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Journal of Stress Physiology & Biochemistry, Vol. 9 No. 2 2013, pp. 253-262 ISSN 1997-0838 Original Text Copyright © 2013 by Tigabu, Andargie and Tesfaye
ORIGINAL ARTICLE
Genotypic Variation for Salinity Tolerance in Sorghum (Sorghum bicolor (L.) Moench) Genotypes at Early Growth Stages
Endalew Tigabu1, Mebeaselassie Andargie2* and Kindie Tesfaye3
1 Biology Department, College of Natural and Computational Sciences (CNCS), Mekelle University (MU), P.O. Box: 231, Mekelle, Ethiopia
2 Biology Department, College of Natural and Computational Sciences (CNCS), Haramaya University (HU), P.O.Box: 217, Haramaya, Ethiopia.
3 Plant Science Department, College of Agriculture and Environmental Sciences (CAES), Haramaya University (HU), Ethiopia
*E-Mail: mebhel@yahoo.com
Received December 31, 2012
Sorghum (Sorghum bicolor L. Moench) is the fifth most economically important crop among cereals in the world. Salinity is an abiotic factor which reduces productivity of sorghum. Exploiting genetic variability to identify salt tolerant genotype is one of the strategies used to overcome salinity. Pot experiment was carried out to evaluate the genetic variation of eleven sorghum genotypes for NaCl salinity response at germination and early seedling stages. The experimental treatments were five NaCl salinity levels (0, 2, 4, 8, and 16 dS m-1) and eleven sorghum genotypes (Gambella1107, Melkam, S-35, ESH-2, Gobye, 97MW6130, Meko, 76T1#23, ICSV-111, Abshir and Teshale). The experimental design was completely randomized design with three replicates. Data was analyzed using SAS (version 9.0) statistical software and means were separated by LSD. Germination rate, final germination percentage, seedling shoot length and seedling root length were measured. The ANOVA for treatments, genotypes and their interaction was found to be highly significant (p<0.001) with regard to all parameters. Genotypes Meko, Gambella1107, ICSV-111 and Melkam were found salt tolerant during germination and seedling growth stages. However, genotypes ESH-2 and Gobye were salt sensitive during both stages. The rest sorghum genotypes were intermediate in their salt tolerance. The study affirmed the presence of wide genotypic variation among the sorghum genotypes for NaCl salt tolerance.
Key words: Germination, NaCl, salinity, seedling, sorghum
ORIGINAL ARTICLE
Genotypic Variation for Salinity Tolerance in Sorghum (Sorghum bicolor (L.) Moench) Genotypes at Early Growth Stages
Endalew Tigabu1, Mebeaselassie Andargie2* and Kindie Tesfaye3
1 Biology Department, College of Natural and Computational Sciences (CNCS), Mekelle University (MU), P.O. Box: 231, Mekelle, Ethiopia
2 Biology Department, College of Natural and Computational Sciences (CNCS), Haramaya University (HU), P.O.Box: 217, Haramaya, Ethiopia.
3 Plant Science Department, College of Agriculture and Environmental Sciences (CAES), Haramaya University (HU), Ethiopia
*E-Mail: mebhel@yahoo.com
Received December 31, 2012
Sorghum (Sorghum bicolor L. Moench) is the fifth most economically important crop among cereals in the world. Salinity is an abiotic factor which reduces productivity of sorghum. Exploiting genetic variability to identify salt tolerant genotype is one of the strategies used to overcome salinity. Pot experiment was carried out to evaluate the genetic variation of eleven sorghum genotypes for NaCl salinity response at germination and early seedling stages. The experimental treatments were five NaCl salinity levels (0, 2, 4, 8, and 16 dS m-1) and eleven sorghum genotypes (Gambella1107, Melkam, S-35, ESH-2, Gobye, 97MW6130, Meko, 76T1#23, ICSV-111, Abshir and Teshale). The experimental design was completely randomized design with three replicates. Data was analyzed using SAS (version 9.0) statistical software and means were separated by LSD. Germination rate, final germination percentage, seedling shoot length and seedling root length were measured. The ANOVA for treatments, genotypes and their interaction was found to be highly significant (p<0.001) with regard to all parameters. Genotypes Meko, Gambella1107, ICSV-111 and Melkam were found salt tolerant during germination and seedling growth stages. However, genotypes ESH-2 and Gobye were salt sensitive during both stages. The rest sorghum genotypes were intermediate in their salt tolerance. The study affirmed the presence of wide genotypic variation among the sorghum genotypes for NaCl salt tolerance.
