In order to study the effect of salts stress on the growth and yield of wheat (cv. Inqalab), a pot experiment was conducted in the wire-house of the Department of Soil Science, Sindh Agriculture University Tando Jam. The soil was artificially salinized to a range of salinity levels i.e . EC 2.16, 4.0, 6.0, 8.0 and 10.0 dS·m -1 with different salts (MgCl 2 + CaCl 2 + Na 2SO 4). The salinized soil used for the experiment was sandy clay in texture, alkaline in reaction (pH > 7.0) and moderate in organic matter (0.95%) content. The results showed that with increasing salinity there was an increase in the ECe, Na +, Ca 2+, Mg 2+ and Cl - and decrease in the K +, SAR and ESP values of the soil Increasing salinity, progressively decreased plant height, spike length, number of spikelets spike -1 1000 grain weight and yield (straw and grain). Adverse effects of salts on plants were associated with the accumulation of less K + and more Na + and Cl - in their flag leaf sap, grains and straw. This resulted in lower K +:5Na + ratio in flag leaf sap, grains and straw of wheat plants. These results indicated that the effects of salts stress were greater at 10 than at 8, 6 and 4 EC dS·m -1.
Wheat (Triticum aestivum L.) is an important cereal crop of the world. It is one of the staple foods for more than one third of the world population. Wheat played a vital role in the development of civilization. The king of cereals wheat is the principal source of food and is extensively grown, consumed and preferred in Pakistan. It contains approximately 60% - 80% protein, 2% - 2.5% glucose, 1.5% - 2% fat and 2% - 3% mineral matter [
Besides the above factors, soil salinity is the major problem, which affects the yield of this important crop. It is commonly observed in arid and semi-arid regions of the world [
Excess amount of salts in the soil affects plant from germination to harvesting [
The relative salt tolerance of wheat crop is 7.0 dS∙m−1 and its yield decrease is 25% at 9.0 dS∙m−1 [
In order to assess the effect of salts stress on the growth and yield of wheat variety Inqabab, a pot experiment was conducted in the wire-house of the Department of Soil Science, Sindh Agriculture University Tando Jam. The following methodology was adopted.
Fertile soil (plough layer) was collected from the arable land of latif Experimental Farm of Sindh Agriculture University, Tando Jam. The soil was air dried ground and passed through 4 mm garden sieve. The air dried soil was placed in plastic containers with drainage holes in bottom. The 9 kg pots were arranged on wooden benches in RCBD with three replications.
Seeds of wheat variety Inqalab were at 4 cm plant to plant distance. Few days after emergence, 7 seedlings were allowed to grow in each pot up to maturity. In order to reduce losses by evapotranspiration, the pots were regularly irrigated by normal irrigation water. The recommended does of NPK was applied in the form of NPK (10:23:15) and urea (46%N) to each pot. Nitrogen was applied at the rate 136 kg N ha−1 in the form of NPK and urea in three splits, first at the time of sowing, second at the 1st irrigation and the remaining at the 2nd irrigation. Phosphorus and K were applied at the rate 67 kg
Different saline soil treatments were prepared artificially by mixing different salts. The quantity of different salts (MgCl2, CaCl2 and Na2SO4) required for the preparation of saline soil treatments was calculated using the method described by Rowell [
T1 (control) 2.16 (dS∙m−1) (Non-saline);
T2 (MgCl2 + CaCl2 + Na2SO4) 4.0 (dS∙m−1) (Saline);
T3 (MgCl2 + CaCl2 + Na2SO4) 6.0 (dS∙m−1) (Slightly saline);
T4 (MgCl2 + CaCl2 + Na2SO4) 8.0 (dS∙m−1) (Moderately saline);
T5 (MgCl2 + CaCl2 + Na2SO4) 10 (dS∙m−1) (Highly saline).
Following agronomic observations were recorded:
・ Plant height (cm),
・ Spike length (cm),
・ Number of spikelet’s spiket−1,
・ Straw dry weight (mg∙plant−1),
・ Grain yield (mg∙plant−1),
・ 1000 grain weight (g).
The flag leaf of three plants from each replication of all the treatments was detached, placed in Eppendorf tubes and stored in a freezer at −10˚C. The lamina of the flag leaves were removed and the sap was extracted and analyzed for Na+, K+ using the method of Gorham [
Straw and grain samples from all the replications of each treatment were prepared for analysis of Na+, K+, Ca2+ and Mag2+.
