Sky Journal of Agricultural Research Vol. 2(10), pp. 120 - 125, November, 2013 Available online http://www.skyjournals.org/SJAR ISSN 2315-8751 ©2013 Sky Journals
Full Length Research Paper
Salt tolerance study of six cultivars of sugar beet (Beta vulgaris, l.) during seedling stage Kandil A. A., Sharief A. E., Abido W. A. E and Areeg M. Awed Department of Agronomy, Faculty of Agriculture, Mansoura University, Egypt. Accepted 11 October, 2013
In order to study response of six sugar beet genotypes (Raspoly, Nada, Strube, Almaz, Toro, Oskarpoly) under seven salinity levels (control treatment, 1500, 3000, 4500, 6000, 7500 and 9000 ppm NaCl) and seed soaking in gibberellic acid levels (control, 100 ppm and 200 ppm of GA3) were studied its effect on early seedling stage. A laboratory experiment in factorial arrangement was conducted by using randomize complete block design with four replications. Root and plumule of seedling lengths and root to shoot ratio, seedling height reduction and response index were measured. Seed soaked in GA3 significantly affected shoot and root lengths (cm), seedling height reduction (SHR %), response index (RI) and root to shoot ratio. Highest averages of these characters were produced from soaking sugar beet seed in 200 ppm of GA3. While, the lowest values of these characters were produced from the control treatment. Sugar beet cultivars significantly differed in all studied characters. Highest averages of these characters were recorded with Raspoly cultivar, followed by Nada and Strube cultivars without significant differences between them. Result of means comparison showed that all studied genotypes recorded a decrease in root and shoot length due to salinity stress increment. Increasing salinity concentration from 0 to 9000 ppm significantly decreased shoot and root lengths (cm) and root to shoot ratio. On the other hand, SHR and RI were increased with increasing salinity concentrations. It could be summarized that seedling parameters were enhanced under salinity stress when seed priming of Raspoly cultivar with 200 ppm GA3. Key words: Sugar beet cultivars, GA3 Levels, salinity stress, seedling parameters.
INTRODUCTION Sugar beet contributes with 45% of world sugar production. Salinity is one of the major stress factors which limit crop production in most of the arid and semiarid regions of the world (Anwer et al., 2001). The excessive increase in population in Egypt needs to increase the total yield of sugar beet in order to overcome this lack in production through its cultivation in the newly reclaimed lands especially under saline soil conditions. Under Egyptian conditions there was shortage in sugar production. Increasing sugar beet productivity could be achieved through sown promising genotypes and sand sowing of sugar beet in newly reclaimed soils.
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Emergence of sugar beet (Beta vulgaris L.) seedlings is a major factor limiting satisfactory stand establishment. The variability in emergence is caused in part by differences in seedling vigor between cultivars (Habib, 2010). Plant growth regulators may enhance germination and adaptation of plants to stress conditions (Banyal and Rai, 1983). Gibberellic acid and kinetin have been reported to increase seedling growth (Kaur et al., 1998). Water uptake could be improved in sugar beet seeds and salt tolerance at early seedling stage (Jamil and Rha, 2007). The exogenous application of gibberellin increased germination percentage and improved length and fresh weight of roots and shoots under salt treatment (Nasri et al., 2012). GA3 increased germination percentage under salt stress and improved fresh and dry weight of plumule and radical along with an increase in their length (Iqbal et
