Journal of Plant Nutrition Plant growth, phosphorus

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Plant growth, phosphorus nutrition, and acid phosphatase enzyme activity in three tomato cultivars grown hydroponically at different zinc concentrations a

b

Cengiz Kaya , David Higgs & Agneta Burton a

University of Harran, Agriculture Faculty,Horticulture Department , Sanhurfa, 63200, Turkey b

University of Hertfordshire, Environmental Sciences, College Lane , Hatfield, Herts, AL10 9AB, United Kingdom Published online: 21 Nov 2008.

To cite this article: Cengiz Kaya , David Higgs & Agneta Burton (2000) Plant growth, phosphorus nutrition, and acid phosphatase enzyme activity in three tomato cultivars grown hydroponically at different zinc concentrations, Journal of Plant Nutrition, 23:5, 569-579, DOI: 10.1080/01904160009382041 To link to this article: http://dx.doi.org/10.1080/01904160009382041

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JOURNAL OF PLANT NUTRITION, 23(5), 569-579 (2000)


Plant Growth, Phosphorus Nutrition, and Acid Phosphatase Enzyme Activity in Three Tomato Cultivars Grown Hydroponically at Different Zinc Concentrations Cengiz Kaya,a David Higgs,b and Agneta Burton b

a

University of Harran, Agriculture Faculty, Horticulture Department, Sanhurfa 63200, Turkey b University of Hertfordshire, Environmental Sciences, College Lane, Hatfield, Herts AL10 9AB, United Kingdom

ABSTRACT Three tomato cvs., Blizzard, Liberto, and Calypso, were grown hydroponically in a controlled temperature (C.T.) room for six weeks at three zinc (Zn) concentrations (0.01, 0.5, and 5.0 mg Zn L-1) in the nutrient solution. There were significant reductions in the dry matter and chlorophyll contents of all three cultivars grown at both low (0.01 mg L-1) and high (5 mg L-1) Zn as compared to 0.5 mg Zn L-1. The concentration of Zn at 0.01 mg L-1 was not sufficient to provide for optimal plant growth, while 5 mg Zn L-1 in the nutrient solution was detrimental to plant growth for all three cultivars. The best results for all parameters tested were for the plants grown at 0.5 mg Zn L-1. The concentration of phosphorus (P) was at an excess level in leaves of plants grown in 0.01 mg Zn L-1, while it was deficient in the 5 mg Zn L-1 treatment. Acid Phosphatase Enzyme [EC.3.1.3.2.] (APE) activity was significantly higher in both the leaves and roots of P-deficient plants, i.e., plants receiving high (5 mg L-1) Zn. Acid Phosphatase Enzyme activity was slightly higher in the

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KAYA, HIGGS, AND BURTON

mature leaves than those in developing leaves, where P concentration was higher. Concentration of P and, in particular Zn, increased in the roots with increasing Zn in the nutrient solution. The APE activity increased in the roots of P-deficient plants receiving high Zn (5 mg L-1).


INTRODUCTION

It is known that plants subjected to low and high level elemental levels differ in the nutrient uptake and accumulation, and plant and root growth. For example, an increase in the Zn concentration in nutrient solution or in soil has been shown to result in P deficiency in the plants, e.g., in okra (Loneragan et al., 1982) and in tomato (Parker et al., 1992). Zinc deficiency, however, may induce P toxicity. In Zn-deficient wheat plants, P concentration was shown to be at a detrimentally high level (Webb and Loneragan, 1990). For many years and in most agricultural production systems, P has been identified as the most frequently occurring essential nutrient element deficiency limiting crop yields, and it is still a nutrient element that continues to receive considerable research attention (Jones, 1998). The effects of high P associated mainly with Zn nutrition and iron (Fe) to some degree are quite well documented. High P levels are known to interfere with normal metabolism. However, enzyme activities associated to P stress have been incompletely characterized. One of the responses of the plant to heavy metal stress is to increase activities of several enzymes (Van Assche et al., 1984). For example, Bielski (1973) has noted that phosphatase activities of intact roots may have a significant role in making non-available P more available for plant use. In the P-deficient plants, APE activity may increase in the leaves resulting in increased uptake of P from growth medium (Besford, 1979). The use of biochemical parameters, particularly enzymes, as markers for the assessment of metabolic potentials and their heredity is a modern trend in testing the potential productivity of genotypes (Jones, 1998). The selection of plants resistant to nutrient element deficiencies or toxicities has also become one of approaches in crop yield improvement (Oerloff, 1987). In this experiment, three commercial cultivars were chosen to investigate tolerance to Zn deficiency and toxicity. The specific aims were to identify relationships between P nutrition and phosphatase enzyme activity in developing and mature leaves and in intact roots of plants grown at different Zn levels in the nutrient solution and also the relationship between Zn supply and plant growth. MATERIALS AND METHODS

