 |
| About Bioline | All Journals | Testimonials | Membership | News |
|
||||||
|
||||||
Vol. 4. No.4, pp. 423-432, 1996 Response of some varieties of durum wheat and tef to salt stress TEKALIGN MAMO, C. RICHTER* and B. HEILIGATAG^1
Agricultural Research Centre, P 0 Box 32, Debre Zeit, Ethiopia (Received 16 January, 1996; accepted 30 October, 1996)
Code Number: CS96083
Sizes of Files:
Text: 34.7K
Graphics: Line drawings (gif) - 16.9K
ABSTRACT Response to salinity of four varieties each of durum wheat (DZ-04-118, DZ-320, DZ-918, and Tob-2) and tef (DZ-01-354, DZ-010787, DZ-01-1445 and DZ-Cr-370) at germination and late vegetative stages was studied using four salinity levels (0, 2, 4 and 8 dSm^-1 NaCl). Results showed that genotypic differences existed in the response to salinity within both crops; germination at the maximum salt level was comparatively higher in durum wheat than in tef. Varietal differences were only significant in durum wheat. In both crops, tolerance to NaCl at germination stage was not confirmed at maturity; at the same time, all plant parameters (plant height, and shoot and root dry weights) were significantly reduced by NaCl application, especially above the 4 dSm^-1 level. Shoot and root NA contents increased while K contents decreased in response to increasing NaCl application. Among the durum wheat varieties, DZ-04-118 was the most sensitive and DZ-01-320 the most tolerant at high levels of NaCl. At the germination stage, tef variety DZ-01-1445 was the most sensitive while DZ-Cr-37 was the most tolerant. It is recommended that further studies should involve screening from large genetic populations of both crops in order to identify more salt tolerant lines that may be used in breeding activities. Key Words: Eragrostis tef, NaCl, salinity, Triticum durum RESUME Le resultat de quatre varietes du ble (DZ-04-118, DZ-918, et TOB-2). et (DZ-01-354, DZ-010787, DZ-011445 et DZ- cr 370 a la germination et les etapes vegetatives 8 dSm^-1 NaCl). Les resultats ont indique que les differences des genotypes ont existe dans le resultat a la salinite dans toutes les cultures; la germination jusqu'au niveau eleve du sol etait comparativement superieure dans le ble. Les differences des varietes etaient considerables dans le ble. Dans les deux cultures, la tolerance a la NaCl a l'etape de germination etait confirmee a la maturite; au meme moment, tous les parametres des plantes (la hauteur relative de la plante, poids relatifs de la pousse et racine de la plante) etaient considerablement reduits de l'application du NaCl, specialement au dessus du niveau de 4 dSm^-1. Les elements de la pousse et racine ont augmente pendant que les elements de k ont diminue en reaction a l'augmentation de l'application du NaCl. Parmi les varietes du ble DZ-04-118 etait la plus sensible et DZ-01-320 est la plus tolerante aux niveaux eleves du NaCl. A l'etape de la germination, les varietes Tef DZ-01-1445 etait la variete la plus sensible pendant que DZ-Cr-37 etait la plus tolerante parmi les quatre varietes. Il a ete recommande qu'en vue d'utiliser le test pour distinguer les populations genetiques em gramole quantite des cultures pour identifier les lignes les plus tolerantes qui pourront etre utilisees dans les activites de la reproduction. Mots Cles: Eragrostis tef, NaCl, salinite, Triticum durum INTRODUCTION Soil salinisation is a serious threat to irrigated crop production in the arid and semi-arid regions of the world. Epstein et al. (1980) reported that about one-third of the world's irrigated land is adversely affected by salinity.
During the past few decades, a lot of information has been published on salt tolerance of various crops, and the existence of genotypic differences in crop, response to salt stress. Some of the numerous studies conducted on the salt tolerance of cereals include barley (Greenway, 1962); maize (Lessani and Marschner, 1978); wheat (Kingsburry and Epstein 1984); sorghum (Francois et al., 1984; Richeter et al. 1995); oats (Verma and Yadava, 1986); pearl millet (Ashraf and McNeilly, 1987), rice (Yoshida, 1967); and triticale (Norrlyn and Epstein, 1984). However, literature on the salt tolerance of durum wheat is very meagre, and that on tef (Eragrostis tef (Zucc.) Trotter) is almost non-existent. According to Rhoades et al. (1992), durum wheat (Triticum durum Desf.) has a lower level of salt tolerance compared to bread wheat.
