Interactive Effect Of Cobalt And Salinity On Tomato Plants I- Growth And Mineral Composition As Affected By Cobalt And Salinity

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1 Research Journal of Agriculture and Biological Sciences 1(3): , , INSInet Publication Interactive Effect Of Cobalt And Salinity On Tomato Plants I- Growth And Mineral Composition As Affected By Cobalt And Salinity Nadia Gad Department of Plant Nutrition. National Research Centre, Cairo, Egypt. Abstract: The study was carried out at the greenhouse, of Faculty of Agriculture Ain Shams University, during 2003 August 15th to study the interactive effect of cobalt and salinity on growth and mineral composition of two tomato varieties differing in their salt tolerance, namely Moneymaker (as salinity sensitive) and Edcawy (as salinity tolerance). A pot experiment was carried using acid washed sand and 10 kg capacity plastic pots. Five weeks old tomatoes seedlings were transferred to each pot. The saline water used was prepared in five concentrations namely 0.0, 1000, 2000, 3000 and 4000 ppm. Cobalt was added once at the first week in the form of CoSO 4.7 H2O in 5 levels: 0.0, 7.5, 15.0, 22.5 and 30.0 ppm cobalt. All treatments were triplicated in complete randomized block design. Fresh and dry weight were recorded at the end of the experiment and analysed for N, P, K, Na, Ca, Mg, Cl and Co, Fe, Mn, Cu and Zn. The obtained results could be summarized as follows: Increasing cobalt level in the culrtural media up to 15.0 ppm cobalt stimulated the growth and dry matter yield of both varieties, shoots and roots at all levels of salinity. Increasing salinity levels in the plant media significantly decreased Mn, Zn and Cu in shoots and roots of both varieties. Increasing salinity level, in the medium resulted in a significant decrease in cobalt concentrations in shoots and roots of both varieties except with the level 7.5 ppm cobalt. When cobalt concentration was increased in the media a progressive depression effect in iron content was noticed. Increasing salinity levels increased Fe in shoots and roots in both varieties, in contrast when cobalt levels were increased Fe content decreased. Salt treatment, in general, decreased the content of N, P and K in both shoots and roots of the two varieties. On the other hand, 7.5 ppm cobalt treatment showed beneficial effect on the status of these elements. Cobalt concentrations up to 15.0 ppm cobalt resulted an increase in Ca and Mg content of shoots and roots while Na and Cl concentration decreased. Key words: Cobalt, salinity, growth, macro and micronutrients. INTRODUCTION salt ions that are observed from the saline soil, to the process of building up the osmotic potential of the plant Salinity became a serious problem for agriculture, all cells, or to the imbalanced of nutritional cations in tissues over the world. Egypt is adopting furrow irrigation- of the salt affected planted or due to reduction in carbon systems and is also expanding in cultivating the desert. fixation during photosynthesis and to increasing carbon Salinity, water shortage and low water quality are the main release in respiration. The retarding action of salinity is problems for agriculture production under such much more sever at the late than the early stages of circumstances. The north coast of Egypt is comprised of growth, obviously due to the commutative effect of the marginal land. The available irrigation water has a salt. Root system was more reduced by salinity than relatively high salt content. Other areas in Egypt, and [1] shoot system many other areas in the arid zones of the world are [2] Ruf et al reported that plant survived under salt experiencing similar problems of increased salinity of stress levels up to 8.7 bars, provided that gradual increase soils, and/or irrigation water. in osmotic pressure has occurred. Their results also The ability of plants to tolerate excess salts in the showed that total dry matter content was increased, shoot rhizosphere is of considerable importance in the arid and growth being reduced to a greater extent than root semi-arid regions where salinization of soils usually growth. Visible signs of wilting were observed on prevails. [3] potatoes at the highest used stress level. Saranga found The adverse effect of salt stress on plant growth is that tomato growth, judged plant height, stem diameter, attributed to the specific toxic effect of ions excessively leaf area, fresh and dry weight of both tops and root was Corresponding Author: Nadia Gad, Department of Plant Nutrition. National Research Centre, Cairo, Egypt. drnadiagad@yahoo.com 261

