, greatly reducing yield

well below the genetic potential (Munns 2002;

Flowers 2004).

Seed germination and subsequent seedling

development are important and vulnerable stages in

the life cycle of crops and determine successful

seedling establishment in the field (Ellis and Roberts

1981; Rehman et al. 1999; De Figueiredo et al. 2003).

There are three main negative effects of high salt

concentrations that influence seed germination and

seedling growth: water deficit, ion toxicity associated

with excessive Cl− and Na+, and interference with

nutrition, leading to nutrient imbalance (Silberbush

and Ben-Asher 2001). Nutrient imbalance can

develop in salt-stressed plants in different ways. It

may result from the effect of salinity on nutrient

availability, uptake, transport, or partitioning within

the plant or may be caused by physiological

inactivation of a given nutrient resulting in an

increase in the plant’s internal requirement for that

essential element (Grattan and Grieve 1999). Hence,

investigating the interaction of NaCl with nutrients

that have key roles in plant development, such as

boron and calcium, and evaluating the effect of seed

and seedling vigor on this interaction are important

to optimize the growth of rapeseed under salt stress.

The presence of Ca2+ as the dominant cation in

agricultural soils generally ensures that the absolute

Ca2+ level is not a primary growth-limiting factor. As

salinity increases, the requirement of plants for Ca2+

increases (Gerard 1971). The interaction between B

and Ca2+ in the nutrition of both mono- and

dicotyledonous plants has long been recognized

(Marsh and Shive 1941). The plant cell wall was

suggested as the place where the B role influenced Ca

metabolism (Yamaguchi et al. 1986). From soilless

culture experiments conducted in a greenhouse,

researchers found that a balanced nutrition of B and

Ca was able to counter-act the deficiency of these

nutrients in salt-stressed plants, leading to a huge

increase in salinity tolerance of symbiotic pea plants

(El-Hamdaoui et al. 2003; Bonilla et al. 2004).

Despite the common occurrence of high boron and

high salinity in many parts of the world, little

research has been done to study the interaction of the

two (Grattan and Grieve 1999). Different factors may

influence alleviatory effects of nutrient elements on

salt tolerance of crop plants. Many reports are

concentrated on genotypic differences on this respect

(Marsh and Shive 1941; Ehret et al. 1990; El-

Hamdaoui et al. 2003; Bonilla et al. 2004). However,

it is not known whether there is any linkage between

high salt tolerance in rapeseed and responsibility to

supplemental boron and calcium nutrition. Therefore,

the main purpose of this study is to determine the

possible effectiveness of high vigor seeds and

supplemental nutrition of calcium and boron on

salinity tolerance of rapeseed.

Materials and methods

Seed preparation and treatments

Seeds of a winter rapeseed (Brassica napus L. var.

oleifera cv. Okapi; Agriculture Organization, Iran)

were divided into two sub-samples. A subsample was

kept as control or high vigor seed lot (V1). The other

sub-sample with about 16% moisture content was

artificially deteriorated at 40°C for 72 hours (V2). As a

result, the two seed lots with 98% (V1) and 88% (V2)

viabilities were provided. For salinity treatments,

NaCl was added at a concentration of 0, 50 mM or

100 mM. Calcium was added as Ca(NO3)2.4H2O and

Boron as H3BO3 in Hoagland-Arnon nutrient

solution. The concentrations of Ca (5 mM and 15 mM)

and B (40 μM, 240 μM and 480 μM) from the

different treatments are summarized in Table 1. The

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Int. J. Biosci. 2015

pH was always checked and adjusted around 6.7.

Previously germinated rapeseed seedlings were

transferred to plastic rectangular pots and cultivated

on Perlite (without release of any Ca, B or salt) with

Hoagland-Arnon medium, as the nutrient solution.

Plants were maintained in the glasshouse conditions.

Irrigation with nutrient solutions was repeated every

4 days. In order to ensure that no increase in

concentration of different ions in the pots occurs,

electro-conductivity of output solution was controlled

after irrigation.

Sampling and measurements

The number of emerged seedlings (full expansion of

cotyledons) from each plot was counted every 24

hours. The rate of emergence was calculated by Ellis

and Roberts (1981) equation. At 25th day of

experiment, seedling length, fresh and dry weight and

leaf number were measured. Twenty seedlings of each

treatment were randomly selected and dried at 80 °C

for 24 h. After milling to ensure homogeneity, 0.5 g of

each sample was electric furnace-ashed (2 h at 550

°C) and acid-digested (10 ml of 1 N HCl). The

concentrations of Na+, K+ and Ca2+ were measured by

flame photometer. The chlorophyll content of

seedling leaves was determined according to Arnon

(1949).