The soil samples were collected before sowing from each treatment. Samples were prepared and analyzed for soil texture, pH, ECe (dS∙m−1), O.M%, cations (Na+, K+, Ca2+ and Mg2+) and anions (
Sodium adsorption ratio (SAR), exchangeable sodium ratio (ESR) and exchangeable sodium percentage (ESP) were calculated using the following formula suggested by Rowell [
・ Sodium Adsorption Ratio (SAR) = (Na+)/(Ca2 + Mg2+)1/2,
・ Exchangeable Sodium Ratio (ESR) = −0.013 + 0.05 SAR,
・ Exchangeable Sodium Percentage (ESP) = 100 ESR/(1 + ESR).
All plant data were analysed by performing ONEWAY-ANOVA using Minitab-12 statistical package. Standard Error for Different between Means (S.E.D) was calculated using the following formula: SED = (2EMS/n)1/2Least Significant Different (LS.D.) = S.E.D × edf t value at 5% probability level.
Physico-chemical properties of soil before sowing and after harvesting of wheat crop
S. No. | Determinations | Method Used | Equipment used | References |
---|---|---|---|---|
1 | Extraction of flag Leaf sap for Na+ and K+ analysis | Centrifuge method | Eppendorf Tubes | Gorham [ |
2 | Preparation and Analysis of straw for Na+ and K+ | Acid wet digestion | EEL-flame photometer | Rowell [ |
3 | Preparation and Analysis of straw and grain samples for Cl− | Dry ash method | Muffle Furnace | Methods Manuals Soils [ |
S. No. | Determinations | Method adopted | Equipment used | References |
---|---|---|---|---|
1 | Soil texture | Bouyoucos Hydrometer | Hydrometer | Kanwar and chopra [ |
2 | ECe (dS∙m−1) | 1:2 soil water Extract | Digital EC Meter | Rowell [ |
3 | pH | 1:2 soil water Extract | Digital pH Meter | Rowell [ |
4 | O.M. (%) | Walkley Black Method No.9 Titration with 0.5 N Ferrous Solution | Burette | Jackson [ |
5 | Soluble Na+ and K+ | Method No. 10 and 11 | EEL-flame Photometer | Handbook- 60 USSL [ |
6 | Soluble Ca2+ and Mg2+ | Method No. 7 Titration with EDTA solution (soil and plant (samples) | Burette | Hand book- 60 USSL [ |
7 | Method No. 12 Titration with Standard H2SO4 Solution (soil and plant samples) | Burette | Hand book- 60 USSL [ | |
8 | Cl− | Method No. 13 Titration with Standard AgNO3 Solution (soil and plant samples) | Burette | Hand book- 60 USSL [ |
are summarized in
The effect of salts stress on plant height is shown in
The effect of salts stress on spike length is shown in
S# | Name | Results |
---|---|---|
1 | Carbonate | Absent in all samples |
2 | Soil organic Matter | 0.95% |
3 | Soil Textural Class | Silty Clay Loam |
Salinity levels EC (dS∙m−1) | Classification | Plant height (cm) | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 52.53 | - |
4.00 | Saline | 46.10 | 12.45 |
6.00 | Slightly saline | 45.43 | 13.52 |
8.00 | Moderately saline | 43.20 | 17.61 |
10.00 | Highly saline | 41.97 | 20.11 |
S. E. D. | 2.6798 | ||
L. S. D. | 1.2028*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | Spike length (cm) | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 13.767 | - |