2 depressed with increasing sodium chloride level in the accumulation have been reported for tomato. When salt growth medium, the effect being more pronounced as the sensitive crops such as tomato, are exposed to high salt level increased. Dry matter percentage of plant top salinity, they cannot adequately control salt uptake in the tended to increase in the salinized plants. The ratios of 12] sensitive shoots. Mass et al revealed that sprinkling top: root were decreased as sodium chloride level irrigation with saline water (15 and 60 meq/l) did not affect increased. The same author also added that tomato (grape [13] the growth and yield of tomato plants. El-Kholi et al variety), which is considered to be salt tolerant, was noticed that the plant dry matter of tomato cv. prichard higher in its values than that of Ace variety, which was decreased with increasing soil salinity ( considered to be sensitive to salinity, with pritchard [14] ppm). Rush found that all the selected progenies [4] variety in between. Dumbrof and Cooper found that the tolerated higher salinity concentration than water did not deleterious effects of salt stress on tomato vegetative [15] survive treatment with 70 % sea water. Salama et al growth were most pronounced when plants were exposed reported that the two higher salinity levels having suction to saline conditions in early seedlings stage. head of 7 to 10 bars) produced reduction in growth of Growth rates remained severely restricted following tomato plants but low salinity level (-3 bar) caused no the removal of stress during this period, but plants reduction in growth of tomato plants. stressed at later times resumed growth at rates similar to [16] Under salinity conditions, pointed out that cobalt control values soon after they were returned to basal was used to reduce the harmful effect of salinity on [5] nutrient solutions. Rush studied the effect of salinity on tomato plants, transpiration rate being reduced. Angelov four ecotypes of Lycopersicon chees manii spp. minor [17] et al showed that cobalt reduced the salinity and/or (Hoak) C.H. Mil compared with Lycopersicon esculentum ethrel injury on tomato plants, a suggestion being Mill cv. VF 36. They found that the growth rates were introduced for possible use of cobalt with transplants reduced in both species under saline condition but the irrigated with saline water to overcome the salinity hazard. esculentum cultivar was more severely affected. Also they found that all Galapagos ecotypes were far more salt MATERIALS AND METHODS tolerance than was the esculentum. They could survive in full strength sea water nutrient solution while the The experiment was designed to study the interactive esculentum cultivar could not in most case withstand effect of concentration cobalt ion and salinity on the [6] level higher than 50% sea water. Tal and Gardi found growth, mineral composition, of two tomato varieties that the dry weight of all young tomato plants decreased differing in their salt tolerance, namely Moneymaker (as a in both diploid and polyploid plants under salinity. salinity sensitive variety), and Edcawy (as a salinity [7] Hoffman reported that the growth of tomato plants, tolerant one). generally, declined markedly as the salt concentration Seeds of tomatoes (Lycopersicon esculentum Mil, [8] rose. Dehan and Tal found that shoot and root growth c.v. Edcawy and Moneymaker) were sown on August 15th of solanum pennellii was not significantly affected by 2003 in trays filled with a mixture of sand and peatmoss [9] NaCl concentration as high as 200 mm. Nukaya et al (1:1 volume basis). Trays were kept under greenhouse showed that the fresh weight of tomato seedlings were condition with all agriculture managements required for greater at 250 and 500 ppm Cl than at zero and 100 ppm Cl. production of tomato seedlings. Plastic pots 35 cm They added that chlorosis and nicrosis occurred on the diameter and 12 kg capacity were filled with 10 kg acid lower leaves at 2000 ppm Cl and they were markedly sever washed sand. at 3000 ppm Cl and developed from lower to upper leaves. Five weeks-old seedlings, with almost the same stem Leaves and fruit yield fresh weight decreased as sea water thickness, were transplanted in the indicated prepared concentrations increased. pots (four seedlings per pot). Irrigation with the prepared The effect of salinity on tomato yield has been saline water was carried out every 5 days to keep the soil investigated with pot culture in greenhouse, however, the almost at its field capacity. results provide little information on the effect of salinity The saline water use was prepared by mixing NaCl, in the field. Since salt tolerance data for the tomato crop [19] CaCl 2 and MgCl 2 salts according to as follows: are neither conclusive nor available to adequately predict [10] yield response under field conditions. Two-year field 3{NaCl} : 1 { 3 (CaCl 2 ) + 1 (MgCl 2)} study was initiated to determine the effect of soil salinity on growth, yield and minerals contents in tomato plants This saline mixture were prepared in five grown under of field condition increasing levels of soil concentration : 0.0, 1000, 2000, 3000 and 4000 ppm. Cobalt [11] salinity. Shanon suggested that the patterns of ion was added in the form of CoSO. 7 H O in 5 levels: 0, 7.5,