Key words: Germination, NaCl, salinity, seedling, sorghum
Sorghum (Sorghum bicolor (L.) Moench) is the hectares of land (Prakash et al., 2010), in 99
fifth most economically important crop among countries (ICRISAT 2009) with an annual production
cereals in the world. It is grown on about 44 million of 60 million tons (Iqbal et al., 2010).
In Ethiopia, sorghum ranks third among major cereal crops in terms of area and production next to tef (Eragrostis tef) and maize (Zea mays) (Asfaw 2007a). It is cultivated on 1.62 million hectares of land and about 2.97 million ton is produced each year in Ethiopia (CSA 2010). It is a staple food crop on which lives of millions of poor Ethiopians depend and has tremendous uses for the farmer and no part of this plant is wasted (Asfaw 2007b).
Despite its importance, sorghum productivity is far below the genetic potential of the crop (Kidane et al., 2001). Salinity is one of the major factors that reduce the productivity of sorghum (Wang et al., 2003). The amount of worldwide salt affected land is about 900 million ha with most of its water containing about 30 g of sodium chloride (NaCl) per liter (Flowers 2004). In African countries like Kenya, Nigeria, Sudan, Tunisia and Tanzania there is a reported 8.2, 5.6, 4.8, 1.8 and 1.7 Mha of salt affected land, respectively (FAO 2000).
Ethiopia has 44 million ha (36% of the country's total) of land area potentially susceptible to salinity problems. Out of the 44 million ha, 33 million ha have dominantly salinity problem (Hawando 1995). Out of the 170,000 ha of land under irrigation by state farms in Awash Valley and in Central Rift-Valley lake area of Ethiopia, almost 10% (11,000 ha) is feared to have been salinized and have already gone out of production (Hawando 1995).
One of the important strategies plant scientists adopted to overcome salinity is to exploit genetic variability of the available germplasm to identify tolerant genotype that may sustain a reasonable yield on salt affected soils (Ashraf et al., 2006). This approach involves understanding the response of plants at different growth stages under saline conditions as reported in different crops such as maize (Khatoon et al., 2010), sorghum (Geressu and
Gezahagn 2008), rice (Momayezi et al., 2009), and millet (Yakubu et al., 2010).
Germination and seedling characteristics are the most viable criteria used for selecting salt tolerant plants due to the fact that the final plant stand of a crop primarily depends on seedling characteristics. Germination percentage, germination rate and seedling growth are most commonly used criteria for genotype selection (Bybordi and Tabatabaei 2009, Endalew et al., 2012). Therefore, this research attempted to investigate the genetic variability of sorghum (Sorghum bicolor, L. Moench) genotypes which grow in the Central Rift Valley of Ethiopia for salt stress during germination and seedling growth stages.