al., 2001). The present investigation was aimed with the objectives to determine the response of sugar beet -1 genotypes to salinity stress (100, 150 and 200 mg L ) with GA3 on seedling stage under controlled conditions. Sidhu et al. (1993), Centeno et al. (2001), Lgbal et al. (2001), Jamil and Rha (2007), and Nasri et al. (2012) soaked sugar beet fruit in GAЗ stimulated shoot and root lengths compared with control treatment. Sugar beet cultivars markedly differed in their seedling characters in this connection, Rao et al. (2002) indicated that some cultivars may have a degree of salt adaptation due to water retention capacity, membrane permeability and osmo protection and or geneticel and morphological factors. Jafarzadeh and Aliasgharzad (2007) reported that among four cultivars of sugar beet cultivars tested 7233 and IC2 cultivars had highest average of root and shoot lengths and root to shoot ratio. Mostafavi (2012) found that all sugar beet under studied (H30916, H30917, H30918, H30919, H30938 and H30973) i.e. were differed at early seedling growth. Salinity is a major factor limiting seedling characters, affecting about 95 million hectares worldwide. In this connection, Bohnert et al. (1995) reported that salinity stress can affect seedling characters through osmotic effect. Neumann (1995) showed that salinity is one of the major obstacles to affecting seedling characters in crop growing areas throughout the world. Crop establishment depend on an interaction between seedbed environment and seed quality (Ghoulam and Fares, 2001; Kafi and Gholdani, 2001; Soltani et al., 2001; Khajeh-Hosseini et al., 2003; Jamil et al., 2006; Hakim et al., 2010). KhajehHosseini et al. (2003), Jamil et al. (2006), Munns et al. (2006) showed that salinity is a major problem that has negative effects on seedling emergence by creating osmotic potential external to the seed and preventing water uptake through the toxic effect of Na+ and Cl- on seedling characters. Maghsoudi Moud and Maghsoudi (2008) and Pattanagule and Thitisaksakul (2008) found that salt stress affects many physiological aspects of plant growth. Khavari-Nejad et al. (2008), Hajiboland et al. (2009), Dadkhah (2010), and Saadat et al. (2012) indicated that germination characters i.e. root and shoot length and root and shoot ratio were decreased as salinity concentration increased. On the other hand, SHR and RI were increased. Regarding to the interaction effect between cultivars and salinity stress in this connection, Ghoulam et al. (2002) indicated that low tolerance to salinity is observed during seedling emergence, but there are variations between sugar beet genotypes at high salt stresses. Jamil and Rha (2007) indicated that water uptake of primed seeds was increased significantly with increasing concentration of GA3 as compared to the control. Atia et al. (2009) indicated that the inhibitory effect of salt stress on seed germination is alleviated by phytohormones, including gibberellic acid (GA3). Jafarzadeh and Aliasgharzad (2007), Pakniyat and Armion (2007),
Hajiboland et al. (2009) and Mostafavi (2012) found that seedling characters were significantly affected by cultivars and salinity levels. Khavari-Nejad et al. (2008) showed that with increasing NaCl concentration root and shoot lengths were significantly increased in ET5 cultivar in comparison with other cultivars. Also in 25 and 50 mM NaCl in ET5 cultivar, seedling parameters were significantly increased. Saadat et al. (2012) found that effects of water potential, type of salt composition and cultivar on root and shoot length, SHR, RI and root to shoot ratio were significant. The present investigation was aimed with the objectives to determine the response of sugar beet genotypes to salinity stress under seed priming with GA3 on seedling stage under controlled conditions. MATERIALS AND METHODS A laboratory experiment was laid out in the Laboratory of Agronomy Department, Faculty of Agriculture at Mansoura University during the period from November and December 2011 to study the response of some sugar beet (Beta vulgaris L.) cultivars to seedling growth characters under salinity levels and some growth regulators to confirm the seedling growth performance for salinity tolerance among sugar beet cultivars. Treatments and experimental design The experiment was arranged in factorial experiment in Randomized Complete Block Design (RCBD) with three replications, the first factor included three concentration of plant growth regulators i.e. gibberellic Acid (GAЗ 10%) i.e. (0, 100, 200 ppm), seed of all