4.00 | Saline | 11.667 | 15.24 |
6.00 | Slightly saline | 11.533 | 16.23 |
8.00 | Moderately saline | 10.800 | 21.55 |
10.00 | Highly saline | 10.500 | 23.73 |
S. E. D. | 0.3949 | ||
L. S. D. | 0.8798*** |
***Highly significant.
The effect of salts stress on number of spikelets spike−1 is shown in
The effect of salts on straw yield is shown in
Salinity Levels EC (dS∙m−1) | Classification | Spikelets spike−1 | Percent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 10.533 | - |
4.00 | Saline | 9.633 | 8.54 |
6.00 | Slightly saline | 9.033 | 14.24 |
8.00 | Moderately saline | 8.733 | 17.09 |
10.00 | Highly saline | 8.367 | 20.56 |
S. E. D. | 0.2118 | ||
L. S. D. | 0.4718*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | Straw yield (mg) spike−1 | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 1051.8 | - |
4.00 | Saline | 910.2 | 13.46 |
6.00 | Slightly saline | 861.5 | 18.10 |
8.00 | Moderately saline | 854.5 | 18.74 |
10.00 | Highly saline | 839.2 | 20.22 |
S. E. D. | 59.4587 | ||
L. S. D. | 132.4741* |
*Non-significant.
produced significantly lower straw yield than in the control. Increasing salinity decreased the straw yield. The decrease in straw yield was greater at high EC (EC 10 dS∙m−1) than at low (EC 6 dS∙m−1) and medium EC (EC 8 dS∙m−1) levels.
The effect of salts stress on grain yield is shown in
The effect of salts stress on 1000 grain weight is shown in
Salinity levels EC (dS∙m−1) | Classification | Grain yield (mg) (spike−1) | Percent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 480.40 | - |
4.00 | Saline | 355.83 | 25.94 |
6.00 | Slightly saline | 231.46 | 51.82 |
8.00 | Moderately saline | 219.31 | 54.25 |
10.00 | Highly saline | 162.31 | 66.52 |
S. E. D. | 40.1995 | ||
L. S. D. | 89.5645*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | 1000 grain Weight (g) | Percent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 357.10 | - |
4.00 | Saline | 228.10 | 36.16 |
6.00 | Slightly saline | 149.07 | 58.26 |
8.00 | Moderately saline | 130.60 | 63.43 |
10.00 | Highly saline | 108.57 | 69.60 |
S. E. D. | 33.89 | ||
L. S. D. | 75.51*** |
***Highly significant.
grain weight was decreasing. These grain were significantly lighter in weight at low (EC 6 dS∙m−1), medium (EC 8 dS∙m−1) and very high at high salinity (EC 10 dS∙m−1) levels.
The effect of salts stress on Na+, K+, and K+/Na+ ratio in flag leaf sap of wheat is presented in Tables 10-12. The effect of increasing soil salinity was to increase Na+ and decrease K+ concentration in the flag leaf sap. This was resulted in lower K+/Na+ ratio. The increase in Na+ and decrease in K+ were more marked in the flag leaf sap of the plants grown in high salinity treatment than in the control and other sol treatments.
The effect of salts mixture on ion concentration in the grains of wheat is shown in Tables 13-16. Salinity significantly increased Cl− and Na+ but decreased K+ and K+/ Na+ ratio contents in the grains at all salinity levels. Plants grown at moderate and high salinity levels had significantly higher Cl− and Na+ but lower K+/Na+ ratio than the plants grown at the control and low salinity level.
Salinity levels EC (dS∙m−1) | Classification | Na+ (%) | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.28333 | - |
4.00 | Saline | 0.34333 | 21.18 |
6.00 | Slightly saline | 0.41000 | 44.70 |
8.00 | Moderately saline | 0.45333 | 60.00 |
10.00 | Highly saline | 0.53667 | 89.41 |
S. E. D. | 0.0313 | ||
L. S. D. | 0.0697*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | K+ (%) | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.7333 | - |
4.00 | Saline | 0.6500 | 11.36 |
6.00 | Slightly saline | 0.4733 | 35.46 |
8.00 | Moderately saline | 0.4133 | 43.64 |
10.00 | Highly saline | 0.3533 | 51.83 |
S. E. D. | 0.1192 | ||
L. S. D. | 0.2655* |
*Non-significant.
Salinity levels EC (dS∙m−1) | Classification | K+/Na+ | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 2.6167 | - |
4.00 | Saline | 1.8700 | 28.54 |
6.00 | Slightly saline | 1.1667 | 55.42 |
8.00 | Moderately saline | 0.9300 | 64.46 |
10.00 | Highly saline | 0.6600 | 74.78 |
S. E. D. | 0.3286 | ||
L. S. D. | 0.7322** |
**Significant.
The effects of different salinity levels on ion concentrations in the straw are shown in the Tables 17-20. Salinity significantly (P < 0.05) increased the toxic ions (Na+ and Cl−) and decreased the concentration of K+ and K+/Na+ ratio in the straw at all levels. At
high salinity level plants accumulated more Na+ and Cl− but less K+ and hence they ex habited lower K+/Na+ in their straw.