MATERIALS AND METHODS
Plant material and growth conditions
The experiment was conducted in a greenhouse at Rare Research Station of Haramaya University, Ethiopia during March-April, 2011. The experiment was conducted following the modified procedures used by Ahmed (2009) using plastic pots with widths 15 cm at the base and 20 cm at the top and 18 cm height. The experiment consisted of 11 sorghum genotypes and 4 salinity levels in the form of NaCl solutions and one control. The specific sorghum genotypes used in the research were Gambella1107, Melkam, S-35, ESH-2, Gobye, 97MW6130, Meko, 76T1 #23, ICSV-111, Abshir and Teshale. The seeds of eleven sorghum genotypes which grow in the Central Rift Valley of Ethiopia were obtained from Melkassa Agricultural Research Center (MARC), Ethiopia. The four NaCl salinity levels used were 2, 4, 8 and 16 dS m-1. This NaCl salinity levels were created by dissolving 1.12, 2.10, 4.95 and 9.9 g NaCl in one liter distilled water, respectively. Tap water was used as control. The
sorghum seeds were surface-sterilized by soaking them in sodium hypochlorite (3%) solution for 5 minutes and then rinsed with distilled water for 5 minutes. The rinsed seeds were then air-dried at room temperature. The experimental soil was taken from Haramaya University's Rare Research field and had (according to the soil analysis done at the Soil Sciences Laboratory of Haramaya University) 0.746% organic carbon, 1.3% organic matter, 6.18 pH, 0.064% total nitrogen, and 0.65 dS m-1 EC (in 1:2.5 water extract). Prior to the experiment, the collected soil was adjusted to 2, 4, 8 and 16 dS m-1 soil salinity by adding 1.08, 2.16, 4.32 and 8.64 g NaCl in 3.5 kg soil as described by Mamo et al., (1996). After the soil was adjusted, 3.5 kg soil was filled into 165 pots. There was no NaCl added to the soil of the control pot. Before adding soil into the pots, pots were lined with polyethylene bags to avoid salt leaching. Then twelve surface sterilized uniform seeds of each sorghum accessions were sown in the plastic pots at uniform depth. Pots were placed in a Completely Randomized Design (CRD) placement and replicated 3 times. Pots were irrigated with equal 100 ml of NaCl solutions of 2, 4, 8 and 16 dS m-1, and tap water as control. The EC of the tap water was measured by EC meter and was 1.52 dS m-1 during the experiment period. Treatment application with the same amount of salt solution continued every other day and germination count started after 72 hours of sowing and continued until the 14th day. The seeds were considered to have germinated when both the plumule and radicle had emerged > 0.5 cm. Fourteen days after sowing, germination count was terminated and application of treatments continued until the 28th day. Germination rate and final germination percentage were obtained from germination counted until the 14th day and seedling
growth parameters were obtained after 28th day as described below.
Germination rate (GR) which is the average number of days needed for plumule or radicle emergence was calculated using MAGUIRE's equation (Maguire 1962) as:
GR (M) = n2/t2 + n4/t4 + n6/t6... + nM/tM;
where n2, n4, n6 .., n14 represent the number of
germinated seeds at times t2, t4, t6 ., t14 (in days).
Final germination percentage (FGP) was calculated as a percent of the total number of seeds germinated during the 14 days over the total number of seeds planted. At the 28th day (14 days after the termination of germination count), the longest shoots and roots of six randomly selected seedlings from each pot were measured using a draftsman ruler to obtain seedling shoot length (SSL) and seedling root length (SRL), respectively. Before measurement, the seedlings were uprooted and washed carefully to remove soil and debris. Statistical analysis
Data analysis was carried out using SAS (version 9.0) statistical software (SAS Institute Inc., USA) where two way analysis of variance (ANOVA) was done. Whenever treatment differences were significant, means were separated using the Least Significant Difference (LSD) test.
RESULTS
Germination rate
Analysis of variance exhibits significant differences among the sorghum genotypes, NaCl salinity levels and their interaction with respect to germination rate. Our results indicated that genotype ICSV-111 followed by S-35 and Meko gave significantly higher mean germination rate than the other genotypes in the control (Table 1). Genotypes Meko, ICSV-111, Teshale and Abshir showed
significantly faster germination rate than the other genotypes in the 2, 4 and 8 dS m-1 treatments. In the highest NaCl salinity level (16 dS m-1), Meko, Gambella1107 and ICSV-111 showed significantly higher mean germination rate than the other genotypes tested. On the other hand, genotypes ESH-2 and Gobye showed significantly slower mean germination rate than the rest of the genotypes at all salinity levels (Table 1). The remaining genotypes were intermediate in their response to NaCl salinity. Final Germination Percentage
Analysis of variance for final germination percentage was found to be highly significant with respect to genotypes, NaCl salinity levels and their interaction. Table 2 indicates that the percent germination generally decreased with increasing salt concentration and degree of reduction varied with the salinity levels and genotypes of sorghum. Remarkable reduction in germination percent was observed at higher levels from 8 to 16 dS/m of salt concentrations as compared to control. Tolerance of the sorghum genotypes against salinity stress showed marked differences.