cultivars were soaking in each concentration for about 8 h. The second factor included six different sugar beet cultivars i.e. (Raspoly, Nada, Strube, Almaz, Toro, Oskarpoly) which were obtained from Research Section of Sugar Research Institute ARC, Ministry of Agriculture, Egypt. All cultivars were stored under normal conditions in paper bags. The third factor included seven different NaCl levels are presented in Table 1. Seeds of cultivars were surface sterilized by immersion for 5 minutes in sodium hypochlorite solution, then repeatedly washed with deionized water. Fifty seeds of uniform size in each treatment for each cultivar were allowed to germinate on a filter paper in 9 cm diameter Petri dishes. Each filter paper was moistened with a water solution at seven different NaCl concentrations. Thus, the whole experiment comprised 378 Petri dishes arranged in factorial experiment in randomized complete block design (RCBD). The Petri dishes were placed in a growth chamber for 14 days at 28 ±1 °C for germination. Seedling characters After 14 days ten seedlings were selected from each
Table 1. Salt concentrations (ppm) and weight of NaCL (g/L). Salt concentrations (ppm) 0 (distilled water as the control) 1500 3000 4500 6000 7500 9000
Weight of NaCL (g/L) 1.464 2.929 4.394 5.859 7.324 8.789
Table 2. Means of shoot and root lengths, seedling height reduction (SHR), response index (RI) and root to shoot ratio as affected by gibberellic acid levels, cultivars, salinity concentrations and their interactions. Characters Shoot length treatments (cm) A: Gibberellic acid levels (ppm): Control 3.16 100 ppm 3.33 200 ppm 3.50 F.test. ** LSD 5% 0.04 LSD 1% 0.05 B:-Cultivars performance: Raspoly 4.51 Nada 3.81 Strube 2.30 Almaz 3.52 Toro 3.21 Oskarpoly 2.63 F.test. ** LSD 5% 0.19 LSD 1% 0.25 C: Salinity Concentration (ppm): Control 4.72 1500 ppm 4.07 3000 ppm 3.60 4500 ppm 3.23 6000 ppm 2.88 7500 ppm 2.61 9000 ppm 2.18 F.test. ** LSD 5% 0.15 LSD 1% 0.20 D:- Interaction F.test : AXB ** AXC ** BXC ** AXBXC NS.
Root length (cm)
Seedling height reduction
Response index
Root to shoot ratio
1.63 1.78 1.97 ** 0.04 0.06
0.00 44.15 62.28 ** 0.54 0.71
0.000 0.093 0.178 ** 0.007 0.009
0.47 0.49 0.51 ** 0.02 0.03
3.26 2.04 1.08 1.75 1.39 1.26 ** 0.39 0.51
43.84 36.66 31.17 36.14 33.69 31.35 ** 0.76 1.00
0.114 0.103 0.068 0.093 0.085 0.079 ** 0.009 0.013
0.69 0.50 0.44 0.46 0.39 0.45 ** 0.04 0.05
3.43 2.54 2.03 1.62 1.26 0.99 0.72 ** 0.18 0.23
0 22.52 28.35 34.88 41.58 48.62 55.14 ** 0.82 1.08
0.050 0.063 0.070 0.087 0.097 0.121 0.147 ** 0.011 0.014
0.72 0.51 0.54 0.48 0.41 0.35 0.31 ** 0.04 0.05
NS. ** ** NS.
** ** ** NS.
** ** ** NS.
NS. NS. NS. NS.
N. S.= Not significant, *= significant at 5%, **= significant at 1%
replicates and then seedlings were evaluated as follows: 1-Shoot length (cm): The length of the ten seedlings from the seed to the tip of the leaf blade were recorded and expressed in centimeters (cm) as the shoot length. 2Root length (cm): The root length of ten seedlings from
the seed to the tip of the root and recorded and expressed in centimeters (cm) as the root length. 3-Seedling height reduction (SHR): The seedling height reduction (SHR) was calculated using the following Islam and Karim (2010) equation (1):
1 4-Response index (RI): RI was calculated at the end of germination according to the equation described by Pollissier (1993) as the following equation (2): 2 Where test = is the number of seed germinated from test treatment. Control = number of seeds germinated from control. If -1 < RI > 0, the effect is inhibition, If 0 < RI > 1, the effect is stimulation. 5- Root to shoot ratio: It was calculated by divided root length on shoot length.
Statistical analysis All data of this study were statistically analyzed according to the technique of variance (ANOVA) for factorial experiment in randomized (RCBD) by Gomez and Gomez (1984). Least Significant Difference (LSD) method was used to test the differences between treatment means at 5% and 1% levels of probability as described by Snedecor and Cochran (1980). The data were analyzed statistically following RCBD design by MSTAT-C computer package developed by Russel (1986).