Three tomato (Lycopersicon esculentum Mill.) cvs., Blizzard, Liberto, and Calypso were grown hydroponically in a controlled temperature (CT) room with relative humidity at 65-70% and temperature at 23±2/l 6±2°C, day/night. The total photoperiod was 16 hours per day and light intensity immediately above the plant


THREE TOMATO CULTIVARS G R O W N HYDROPONICALLY

571

canopy was between 20, 000-22, 000 Lux., depending on the exact height of the plants. Seeds were germinated on glass beads moistened with 10% strength nutrient solution. At the stage of the first true leaves homogeneous seedlings were transplanted into 4-L capacity polyethylene black-painted pots (three seedlings per pot). Zinc concentrations in the nutrient solution were 0.01, 0.5, and 5 mg L 1 , providing Zn deficient, adequate, and toxic conditions, respectively. Each treatment was replicated three times and each replicate include three pots (i.e., 9 plants per treatment). All solutions were prepared from analytical grade chemicals. The pH was adjusted to 5.6±0.2 immediately prior to use with 0.1 M potassium hydroxide (KOH). Iron was added in chelate form rather than as inorganic Fe in order to prevent precipitation. Composition of the nutrient solution used in this experiment is shown in Table 1. Plants were grown on for a further 32 days in different Zn treatments. One plant per pot was taken for determination of APE activity and leaf chlorophyll content. The second leaves from apex and base of plant were taken to represent developing and mature leaves, respectively. Acid Phosphatase Enzyme (APE) in Leaf Enzyme extraction was carried out by grinding fresh leaf material ( 1 g), using a cooled pestle and mortar, with 20 mL 0.1M sodium acetate-acetic acid buffer, pH 5.8 for 4 minutes at 2°C. The resulting homogenate was centrifuged at 30 000 g for 10 minutes at 2°C and the supernatant was assayed for APE activity (Besford, 1979). Acid Phosphatase Assay The enzyme assay based on the hydrolysis of p-nitrophnyl phosphate. Absorbance was read at 405 nm on a UV/VIS spectrophotometer. The APE activity was determined by the reference to standard curves of p-nitrophenol (Clark, 1975). Standards ranging from 0-16 uM were prepared in deionized water. Acid Phosphatase Enzyme (APE) in Root The roots of two plants were transferred to beakers each containing 250 mL nutrient solution for each Zn concentration (0.01, 0.5, and 5 mg L 1 ). A standard volume of p-nitrophenyl phosphate to give a concentration of 0.1 mM was added to each beaker and pH adjusted to 4.0 with hydrochloric acid (HC1). Control reactions were an aerated solution without plants. After 30 minutes, 3.0 mL samples were drawn from each beaker and added to test tubes containing 1.0 mL 2 TVNaOH. The tubes were shaken and centrifuged at 3, 000 g for 2 minutes and absorbance was read specrrophotometrically at 405 nm. Concentration of p-nitrophenol formed by the phosphatase mediated hydrolysis of p-nitrophenyl phosphate were determined by reference to standard curves of p-nitrophenol (Clark, 1975). A range of standards from 0-6 uM were prepared in deionized water.

