CADMIUM AND LEAD STATUS IN CORN HYBRIDS GROWN ON ACID SOIL OF EASTERN CROATIA

ISSN 1330-7142

UDK = 633.15:632.122.1+631.415.2

CADMIUM AND LEAD STATUS IN CORN HYBRIDS GROWN ON ACID SOIL OF

EASTERN CROATIA

V. Kovačević

_{, I. Kadar}

_{, J. Koncz}

_{, I. Brkić}

_{, Đ. Banaj}

Original scientific paper

SUMMARY

Twenty corn (Zea mays L.) hybrids were grown under field conditions in the west part of Brodsko-posavska county in Eastern Croatia during 2000 and 2001 growing seasons. The field trial was conducted in four replicates. The ear-leaf at beginning of silking stage (the second decade of July) was taken for chemical analysis from each plot. Mean soil sample was taken by auger to 30 cm of depth. The total amounts of Cd and Pb in corn leaves were measured by ICP-AES technique after their microwave digestion using concentrated HNO3+H2O2. Mobile fraction of these elements in soil was extracted by ammonium acetate-EDTA solution. The experimental field is acid hydromorphic soil (locality Malino) with moderate levels of mobile fractions of calcium, magnesium and aluminum. Also, mobile fraction of cadmium and lead are tolerable for growing of health food. Weather conditions during the study differed from the long-term mean. Low rainfall quantities during 5-months period and the higher air-temperatures characterized the 2000 growing season. Excess of rainfall in June and September, their shortage in July and August, as well as high temperatures in August, are main characteristics of weather during the corn growing seasons in 2001. Mean concentrations of cadmium and lead in corn leaves in our investigations were 0.14 ppm Cd and 0.420 ppm Pb. These amounts are low and not dangerous for plants, because critical concentrations of Cd and Pb in plants ranged from 5 to 10 ppm Cd and 10-20 ppm Pb. Considerable differences of cadmium and lead status in the ear-leaf were found among tested corn hybrids. For example, genetically induced differences from 0.07 to 0.21 ppm Cd were found, while these values for Pb were from 0.241 to 0.569 ppm Pb. Especially low Cd concentrations were found in six corn hybrids (OsSK373, E9917/99, Bc278, OsSK2-191, OsSK382 and Clarica: mean 0.092 ppm Cd), while in three hybrids it was considerably higher, but acceptable from the aspect of plant and animal health (OsSK395, OsSK378 and Tvrtko 303: mean 0.200 ppm Cd). Very low Pb concentrations were found in two hybrids (Clarica and OsSK373: mean 0.268 ppm Pb), while in three hybrids they were above 0.500 ppm Pb (RK1456/99, osSK382 and Bc278: mean 0.542 ppm Pb). In general, production of healthy food based on principles of sustainable agriculture is possible under tested environmental conditions

Key-words: acid soil, cadmium, corn hybrids, lead, yield, Croatia

INTRODUCTION

Corn properties are under environmental and genetically influences. Although corn hybrids have high genetically potential for yield, their corn yields are considerably lower under different environmental stresses including low pH and moderate supplies of some nutrients. Also, harmful metals uptaken by plants have drawn more attention in recent period because of their possible toxic influences on man. Aim of this study was testing amounts of cadmium (Cd) and lead (Pb) in corn plants on “non-contaminated area” of the eastern Croatia, as well as role of inheritance (differences among corn hybrids) on this Cd and Pb status in corn. General aspects of Cd and Pb uptaken by plants were shown by Mengel and Kirkby (1987), Bergmann (1992) etc.

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MATERIAL AND METHODS

Twenty corn (Zea mays L.) hybrids were grown under field conditions (hydromorphic soil, characterizing moderate supplies of plant available phosphorus) in the west part of Brodsko-posavska County (locality Malino) in Eastern Croatia during 2000 and 2001 growing seasons. Corn was sown manually by planter at the beginning of May (in row 20 cm apart = theoretical plant density or TPD 71429 plants/ha). The experiment treatments were replicated four times. An experiment plot for a hybrid was 7.0 m2, or one 10-m rows. As for two year of testing plant density realization was different, (means 62% and 92%, for 2000 and 2001, respectively, grain yields were calculated on different plant density (70% for the growing season 2000 and 90% for 2000 and 2001, respectively).