Salinity levels EC (dS∙m−1) | Classification | Na+ (%) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.3733 | - |
4.00 | Saline | 0.5033 | 34.82 |
6.00 | Slightly saline | 0.7033 | 88.40 |
8.00 | Moderately saline | 0.9033 | 141.97 |
10.00 | Highly saline | 1.1100 | 197.34 |
S. E. D. | 0.0549 | ||
L. S. D. | 0.1223*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | K+ (%) | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.35333 | - |
4.00 | Saline | 0.25667 | 27.36 |
6.00 | Slightly saline | 0.22000 | 37.74 |
8.00 | Moderately saline | 0.16333 | 35.78 |
10.00 | Highly saline | 0.11667 | 66.98 |
S. E. D. | 0.0300 | ||
L. S. D. | 0.0668*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | K+/Na+ | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.9440 | - |
4.00 | Saline | 0.5092 | 46.07 |
6.00 | Slightly saline | 0.3114 | 67.01 |
8.00 | Moderately saline | 0.1821 | 80.71 |
10.00 | Highly saline | 0.1038 | 89.01 |
S. E. D. | 0.0489 | ||
L. S. D. | 0.1089*** |
***Highly significant.
The effect of salts stress on Ca2+ and Mg2+ contents in grains and straw of wheat are shown in the Tables 21-24. The results indicated that with the increasing concentration of soluble salts in soil (
The soil used in this experiment was sandy clay with 37.5% clay and 0.95% organic matter. When this soil was treated with salts it showed properties typical to those of saline soils of Sindh (Ghafoor, 2004).
Salinity levels EC (dS∙m−1) | Classification | Cl− (meq 100 g−1) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 50.00 | - |
4.00 | Saline | 81.67 | 63.36 |
6.00 | Slightly saline | 92.33 | 84.66 |
8.00 | Moderately saline | 102.33 | 104.66 |
10.00 | Highly saline | 115.67 | 131.34 |
S. E. D. | 13.9044 | ||
L. S. D. | 30.9790*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | Na+ (%) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.4900 | - |
4.00 | Saline | 0.6733 | 37.40 |
6.00 | Slightly saline | 0.7700 | 57.14 |
8.00 | Moderately saline | 1.1333 | 131.28 |
10.00 | Highly saline | 1.3833 | 182.30 |
S. E. D. | 0.0848 | ||
L. S. D. | 0.1891*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | K+ (%) | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 1.7000 | - |
4.00 | Saline | 1.2333 | 8.14 |
6.00 | Slightly saline | 1.1467 | 20.46 |
8.00 | Moderately saline | 1.0700 | 29.46 |
10.00 | Highly saline | 0.9267 | 32.53 |
S. E. D. | 0.0870 | ||
L. S. D. | 0.1951*** |
***Highly significant.
The results obtained in this experiment showed that salinity had adverse effects on almost all growth and yield parameters. The effects of high salinity on soot height (
Salinity levels EC (dS∙m−1) | Classification | K+/Na+ | Per cent Decrease over Control |
---|---|---|---|
Control (2.16) | Non-saline | 3.0874 | - |
4.00 | Saline | 2.1039 | 31.86 |
6.00 | Slightly saline | 1.5828 | 48.73 |
8.00 | Moderately saline | 0.9622 | 68.83 |
10.00 | Highly saline | 0.7410 | 76.00 |
S. E. D. | 0.3435 | ||
L. S. D. | 0.7653*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | Cl− (meq 100 g−1) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 75.00 | - |
4.00 | Saline | 91.33 | 21.77 |
6.00 | Slightly saline | 113.00 | 50.66 |
8.00 | Moderately saline | 125.67 | 67.56 |
10.00 | Highly saline | 131.00 | 74.66 |
S. E. D. | 7.8951 | ||
L. S. D. | 17.5903*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | Ca2+ (%) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.8333 | - |
4.00 | Saline | 1.0733 | 28.80 |
6.00 | Slightly saline | 1.1100 | 33.21 |
8.00 | Moderately saline | 1.1433 | 37.20 |
10.00 | Highly saline | 1.1833 | 42.00 |
S. E. D. | 0.0816 | ||
L. S. D. | 0.1818* |
*Non-significant.
