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Journal of Agronomy

Year: 2004 | Volume: 3 | Issue: 1 | Page No.: 25-30
Research Article

Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity

Maher N. Noaman
Department of Aridland Agriculture, College of Food Systems, UAE University, Al-Ain-1 7555, UAE

ABSTRACT

A field experiment was carried out at Nahshala Farm, about 50 km from Al-Ain, UAE during the 2001/2002 growing seasons, using five halophyte species; Spartina sp., Distichlis palmeri., Paspalum vaginatum, Juncus roemerianus and Batis maritima, under six levels of N and K fertilizer combinations irrigated with salinity water of 20 g L-1. The objectives of the experiment were twofold; 1) to find out the optimum rate of potassium and nitrogen under such high salinity stress and 2) to study the response (growth and biomass production) of such halophytes to different levels of K and N as an anti-salinity nutrients. The experiment was conducted in triplicate with a split-plot design arranged in randomized complete block. Results indicate that controlling soil fertility especially N and K under saline soils condition is considered one of the most important factors in order to conduct reliable study on the evaluation of tolerance of plants to salinity stress. Nitrogen and potassium proved to increase plant salt tolerance to produce high biomass. This study also supports the idea of using high saline water of about 20 g L-1 salt concentration in agriculture along with N and K fertilizers accompanied with increasing leaching fraction to maintain satisfactory yield production of such halophytes.
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INTRODUCTION

Under sodic saline conditions, the mineral nutrition of most plants can be expected to be detrimentally affected. The interactions between K and Na may be emphasized under such conditions and ultimately decrease plant growth. Soil structure has also been shown to be adversely affected by high levels of Na[1]. Although Na has been shown to replace K in some of its physiological roles in sugar beets[2], other plants show much less ability to substitute Na for K[3]. The significance of K in stomatal regulation has been well established[4]. The proportion of the total K that is actively capable of fulfilling the role in stomatal regulation may be inadequate when Na is present in high amounts.

Reduction in plant growth under salt stress is usually attributed to osmotic stress due to a lowering of external water potential[5], or to specific ion effect on metabolic processes in the cell. The two effects are not mutually exclusive. Thus, ion regulation and osmo-regulation are subjects of intensive research into possible mechanisms of salt tolerance[5]. It is commonly accepted that correlation exists between Na and K leading to a reduced level of internal K+ at high external NaCl concentrations. This phenomenon has been described in plants as well as cultured cells. Detailed studies with cotton plants showed a reduced content of K+ in roots subjected to high NaCl concentrations and that K+/Na+ selectivity is an important factor in salt tolerance of plants[6]. Leigh and Wyn Jones[7] hypothesized that critical K+ concentration is correlated with growth of plant cells.

Studies of cell cultures of tobacco[8] showed that a higher level of internal K+ could be correlated with a higher level of salt tolerance. Fertilization assumes an important role since sodic soils are poor in fertility[9]. A higher rate of N than one utilized on non-sodic soils[10] and the application of Zn during the years of soil reclamation[11] result in increased crop yields.

Sodic soils contain high amounts up to 136 kg ha-1 of NaCO3 extractable P, which decreases with increasing soil depth[12]. Sodic soils are dominated by Na which adversely affects K concentration of the plants[3-16]. However, information on the beneficial effect of potassium fertilizers to crops grown in sodic soils is badly lacking.

Dvorak and Noaman[17] in study of the effect of Kna1 locus transferred from Triticum aestivum to durum wheat found that under salt stress, the Kna1+ families had higher K+/Na+ ratios in the flag leaves and higher yields of grain and biomass than the Kna1¯ families. They concluded that K+/Na+ ratio is one of the factors responsible for the higher salt tolerance in wheat.

The addition of K to the root medium of barley and rye grass was found to reduce the harmful effects of high Na concentrations[18,19].

Noaman et al.[20] studying the effects of potassium on barley crop under salinity stress found that on the average, overall salinity levels, the application of 57 kg K2O ha-1 increased biological and grain yield significantly by about 20 and 14%, respectively over the control treatment. They also found that higher levels of K (114 kg K2O ha-1) caused some non-significant reduction in both characteristics by about 5.5 and 4%, respectively.

The main objective of this study was, therefore to study the effects of soil salinity and potassium and nitrogen application on the performance of five halophytes grown under salinity stress.