The ear-leaf at the beginning of silking stage (the second decade of July) was taken for chemical analysis (about 25 leaves in mean sample) from each plot. Mean soil sample was taken by auger to 30 cm of depth. The total amounts of Cd and Pb in corn leaves were measured by ICP-AES technique after their microwave digestion using concentrated HNO3+H2O2. Mobile fraction of these elements in

soil were also determined by ICP-AES after their extraction by ammonium acetate-EDTA (pH 4.65) solution by Lakanen and Ervio (1971) method. Plant and soil analysis were made in the laboratory of the Research Institute for Soil Science and Agricultural Chemistry (RISSAC) Budapest, Hungary. The experimental field is acid hydromorphic soil with moderate levels of mobile fractions of calcium, magnesium and aluminum. Also, mobile fraction of cadmium and lead are tolerable for health food growing (Table 1).

Table 1. Soil properties Tablica 1. Svojstva tla

pH %

Humus

Mobile fraction (NH4Acetate-EDTA extraction)

Mobilna frakcija (ekstrakcija s NH4Acetate-EDTA)

% ppm

H2O KCl Ca Mg Al Cd Pb

5.94 4.77 2.41 0.375 0.021 77 0.17 3.6

Weather conditions during the study differed from the long-term mean. Low rainfall quantities during 5-months period and higher air-temperatures characterized the 2000 growing season. Excess of rainfall in June and September, their shortage in July and August, as well as high temperatures in August, are main characteristics of weather during growing seasons of corn in 2001 (Table 2). In general, under our environmental conditions, low yields of corn are in connection with shortage of rainfall and higher air-temperatures during July and August (Kovačević and Josipović, 1998).

Table 2. Weather data for Slavonski Brod Tablica 2. Meteorološki podaci za Slavonski Brod

Rainfall (mm) and mean monthly air-temp. (oC) - Slavonski Brod Weather Bureau1 Oborine (mm) i srednje mjesečne tempetarure zraka (o

C) – meteorološka postaja Slavonski Brod1

Total Ukupno

mm

Mean Prosjek

o

C The growing season

Vegetacija

May Svibanj

June Lipanj

July Srpanj

August Kolovoz

Sept. Rujan

2000 mm

o

C

27 17.3

25 21.6

87 21.2

10 23.0

47

16.1 196 19.8 2001 mm

o

C

32 17.9

188 17.8

25 21.9

32 22.2

224

14.5 501 18.9 Long-term means

Višegod. prosjek 1981-1999

mm

o

C

68 16.3

85 19.4

75 21.5

69 20.8

71

16.6 368 18.9

1

RESULTS AND DISCUSSION

Under conditions of moderate fertile acid hydromorphic soil, there were considerable influences of inheritance on yields, as well as Cd and Pb status in corn plants. For example, grain yields of tested corn hybrids (2-year means) ranged from 4.06 to 11.69 t/ha (Table 3). Six hybrids yielded less than 7 t/ha (Alpos, OsSK2-191, OsSK247, Bc278 and Clarica: mean 5.49 t/ha). At the same time, yields of three hybrids were above 10 t/ha (OsSK378, OssK298 and RK1458/99: mean 10.91 t/ha.

Table 3. Response of corn hybrids on acid soil (Malino, 2000 and 2001) Tablica 3. Reakcija hibrida kukuruza na kiselom tlu (Malino, 2000. i 2001. g)

Corn hybrid Hibrid kukuruza

Grain yields (t/ha) and the ear-leaf Cd and Pb (on dry matter basis) of corn hybrid (factor B) at silking for two growing seasons (the factor A)

Prinosi zrna (t/ha) i koncentracije Cd I Pb u listu ispod klipa (u suhoj tvari) hibrida kukuruza (faktor B) u fazi svilanja tijekom dvije vegetacije (faktor A)

Grain yield (t/ha) Prinos zrna (t/ha)