Durum wheat and tef are two of the commonly grown crops in Ethiopian agriculture. Durum wheat previously accounted for about 70% of the total wheat produced in the country (Tassema and Mohammed, 1982), and is generally produced under low input, subsistence agriculture. The mean national yield is about 1.3 t ha^-1. Tef, on the other hand, is native to Ethiopia and ranks first both in production and consumption when compared to other crops in the country (Berhe, 1981). However, due to its geographically restricted usage (i.e., in Ethiopia only), tef has been one of the least scientifically studied crops. The national yield average of tef is often less than 1 t ha^-1 (Berhe, 1981 ), mainly due to low usage of fertilizers by farmers. In addition, it has a lodging problem which also contributes to its low yield. At present, both crops are receiving much national emphasis in order to improve grain yield. One such attempt is the characterization work that has been carried out on landrace populations. There are good prospects for improving the yield of the two crops since they show an enormous genetic diversity. Today, tolerance to water logging is of great practical importance in Ethiopia. There are also moves to introduce irrigated agriculture in the country for the production of various crops, including tef and wheat. Since almost all irrigation projects suffer from salinity problems, a need was felt to study the salt tolerance of some popular varieties of durum wheat and tef if interested users are to grow them under irrigation. This paper reports the results of a study which was conducted to investigate the response of four varieties of the two crops to salinity stress during germination and late vegetative stages. MATERIALS AND METHODS Seeds of four durum wheat and four tef varieties were obtained from Debre Zeit Agricultural Research Center in Ethiopia, where improvement programmes on both crops are being carried out. The durum wheat varieties used in the studies were DZ-04-118, DZ-320, DZ-918, and Tob-2, while the four tef varieties were DZ-01-354, DZ010787, DZ-01-1445, and DZ-Cr-37. All varieties are improved and are under production by farmers. Germination responses. The study was conducted in a laboratory at room temperature 20+/-1 C with 12h day length. The experiments assessed durum wheat and tef germination and seedling growth in response to salt levels. Twenty seeds of each variety were germinated in glass petri-dishes lined with filter paper. The NaCl treatments used were 0 (control), 2, 4, and 8 dSm^-1 dissolved in distilled water. The petri dishes were arranged in a completely randomised design with four replications, and were covered with a polyethylene sheet to reduce moisture loss by evaporation. Ten ml of the appropriate solution were applied on alternate days to each petri dish.
The number of germinated seeds was recorded at 48 hr in the case of durum wheat and at 72 hr for tef. A seed was considered to have germinated when both the plumule and radical had emerged >0.5 cm. Durum wheat seedling shoot dry weight was measured after 7 days. Tef seedling growth was slow, and there was inadequate biomass for measurement. Total germination was expressed as a percentage of the control treatment for each variety and the data were then arcsine transformed for statistical analysis. Plant growth. The soil used in the study was a loam developed from a loess in Hebenshausen, Hesse, Germany, with a pH (CaCl2) of 6.8; 0.5% CaCO3; 2% organic matter; sufficient P and Mg supply; and a low Na and salt (0.326 dSm^-1 in the saturation extract) content. Some other physicochemical properties of the soil were given in another report (Mamo et al. 1996).
The amount of NaCl to be applied was calculated as described earlier (Mamo et al., 1996), and this was 2.16, 4.32, and 8.64 g NaCl per 3.5 kg soil, corresponding to the three salinity levels of 2, 4 and 8 dSm^-1. The NaCl was dissolved in 200 ml distilled water and applied to each pot in two splits: just before planting and 3-5 days later.