3 15.0, 22.5, and 30.0 ppm cobalt. These concentrations were Nutritional status in plants: Data in Tables (2a and 2b) added once at the beginning of the experiment. Moisture clearly indicated the following: content in the pots were kept constant at 70 % of the total holding capacity throughout the experiment by compensating the loss of water due evapotranspiration by 3 distilled water. I addition, 500 cm /pot of complete [20] Hogland solution was added at biweekly intervals till the end of the experiment as a nutritive resource. Complete randomized blocks design with three replicates were adapted and the obtained data were statistically [21] analyzed at 5 % level according to the. To represent the vegetative growth just before flowering stage, plant samples were separated to shoots and roots to evaluate their fresh and dry weights. Samples being then grinded and digested for assayment of cobalt as well as iron, manganese, zinc and copper as well as Nitrogen, Phosphorous, potassium, Magnesium, Calsium [22] and Chloride according to. RESULTS AND DISCUSSIONS Plant tolerance to cobalt: The relative tolerance to cobalt concentration of Edcawy and Moneymaker tomato varieties, which showed wide range of salt tolerance, was estimated using sand culture experiment. The results presented in Table (1) showed that increasing cobalt concentrations in the cultural media up to 15.0 ppm cobalt stimulated the growth and dry matter yield of both varieties, shoots and roots. Such trend appeared to be reversed as applied cobalt concentration increased, least growth being obtained at 30.0 ppm rate in spite of similarity of 22.5 ppm cobalt treatment with that of control approximately. Also, data revealed that, at a concentration of cobalt ranging from ppm the shoots and roots of Edcawy were less affected by increasing the salinity levels than Moneymaker indicating that Edcawy were more resistant to higher than Moneymaker plants. Salt treatments, in general, decreased dry matter yield of both shoots and roots of the two varieties, the dry matter yield of Edcawy plants a saline-tolerant was less affected by salt mixture than Moneymaker as salt-sensitive plants. Increasing cobalt concentration up to 15.0 ppm was associated with an increase in dry matter for both varieties. The greatest effect of cobalt on dry matter production was observed at 1000 ppm salt mixture and 7.5 ppm cobalt. Increasing cobalt concentration up to 15.0 ppm for both of the two varieties at all levels of salinity. However, higher cobalt levels, above 15.0 ppm, were depressive and caused reduction in plant growth due to the effect of salinity. For cobalt: Increasing cobalt levels in plant media increased cobalt content in shoots and roots for both salttolerant (Edcawy) and salt-sensitive (Monymaker) plants. Increasing salinity level, in the medium was associated with significant decrease in cobalt concentrations in shoots and roots of both varieties except with the level 7.5 ppm cobalt at which cobalt content increased. Results also showed that status of cobalt was higher in roots than in shoots at all levels of salinity. For iron: Increasing salinity levels in the medium consistently increased the concentration of Fe in shoots and roots for both varieties. These results are in harmony [23] with that of. Results also indicated that root had continuously higher Fe contents than shoots. Increasing cobalt concentration in the plant media resulted in a progressive depression effect on iron status in shoots and roots of both varieties. This may be explained on the basis of [24] [25] results by and who indicated certain antagonistic relatioships between the two elements (Co, Fe). Hazardous effects of cobalt being severely involved in wilting appearance and reductions for net photosynthesis. Other trace elements: Salinity affected plant contents of Mn, Zn and Cu by: i)changing the available levels of these elements in plant media. ii) Altering their absorption by plant roots, and iii) Inhibiting cell expansion and plant [26] growth. Data indicated that increasing salinity levels in the plant media significantly decreased Mn, Zn and Cu in shoots and roots of both varieties. Same results were also obtained with increasing cobalt concentrations. The concentration of Mn, Zn and Cu of roots was higher than that of shoots at all levels of salinity. Salinity stress may have stimulatory or inhibitory effects on the uptake of some trace elements namely, Mn, Zn and Cu by [12,26] plants. Mechanisms involved in salt-induced mobility of trace elements include (1) decreased the activity coefficient of metal ions due to high ionic strength. (2) Dissolutions of insoluble metal-compounds, due to the reduced soil ph. (3) Depletion of free metal ions due to metal complex formation. 263

4 Table 1: Effect of various levels of cobalt on tomato shoots dry weight (g/plant) micro nutrients content as affected by salinity application. Co treatment (ppm) Zero Salinity treat. (ppm) Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Shoot Control Root Control Table 2a: Effect of various levels of cobalt on tomato shoots micro nutrients content as affected by salinity application Element Salinity treatment Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Co Control Fe Control Mn Control Zn Control