Cadmium (ppm Cd) Kadmij (ppm Cd)

Lead (ppm Pb) Olovo (ppm Pb)

2000 2001 Mean

Prosjek 2000 2001

Mean

Prosjek 2000 2001

Mean Prosjek 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Alpos OsSK2-191 Code 1* OsSK373 OsSK233 OsSK351 OsSK298 OsSK378 E9916 E9917/99 RK1458/99 Tvrtko 303 RK1456/99 OsSK395 OsSK332 OsSK382 OsSK247 Bc278 Clarica Podravec 36 4.65 6.15 8.25 8.20 9.15 10.20 11.85 13.80 11.20 9.50 11.65 9.40 8.20 8.75 8.65 8.65 6.25 9.80 8.20 8.85 3.47 5.72 8.49 10.09 9.84 9.00 9.71 9.58 8.61 6.56 8.87 7.65 8.42 9.39 8.16 7.71 5.46 3.99 4.82 8.55 4.06 5.94 8.37 9.15 9.50 9.60 10.78 11.69 9.91 8.03 10.26 8.53 8.31 9.07 8.41 8.18 5.86 5.10 6.51 8.70 0.12 0.09 0.11 0.04 0.10 0.15 0.16 0.19 0.12 0.07 0.12 0.21 0.13 0.18 0.16 0.11 0.14 0.10 0.13 0.13 0.13 0.11 0.13 0.11 0.14 0.17 0.16 0.18 0.13 0.07 0.11 0.18 0.12 0.23 0.15 0.10 0.11 0.07 0.09 0.12 0.13 0.10 0.12 0.07 0.12 0.16 0.16 0.19 0.13 0.07 0.12 0.20 0.13 0.21 0.16 0.11 0.13 0.09 0.11 0.13 0.377 0.387 0.300 0.293 0.480 0.285 0.280 0.528 0.298 0.278 0.433 0.323 0.455 0.303 0.280 0.548 0.395 0.423 0.275 0.365 0.535 0.605 0.363 0.295 0.500 0.403 0.425 0.320 0.385 0.485 0.558 0.667 0.683 0.412 0.423 0.522 0.570 0.623 0.208 0.505 0.456 0.496 0.331 0.294 0.490 0.344 0.353 0.424 0.341 0.381 0.495 0.495 0.569 0.358 0.351 0.535 0.482 0.523 0.241 0.435 Mean A

Prosjek A 9.07 7.70 0.13 0.14 0.365 0.474

LSD5% LSD1%

A: 0.59 B: 0.74 AB: 1.45 1.08 0.97 2.40

A: n.s. B: 0.06 AB: 0.10 0.08 n.s.

A: 0.066 B:0.183 AB: n.s.

0.120 n.s. *Code 1 =E9923/LG23/10xLG28/10

hybrids they were above 0.500 ppm Pb (RK1456/99, osSK382 and Bc278: mean 0.542 ppm Pb). Significant influences of rowing season influences on yields and Pb status was found by our study, while Cd in corn leaves was similar in both year of testing.

Cadmium is toxic for human, animal and plants even at low concentrations. Cadmium can enter the soil with different sources including phosphate fertilizers. Kloke (1980) estimated Cd inputs by P fertilization very low - at 3 g/ha/year. Baechle and Wolstein (1984) found range of mean Cd contents in various rock phosphates from 0.3 to 84.o ppm Cd. Kloke (1973) found that Cd contents in high plants normally vary between 0.2 and 3.0 ppm. Chaney et al. (1977) found toxic Cd levels of 4 ppm Cd in soybean leaves. Cadmium and zinc are chemically very similar and Cd is thus able to mimic the behavior of the Zn in its uptake and functions. The basic cause of the toxicity probably lies in much higher affinity for thiol groupings (SH) in enzymes and other proteins. The presence of Cd therefore disturbs enzyme activity. In plants excess Cd may also disturb Fe metabolism and cause chlorosis. Cd availability in the soil decreases as the soil pH increases. Kaferstein (1979) reported acceptable maximum Pb and Cd levels in edible parts or food plants - for cereals these values are less than 0.5 ppm Pb and less than 0.1 ppm Cd. Davis et al. (1978) found Cd and Pb levels in young summer barley plants at tillering (5-leaf stage) with 10% loss of yield as follows: 15 ppm Cd and 26 ppm Pb. Fritz et al. (1977) found less than 1 ppm Cd and from 5.3 to 28.7 ppm Pb in fruit, root, tuber and leaf vegetables from "non-contaminated regions".