The two experiments were conducted separately in a climatic chamber which was maintained at a day/night temperature of 18/15 C, 60% relative humidity and 10,0000 lux illumination for 12 hr per day. For durum wheat, 20 pre- germinated seeds were planted and later thinned to 12 per pot. Tef, on the other hand, was planted (20 per pot) in the form of one week old seedlings, since the seeds are very minute and uniform seeding is quite difficult. Pots were arranged in a randomized complete block design with four replications. Supplemental nitrogen (as NH4NO3) was applied to the pots at the rate of 50 mg per pot in a solution form in order to ensure that nitrogen was not limiting the growth of plants. Wheat plants were grown for 42 days, and tef plants for 55 days, during which they were supplied with a measured quantity of distilled water as often as necessary. Before harvest height of plants was taken and average height of the plants per pot obtained.
Plants were harvested by cutting at the soil level at the specified dates and rinsed in distilled water to remove any contamination. Roots were rinsed several times to remove adhering soil particles. The parts were then put in paper bags and oven-dried at 70 C for 48 hr. Shoots and roots were weighed before samples were ground using a tractor plant mill. For mineral analysis, 0.2 g of the material was dry ashed at 550 C for 5 hr, dissolved in 10 ml conc. HCl and diluted with distilled water to 100 ml. The concentrations of Na and K were then read by flame photometry. For yield parameters, the relative values at a specific salt treatment were computed as percentage of the respective control. Data were analysed for statistical significance using the SAS package. RESULTS AND DISCUSSION Germination and seedling growth. Germination of durum wheat seeds was significantly (P<0.001) influenced by salt levels and varietal differences, but not by their interaction. On average, varietal differences were in the order: DZ-04-118 > DZ918 > Tob-2 > DZ-320. Except for variety DZ04-118, there was a consistent decrease in germination with increasing salt levels (Fig. 1).
Figure 2. Mean seedling shoot dry weight of four wheat varieties.
Wheat seedling relative shoot dry weight data (Fig. 2) showed that the effects of salt levels and varieties were highly significant (P<0.05). In general, variety DZ-04-118 had the highest overall seedling mean relative dry weight while the other three had comparable values.
The germination of tef seeds was significantly (P<0.001) influenced by salt levels, varietal differences and the interaction of both. Data given in Fig. 3 show that the percentage emergence of all varieties was reduced by increasing salt levels. The highest mean germination percentage was recorded for variety DZ-Cr-37 and the lowest for variety DZ-02-1445. Seeds of the latter practically failed to germinate at the 8 dSm^-1 salt level, and no improvement in germination was observed even after 7 days. Varieties DZ-01-787 and DZ-01-1445 were similar in their germination response to salt application. Averaged across all varieties, the drop in germination between the 0 and 2 dSm^-1 treatments was not statistically significant (P>0.05). Germination of the varieties DZ-01-354 and DZ-Cr-37 was not significantly influenced by salt application up to the 4 dSm^-1 salt level. However, for variety DZ-01-1445, which was the most sensitive, every increment in salt level significantly decreased germination.
Figure 4. Mean relative wheat plant height as influenced by four NaCl levels.
Relative shoot plant height was significantly (P<0.001) influenced by salt levels (Fig. 4). The effect of variety and the interaction of both factors were not significant. At the maximum salt concentration, plant height was only reduced by about 10-13% when compared with the first two salt levels. Relative shoot dry weight (Table 1), on the other hand, was significantly affected by both treatment factors (P<0.001 for salt levels, and P<0.01 for varietal differences), while the interaction effect was not significant. Relative shot dry weight was highest for variety DZ-04118, but similar for the other three. It was not significantly (P<0.05) influenced by salt application up to the 4 dSm^-1 salt level. In variety DZ-04-118, shoot dry weight was slightly but non-significantly improved by NaCl application at the 4 dSm^-1 salt level. TABLE 1. Relative shoot dry weight (RSDW, %) and relative root dry weight (RRDW, %) of four wheat varieties in response to NaCl levels (dS/m)
---------------------------------------------------------------------------
Variety RSDW RRDW
------------------------------ ------------------------------
2 4 8 Mean 2 4 8 Mean
---------------------------------------------------------------------------
DZ-04-118 98.9 64.8 89.0 111.4 106.4 40.2 86.0
DZ-320 97.3 82.9 33.3 71.1 140.5 129.2 72.9 114.2
DZ-918 98.0 67.9 43.2 69.7 102.4 123.6 68.1 98.0
Tob-2 97.7 78.1 42.7 72.8 97.1 92.2 55.4 81.5,
Mean 97.5 83.1 46.0 112.9 112.9 59.2
LSD (5%): Salt = 7.8 LSD (5%): Salt = 14.5
Variety = 9.0 Variety = 16.8
---------------------------------------------------------------------------
Relative root dry weight (Table 1) was also significantly (P<0.001 ) affected by salt levels and varietal differences, but not by their interaction effects. Generally, root relative dry weight was lowest at the maximum salt application, and highest at the first two (2 and 4 dSm^-1) salt levels (Table 1).
