沙漠研究 19-1, 193- 195 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

Effect of Magnesium Sulphate on First Stadium of Development of Lucerne(Medicago sativa) Cultivated in Gabes Oasis
Mabrouka ABID1, Mansour HADDAD1, Ali FERCHICHI1
Abstract: In the South of Tunisia, water used in irrigation, especially geothermic water is richin sulphate. The object of this study is to evaluate the effect of increasing concentrations ofmagnesium sulphate (MgSO4) from 0 to 5g l-1 on the development of alfalfa (Medicago sativaL.) during its first stadiums of growth. Results showed that high percentages of germination (>90%) were detected at even the high concentrations. However for the concentration 5g l-1 ofMgSO4, 90% germination was not induced until 36 hours after initiation of the experiment.
High concentrations reduced leaf surface and induced decreasing of succulence sign andlimited production (88% for the concentration 5g l-1). In all cases leaves are rich in Na+ and K+.
Keys words: Development, Germination, Lucerne, Magnesium sulphate, Production

1. Introduction
In the oasis of Gabès, food production depends mainly on irrigation from underground resources.
Therefore, these resources have been intensively exploited. The impact of this exploitation in thetablecloths hydrochemistry is using saline water (Mamou, 1993); this induces a progressive increasesalinity of irrigation water as well as the soils of the oasis (Mtimet, 1994).
The extension of salinity and the scarcity of water are the most important problems of warms aridzones. Search of resistant plants to these conditions is very necessary for the restoration and the planningof the surroundings. Among many crops, lucerne (Medicago sativa) or alfalfa represents an importantalternative given its potential for fodder production.
Crops are subjected under natural conditions to saline stress driven mainly by NaCl. However, otherchloride, sulphate and others salts play a significant role in affecting plant growth and development.
The aim of this work is to study the effect of magnesium sulphate on the first stage of development ofLucerne Medicago sativa cultivated in the oasis of Gabes.
2. Materials and Methods
To study the effect of MgSO4 on lucerne germination, 50 seeds were placed in Petri dishes which weresealed with water soaked cotton. Five concentrations were applied: 0; 2; 3; 4 and 5 g l-1 with threereplications for each treatment. The capacity of germination was calculated using the following formula:% PG = GG/TN*100
where: GG = number of germinated seeds, TN = total number of seeds.
A second experiment was conducted in plastic pots with 5 l volume each to study the effect of MgSO4on lucerne growth. In each pot, 20 seeds were grown with three replications. Five concentrations wereapplied C1:2 g l-1; C2:3 g l-1; C3:4 g l-1; C4:5 g l-1, the water used in irrigation in the oasis (1 g l-1 ofMgSO4) was chosen as a control treatment (T). Four cuts collected at the following intervals; 60, 90, 120
and 150 days respectively. Five plants by treatment are used to measure: leaves surface, succulence index
and the nutrients content
3. Results and Discussions
3.1. Influence of magnesium sulphate on lucerne germination
Percentages of germination are illustrated by Figure 1. Seeds of Lucerne showed raised rates (>90 %) even for the high concentrations of MgSO4. The effect of the magnesium sulphate resulted indelayed of germination for the 5 g l-1 treatment that reduces the germination percentage to 50% for day 1ascompared to the other treatments. NaCl is the most applied salt in studying germination, several studies

1Institute of Arid Regions, Arid and oasis cultivation Laboratory Km 22, 4119 ElFjé Mednine Tunisia
E-mail: abid.mabrouka@yahoo.fr, Fax number: 75228088

194
120
100T

PG %802g/l
603g/l4g/l405g/l200012345DaysFig. 1. Effect of MgSO4 on % of germination.

showed that the percentage of wheat germination reduces until 3 g l-1 of NaCl (Bizid and Zid, 1986) andthe effect of NaCl results in a delay of the germination speed (Belkhodja and Soltani, 1992).
3.2. Influence of magnesium sulphate on plant growth
3.2.1. Leaves surface
The leaf surface variation under different concentrations of MgSO4 is outlined in Figure 2. The
concentrations 2 and 3 g l-1 offers the most elevated leaves surface compared to the others treatments.
The reduced surface (0.9 cm2) was unregistered by the treatment 5 g l-1 of MgSO4.
161412102SF (cm ) 86420C4C3C2C1
T2g/l

3g/l

4g/l

5g/l

MgSO4 (g/l)

Fig. 2. Influence of MgSO4 on leaves surface (C1:60days, C2:90days, C3:120days and C4:150days).

DM/FM

3.2.2. Succulence index
Water status of plant is expressed by DM/FM (DM: dry matter, FM: fresh matter) report of aerial parts(Figure 3). During the second cut, this index was increased; despite in the fourth cut, this parameter
declined and was significantly lower for the 5 g l-1 treatment compared to the other treatment. This impacts
drought and dehydration.
1412
10
8
6
4
20C1C2C3C4

T

2g/l

3g/l

4g/l

5g/l

Mg SO4(g/l)

Fig. 3. Influence of MgSO4 on succulence index (C1:60days, C2: 90days, C3: 120days and C4:150days).

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3.3. Influence of magnesium sulphate on nutrients content
Results illustrated by Table 1 indicated an increase in sodium content with the increase of MgSO4concentration. The largest concentration showed the highest content (4%). Our results showed asignificant increase of potassium content in leaves and steams of lucerne (between 2 and 5%) for alltreatments. Our results showed a capacity of alfalfa to maintain an elevated content in K+ in presence ofincrease of Na+. Lachaal (1996) considers this phenomenon as criteria of tolerance. The same author
showed the existence of a positive interrelationship between tolerance to salt and the content of leaves in
K+ of lentil.
Table 1. Leaves and stems contents in sodium and potassium during the second and the fourth
cut for the different concentrations of MgSO4.

Second cut
Leaves
Stems
TC1
C2
C3
C4

0.44
0.39
0.34
0.44
0.56

0.79
0.49
0.34
0.54
1.7

TC1
C2
C3
C4

2.08
2.43
2.62
1.98
2.05

3.39
3.39
0.74
3.39
8.96

fourth cut
LeavesStems
Na+ (%)
0.79
0.63
0.59
0.59
1K+ (%)
2.6
2.86
1.21
2.27
3.39

0.59
0.59
0.2
0.59
12.61
2.86
0.73
2.38
3.45

4. Conclusion
In this study, lucerne showed a higher percentage of germination (up 50%) for all the treatments.
There was a strong decrease in leaf surface especially in the seedling treated with 5 g l-1. The presence ofMgSO4 induces an increase of the content of sodium, observed for all the treatments. This increase isreputed among characteristic of plant tolerance to salt. Thus, the plant appears capable to surmountincrease of MgSO4 concentrations. This adaptation may lead to the cultivation of lucerne in the oasis ofGabès.
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Bizid E, Zid E. (1986): Ionic aspect of the wheat adaptation to the chloride of sodium. Colloquium about plants in arid environment.
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