Genotypes S-35, ICSV-111, Meko, Melkam and Teshale showed significantly higher mean final germination percentage than the other genotypes while ESH-2 and Gobye showed slower mean final germination percentage than the rest in the control,
2 and 4 dS m-1 treatments. The sorghum genotypes such as Gambella1107, Abshir and ICSV-111 showed tolerant behavior and rest of the genotypes seemed to be salt sensitive at 8 dS m-1 salt concentration. Sorghum genotypes such as Meko, Gambella1107, ICSV-111 and Melkam showed significantly higher mean final germination percentage than the other genotypes in the 16 dS m-1 salinity level. A large reduction is observed in ESH-2 and 97MW6130 as
salt concentration increase from 8 to 16 dS m-1 (Table 2).
Effect of salinity on seedling growth
The experiment was conducted to observe the influence of salinity on the seedling growth of sorghum genotypes. The results obtained indicate that increasing salt concentration caused delayed emergence of plumule and redicle as compared to control. At the early seedling stage, reduction in root length and shoot length clearly demonstrated genetic variation in vegetative growth responses to salinity among sorghum genotypes. The average length of root and shoot for 11 genotypes of sorghum shows a strong inhibition with the increasing salinity levels particularly at high salt concentration (8 to 16 dS m-1). Tables 3 and 4 indicate that the reduction of shoot and root growth in ESH-2, Gobye and 97MW6130 was highest in comparison with Abshir, Melkam and 76T1#23 at 2, 4 and 8 dS m-1 salinity levels. These results showed sign of great inhibition of shoot and root growth with salt treatments. Genotypes Meko, ICSV-111 and Gambella1107 had more length of shoot while genotypes Gambella1107, Meko and Melkam had more length of roots as compared to other genotypes and showed tolerant behavior up to 16 dS m-1.
DISCUSSION
The main purpose of the study was to identify salt tolerant genotypes in sorghum germplasm at early vegetative growth stages under different levels of salinity. The analysis of variance for genotypes, NaCl salinity levels and their interaction was found to be significant for all parameters; reflecting that all the genotypes responded differently to salt stress with respect to all parameters.
Table 1 Mean germination rates of sorghum genotypes under different NaCl levels
Salinity (NaCl) level (dS m-1)
Genotype 0 2 4 8 16 Mean
S-35 7.95 7.49 8.19 7.15 1.31 6.42
ESH-2 2.03 1.81 2.26 1.69 0.03 1.56
Gamb* 6.55 5.23 6.28 7.00 2.07 5.43
Melkam 7.18 7.56 7.67 6.21 1.56 6.04
Gobye 2.68 3.65 2.55 2.55 0.39 2.36
97M* 4.59 6.07 5.08 4.18 0.43 4.07
Meko 7.78 9.07 8.68 6.57 2.31 6.88
76T1#23 4.55 6.40 5.96 5.15 1.54 4.72
ICSV-111 8.37 8.25 8.89 7.77 1.72 7.00
Abshir 7.49 8.07 7.45 8.21 0.71 6.39
Teshale 7.72 8.24 8.32 6.94 1.22 6.49
Mean 6.08 6.53 6.48 5.76 1.21
LSD (P<_0.05)
S=0.23 G =0.35 S x G = 1.07 CV(%)=9.15
S=salinity levels; G=genotypes; CV=coefficient of variation; 97M*=97MW6130; Gamb*= Gambella1107
Table 2 Mean final germination percentage (%) of sorghum genotypes under different NaCl levels
Salinity (NaCl) level (dS m-1)
Genotype 0 2 4 8 16 Mean
S-35 94.47 88.87 89.57 80.53 22.17 75.12
ESH-2 36.07 24.97 24.97 24.97 2.77 22.75
Gamb* 75.00 72.23 66.67 91.67 36.10 68.33
Melkam 80.43 88.90 86.13 75.00 27.73 71.64
Gobye 41.67 41.67 36.10 36.07 11.07 33.32