decreased straw yield by 20.22%, grain yield by 66.52% other workers [
Salinity levels EC (dS∙m−1) | Classification | Mg2+ (%) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 1.2867 | - |
4.00 | Saline | 1.4267 | 10.88 |
6.00 | Slightly saline | 1.5600 | 21.24 |
8.00 | Moderately saline | 1.6667 | 29.53 |
10.00 | Highly saline | 1.8167 | 41.19 |
S. E. D. | 0.0423 | ||
L. S. D. | 0.0944*** |
***Highly significant.
Salinity levels EC (dS∙m−1) | Classification | Ca2+ (%) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 0.9733 | - |
4.00 | Saline | 1.1067 | 13.71 |
6.00 | Slightly saline | 1.1600 | 19.18 |
8.00 | Moderately saline | 1.2400 | 27.40 |
10.00 | Highly saline | 1.2933 | 32.88 |
S. E. D. | 0.1194 | ||
L. S. D. | NS |
Salinity levels EC (dS∙m−1) | Classification | Mg2+ (%) | Per cent Increase over Control |
---|---|---|---|
Control (2.16) | Non-saline | 1.2933 | - |
4.00 | Saline | 1.9667 | 52.07 |
6.00 | Slightly saline | 2.3300 | 80.16 |
8.00 | Moderately saline | 2.5200 | 94.85 |
10.00 | Highly saline | 2.9100 | 125.00 |
S. E. D. | 0.3521 | ||
L. S. D. | 0.7846* |
*Non-significant.
[
The greater effects of salinity on plants were associated with larger effects on ions (Tables 9-23). As was expected, the effects of salinity on plants was to increase Na+, Cl−, Ca2+ and Mg2+ and decrease K+ and K+/Na+ ratio compared to control plants. The increase in Na+, Cl−, Ca2+ and Mg2+ contents may be attributed to the increase amount of sodium, calcium and magnesium in soil solution due to the addition of salts (MgCl2 + CaCl2 + Na2S04) when soils were prepared. Similar effects of salinity on wheat plants for ions content have been reported by many workers [
A pot experiment was conducted in the wire-house of the department of Soil Science, Sindh Agriculture University Tando Jam to see the effects of salts stress on the growth and yield of wheat (Cv. Inqalab).
The soil used in the experiment was clay loam in texture, alkaline in reaction (pH > 7.0), moderate in organic matter (0.95%). The soil was artificially salinized to different salinity levels i.e. ECe 2.16, 4.0, 6.0, 8.0 and 10.0 dS∙m−1 with different salts (MgCl2 + CaCl2 + Na2SO4). The plant data were subjected to statistical analysis.
Following key points have been observed during this study.
1) Increasing salinity increased the ECe, Na+ Ca2+, Mg2+ and Cl− content and decreased the K+, SAR and ESP values in the soil.
2) Increasing salinity significantly decreased plant height, spike length, number of spikelets Spike−1, 1000 grain weight, and straw and grain yields plant−1. Increasing salinity significantly increased Na+ concentration but decreased K+ concentration and K+/Na+ ratio in the flag leaf sap.
3) Increasing salinity increased Na+, Ca2+, Mg2+ and Cl− content while decreased K+ and K+/Na+ ratio in straw and grains.
4) Effect of salts (MgCl2 + CaCl2 + Na2SO4) stress on almost all parameters was significant.
It was concluded from the present study that salts stress (MgCl2 + CaCl2 + Na2SO4) adversely affects the growth and yield of cultivar Inqalab. Due to the osmotic and ionic toxicity effects, its yield immediately decreased as salinity level increased.
Kalhoro, N.A., Rajpar, I., Kalhoro, S.A., Ali, A., Raza, S., Ahmed, M., Kalhoro, F.A., Ramzan, M. and Wahid, F. (2016) Effect of Salts Stress on the Growth and Yield of Wheat (Triticum aestivum L.). American Journal of Plant Sci- ences, 7, 2257-2271. http://dx.doi.org/10.4236/ajps.2016.715199