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KAYA, HIGGS, AND BURTON TABLE 1. Compositions of nutrient solution (modified Hoagland and Arnon nutrient solution). Reagents KNOj Ca(NO 3 ) 2 -4H 2 O MgSO 4 -7H 2 O KH 2 PO 4


HJBOJ

MnCIj-4H 2 O CUSO 4 -5H 2 O H 2 MoO 4 NaFeEDTA1.5H2O ZnSO 4 -7H 2 O

Elements

K;N Ca;N Mg;S

K;P B Mn Cu MO Fe Zn

Concentrations (mg L"1) 195; 70 200; 140 48; 64 39; 31

0.5 0.5 0.02 0.01

2.8 0.05

Chlorophyll Determination

Leaf samples (fully expanded developing leaf) from the same plant used to assay APE activity were washed with deionized water to remove surface contamination prior to extraction. Chlorophyll extraction in 90% acetone was carried out on fresh leaf material ( 1 g) using a pestle and mortar. Absorbance was measured with a Pye Unicam SP6-550 UV/VIS spectrophotometer and chlorophyll concentrations were calculated using the equation from Strain and Svec (1966). Dry Weight and Chemical Analyses The two plants used to determine APE activity in intact roots were harvested, divided into component parts, and dried at 70°C for 48 hours to constant weight to determine dry weight and elemental concentration. Chemical analyses were carried out on plant material dried at 70°C for 48 hours, ground to powder using a pestle and mortar, and stored in polyethylene bottles. Sample aliquots of 0.2-0.5 g dry weight of powdered plant material were dry ashed at 550°C in a muffle furnace. The white ash was taken up in hot 2 M Analar HC1, filtered, and diluted to 50 mL with deionized water. Samples were analyzed for Zn by atomic adsorption spectrometry (Unicam Solar 929 AAS) in an air-acetylene flame. Phosphorus was determined spectrophotometrically by the vanadate molybdate method using a Pye Unicam SP6-550 UV7VIS spectrophotometer (Chapman and Pratt, 1982). Data were analyzed for statistical test using a Statview ANOVA programme. Statistically different groups were determined by LSD test.

THREE TOMATO CULTIVARS GROWN HYDROPONICALLY

573

RESULTS AND DISCUSSION


Visual Symptoms Tomato plants grown in the low (0.01 mg I/1) Zn treatment exhibited typical Zn deficiency symptoms such as little leaf rosette and interveinal chlorosis. Both root and shoot growth were also suppressed. Those symptoms are similar to those described for tomato plant by Winsor and Adams (1987). Plants grown at high Zn concentration shown Zn toxicity symptoms; those were inhibition of shoot and root growth, brown color root, smaller size of leaves than normal, and general chlorosis in plant. In the present experiment, initial ^symptoms of Zn deficiency and toxicity appeared within two weeks of application of Zn at low (0.01 mg L"1) and high (5 mg I/1) levels. Plant Growth Differences in both dry matter and chlorophyll concentration between treatments were used to assess the plant growth. There were significant reductions in dry matter and chlorophyll contents of plants grown in 0.01 and 5 mg Zn L 1 treatments compared with those in 0.5 mg L 1 for all cultivars (Tables 2 and 3). Decreases in the dry matter and chlorophyll contents with low (0.01 mg L"1) Zn treatment were greater than those with high (5 mg L 1 ) Zn for all three cultivars. Lu et al. (1998) observed in pot experiment that the high ( 10 mg kg'1 soil) Zn application drastically reduced the oilseed rape dry matter. A decrease in the concentrations of both chlorophyll a and b in Zn-deficient tomato plants grown in culture solution has been reported by Zhang and Wu (1989). The adverse effects of low and high Zn treatment were more striking on shoot growth than root growth. The ratios of shoot to root were lower for plants in 0.01 and 5 mg Zn L 1 compared with these for plants in 0.5 mg L"1. There were no major cultivar differences in reductions in dry matter and chlorophyll contents of plants in low and high Zn treatments, but Liberto and Calypso produced slightly more dry matter and chlorophyll than Blizzard. Reduction in chlorophyll content were less than that in dry matter in both low and high Zn treatments. The ratios of chlorophyll a to chlorophyll b were higher for plants grown in 0.01 and 5 mg Zn L 1 treatments compared with those for plants at 0.5 mg I/1. Zinc Increased Zn concentration in the nutrient solution resulted in a corresponding increase in both leaves and roots with Zn concentrations sharply increased in the root and reached a detrimental level at the 5 mg Zn L"1 concentration level. The 0.01 mg Zn L 1 concentration level was inadequate for plant growth when compared with standard data (Adams, 1986) for tomato plants, while the 0.5 mg Zn L"'