97M* 69.43 74.97 63.90 61.07 8.30 55.53
Meko 83.37 97.23 91.67 80.53 41.63 78.89
76T1#23 69.47 72.17 72.20 63.87 22.20 59.98
ICSV-111 91.67 88.90 97.23 83.30 27.73 77.77
Abshir 80.57 86.10 83.30 86.10 11.10 69.43
Teshale 83.33 86.10 94.47 77.73 19.27 72.18
Mean 73.22 74.74 73.29 69.17 20.91
LSD (P<_0.05)
S=1.65 G =2.45 S x G = 1.07 CV(%)=6.41
S=salinity levels; G=genotypes; CV=coefficient of variation 97M*=97MW6130; Gamb*= Gambella1107
Table 3 Mean seedling shoot length (cm 6 plants-1) of sorghum genotypes under different NaCl levels
Salinity (NaCl) level (dS m-1)
Genotype 0 2 4 8 16 Mean
S-35 205.67 199.67 191.67 132.00 0.00 145.80
ESH-2 137.83 130.67 117.00 38.00 0.00 84.70
Gamb* 214.83 203.00 153.67 104.33 26.33 140.43
Melkam 206.67 211.67 204.67 155.00 23.00 160.20
Gobye 139.67 140.00 96.33 60.33 0.00 87.27
97M* 209.50 180.67 197.67 119.00 0.00 141.37
Meko 215.00 204.33 187.00 122.67 31.00 152.00
76T1#23 254.00 250.33 177.67 144.33 16.33 168.53
ICSV-111 200.33 222.17 163.67 130.67 28.67 149.10
Abshir 220.83 203.67 205.67 145.33 0.00 155.10
Teshale 192.67 192.00 185.00 130.67 11.33 142.33
Mean 199.73 194.38 170.91 116.57 12.42
LSD (P<_0.05)
S=5.13 G=7.61 S x G = 10.8 CV(%) =9.12
S=salinity levels; G=genotypes; CV=coefficient of variation; 97M*=97MW6130; Gamb*= Gambella1107
Table 4 Mean seedling root length (cm 6 plants-1) of sorghum genotypes under different NaCl levels
Salinity (NaCl) level (dS m-1)
Genotype 0 2 4 8 16 Mean
S-35 144.33 133.67 124.33 84.67 0.00 97.40
ESH-2 93.67 54.33 57.00 10.67 0.00 43.13
Gamb* 166.67 134.50 87.67 46.33 10.00 89.03
Melkam 140.33 119.67 134.17 50.67 7.67 90.50
Gobye 65.83 75.00 50.00 35.17 0.00 45.20
97M* 132.67 78.67 103.67 39.33 0.00 70.87
Meko 161.33 142.50 104.67 59.00 9.67 95.43
76T1#23 146.67 144.00 82.00 34.67 0.00 81.47
ICSV-111 140.00 133.33 140.00 68.67 3.33 97.07
Abshir 123.83 102.17 102.00 35.00 0.00 72.60
Teshale 167.33 171.33 130.67 58.67 3.00 106.20
Mean 134.79 117.20 101.47 47.53 3.06
LSD (P<_0.05)
S=2.95 G=4.37 S x G=29.16 CV(%)=7.96
S=salinity levels; G=genotypes; CV=coefficient of variation; 97M*=97MW6130; Gamb*= Gambella1107
Increment in NaCl salinity level caused significant reduction in germination rate (GR) of sorghum genotypes. However, the reduction was sharp at 8 and 16 dS m-1 NaCl salinity levels. On the basis of germination rate for the soils having 16 dS m-1of salinity, the genotypes Meko, Gambella1107 and ICSV-111 can be recommended. It is a well documented fact that if a crop stand is good then the yield will be higher than that crop with poor stand. There are many reports which indicate that the genotypes which maintained higher germination under saline conditions produced higher biomass and yield (Ashraf et al., 2006; Krishnamurthy et al., 2007). The reduction in germination rate could be due to toxic effects of certain ions and also higher concentration of salt reduces the water potential in the medium which hinders water absorption by germinating seeds and thus reduces germination (Jamil et al., 2006). Results of Abari et al., (2011) also confirmed the present findings. Higher salinity level retard seed germination and root emergence due to osmotic effect which is deleterious and prevent the plants from maintaining their proper nutritional requirements necessary for their healthy growth (Krishnamurthy et al., 2007).