Results and Discussion Plant growth regulators effect Soaking sugar beet seed in GA3 significantly affected shoot and root lengths (cm), SHR%, RI and root to shoot ratio as shown in Table 2. Highest averages of these characters were produced from soaking sugar beet seeds in 200 ppm of GA3. It could be noticed that seed soaked in GA3 at 200 ppm significantly increased shoot length and root length by 9.71% and 17.25 %, respectively compared with the control treatment. Seed soaked in GA3 at 200 ppm significantly increased SHR, RI and root to shoot ratio percentage by 100 %, 100% and 4.6%, respectively compared with the control treatment. The desirable effect on characters as result of using GA3 might be attributed to development processes such as hypoctyle elongation. In addition, enhancing the mobilization of starch reserves and increasing amylase activity in cotyledons, which ultimately leads to better
seedlings growth. Kaur et al. (1998) reported that gibberellic acid increase seedling growth under salt stress by enhancing the mobilization of starch reserves and increasing amylase activity in cotyledons, which ultimately leads to better seedlings growth. The stimulatory effect of gibberellic acid on seedling growth has been also reported in wheat (Akman, 2009). These results are in good agreement with those reported by Sidhu et al. (1993), Lgbal et al. (2001), Asahina et al. (2002), Jamil and Rah (2007), and Nasri et al. (2012).
Cultivars performance All studied sugar beet cultivars significantly differed in shoot and root lengths (cm), SHR%, RI and root to shoot ratio as shown in Table 2. Highest averages of shoot length (cm) and root length (cm), SHR, RI and root to shoot ratio were recorded with Raspoly cultivar, (4.51 cm, 3.26 cm, 43.84%, 0.11 and 0.69, respectively) followed by Nada and Almaz cultivars (3.81 and 3.52 cm respectively). However, the shortest shoot was recorded from sown Strube cultivar (2.30 cm). It could be stated that Raspoly cultivar exceeded Strube, Oskarpoly, Toro, Almaz and Nada cultivars in shoot and root lengths, SHR, RI and root to shoot ratio by (49.00, 41.68, 28.82, 21.95 and 15.52%), (66.87, 61.34, 57.36, 46.31 and 37.42%), (28.90, 28.48, 23.15, 17.56 and 16.37%), (45.45, 36.36, 27.27, 18.18 and 9.09%) and (25, 24, 30, 23 and 19%), respectively. The differences between studied cultivars in seedling parameters might be due to genetical factors and heredity variation among the five sugar beet cultivars. The variation among genotypes showed that seedling parameters decreased with the increase in NaCl concentration under all studied genotypes. However H30917 and H30938 cultivars performed better than other cultivars (Mostafavi, 2012). Some cultivars may have a degree of salt adaptation due to water retention capacity, membrane permeability and osmo protection and or genetical and morphological factors (Rao et al., 2002). Similar results were confirmed by Khajeh-Hosseini et al. (2003), Jamil et al. (2006), Munns et al. (2006) Jafarzadeh and Aliasgharzad (2007).
Salinity concentrations Results presented in Table 2 clearly showed that shoot and root lengths (cm), SHR, RI and root to shoot ratio significantly affected by salinity concentrations. Increasing salinity concentrations from 0 to 9000 ppm significantly decreased all studied characters, except SHR and RI values were increased with increasing salinity concentrations. Increasing salinity concentrations from 0 to 9000 ppm significantly decreased shoot and root lengths and root to shoot ratio by (13.77, 23.72, 31.56, 38.98, 44.70 and 53.81%), (25.94, 40.81, 52.76,
Figure 1. Averages of shoot length as affected by the interaction between sugar beet cultivars and gibberellic acid concentration.
Figure 2. Averages of seedling height reduction as affected by the interaction between cultivars and gibberellic acid concentration.