A factorial soilless culture experiment on the basis of

randomized complete block design with three

replications was conducted to evaluate salt tolerance

of rapeseed seedlings, affected by seed vigor level and

supplemental nutrition of calcium and boron. All the

measurements were repeated at least two times and

data was statistically analysed by the two-way

ANOVA. The means were compared in accordance

with the Duncan’s multiple range test at p< 0.05.

Results

The percentage of seedling emergence was

significantly (P≤ 0.01) reduced with increased levels

of seed deterioration and salinity (figure 1).

Deteriorated seeds had the minimum emergence of

seedlings in 100 mM NaCl with about 50% reduction

compared to control. The inhibitory effect of NaCl on

the establishment of seedlings from poor vigor seeds

was greater than those from high vigor ones. Different

concentrations of boron and calcium had no

significant effect on seedling emergence in any

concentrations of salt. Rapeseed seedlings slowly

emerged, as different NaCl concentrations were

added into the germination medium (table 2). The

third level of salinity illustrated the minimum value of

seedling emergence rate with about 25% decrease

compared with non-saline condition. Moreover, the

rate of emergence was significantly decreased in the

deteriorated seeds (figure 2). The presence of

increasing concentration of B or Ca (+6B+1Ca,

+12B+1Ca and +1B+3Ca supplements) but not both

significantly improved the emergence rate in non-

deteriorated vigorous seeds in comparison with

deteriorated ones. These observations suggest that

the vigor of the seed lot has influenced the advantage

of B-Ca2+supplementation in the seedling growth

medium.

The length and dry weight of seedlings produced from

deteriorated poor vigor seeds were about 5 cm and

35% less than those of high vigor ones, respectively

(table 3). Increasing concentrations of boron

(+12B+1Ca) and calcium (+1B+3Ca) negligibly but no

significantly increased the length and dry weight of

seedlings compared to base concentrations of these

elements in the nutrient solution. On the other hand,

the levels of 3Ca combined with high boron

concentrations (+6B and +12B) reduced rapeseed

seedling growth. The length and dry weight of

rapeseed seedling was significantly reduced when the

salt concentration increased, in a way that 100 mM of

NaCl decreased these parameters approximately 30%

and 33% respectively, compared with the control. The

results indicated that as the salinity increased, the leaf

number of seedlings was significantly decreased

(figure 3 and 4). The number of leaves of seedlings

obtained from deteriorated seed lot was more

decreased when NaCl concentration increased,

compared to those from non-deteriorated vigorous

seeds. The mean leaf number of seedlings from high

and low vigor seed lots were statistically the same in

the salt-free medium (figure 3). The presence of

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increasing concentration of B or Ca (+6B+1Ca,

+12B+1Ca and +1B+3Ca supplements) but not both

significantly increased the number of leaves of

seedlings only when no salt was applied to the

nutrient solution. Although, boron and calcium were

added into the perlite as nutrient supplements, the

mean leaf number of seedlings was statistically the

same under NaCl imposed salinity stress (figure 4).

These observations suggest that the B-Ca

supplementation did not overcome the negative effect

of salinity on leaf number of rapeseed seedlings.

Table 1. Boron and calcium treatments used in this experiment.

5 mM Ca2+ 15 mM Ca2+

40 μM B +B+Ca +B+3Ca

240 μM B +6B+Ca +6B+3Ca

480 μM B +12B+Ca +12B+3Ca

Table 2. Seedling emergence rate at different salinity levels.

Salinity Seedling emergence rate (d-1)

S0 (control) 0.463a

S50 0.321b

S100 0.217c

Different letters indicate the significant difference at p<0.05.

Table 3. Length, dry weight and chlorophyll a content of oilseed rape seedling affected by different levels of seed

vigour, B-Ca combinations and salinity.

Seedling length (cm) Seedling dry weight (mg) chlorophyll a

(mg.g-1 FW)

Seed vigour V1 (control) 15.0a 51.8a 159.1a

V2 10.0b 34.2b 138.0b

B-Ca combinations +1B+1Ca (control) 11.8b 40.7b 144.7b

+6B+1Ca 13.1a 45.1a 150.6a

+12B+1Ca 13.1a 45.4a 151.8a

+1B+3Ca 13.2a 45.4a 152.4a

+6B+3Ca 11.8b 40.7b 145.7b

+12B+3Ca 11.9b 40.8b 146.0b

Salinity S0 (control) 14.8a 51.6a 198.8a

S50 12.6b 43.0b 144.9b

S100 10.2c 34.4c 101.9c

Different letters indicate the significant difference at p<0.05.