The data regarding final germination percentage indicated that the genotypes Meko, Gambella1107, ICSV-111 and Melkam showed significantly higher FGP in the highest (16 dS m-1) NaCl salinity level while genotypes ESH-2 and 97MW6130 showed significantly reduced FGP than the other genotypes tested. These differences might be due to the genetic variation among genotypes (Krishnamurthy et al., 2007). Overall, final germination rate of all genotypes exhibited decline with all increasing level of salinity. Reduction in plant growth due to the adverse effect of salinity has been also reported in many other crops (Abari et al., 2011; Hakim et al., 2010; Ates and Tekeli 2007).
In the present experiment, effect of salinity on seedling growth particularly that of the shoot length showed that Meko, ICSV-111 and Gambella1107 could be grown as salt tolerant varieties up to 16 dS m-1 NaCl salinity because they produced the maximum shoot length and it is well known fact that tolerant genotypes have a higher mean seedling shoot length under saline environment than sensitive genotypes (Bashir et al., 2011; Hakim et al., 2010). Reduction of seedling shoot length is a common phenomenon in many crop plants that are grown under saline conditions
(Amin et al., 1996). The reason for the reduced shoot development could be due to the toxic effects of the NaCl used as well as the unbalanced nutrient uptake by the seedlings. Another possible reason may be slowing down of the water uptake by the plant because of inhibition of root and shoot elongation by high salinity (Werner and Finkelstein 1995).
The results of the current study also showed increasing the amount of salt caused significant reduction in seedling root length of most of the genotypes. Genotypes Gambella1107, Meko and Melkam produced significantly higher seedling root length than the other genotypes in the 16 dS m-1 NaCl salinity level though most of the genotypes could not produce sufficient root growth. Neumann
(1995) indicated that salinity can rapidly inhibit root growth and hence capacity of water uptake and essential mineral nutrition from soil. Plants vary in their tolerance to salinity that depends on their efficiency of root system with regards to nutrient absorption and K, Na uptake discrimination (Khan et al., 1995) or mainly the translocation of sodium and chloride ions. In sorghum sodium mainly remained in roots as compared to shoots (Khan & Ashraf 1990) that might be due to the mechanism of retention more of Na+ in roots (Khan et al., 1995) as compared to other plant parts. Keeping in view the above results it is clear that salinity reduced all growth parameters at all levels. Reduction in growth may be due to lower transport rate of essential ions like NO3- that reduced the N compounds and increased Na+ in plant under high salinity (Hamid et al., 2008).
Generally, one of the important strategies plant scientists adopted to overcome salinity is to exploit genetic variability of the available germplasm to identify tolerant genotype that may sustain a
reasonable yield on salt affected soils (Ashraf et al., 2006). Germination and seedling characteristics are the most viable criteria used for selecting salt tolerant genotypes due to the fact that the final plant stand of a crop primarily depends on seedling characteristics (Bybordi and Tabatabaei 2009). Hence based on the parameters evaluated; the above sorghum genotypes which had significantly better results at both germination and seedling growth stages could germinate and establish themselves effectively on moderately saline soils. These genetic differences presents a good basis to provide information about genotypes of sorghum that could be grown in salt-affected areas to chance crop productivity, and also for determining degree of salt tolerance in different plant species to further utilize them in breeding programme.