Lead is major chemical pollutant of the environment, and is high toxic to man. By many studies it was shown that Pb contents very clearly follows the motorway areas. Vegetation of the side of the road may have levels of 50 ppm Pb but at distance of only 150 m away from the motorway the level is normal about 2 or 3 ppm (Mengel and Kirkby, 1987).Grun et al. (1989) tested heavy metals contamination of soil and plants (total 124 samples) near Berlin in former DDR. They found that Cd contents in corn irrigated by waste water ranged from less than 0.3 ppm Cd (18% samples) to more than 5.0 ppm Cd (4% samples), while on the control (uncontaminated) was 0.11 ppm Cd. According to this study, corn is in the group of high Cd uptaken in vegetative parts.

Kadar et al. (2002) tested influences of soil contamination with 13 pollutants, their mobility and phytotoxicity for corn, carrot and potato in calcareous chernozem. Cd and Pb were very mobile in soil, but they accumulated moderately (Cd) and weakly (Pb) in plant. Carrot root and potato tuber yields significantly decreased in the Cr, Hg, and Se treatments. Other applied elements did not affect yield substantionally. By testing rabbits feeding with fodder carrot enriched with Mo, Cd, Pb, Hg and Se, their different distributions in organs, hard excrement and urine (Kadar and Koncz, 2000) were found. By comparison of these data with our results, low quantities of tested pollutants were found in corn leaves and production of healthy food is possible on arable lands in Croatia.

CONCLUSION

Mean concentrations of cadmium and lead in corn leaves in our investigations were low (0.14 ppm Cd and 0.420 ppm Pb) and these findings are indication for the clearly and healthy environment. Considerable differences of cadmium and lead status in the ear-leaf were found among tested twenty corn hybrids: from 0.07 to 0.21 ppm Cd and from 0.241 to 0.569 ppm Pb. Especially low Cd concentrations were found in six corn hybrids (OsSK373, E9917/99, Bc278, OsSK2-191, OsSK382 and Clarica: mean 0.092 ppm Cd). Also, very low Pb concentrations were found in two hybrids (Clarica and OsSK373: mean 0.268 ppm Pb).

REFERENCES

1. Baechle H.T., Wolstein F.(1984): Cadmium compounds in mineral fertilizers, The Fertilizer Society, Proc. No 226, London.

2. Bergman W. 1992. Nutritional disorders of plants - development, visual and analytical diagnosis. Gustav Fischer Vela Jena, Stuttgart, New York.

4. Davis R. D., Beckett P. H. T., Wollan E. (1978): Critical levels of twenty potentially toxic elements in young spring barley. Plant and Soil, 49:395-408.

5. Fritz P. D., Foroughi M., Venter F. (1977): Schwermetallgehalte in einige Gemusearten. Landw. Forschung. Sonderheft 33:335-343.

6. Grun M., Machelett B., Kronemann H., Metz R., Podlesak W. (1989.): Kontrollierte landwirtschaftliche Nutzung schwermetallbelasteter Gebiete. In: Wissenschaftlicher Jahresbericht 1989, Institute fur Pflanzenernahrung and Okotoxicologie, Jena, DDR. p. 58.-62.

7. Kadar I., Koncz J., Fekete S. (2002): Movement of Cd, Hg, Mo, Pb and Se in soil - plant - animal chain. Proceedings of the Alps-Adria Scientific Workshop, Opatija 4-8 March 2002, Hungarian Academy of Sciences, Crop Production Committee, Soil Science and Agrochemistry Committee, Budapest, Hungary, p. 90-94.