Data for shoot and root Na and K concentrations are given in Table 2. Shoot Na concentration significantly (P<0.001) increased with increase in salt levels, and the mean Na content at the highest salt application level was 20 to 30 times higher than that in the control treatment. Varietal differences in Na accumulation were also significant (P<0.01 ), as was the interaction of the two factors (P<0.05). Na accumulation, especially at the maximum salt treatment, was higher in varieties DZ-918 and Tob-2 than in the other two varieties.
Root Na accumulation was also significantly influenced (P<0.001) by salt levels and varietal differences (Table 2). In addition, the extent to which root Na content was influenced by increasing salinity differed in the varieties (salt x variety interaction was significant at P<0.001). Root Na concentration at the highest salt level, in comparison with the control treatment, was higher by 13, 9, 7, and 7 times in varieties DZ-04-118, DZ-320, DZ-918 and Tob-2, respectively. In general, root Na contraction was about half that of the shoots. TABLE 2. Shoot and root Na and K concentrations (mg/g dry weight) of wheat varieties as influenced by NaCl levels (dS/m) Roots
---------------------------------------------------------------------
Variety Na concentration
---------------------------------------------------------
Shoots Roots
---------------------------- ---------------------------
0 2 4 8 0 2 4 8
---------------------------------------------------------------------
DZ-04-118 0.86 6.60 12.27 26.67 1.24 4.60 6.20 13.20
DZ-320 1.52 7.17 11.62 24.80 1.17 2.99 5.06 9.24
DZ-918 1.05 8.97 12.63 3.94 1.11 3.55 4.96 7.33
Tob 2 1.37 7.71 13.37 29.31 1.12 3.65 4.91 7.10
LSD (5%) S/V = 1.231 LSD (5%): S/V = 0.404
S x V = 2.462 S x V = 0.809
-----------------------------------------------------------------------
Variety K concentration
-----------------------------------------------------------
Shoots Roots
---------------------------- ----------------------------
0 2 4 8 0 2 4 8
-----------------------------------------------------------------------
DZ-04-118 42.63 31.51 25.98 20.07 12.26 14.47 12.27 8.48
DZ-320 44.46 29.28 24.17 21.34 12.37 8.71 9.89 9.90
DZ-918 43.33 31.61 28.69 20.13 12.02 7.89 10.67 8.21
Tob 2 36.87 29.85 25.77 20.54 10.39 7.35 7.74 6.65
LSF (5%): S/V = 0.762 LSD (5%): S/V = 1.089
SxV = 1.524 SxV = 2.179
S/V indicates LSD (5%) for differences among salt levels within one
varietyS/V indicates LSD (5%) for differences among salt levels across varieties --------------------------------------------------------------------------- As expected, shoot K content was reduced by increasing salt levels, and the effect was highly significant (P<0.001 ). In addition, varietal factors and the interaction between salt levels and varieties were all significant (P<0.001). In all varieties DZ-918, shoot K concentration was significantly (P<0.05) reduced with every increment in NaCl level. In the latter, however, the drop in K content between the 2 and 4 dSm^-1 salt levels was not significant. In general terms, shoot K content at the highest salt treatment level was about half that of the control treatment.