The sodium content of the seedlings from low vigor

seeds was about 14% more than those from vigorous

seed lot (Table 4). As typically occurs, increasing NaCl

concentration in the nutrient solution increased Na+

level in rapeseed seedlings (Figure 5). Surprisingly,

adding supplementary concentrations of +6B and

+12B or +3Ca to the nutrient solution more

significantly reduced the sodium content of the

seedlings under different strengths (50 and 100 mM

NaCl) of salinity. However, +6B+3Ca and +12B+3Ca

combinations led to a minor decline in Na+ content of

seedling which was not statistically significant. More

salinity and seed deterioration reduced the amount of

potassium in rapeseed seedlings (Figure 6); in a way

that the highest K+ content was observed in the

seedlings obtained from vigorous seeds under non-

saline conditions (168.24 ppm), and the lowest one

was observed in the seedlings from poor vigor seeds

in 100mM salinity (133.04 ppm). Adding further

concentrations of boron and calcium led to increased

potassium level of seedlings only in 50 and 100mM

salinity (Figure 7). In salinity treatments, seedlings

grown in +6B, +12B and 3Ca supplements contained

the maximum amounts of K+ as compared to the

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Int. J. Biosci. 2015

control. Supplemental concentrations of boron (+6B

and +12B) in combination with +3Ca concentration

were not significantly different from the control in

terms of this attribute. Artificial aging of rapeseed

seeds negligibly but significantly decreased calcium

content of the seedlings (Table 4). The more saline

medium also led to a significant reduction in the

amount of calcium in seedlings (Figure 8). Adding

supplementary calcium with all concentrations of

boron (+1B+3Ca, +6B+3Ca, +12B+3Ca) in different

NaCl levels increased Ca2+ content in rapeseed

seedlings. On the other hand, boron had no

statistically significant effect on calcium content of

seedlings.

Table 4. The amounts of Na+ and Ca2+ in oilseed rape seedlings affected by different levels of seed vigour.

Seed vigour Na+ (ppm) Ca2+ (ppm)

V1 (control) 155.7b 35.8a

V2 180.3a 34.3b

Different letters indicate the significant difference at p<0.05.

Table 5. The chlorophyll a content of seedlings affected by different levels of seed vigour, B-Ca2+ combinations

and salinity.

chlorophyll a (mg.g-1 FW)

159.1a V1 (control) Seed vigour

138.0b V2

144.7b +1B+1Ca (control) B-Ca Combinations

150.6a +6B+1Ca

151.8a +12B+1Ca

152.4a +1B+3Ca

145.7b +6B+3Ca

146.0b +12B+3Ca

198.8a S0 (control) Salinity

144.9b S50

101.9c S100

Different letters indicate the significant difference at p<0.05.

Seed vigor reduction led to a decline in the amount of

chlorophyll a and b in rapeseed seedlings (Table 3

and Figure 9). Different concentrations of boron and

calcium increased the amount of chlorophyll a, as the

seedlings grown in +6B+1Ca, +12B+1Ca, and

+1B+3Ca combinations had the highest leaf

greenness. The salinity stress decreased chlorophyll a

in the leaves, as 100mM NaCl diminished chlorophyll

a level in leaves by approximately 50% (Table 3).

Seedlings from aged poor vigor seeds in 100mM

salinity had the minimum level (about 25 mg.g-1 FW)

of chlorophyll b (Figure 9). In general, salt stress

caused the loss of chlorophyll b of rapeseed seedlings

by more than two to three folds in comparison with

control (no salt). Additional concentrations of boron

and calcium in 50 and 100mM salinity reduced the

negative effects of salt stress on chlorophyll b of

leaves (Figure 10). Combined treatments of +6B+3Ca

and +12B+3Ca were not significantly different from

the control in terms of the amount of chlorophyll b.

Therefore, it can be concluded that the exogenous

application of B and Ca supplements would be more

effective when the concentration of salt in seedling

growth medium is high. Also, concomitant increase of

B and Ca concentrations had no significant advantage

on rapeseed germinability and seedling development

under salinity stress.

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Fig. 1. The percentage of seedling emergence affected

by different levels of seed vigour and salinity.