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TABLE 2. (g plant 1 ).

Dry matter' of three tomato cultivars grown at various zinc concentrations

Zn cone. (mgL-1) Shoot

%2

Root

0.01 0.50 5.00

1.85a3 6.02c 2.25b

69 63

0.31a 0.64 c 0.45b

0.01 0.50 5.00

1.75a 7.05c 3.15b

75 55

0.34 0.74 0.48

0.01 0.50 5.00

1.74a 6.85c 2.90b

75 58

0.30a 0.66c 0.40b

•

%

Shoot/Root

Blizzard 52 5.97b 9.41c 30 5.00a Liberto 54 5.15a 9.53c 35 6.56b Calypso 55 5.80a 10.38c 39 7.25b

%

Total Plant

%

37 47

2.16a 6.66c 2.70b

68 59

46

73

31

2.09a 7.79c 3.59b

44 30

2.04a 7.5 1c 3.30b

73

54

56

'Means of three replicates and each replicate includes two plants. %: Percentage decreases compared with 0.5 mg Zn L 1 treatment. 3 Within each column, same letter indicates no significant difference between treatments

2

TABLE 3. Chlorophyll concentration (mg kg"1 fresh leaf)' of three tomato cultivars grown at various zinc concentrations. Zn cone. Chi. a (mgL-1)

%2

Chl.b

%

0.01 0.50 5.00

755a3 980c 850b

22 • 13

350a 650b 380a

46 42

0.01 0.50 5.00

755a 1055c 920b

28 13

345a 720c 420b

52

0.01 0.50 5.00

740a 1020c 895b

27

340a 685b 365a

50 . 47

12

42

Chl.a/Chl.b Chi. a+b Blizzard 2.16b 1.51a 2.24b Liberto 2.19b 1.47a 2.19b Calypso 2.18b 1.49a 2.45c

1105a 1630c 1230b

%

32 25

1100a 1775c 1340b

38

1080a 1705e 1260b

37

25

26

'Means of three replicates and each replicate includes one plant. %: Percentage decreases compared with 0.5 mg Zn L"' treatment. 3 Within each column, same letter indicates no significant difference between treatments (P>0.01) 2


575

TABLE 4. Zinc concentration (mg kg"1 dry matter)1 of three tomato cultivars grown at various zinc concentrations. Cultivars


Zn Cone. (mgL 1 ) 0.01 0.50 5.00

D.L.

Blizzard M.L.5

1

17a« 48b 364c

22a 64b 455c

Roots

Liberto D.L. M.L.

Roots

Calypso D.L. ML.