Similarly, root K concentration was significantly (P<0.001) influenced by the two treatment factors and their interaction effects. Variety DZ-04-118 had the highest mean K content while the lowest was found in variety Tob-2. Although root K concentration generally decreased with increasing salt level, the change in K content between the 2 and 8 dSm^-1 salt levels in varieties DZ-320 and Tob-2 was not significant. In addition, in variety DZ-04-118, root K concentration was not significantly affected up to the 4 dSm^-1 salt treatment. However, in variety DZ-918, root K concentration, for reasons not clear, significantly increased between 2 and 4 dSm^-1 salt levels. Tef plant growth and ion content. Tef relative plant height was significantly (P<0.001) influenced only by salt levels (Table 3). The relative mean plant height for the three salt levels 99.2, 97.3 and 87.5% respectively. Only the height reduction at the maximum salt application level was significantly different from the others.
TABLE 3. Mean relative plant height (RPH, %), relative shoot dry weight (RSDW, %), relative root dry weight (RRDW, %) and root Na and K concentrations (mg/g dry weight) of four tef varieties as influenced by four NaCl levels (dS/m)
----------------------------------------------------------
Salt levels RPH RSDW RSDW Root Na Root K
(dS/m) Content content
----------------------------------------------------------
- - - 5.94 9.03
2 99.2 92.5 100.8 7.15 7.68
4 97.3 85.0 88.9 7.45 6.57
8 87.5 61.6 50.7 11.84 6.45
Mean 98.5 79.7 80.1 8.09 7.43
LSD (0.05) 4.2 6.1 11.5 0.67 0.73
----------------------------------------------------------
Data for tef shoot and root relative dry weights (Table 3) show that both parameters were reduced by increasing salt levels. The effect of salt levels in both shoots and roots were highly significant (P<0.001) whereas varietal effects were nonsignificant. Also, none of the interaction effects were significant for either parameters. As shown in Table 3, every increment in salt level significantly influenced relative shoot and root dry weights.
Shoot Na concentration (Table 4) was significantly (P<0.001) increased by increasing salt levels. Varietal differences were not significant but the salt by variety interaction was significant at P<0.001. In varieties DZ-01-354 and DZ-01-787, every increment in salt level significantly (P<0.05) influenced shoot Na content, while in the other two varieties only the highest salt level brought about a significant increase in shoot Na content.
TABLE 4. Shoot Na and K concentrations (mg/g dry weight) of the four tef varieties as influenced by NaCl levels (dS/ m)
-----------------------------------------------------------------------
Variety Na concentration K concentration
-------------------------- -----------------------------
0 2 4 8 0 2 4 8
-----------------------------------------------------------------------
DZ-01-354 5.57 6.60 7.59 9.56 17.86 15.12 20.32 21.13
DZ-01-787 5.66 6.28 7.22 8.74 15.66 16.01 19.92 19.95
DZ-01-1445 5.72 6.17 6.72 10.82 18.75 17.22 15.64 13.96
DZ-Cr-37 5.86 6.17 6.68 9.51 13.92 17.81 16.92 20.76
LSD (5%): S/V = 0.422 LSD (5%): S/V = 1.191
S x V = 0.844 S x V = 2.382
S/V indicates LSD (5%) for differences among salt levels within one variety
S x V indicates LSd (5%) for differences among salt levels across
varieties--------------------------------------------------------------------------- Shoot K concentration, on the other hand, was significantly (P<0.001 ) influenced by salt levels, varieties and the interaction of both factors. In variety DZ-01-354, shoot K content was only significantly reduced between the first two salt levels (Table 4). In variety DZ-01-787, however, the first two salt levels and the last two salt levels response of durum wheat and tef varieties were comparable in K content. However, the K content between both groups differed significantly, and it was higher in the 4 and 8 dSm^-1 salt levels. This was possibly due to the comparatively higher shoot dry weight at the 0 and 2 dSm^-1 salt levels, thus causing dilution. In varieties DZ-01-1445, shoot K content consistently decreased with increasing salt levels.