Fig. 2. The seedling emergence rate affected by

different levels of seed vigour and B-Ca combinations.

Discussion

Generally, it has been observed that plants are more

sensitive to stress factors at the early growth stages

and more resistant at the advanced vegetative growth

(Knight and Knight 1999). Ajouri et al. (2004)

reported that high seed vigor not only increases

germination rate and uniform emergence, but also

enhances the future seedlings’ tolerance to

environmental stresses. Previously, it has been shown

that the rapeseed seed vigor level can influence the

seedling establishment under low temperature stress

(Ghassemi-Golezani et al. 2008). As well, previous

researches (El-Hamdaoui et al. 2003; Bonilla et al.

2004) focused on the alleviatory effects of

exogenously applied boron and calcium on pea

seedling growth under salinity stress. Therefore, the

necessity of conducting the present research was felt;

as interactive effects of seed vigor and supplemental

boron and calcium on rapeseed seedling

establishment under salinity were investigated. The

results presented here show that salt stress also

influenced early events of rapeseed seedling growth

(Figure 1 and Table 2 and 3) and that the addition of

both nutrients (boron and calcium) also increased

seedling development (Figure 2 and Table 3).

Fig. 3. The leaf number of seedlings affected by

different levels of seed vigour and salinity.

Fig. 4. The leaf number of seedlings affected by

salinity and B-Ca combinations.

A concentration of 100 mM NaCl caused more

inhibitory effects on rapeseed seedling emergence and

other growth parameters (Figure 1 and Table 2 and

3). According to Bonilla et al. (2004), this can be

overcome by addition of extra B or Ca, provided

excessive both B and Ca were avoided. More other

researchers also reported the deleterious effects of

NaCl (as an abundant salt in the soil) on seedling

emergence and growth of all field crops. The reduced

emergence percentage can be attributed to primary

water uptake reduction and the negative effect of

osmotic potential and ion toxicity on catabolic and

anabolic biochemical processes of seed germination

(Allen et al. 1986; Torres-Schumann et al. 1989;

Shalhevet 1993; Misra et al. 1995; Safarnejad 1996;

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Int. J. Biosci. 2015

Peñuelas et al. 1997). Comparison of our results with

findings of Bonilla et al. (2004) on pea suggested that

the prescribed alleviatory effect of boron and calcium

on seedling establishment and subsequent

development under salt stress is species specific.

Fig. 5. The amounts of Na+ in oilseed rape seedlings

affected by salinity and B-Ca combinations.

Fig. 6. The amounts of K+ in oilseed rape seedlings

affected by different levels of seed vigour and salinity.

In general, the results showed that high vigor seeds

have a higher seedling emergence percentage in salt

stress conditions; as compared to low vigor ones

(Figure 1). The low emergence rate of seedlings from

deteriorated seeds is likely due to the interruption

occurring at the beginning of germination process in

deteriorated seeds (Berjake and Villers 1972; Bailly et

al. 1998 and 2000; Basra et al. 2003; Verma et al.

2003). Researchers have claimed that adding boron

and calcium leads to the increased seedling

emergence rate in salinity conditions (El-Hamdaoui

et al. 2003; Bonilla et al. 2004). Boron influences cell

growth and division, and DNA synthesis; as the level

of RNA in the cell nucleus is greatly reduced under

boron deficiency. Calcium increases the activity of

amylases which are essential for the hydrolysis of

seed endosperm (Marschner 1995). Accordingly, the

above-mentioned factors might be the possible

reasons for promotive effects of boron and calcium on

seed germinability and subsequent seedling

establishment especially the emergence rate of

seedlings produced from aged low vigor seed lot

(Figure 2).

Fig. 7. The amounts of K+ in oilseed rape seedlings

affected by salinity and B-Ca combinations.

Fig. 8. The amounts of Ca2+ in oilseed rape seedlings

affected by salinity and B-Ca combinations.

The reductions in seedling length and dry weight are

the ultimate result of seed vigor loss (Machado et al.

2001; Verma et al. 2003). O'Neill et al. (2004)

reported that boron has a direct effect on cell growth

and differentiation in meristems. Marschner (1995)

also stated that calcium withdrawal from the outside

stops root growth in several hours. Thus, elongation

of rapeseed seedlings resulted from boron and

calcium can be attributed to the increase of cell

growth and division. Hydrolysis of stored nutrients

and also their transfer to the developing embryonic

axis is reduced under salt stress conditions resulting

in low vegetative growth (Dubois 1956; de Lacerda et

al. 2003). Boron stimulates vegetative growth as well

as carbohydrate distribution to vegetative organs

(Smith et al. 1988). However, dry matter

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Int. J. Biosci. 2015

accumulation in rapeseed seedlings can be the result

of stimulation of this process by boron. On the other

hand, affecting cell division and growth, calcium leads

to increased seedling dry weight (Marschner 1995).