Roots

30a 85a 8510b

16a 52b 392c

35a 92a 8050b

15a 54b 376c

39a 98a 7960b

21a 74b 485c

24a 72b 468c

'Means of three replicates and each replicate includes two plants. D.L.: Developing leaf 3 M.L: Mature leaf. 4 Within each column, same letter indicates no significant difference between treatments 2

concentration level seems to be adequate. The results of this experiment are in agreement with those done for okra (Loneragan et al., 1982) and bush bean (Ruano, 1988). Zinc concentration was highest in the root, especially with the 5 mg Zn L"1 treatment, intermediate in mature leaves and lowest in the developing leaves (Table 4). There appears to be no major differences in Zn concentration among the cultivars. Phosphorus The 5 mg Zn L"1 concentration level in the nutrient solution produced P-deficient plants as evidenced by leaf P concentrations less than 0.30% in some cases (Adams, 1986) and by a marked depression in dry matter production, while P concentrations in the leaves of plant growing in the 0.01 mg Zn I/ 1 treatment level was excessive (Table 5). Toxic levels of P have not been clearly identified for most vegetable crops. Jones (1998) has observed the occurrence of elemental stress in tomato plants when the P level exceeds 1% of dry matter, mainly occurring for container-grown plants and those being grown hydroponically. Lu et al. (1998) reported that P concentrations in plants was significantly higher at nil-Zn treatment level plants compared to those receiving Zn at recommended application levels. Higher concentration of P accumulated in the root of plants in 5 mg Zn L"1 treatment compared with the other treatments. Phosphorus concentration was generally higher in the developing leaves than mature leaves presumably due to its mobility within plant.


576

TABLE 5. Phosphorus concentration (% dry matter)1 in developing and mature leaves and intact roots of three tomato cultivars grown at various zinc concentrations Cultivars


Zn Cone. (mgl/ 1 ) 0.01 0.50 5.00

Blizzard D.L.2 MX.1 1.60c4 0.80b 0.25a

1.40c 0.70b 0.20a

Roots

Liberto D.L. M.L.

Roots

Calypso D.L. MX.

Roots

1.20a 1.30a 2.60b

1.55c 0.75b 0.32a

1.25a 1.32a 2.58b

1.48c 0.73b 0.35a

1.12a 1.34a 2.40b

1.44c 0.70b 0.28a

1.36c 0.68b 0.32a

'Means of three replicates and each replicate includes two plants. D.L.: Developing leaf 3 M.L.: Mature leaf. 4 Within each column, same letter indicates no significant difference between treatments 2

There were no consistent changes in the P concentration with different Zn treatments between cultivars; the values for P were almost the same within a given Zn treatment, but leaf-P values appeared to be slightly lower in Blizzard in the 5 mg Zn L"1 treatment.

TABLE 6. Acid phosphatase activity 1 (urn P-nitrophenol g 1 fresh leaf) in developing and mature leaves and (urn P-nitrophenol g 1 dry weight root h ' ) intact roots of three tomato cultivars grown at various Zn concentrations Cultivars Zn Cone. (mgL-1) 0.01 0.50 5.00

Blizzard D.L.2 MX.' 1.20a4 2.45b 10.45c

1.31a 3.43b 13.25c

Roots

Liberto D.L. MX.

Roots

Calypso DX. MX.

Root

76a 95b 255c

1.05a 3.10b 10.15c

74a 105b 245c

1.10a 3.20b 10.30c

82a 114b 238c

1.21a 3.45b 12.25c

1.36a 3.55b 11.15c

'Means of three replicates and each replicate includes one plant for APE in developing and mature leaves and two plants for APE activity in intact roots. 2 D.L.: Developing leaf 3 M.L.: Mature leaf. 4 Within each column, same letter indicates no significant difference between treatments


577


Acid Phosphatase Enzyme (APE) Activity

The APE increased markedly in the developing and mature leaves, and in intact roots of P-deficient plants receving Zn at 5 mg I/ 1 . Acid Phosphate Enzyme activity was generally slightly higher in mature compared to young leaf (Table 6); this may be related to a lower level P in the mature leaf. These data are supported by the work of Wasaki ( 1997) who reported that P deficiency induces the synthesis of acid phosphatase in the roots of lupin plants and Römer and Fanning (1998) noted that the activity of root phosphatase increased with declining P status of shoot ofLolium multiflorum inbred lines. Kummerova et al. (1995) showed that the absence of P in nutrient solution for the whole time of cultivation induced an unambiguous increase in acid phosphatase activity in both roots and leaves of spring barley. In this study, the lowest APE was found in the leaves of plant receiving low (0.01 mg L"1) Zn in nutrient solution and having excess levels of P in their leaves. CONCLUSIONS