ACKNOWLEDGMENTS
Our great gratitude and thanks goes to Ato Elias Abrahim for his genuine technical support during the experiment. We would like to express our heartfelt thanks to the Ethiopian Ministry of Education for its financial assistance. Moreover, we are greatly indebted to Haramaya University, Department of Plant Sciences, for providing the greenhouse and also the Melkassa Agricultural Research Center (MARC), Ethiopia for supplying all the sorghum genotype seeds.
REFERENCES
Abari, A.K., Nasr, M.H., Hojjati, M. and Bayat, D.
(2011). Salt effects on seed germination and seedling emergence of two Acacia species. African Journal of Agricultural Research. 5(1): 52-56.
Ahmed, S. (2009). Effect of soil salinity on the yield and yield Components of mungbean. Pakistan Journal of Botany. 41(1): 263-268.
Amin, M., Hamid, A., Islam, M.T. and Karim, M.A.
(1996). Root and shoot growth of rice cultivars in response to salinity. Bangladesh Agronomy Journal. 6: 41- 46.
Asfaw, A. (2007a). Assesment of Yield Stability in Sorghum. African Crop Science Journal. 15(2): 83 - 92.
Asfaw, A. (2007b). The role of introduced sorghum and millets in Ethiopian agriculture. SAT eJournal. 3(1).
Ashraf, M.Y., Akhtar, K., Hussain, F. and Iqbal, J. (2006). Screening of different accession of three potential grass species from Cholistan desert for salt tolerance. Pakistan Journal of Botany. 38: 1589-1597.
Ates, A. and Tekeli, A.S. (2007). Salinity tolerance of Persian Clover (Trifolium resupinatum Var. Majus Boiss) lines at germination and seedling stage. Warsaw Journal of Agricultural Sciences. 3(1): 71-79.
Bashir, F., Ali, M., Hussain, K., Majeed, A. and Nawaz, K. (2011). Morphological variations in sorghum (Sorghum bicolor L.) under different levels of Na2SO4 salinity. Botany Research International. 4(1): 01-03.
Bybordi, A. and Tabatabaei, J. (2009). Effect of salinity stress on germination and seedling properties in Canola Cultivars (Brassica napus L.). Notulae Botanicae Horti Agrobotanici Cluj-Napoca. 37(1): 71-76.
CSA (Central Statistics Authority). (2010). Agricultural Sample Survey 2009/2010, Volume IV. Report on area and production of crops. Addis Ababa, 156pp.
Endalew, T., Mebeaselassie, A. and Kindie, T.
(2012). Response of sorghum (Sorghum biclor (L) Moench) genotypes to sodium chloride
levels at early growth stages. African Journal of Agricultural Research.7(43): 5711-5718.
FAO. (2000). [Online] Available
http://www.fao. orglag/agl/agll/spush/topic. ht m. November, 2000. Accessed 13 May 2011.
Flowers, T.J. (2004). Improving crop salt tolerance. Journal of Experimental Botany. 55(396): 307319.
Geressu, K. and Gezahagn, M. (2008). Response of some lowland growing sorghum (Sorghum bicolor L. Moench) accessions to salt stress during germination and seedling growth. African Journal of Agricultural Research. 3(1): 044-048.
Hakim, M.A., Juraimi, A.S., Begum, M., Hanafi, M.M., Ismail, M.R. and Selamat, A. (2010). Effect of salt stress on germination and early seedling growth of rice (Oryza sativa L.). African Journal of Biotechnology. 9(13): 19111918.
Hamid, M., Ashraf, M.Y., Rehman, K.U. and Arshad, M. (2008). Influence of salicylic acid seed priming on growth and some biochemical attributes on wheat growth under saline conditions. Pakistan Journal of Botany. 40(1): 361-367.
Hawando, T. (1995). The survey of the soil and water resources of Ethiopia. UNU/Toko, 218pp.