Since the presence of high concentrations of both

boron and calcium has not had an improving effect on

rapeseed seedling growth (Table 3), we may state that

there is a rather antagonistic relationship between

boron and calcium in these concentrations.

Fig. 9. The chlorophyll b content of seedlings

affected by different levels of seed vigour and salinity.

Several researchers have reported sodium increase

and potassium decline in salinity conditions which

corresponds well with the results of the present

research (Chhipa and Lal 1995; Sairam et al. 2002).

Under salinity stress conditions, sodium is absorbed

by root cells and through cationic vectors or via the

apoplastic route into the xylem stream and the whole

plant (Hasegawa et al. 2000). Sodium’s competition

with essential elements such as potassium, calcium,

and magnesium due to high levels of these ions is a

harmful effect damaging the plants (Sairam et al.

2002). Loss of K+ content in seedlings under salt

stress may be due to the high level of Na+ in the plant

growth medium and hence it’s higher uptake. Bonilla

et al. (2004) reported that some concentrations of

boron and calcium in salinity conditions lead to

sodium decline in the roots of pea seedlings. Also, 10

mM Ca2+ concentration in salinity conditions leads to

a decline in sodium absorption and a gain in

potassium uptake for rice (Knight and Knight 1999).

High levels of calcium can reduce the permeability of

the plasma membrane to sodium which leads to Na+

loss in the root (Cramer et al. 1985). Increased

cellular Ca2+ due to a rapid response to increased ABA

levels induced by non-living stresses (Knight et al.

1996), the necessity of calcium presence for the

expression of many stress genes and ultimately,

calcium increase during the promoter activation of

stress genes (Sheen 1996) are evidences that confirm

the alleviatory effects of calcium on various

environmental stresses. Calcium (Ca) plays a vital

nutritional and physiological role in plant

metabolism. Because Ca2+ is readily displaced from its

extracellular binding sites by other cations, these

functions may become seriously impaired by reduced

Ca2+ availability. Bonilla et al. (2004) reported that

salinity led to an extremely high concentration of Na+

ions, and to a decrease of B and Ca concentrations.

They concluded that this can be overcome by addition

of both nutrients, increasing salt tolerance of

developing pea plants. In this regard, there is

evidence pointing to B-Ca relationship in cell

membrane stability especially under abiotic stresses

(Tang and De la Fuente 1986; Kobayashi et al. 1999).

Sodium-induced Ca2+ deficiencies have notorious

growth-distorting effects on developing leaves as

illustrated on some grass species grown in solution

cultures (Ehret et al. 1990).

Fig. 10. The chlorophyll b content of seedlings

affected by salinity and B-Ca combinations.

Chlorophyll changes are considered as a short-term

response to environmental stresses. Under salinity,

this pigment is damaged due to the excess of Na+ in

leaves. Also, given that Mg2+ is an essential cation in

chlorophyll structure, one reason for the chlorophyll

loss under salt stress can be attributed to the reduced

amount of magnesium. Moreover, it appears that

chlorophyll loss under stress is due to the effects of

chlorophyllase, peroxidase and phenolic compounds

and hence chlorophyll decomposition (Ashraf and

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Int. J. Biosci. 2015

Harris 2004). Grewal et al. (1998) stated that the

increased availability of zinc and boron significantly

increases the chlorophyll content of young leaves of

rapeseed. Boron stimulates vegetative growth as well

as carbohydrate transfer to vegetative organs to be

used for chlorophyll production (Smith et al. 1988).

Ghassemi-Golezani et al. (2008) reported that the

amount of chlorophyll a and b in the leaves of

rapeseed seedlings is declined with increased seed

deterioration.

Overall the results indicate that a balanced B-Ca

relationship also increases salt tolerance during the

early stages of rapeseed seedling development and

growth. Nevertheless, besides genetic approaches

searching for tolerant cultivars, concomitantly

studying both the seed vigor status and the

nutritional relationship between B and Ca for other

crops can lead to applied approaches to increase salt-

tolerance and field crop production.

Acknowledgements

The authors wish to thank the Research and post-

graduation Committee of University of Mohaghegh

Ardabili for a research grant in support of this

project..

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