From the results of this study, it can be concluded that: 0.5 mg Zn L 1 concentration in the nutrient solution may be considered to be adequate levels for tomato cultivars used in this experiment. 2. 0.01 mg Zn L"1 concentration in the nutrient solution can be considered to be inadequate for healthy growth of tomato plant. 3. 5 mg Zn L"1 concentration in the nutrient solution was too high and detrimental to growth. 4. Zinc-deficient plants exhibited P toxicity and zinc-toxic plants produced P deficiency. 5. APE activity increased significantly in the leaves and roots of plants grown at high Zn-may be a response to P deficiency. 6. APE activity was slightly higher in mature than developing leaves-may be due to lower P in mature leaves. 7. Liberto and Calypso cultivars produced slightly higher dry matter and chlorophyll than Blizzard. 1.

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Chapman, H.D. and P.F. Pratt. 1982. Methods of Analysis for Soils, Plants, and Water. Chapman Publisher, Berkeley, CA. Clark, R.B. 1975. Characterisation of phosphatase of intact maize roots. J. Agric. Food Chem. 23:458-460.


Jones, Jr., J.B. 1998. Phosphorus-toxicity in tomata plants: When and how does it occur? Commun. Soil Sci. Plant Anal. 29:1779-1784. Kummerova, M., M. Hladilova, and R. Brandejsova. 1995. Acid phosphatase activity of spring barley in dependence on phosphate nutrition. Rostlinna Vyroba 41:197-200. Loneragan, J.F., D.L. Grunes, R.M. Welch, E. A. Aduayi, A. Tengah, V.A. Lazar, and E.E. Cary. 1982. Phosphorus accumulation and toxicity in leaves in relation to zinc supply. Soil Sci. Soc. Am. J. 46:345-352. Lu, Z.G., H.S. Grewal, and R.D. Graham. 1998. Dry matter production and uptake of zinc and phosphorus in two oilseed rape genotypes under differential rates of zinc and phosphorus supply. J. Plant Nutr. 21:25-38. Oerlof, G.C. 1987. Intact-plant screening for tolerance of nutrient-deficiency stress. Plant Soil 99:3-16. Parker, D. R., J.J. Aguilera, and D.N. Thomason. 1992. Zinc-phosphorus interaction in two cultivars of tomato (Lycopersicon esculentum L.) grown in chelator-buffered nutrient solutions. Plant Soil 143:163-177. Romer, W. and J. Fahnin. 1998. Uptake and utilization of phosphorus by three inbred lines of Lolium multiflorum L. and their hiybrids. Zeitschrift für Pflanzener-nahrang und Boden kunte 161:35-39. Ruano, A., J. Arcelo, and C.H. Oschenrieder. 1988. Growth and biomass of zinc-toxic bush beans. J. Plant Nutr. 11:577-588. Strain, H.H. and W.A. Svec. 1996. Extraction, speration, estimation, and isolation of chlorophylls, pp. 21-66. In: L.P. Vernon and G.R. Seely (eds.), The Chlorophylls. Academic Press, New York, NY. Van Assche, F. and H. Clijsters. 1990. Effects of metals on enzyme activity in plants. Plant Cell Environ. 13:195-206. Wasaki, J., M. Ando, K. Ozawa, M. Omura, M. Osaki, H. Ito, and H. Matsui. 1997. Properties of secretary acid phosphatase from lupin roots under phosphorus-deficient conditions. Soil Sci. Plant Nutr. 43:981-986. Webb, M. J. and J.F. Loneragan. 1990 Zinc translocation to wheat roots and its implications for a phosphorus zinc interaction in wheat plant. J. Plant Nutr. 13:1499-1512.

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