63.26, 71.13 and 79.00%) and (29.16, 25.00, 33.33, 43.05, 51.38 and 56.94%), respectively compared with the control treatment. Moreover, decreasing salinity concentrations from 9000 to 1500 ppm significantly decreased SHR by (11.82, 24.59, 36.74, 26.79 and 59.15%), respectively compared with 9000 ppm. Increasing salinity concentrations from 0 to 9000 ppm significantly increasing RI by 20.63, 28.57, 42.52, 48.45, 58.67 and 65.98% compared with the control treatment. Salinity affects growth through reducing water potential and toxicity of specific ions such as sodium, chloride along with reducing required dietary ions such as calcium and potassium (Ghoulam and Fares, 2001). The inhibitory influence of salinity on sugar beet seeding characters was mostly due to osmotic effect and a small portion of the inhibition could be attributed specific ionic effect (Saadat et al., 2012). These results are in good
accordance with those reported by Bohnert et al. (1995), Ghoulam and Fares (2001), Khajeh-Hosseini et al. (2003), Jamil et al. (2006), Khavari-Nejad et al. (2008), Maghsoudi Moud and Maghsoudi (2008) and Dadkhah (2010).
Interaction effects Results concluded that the interaction between the studied cultivars of sugar beet and seed soaking in GA3 levels significantly affected shoot length (Figure 1), SHR (Figure 2) and RI (Figure 3). Moreover, Results revealed that seed soaking of Raspoly cultivar in GA3 at concentration of 200 ppm produced highest shoot length, SHR and RI which were 4.71 cm, 78.01% and 0.22, respectively followed by Nada and Almaz cultivars at the
Figure 3. Averages of response index as affected by the interaction between cultivars and gibberellic acid concentration.
Figure 4. Averages of shoot length as affected by the interaction between salinity concentration and gibberellic acid level.
same GA3 rate without significant differences, which were (4.01 and 3.72 cm), (64.04 and 63.16%) and (0.20 and 0.17), respectively. However, lowest averages of these characters were recorded from sown Strube and Oskarpoly cultivars without seed soaking in GA3. These results are good in agreement with those reported by Ghoulam et al. (2002), Jafarzadeh and Aliasgharzad (2007), Jamil and Rha (2007), Hajiboland et al. (2009), and Saadat et al. (2012). Concerning the interaction between seed soaking in GA3 levels and salinity concentrations significantly affected shoot and root lengths (Figures 4 and 5), SHR (Figure 6) and RI (Figure 7). Highest averages of these characters were obtained from the control treatment and GA3 at 200 ppm (100% , 892, 5.09 cm, 3.82 cm,
respectively). Moreover, highest averages of SHR and RI were obtained from highest salinity concentration i.e. 9000 ppm and seed soaking in GA3 at 200 ppm (92.45% and 0.28, respectively). While, lowest values of these characters was obtained from the control treatment i.e. without salinity and without GA3. The type of cultivars has not any effects on the results. These results are good accordance with those reported by Ghoulam et al. (2002), Jafarzadeh and Aliasgharzad (2007), Jamil and Rha (2007), Hajiboland et al. (2009) and Saadat et al. (2012). Regarding to the interaction between sugar beet cultivars and salinity concentrations results showed a significant effect on shoot and root lengths (Figures 8 and 9), SHR (Figure 10) and RI (Figure 11). Moreover, Raspoly cultivar without salinity recorded highest
Figure 5. Averages of root length as affected by the interaction between salinity concentration and gibberellic acid level.
Figure 6. Averages of seedling height reduction as affected by the interaction between salinity concentration and gibberellic acid level.
Figure 7. Averages of response index as affected by the interaction between salinity concentration and gibberellic acid level.
Figure 8. Averages of shoot length as affected by the interaction between cultivars and salinity concentration.
Figure 9. Averages of root length as affected by the interaction between cultivars and salinity concentration.
Figure 10. Averages of seedling height reduction as affected by the interaction between sugar beet cultivars and salinity concentration.
Figure 11. Averages of response index as affected by the interaction between cultivars and salinity concentration.
averages of shoot and root lengths. In addition, the lowest percentages of these characters were recorded from sown Strube and Oskarpoly cultivars under highest salinity concentration i.e. 9000 ppm without significant differences between them. Results indicated that Raspoly cultivar under higher salinity concentration 9000 ppm recorded highest averages of SHR and RI. While, lowest averages of these characters were recorded from sown Strube cultivar under without salinity stress. These results are in good accordance with those reported by Ghoulam et al. (2002), Jafarzadeh and Aliasgharzad (2007), Jamil and Rha (2007), Khavari-Nejad et al. (2008), Hajiboland et al. (2009), and Saadat et al. (2012).
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