Root Na concentration (Table 3) was only influenced by salt levels. The Na content increased significantly with increasing salt levels, but the increments between the 2 and 4 dSm^-1 salt levels were not significant. On the other hand, root K content was significantly (P<0.001) influenced by salt levels and varietal differences. Varieties DZ-01-354 and Dz-01-787 were similar in their K contents, but had significantly (P<0.05) lower figures when compared to varieties DZ-01-1445 and DZ-Cr-37; the latter two also had similar K contents. CONCLUSION The results of this study showed that varietal differences existed in the response to salinity of durum wheat and tef. In both crops, all plant parameters were significantly affected by salt application, especially at the 4 dSm^-1 NaCl level. In addition, sensitivity and tolerance to NaCl stress varied with the stage of plant development. In general, germination at the maximum salt level was comparatively higher in durum wheat than in tef. Among the tef varieties although DZ-01-1445 had an overall good germination percentage up to the 2 dSm^-1 NaCl, it failed to germinate at the highest NaCl level. However, such differences were not observed at late vegetative stage. Thus, tef is similar to other cereals in which tolerance observed at the germination stage may or may not be reconfirmed at later vegetative stages. According to Maas (1986), crops such as barley, corn, cowpea, rice, sorghum and wheat are most sensitive during early seedling growth and then become increasingly tolerant during later stages of growth and development. Shoot dry matter production was slightly improved at the 2 dSm^-1 salt level in one durum wheat variety (DZ-04-118), while in roots such improvement was observed for most of the varieties. Why dry weight was enhanced at low levels of Na is not clear, although other workers have also reported similar observations in maize (Marschner, 1995), barley (Greenway and Rogers, 1963) and sorghum (Azhar and Mcneilly, 1989). One possible reason may be growth stimulation as a result of the replacement of K by Na (Marschner, 1995).
It is a known fact that good seed germination and seedling vigour under salt stress are important plant characters correlated with plant vigour during the later growth stages. However, comparison of salt tolerance exhibited during germination and emergence with later growth states is difficult because different criteria must be used to evaluate plant response: tolerance at emergence is based on survival, whereas tolerance after emergence is base on decrease in growth. From this point of view, variety DZ-01-1445 may be considered as the most sensitive during germination, especially under higher Na levels, but this conclusion does not apply to post-emergence growth.
Plants initially adjust to saline conditions by decreasing tissue water content through osmotic adjustment (Marschner, 1995). Further growth and salt tolerance under saline conditions are possible either through salt exclusion (either the synthesis of organic solutes such as sugars and amino acids or the increased uptake of K^+, Ca^2+ or NO3^-), or salt inclusion whereby osmotic adjustment is achieved by increased uptake of salts, mainly NaCl, in the leaf tissue (Flowers, 1988). According to Lauchli (1984), most salt tolerant crops respond to salinity by exclusion of sodium and/or chloride from the leaves. From our results on shoot and root Na concentrations, it may be generalized that Na was included as a function of increased salt application.
In an earlier work (Mamo et al., 1996), species as well as varietal differences were observed in the salt tolerance of chickpea and lentil. In addition, it was found that chloride toxicity was more important than sodium toxicity. In many herbaceous crop and fruit tree species, chloride toxicity may be a major constraint to plant growth (Marschner, 1995). As damage by chloride seems to be less important in cereals than in legumes (Maas, 1986), Cl analysis was not conducted on our samples.
In the study involving wheat, the variety (DZ04-118 ) that showed the highest mean germination percentage and relative seedling shoot dry weight also had the highest mean relative shoot dry weight at the late vegetative stage. On the other hand, variety DZ-320 which had a slow start at germination and seedling stages exhibited the highest mean relative root dry weight at a later stage. These results confirm that whether the degree of emergence and seedling vigour was positively correlated with relative dry matter yield at maturity depended on the varieties. This observation supported the general belief that salt tolerance is not a constant trait over the plant's life cycle but varies with the environment and growth stage of the plant (Ungar, 1974). Similar findings were reported by Kingsburry and Epstein (1984) for spring wheat varieties.
Variety DZ-320 also had the lowest mean shoot Na content, thus exhibiting some degree of Na exclusion. Interestingly, this variety has been recommended in Ethiopia for waterlogged Vertisol areas of about soil pH(H2O) 7.8. Thus, it is also adopted to slightly alkaline soil conditions. From examination of the foregoing results on durum wheat, it may be deduced that DZ-04-118 is the most salt sensitive of all the varieties. Since the ultimate objective of testing varieties for salt tolerance is to achieve higher yield on salt stressed soils, it may be generalized that variety DZ-320 has superiority over the other varieties.