8. Kadar I., Koncz J. (2000): Phytotoxicity of some micropollutants on calcareous chernozem soil. In: 36th Croatian Symposium on Agriculture with an International Participation "Achievement and Perspectives of Croatian Agriculture" - collection of summaries, University J. J. Strossmayer in Osijek, Faculty of Agriculture Osijek, Croatia, p. 25.

9. Kaferstein F. K. (1979.): Blei, Cadmium und Quecksilber. Ursachen, Konsequenzen, Erfordernisse - Modellstudie. ZEBS-Bericht. Dietrich Reimer, Berlin.

10.Kloke A. (1973.): Schwermetalle in Nahrungs- und Futterpflanzen. Dtsch. Lebensm.-Rdsch. H.1, 45.-49.

11.Kloke A. (1980.): Der Einfluss von Phosphatdungunern auf den Cadmiumgehalt in Pflanzen. Gesunde Pflanzen 32:261.-267.

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Croatia. M. In: Fifth Congress of ESA (European Society for Agronomy), 28 June - 2 July, 1998, Nitra, The Slovak Republic. Short Communications, Volume II. (Zima and M. L. Bartosova, ed), p. 157-158.

13.Lakanen E., Ervio R. (1971): A comparison of eight extractans for the determination of plant available micronutrients in soils. Acta Agr. Fenn. 123:223-232.

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KADMIJ I OLOVO U HIBRIDIMA KUKURUZA UZGAJANIM NA KISELOM TLU

ISTOČNE HRVATSKE

SAŽETAK

Dvadeset hibrida kukuruza uzgajano je tijekom dvije vegetacije (2000. i 2001.) u poljskim uvjetima u zapadnom dijelu Brodsko-posavske županije u istočnoj Hrvatskoj. Poljski pokus je postavljen u četiri ponavljanja. List ispod klipa početkom svilanja (druga dekada srpnja) je uzet sa svake parcelice za kemijske analize. Prosječan uzorak tla je uzet sondom do dubine 30 cm. Ukupne količine kadmija (Cd) i olova (Pb) u

listovima kukuruza je mjeren ICP-AES tehnikom nakon razaranja uzorka s HNO3+H2O2. Mobilna frakcija tih elemenata u tlu je određena nakon ekstrakcije s amonij acetat-EDTA otopinom. Eksperimentalna površina je kiselo hidromorfno tlo (lolakitet Malino) koje sadrži skromne količine mobilne frakcije kalcija, magnezija i aluminija. Također, sadržaj mobilne frakcije Cd i Pb je tolerantan sa stajališta proizvodnje zdrave hrane. Vremenske prilike tijekom istraživanja bile su različite od višegodišnjeg prosjeka. Količina oborina tijekom

razdoblja od pet mjeseci 2000. bila je niska, a temperature zraka veće. Višak oborina u lipnju i rujnu te

njihov manjak u srpnju i kolovozu, kao i visoke temperature tijekom kolovoza, glavne su karakteristike vremenskih prilika tijekom vegetacije kukuruza 2001. Prosječne koncentracije Cd i Pb u listu kukuruza iznosile su 0,14 ppm Cd i 0,420 ppm Pb. Te količine su niske sa stajališta tolerancije biljaka i ljudske ishrane, jer prema navodima iz literature kritične koncentracije tih elemenata u biljkama su od 5 do 10 ppm Cd i

10-20 ppm Pb. Značajne razlike u koncentracijama Cd i Pb u listu ustanovljene su između pojedinih hibrida

kukuruza: od 0,07 do 0,21 ppm Cd, odnosno od 0,241 do 0,569 ppm Pb. Osobito niske koncentracije Cd je imalo šest hibrida (OsSK373, E9917/99, Bc278, OsSK2-191, OsSK382 i Clarica: prosjek 0,092 ppm Cd), dok

(RK1456/99, osSK382 i Bc278: prosjek 0,542 ppm Pb). Općenito, u istraživanim uvjetima je moguća

proizvodnja zdrave hrane na principima održive poljoprivrede.

Ključne riječi: kiselo tlo, kadmij, hibridi kukuruza, olovo, prinos, Hrvatska