MATERIALS AND METHODS

A field experiment was carried out at Nahshala Farm, about 50 km from Al-Ain, UAE, during the 2001/2002 growing seasons, using five halophyte species; Spartina sp., Distichlis palmeri., Paspalum vaginatum, Juncus roemerianus and Batis maritima, under three levels of Nitrogen fertilizer (40, 100 and 160 kg N ha-1) and two levels of Potassium fertilizer (48 and 96 kg K2O ha-1) in six combinations as follow:

● F1 = 40 Kg N ha-1 + 48 kg K2O ha-1,
● F2 = 40 Kg N ha-1 + 96 kg K2O ha
● F3 = 80 Kg N ha-1 + 48 kg K2O ha-1,
● F4 = 80 Kg N ha-1 + 96 kg K2O ha-1
● F5 = 120 Kg N ha-1 + 48 kg K2O ha-1 and
● F6 = 120 Kg N ha-1 + 96 kg K2O ha-1,

irrigated with saline water of about 22 g l-1 (22,000 ppm) concentration. The experiment was conducted in triplicate with a split-plot design arranged in randomized complete block with the halophyte species as the main plot, nitrogen fertilizer as sub-plots and potassium fertilizer as sub-sub-plots. Plot area was 3.6 m2 for each treatment in six rows 30 cm apart and 2 m long. The original plant materials were introduced from Arizona, USA, then seedlings were propagated by stem cuttings in January 1999. These species were chosen primarily not only because they represent a wide range of physiotypes, but also because they have already been used to some extent for beneficial purposes such as animal fodder, grain, camel feed and landscaping. Distichlis palmeri, a C4 perennial salt-tolerant grass, Batis maritima, a C3 perennial succulent plant, Spartina sp. a C3 perennial grass, Paspalum vaginatum and Juncus roemerianus, are C3 herbaceous perennials. Potassium fertilizer was added before planting during land preparation while the nitrogen fertilizers were spited into three equal doses added in weekly intervals starting 20 days after planting to avoid any nitrogen losses or leaching. The plants of different species included in the experiment were first grown from seed or from stem cuttings in greenhouse pots for about 6-8 weeks, then seedlings were transplanted into the field and were irrigated with saline water. Growth rate was measured using plant height development where individual plant heights were measured at four stages of plant growth during the course of the experiment and immediately before harvest. The time between measurements was about 15-20 days. Total biomass was determined by harvesting the entire plants of each species, weighed for fresh weight measurement and then washed, dried at 60°C for 3 days and their respective dry weight was determined. The analyses of variance were performed for the split-plot design by the procedures outlined in Steel and Torrie[21] at P-value = 0.05 and 0.01. Once the significance level of the treatment effects were established by F-tests, the significance of the observed differences among species at the different salt levels and fertilizer treatments was evaluated by the Least significant differences (LSD) test method.

RESULTS AND DISCUSSION

Effect of P and N fertilizers on plant development: The differences between fertilizer treatments for different halophyte species regarding plant height were not significant at the initial stage of growth and thereafter the differences became apparent at the third stage (55-60 days after planting and application of N and K fertilizer). Table 1 shows plant heights of the five halophytes at four growth stages including the time of harvest under six levels of N and K fertilizer treatments along with applicable statistical parameters. The data in this Table indicate that application of nitrogen and potassium did not affect plant height at the early growth stages until the second stage, but at the third stage the differences between fertilizer treatments regarding plant height started to appear with increasing N and k fertilizer up to F5 for most halophyte species, significantly (P<0.05). Further increase in fertilizer did not cause significant increase in plant height with some exceptions in some halophyte species such as Spartina sp. and Distichlis sp. At harvest, plant height differences among different fertilizer treatments reached the maximum except for Juncus sp. and Batis sp. where they were stable in plant height at higher fertilizer levels.

Table 1: Plant height (cm) of five halophyte species measured at four growth stages as correlated to the mean fertilizer treatments grown at Nahshala Farm, 2001/2002
Image for - Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity
Image for - Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity

Table 2: Fresh weight in (t ha-1) of five halophyte species under different N and K fertilizer treatments in an experiment grown at Nahshala Farm, 2001/2002
Image for - Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity

Regarding the differences among halophyte species at different fertilizer treatments, two halophytes did not response to increasing fertilizer application, they are Juncus roemerianus and Batis maritime and no significant differences were found among different fertilizer treatments. The highest significant response to fertilizer treatments of all halophytes was found in the two grasses, Spartina sp. and Distichlis palmeri (P<0.05) especially at the third stage and at harvest.

It was concluded from this part of study that nitrogen and potassium fertilizer are very important to the three halophyte species; Spartina, Distichlis and Paspalum sp. and to less extent to the other two halophytes, Juncus sp. and Batis sp. at high salinity levels.