In conclusion, it has been shown that, even with the small number of varieties considered in the study, more variation existed within durum wheat for salt tolerance than in tef. Since large germplasm collections of both crop species already exist in Ethiopia, further screening of these collections for tolerance could be carried out in order to identify useful genetic sources of tolerance. The important characters for salt tolerance selection criteria in these crops must also be identified and established for further breeding work. REFERENCES Ashraf, M. and McNeilly, T. 1987. Salinity effects on five cultivars/lines for pearl millet (Pennisetum americanum (L.) Leek). Plant and Soil 103:13-19. Azhar, F.M. and Mc Neilly, T. 1989. The response of our sorghum accessions/cultivars to salinity during plant development. Journal of Agronomy and Crop Science 163:33-43. Berhe, T. 1981. Inheritance of Lemma Color, Seed Color and Panicle Form Among Four Cultivars of Eragrostis tef (Zucc.) Trotter. Ph.D. Thesis, University of Nebraska, USA. Epstein, E. Rush, D.W., Kingsburry, R.W., Kelley, D.B., Cunningham, G.A. and Wrona, A.F. 1980. Saline culture of crops: A genetic approach. Science 210:299-304. Flowers, T.J. 1988. Chloride as a nutrient and as anosmoticum. In: Advances in Plant Nutrition. Tinker, B. and Lauchli, A. (Eds.), 3:55-78. Praeger, New York. Francois, L.E., Donovan, T. and Maas, E.V. 1984. Salinity effects on seed yield, growth and germination of grain sorghum. Agronomy Journal 76:741-744. Greenway, H. 1962. Plant response to saline substrates. I. Growth and ion uptake of several varieties of Hordeum during and after sodium chloride treatment. Australian Journal of Biological Sciences 15: 16-38. Greenway, H. and Rogers, A. 1963. Growth and ion uptake of Agropyron elongatum on saline substrates as compared with a salt-tolerant variety of Hordeum vulgare. Plant and Soil 18:21-30. Kingsburry, R.W. and Epstein, E. 19 84. Selection for salt tolerance in spring wheat. Crop Science 24:310-315. Lauchli, A. 1984. Salt exclusion: An adaptation of legumes for crops and pastures under saline conditions. In: Salinity Tolerance in Plants: Strategies for Crop Improvement. Staples, R.C. and Tonnisses, G.H. (Eds.), pp 171- 187. John Wiley and Sons, New York. Lessani, H. and Marschner, H. 1978. Relation between salt tolerance and long distance transport of sodium and chloride in various crop species. Australian Journal of Plant Physiology 5:27-37. Maas, E.V. 1986. Salt tolerance of plants. Applied Agricultural Research 1:12-26. 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. Marschner, H. 1995. Mineral Nutrition of Higher Plants. Second ed. Academic Press, London, U.K. 889 pp. Norlyn, J.D. and Epstein, E. 1984. Variability in salt tolerance of four triticale lines at germination and emergence. Crop Science 24: 1090-1092. Rhoades, J.D., Kandiah, A. and Mashali, A.M. 1992. Water quality assessment. In: The Use of Saline Waters for Crop Production. pp. 23-69. Food and Agriculture Organization, Rome, Italy. Richter, C., Heiligtag, B., Gertling and Abdullahzadeh, A. 1995. Salt tolerance of different varieties of Sorghum bicolor and Vicia faba. Der Tropenlandwirt, Journal of Agriculture in the Tropics and Subtropics 96:141-152. Tessema, T. and Mohammed, J. 1982. Review of wheat breeding in Ethiopia. Ethiopian Journal of Agricultural Sciences 4:11-24. Ungar, I. 1974. The effect of salinity and temperatures on seed germination and growth of Hordeum jabatum. Canadian Journal of Botany 52:1357-1362. Verma, O.P.S. and Yadava, R.B.R. 1986. Salt tolerance of some oats (Avena sativa L.) varieties at germination and seedling stage. Journal of Agronomy and Crop Science 156: 123-127. Yoshida, S. 1967. Salt tolerance of the rice plant. In: Annual Report 1966. The International Rice Research Institute (IRRI), pp. 32-36. Copyright 1996 The African Crop Science Society |
| |||||||||