5 Table 2a: Continued. Cu Control Table 2b: Effect of various levels of cobalt on tomato roots micro nutrients content (ppm) as affected by salinity application Element Salinity treatment Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Co Control Fe Control Mn Control Zn Control Cu Control (4) Displacement of exchangeable metals by Na, Ca Nitrogen, phosphorus and potassium content: Results ++ and Mg, and/or the reduction of some metal- presents in Tables (4a and 4b) show the effect of salinized [27] bearing oxides by certain anions saline solutions. irrigation water on N, P and K content of different tomato 265

6 Table 3a: Effect of various levels of cobalt on tomato shoots macro nutrients content (%) as affected by salinity application. Element (%) Salinity treatment Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker N Control P Control K Control Table 3b: Effect of various levels of cobalt on tomato roots macro nutrients content (%) as affected by salinity application. Element (%) Salinity treatment Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker N Control P Control K Control

7 Table 4a: Effect of various levels of cobalt on tomato shoots Na, Ca, Mg and Cl content as affected by salinity application Element (%) Salinity treatment Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Na Control Ca Control Mg Control Cl Control Table 4b: Effect of various levels of cobalt on tomato roots Na, Ca, Mg and Cl content as affected by salinity application Element (%) Salinity treatment Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Edcawy Moneymaker Na Control Ca Control Mg Control

8 Table 4b: Continued Cl Control varieties. Salts treatments in general, decreased the ppm was followed by decreasing Ca concentration content of N, p and K in both shoots and roots of the two in both shoots and roots. varieties. Data also reported that addition of low Results in tables (5 and 6) showed that chloride concentration of cobalt (7.5 ppm) have shown a content was much higher in shoots than in roots for both significant beneficial effect on the status of salt-tolerant (Edcawy) and salt-sensitive (Moneymaker) macronutrients (N, P and K) in tomatoes. Increasing plants. Chloride concentration in shoots and roots cobalt level up to 15.0 ppm in plant medium increased N, decreased gradually with increasing cobalt concentration. P and K contents than that of control for both two varieties at all levels of salinity. However, higher cobalt REFERNCES level above 15.0 ppm being depressive caused reduction in N, P and K status due to the effect of salinity. Recently 1 El-Lawendy, W.I., Effect of salinity and drought low cobalt level was found to be promotive for better on sugar beat. Ph.D.Thesis, Fac.Agric. Al-Azhar status of N, P and K in tomato plants. This results are in Univ., Girls Branch. [28] harmony with. 2 Ruf, R.H., R.E. Jr.Eckert and R.O. Giforl, Osmotic adjustment of cell sap to increase in root mediam Sodium, calcium, magnesium and chloride: Data osmotic stress. Soil Sci., 96: tabulated in Tables (5a and 5b) showed the effect of 3 Saranga, M.E., Evaluation of some tomato salinized irrigation water on Na, Ca, Mg and Cl varieties to salt tolerance. M. Sc. Thesis, Fac. Agric. contents of the two different tomato varieties. Data Ain Shams Univ., Egypt. + revealed that Na content generally increased with the 4 Dumroff, E.B. and A.W. Cooper, Effect of salt increase in salt concentration in irrigation water regardless of tomato varieties. Sodium content of shoots was higher whereas that of roots was lower in salt-tolerant plants compared to salt-sensitive plants. Increasing in cobalt concentration in the medium decreased Na-concentration in shoots but increased that of roots. This effect was observed at all salinity levels. These results confirmed [29] with those reported by. Data clearly noticed that calcium content generally increased with the increase of salinity levels. Calcium concentration of shoots was higher than in roots. Calcium content in shoots increased with increase in salinity of levels. However, beyond that level in roots was adversely affected. Data also revealed that increasing cobalt addition up to 15.0 ppm was associated with an increase in Ca ++ content for both varieties shoots and roots. Excessive amounts of cobalt in the cultural media more than 268 stress applied in balanced nutrients at several stages during growth of tomato. Botanical Gazett 135 (3): Waterloo Univ. Canada. 5 Rush, D.W., Genotypic responses to salinity. Plant Physiol. 57: Tal, M. and A. Gardi, Physilogical of poly ploid plants: water balance in auto tetraploid and diploid tomato under low and high salinity. Physiologia plantarum, 38(4): (C.F. Hort. Abst., 47(6): 5667, 1977). 7 Hoffman, G.J., Tomato growth and yield as influenced by different levels of saline water applications. Mesopotomia J. of Agric., 13 (1) : (C.F. Hort. Abst. 49(6) 4263, 1979). 8 Dehan, K. and M. Tal, Salt tolerance in the wild relatives of the cultivated tomato: responses of solanum pennelii to high salinity. Irrig. Sci., (1):71-76.

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