Table 3: Dry matter in kg ha-1 of five halophyte species under different N and K fertilizer treatments in an experiment grown at Nahshala Farm, 2001/2002
Image for - Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity

Table 4: Concentration of some nutrients in plant tissues of five halophytes grown under different levels of N and K fertilizers at Nahshala Farm, 2001/2002
Image for - Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity
Image for - Effect of Potassium and Nitrogen Fertilizers on the Growth and Biomass of Some Halophytes Grown under High Levels of Salinity

Effect of fertilizer application on biomass and yield production: Halophytic plants, which have evolved in saline environment, responded differently in terms of biomass and yield production to increasing N and K fertilizer. In general, their biomass and yield production significantly increased as the fertilizer increased (P<0.05) with no exception. The relative effects of N and K on vegetative and reproductive growth seem to vary from species to species. However, at higher fertility, biomass production of Batis sp. was extremely high and reached over 51,000 t ha-1 total fresh weight from four cuts and it was followed by Paspalum sp. with no significant differences between the two species. The lowest fresh and dry weight biomass production was obtained from Spartina sp., which gave about 10,000 t ha-1 from the same number of cuttings (Table 2). We conclude from this part of study that it is important to add N and K in order to obtain high yielding halophytes especially for Batis sp. and Paspalum sp. which produce very high yields when applying high levels of N and K fertilizer.

Dry matter production obtained per each species is shown in Table 3. The story here is different due to huge differences in water content of the different halophyte species. It was found that Batis sp., which gave the highest fresh weight is giving the second least dry matter production due to its high water content (succulent plant), whereas Paspalum sp. stayed on the top regarding dry matter production with significant differences compared to all other halophyte species (P<0.05) (Table 3).

It was obvious that Spartina sp. was the lowest in both fresh and dry matter production among all five species, significantly (Tables 2 and 3), while the highest fresh and dry matter production was Paspalum vaginatum, which can be used as a forage crop for animal feeding under high saline soils[22].

Plant Nutrients content as affected by fertilizer treatments: As we mentioned earlier that K is a major plant nutrient and could be useful against high soil salinity as was found by Dvorak et al.[17] who concluded that higher K+/Na+ ratios in the flag leaves is one of the factors responsible for the higher salt tolerance in wheat. It was also found that the addition of K to the root medium of barley and rye grass reduced the harmful effects of high Na concentrations[18,19]. Therefore, one of the objectives of this study was to measure K and Na content in plant tissues of these halophyte species and relate that to salt tolerance and yielding capacity under salt stress. Table 4 shows concentration of some nutrients in plant tissues of the five halophyte species under different levels of N and K fertilizers. It was obvious that K/Na ratio for each species behaved differently under different levels of N and K fertilizer. For example, the ratio was extremely low for Batis sp. (ranging from 0.05 to 0.16) compared to the highest valued from Juncus sp. (0.52 to 0.83). Sodium content in plant tissues of this was extremely high with an average of 39550 mg L-1 with relatively lower K content with an average of 4570 mg L-1 (Table 4). Regarding Paspalum sp., which gave the highest fresh and dry biomass, the K Na-1 ration was intermedium ranging from 0.34 to 0.53), but the K content was the highest compared to the other four halophytes ranging from 5250 to 9024 mg L-1. In general, the relationship between K/Na ratio and N and K in one hand and biomass production in the other hand was not evident in this study (Table 4). There was no clear trend between the values of K/Na and the biomass production and nutrient content in plant tissues. However, nitrogen and phosphorus content in plant tissue did not reflect the salinity tolerance or biomass production in different halophyte species which indicates that they are independent criteria and it can not be rely upon in the selection procedure for salt tolerance.

DISCUSSION

Controlling soil fertility especially N and K under saline soils condition is considered one of the most important factors in order to conduct reliable study on the evaluation of tolerance of plants to salinity stress. In the present study N and K were applied in an adequate rate to increase plant salt tolerance to produce high biomass, especially Paspalum sp. which produced high fresh and dry biomass for forage use. Paspalum vaginatum proved to be salt tolerant species under high and intermediate salt stress as was concluded by Noaman and El-Haddad[22] and can tolerate more than 20 g l-1 of salt concentration. Under this salt stress using N and K fertilizer, most halophyte species under study gave satisfactory biomass production with some differences in values among them. It should be recognized that soil salinity under the high salt treatments will continue to rise and plant growth may deteriorate unless the same high level of leaching fraction should be applied for a long period of time along with N and K fertilizers. The present study showed that most of the tested halophyte species can produce high yield and biomass if they are fertilized with K and N at moderate levels such as 120 kg N ha-1 and 48 kg K2O ha-1 and can grow satisfactorily using brackish water of 20 g l-1 salinity. However, such a practice will cause salinity accumulation in the drainage water which may exceed that of seawater salinity. Therefore, irrigation strategies for using such seawater should involve higher levels of leaching and also more frequent water applications[22]. Our study also supports the idea of using high saline water of about 20 g L-1 salt concentration in agriculture along with N and K fertilizers accompanied with increasing leaching fraction to maintain satisfactory yield production of such halophytes.

ACKNOWLEDGMENTS

The author expresses his gratitude to the Head of the Department of Aridland Agriculture and the Dean of the College of Food Systems for their continuous support to achieve this research successfully.