ICRISAT (International Crops Research Institute for the Semi-Arid Tropics). (2009). [Online]
Available on the website
http://www.icrisat.org/.
ICRISAT (International Crops Research Institute for the Semi-Arid Tropics). 2009. [Online] Available on the website http://www.icrisat.org/.
Iqbal, A., Sadia, B., Khan, A.I., Awan, F.S., Kainth, R.A. and Sadaqat, H.A. (2010). Biodiversity in
the sorghum (Sorghum bicolor L. Moench) germplasm of Pakistan. Genetics and Molecular Research. 9(2): 756-764.
Jamil, M., Lee, D.B., Jung, K.Y., Ashraf, M., Lee, S.C. and Rha, E.S. (2006). Effect of Salt (NaCl) Stress on Germination and Early Seedling Growth of Four Vegetables Species. Journal of Central European Agriculture. 7(2): 273-282.
Khan, A.H. and M.Y. Ashraf. (1990). Effect of sodium chloride on growth and nitrogen metabolism of sorghum. Acta Physiologiae Plantarum. 12: 233-238.
Khan, A.H., Ashraf, S.S, Naqvi, B. K. and Ali. M. (1995). Growth, ion and solute contents of sorghum grown under NaCl and Na2SO4 salinity stress. Acta Physiologiae Plantarum. 17(3): 261-268.
Khatoon, T., Hussain, K., Majeed, A., Nawaz, K. and Nisar, M.F. (2010). Morphological Variations in Maize (Zea mays L.) Under Different Levels of Nacl at Germinating Stage. Warsaw Agricultural Science Journal. 8(10): 1294-1297.
Kidane, G., John, H.S., Della, E.M., Eliud, O. and Thomas, W. (2001). Agricultural Technology for the Semi-Arid Africa Horn. Country Study. Ethiopia. Country report (revised) from Intsormil publication 003 Volume 2, 197pp.
Krishnamurthy, L., Serraj, R., Hash, A.J. and Reddy, B.V. (2007). Screening sorghum genotypes for salinity tolerant biomass production. Euphytica.156: 15-24.
Maguire, J.D. (1962). Speed of germination-aid in selection and evaluation for seedling emergence and vigor. Crop Science. 2: 176-177.
Mamo, T., Richter, C. and Heiligtag, B. (1996).
Salinity effects on the growth and ion contents of some chickpea (Cicer arietinum L.) and lentil (Lens culinaris Medic.) varieties. Journal of Agronomy and Crop Science. 176: 235-247.
Momayezi, M.R., Zaharah, A.R., Hanafi, M.M. and Razi, I.M. (2009). Seed Germination and Proline Accumulation in Rice (Oryza sativa L.) as Affected by Salt Concentrations. Pertanika Journal of Tropical Agricultural Science. 32(2): 247-259.
Neumann, P.M. (1995). Inhibition of root growth by salinity stress: toxicity or adaptive biophysical response? In: Baluska, F., M. Ciamporova, O. Gasparikova and P.W. Barlow, (Eds.), Structure and Function of Roots: Developments in Plant and Soil Sciences. Kluwer Academic Pubishers, Netherlands, pp 299-304.
Prakash, R., Ganesamurthy, K., Nirmalakumari, A. and Nagarajan, P. (2010). Heterosis for fodder yield in sorghum (Sorghum bicolor L. Moench). Experimental Journal of Plant Biology. 1(3): 319-327.
Wang, W., Vinocur, B. and Altman, A. (2003). Plant responses to drought, salinity and extreme temperatures: towards genetic engineering for stress tolerance. Planta. 218: 1-14.
Werner, J.E. and Finkelstein, R.R. (1995). Arabidopsis mutants with reduced response to NaCl and osmotic stress. Physiologia Plantarum. 93: 659-666.
Yakubu, H., Ngala, A.L. and Dugje, I.Y. (2010). Screening of Millet (Pennisetum glaucum L.) Varieties for Salt Tolerance in Semi-Arid Soil of Northern Nigeria. Warsaw Journal of Agricultural Sciences. 6(4): 374-380.