REFERENCES

  1. Mcneal, B.L. and N.T. Coleman, 1966. Effects of solution composition on soil hydraulic conductivity. Soil Sci. Soc. Am. Proc., 30: 308-312.
  2. El-Sheikh, A.M., A. Ulrich and. T.G. Broyer, 1967. Sodium and rubidium as possible nutrients for sugar beet plants. Plant Physiol., 42: 1202-1208.
  3. Lehr, J.J., 1953. Sodium as a plant nutrient. J. Sci. Food Agric., 141: 460-471.
  4. Fisher, R.A., 1968. Stomatal opening: Role of potassium uptake by guard cells. Science, 160: 784-785.
  5. Maas, V. and R.H. Nieman, 1978. Physiology of Land Tolerance to Salinity. In: Crop Tolerance to Suboptimal Land Conditions, Yung, G.A. (Ed.). ASA, CSSA, Madison, WI., pp: 277-299.
  6. Kent, L.M. and A. Lauchli, 1985. Germination and seedling growth of cotton: Salinity-calcium interactions. Plant Cell Environ., 8: 155-159.
    CrossRefDirect Link
  7. Leigh, R.A. and R.G.W. Jones, 1984. A hypothesis relating critical potassium concentrations for growth to the distribution and functions of this ion in the plant cell. New Phytot, 97: 1-14.
  8. Watad, A.A., L. Reinhold and H.R. Lerner, 1983. Comparison between a stable NaCl selected Nicotiana cell line and the wild type: K, Na and proline pools as a function of salinity. Plant Physiol., 73: 624-629.
    Direct Link
  9. Singh, N.T., D.R. Bhumbla and J.S. Kanwar, 1969. Effect of gypsum alone and in combination with plant nutrient on crop yields and amelioration of saline-sodic soils. Indian J. Agric. Sci., 139: 1--9.
  10. Nitana, H.C., K.S. Dargan and I.P. Abrol, 1972. Annual Report. Central Soil Salinity Research Institute, Karnal, India.
  11. Takkar, P.N. and T. Singh, 1978. Zinc nutrition of rice as influenced by rates of gypsum and zinc fertilization of alkali soils. Agron. J., 70: 447-450.
  12. Chhabra, R., I.P. Abrol and M. Singh, 1980. Dynamics of phosphorus during reclamation of sodic soils. Soil Sci., 132: 319-324.
    Direct Link
  13. Pearson, G.A. and L. Bernstein, 1958. Influence of exchangeable sodium on yield and chemical composition of plants. II. Wheat, barley, oats, rice, tall fescue and tall wheat grass. Soil Sci., 86: 254-261.
  14. Mustafa, A.H., A.I. Shabassy, A.T. Gohar, E.M. Abdel Naim, A.A. Rahman and M.E. Elshad, 1966. Growth and cationic accumulation by wheat and barley as influenced by various levels of exchangeable sodium. Agric. Res. Rev., 44: 1-17.
  15. Mehrotra, C.L. and S.K. Das, 1973. Influence of exchangeable sodium on the chemical composition of important crops at different stages of growth. J. Indian Soc. Soil Sci., 21: 355-366.
  16. Joshi, Y.C., A. Qadar and R.S. Rana, 1979. Differential sodium and potassium accumulation related to sodicity tolerance in wheat. Indian J. Plant Physiol., 22: 226-230.
    Direct Link
  17. Dvorak, J., M.M. Noaman, S. Goyal and J. Gorham, 1994. Enhancement of the salt tolerance of Triticum turgidum L. by the Kna1 locus transferred from the Triticum aestivum L. chromosome 4D by homoeologous recombination. Theor. Applied Genet., 87: 872-877.
    CrossRefDirect Link
  18. Hylton, L.O., A. Ulrich and D.R. Cornlivs, 1967. Potassium and sodium inter-relations in growth and mineral content of Italian rye grass. Agron. J., 59: 311-314.
  19. Helal, M., K. Koch and K. Mengel, 1975. Effect of salinity and potassium on the uptake of nitrogen and on nitrogen metabolism in young barley plants. Agron. J., 351: 310-313.
    CrossRefDirect Link
  20. Noaman, M.N., M. Khodir, A.A. El-Sayed and W. Kadry, 1997. Field screening of barley genotypes under different levels of soil salinity and potassium. Emirates J. Agric. Sci., 9: 23-33.
  21. Steel, R.G.D. and J.H. Torrie, 1984. Principles and Procedures of Statistics. 2nd Edn., McGraw Hill Book Co. Inc., New York, pp: 172-177.
  22. Noaman, M.N. and E. El-Haddad, 2000. Effects of irrigation water salinity and leaching fraction on the growth of six Halophyte species. J. Agric. Sci., 135: 279-285.
    CrossRefDirect Link

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