Physiology of genotypic differences in zinc and copper uptake in rice and tomato
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Excised roots of rice (Oryzae sativa L.) cv IR26 absorbed both Zn2+ and Cu2+ from 0.01 mM to 0.50 mM external solutions at rates twice those of cv M101 over a 30-min period. However, the latter have a two-fold greater affinity (1/Km) for Zn2+ and Cu2+ than do those of the former. Zinc2+ and Cu2+ mutually and competitively inhibited uptake of each other, indicating that both micronutrient cations are absorbed through the same uptake mechanism or carrier sites. Further, these differences in uptake rates are restricted to roots but they cannot be explained by variations in root surface areas.
Excised roots of tomato (Lycopersicon esculentum L.) cv Kewalo absorbed Zn2+ and Cu2+ much more rapidly than did cv Sel 7625-2. Uptake of each cation was competitively and reciprocally inhibited by the other, so Zn2+ and Cu2+ are seemingly accumulated through the same uptake system in tomato also. Tomato cultivars Kewalo and Sel 7625-2 did not differ with regard to affinities of the root apices for Zn2+ and Cu2+; however. Vmax values for Zn2+ and Cu2+ uptake by roots of cv Kewalo were three-fold greater than those for cv Sel 7625-2.
Key wordsCopper Genotypes Rice Tomato Zinc
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- 1.Bowen J E 1969 Absorption of copper, zinc and manganese by sugarcane leaf tissue. Plant Physiol. 44, 255–261.Google Scholar
- 3.Bowen J E 1986 Kinetics of zinc uptake by two rice cultivars. Plant and Soil 94, 99–107.Google Scholar
- 4.Bowen J E and Nissen P 1976 Boron uptake by excised barley roots. I. Uptake into the free space. Plant Physiol. 57, 353–357.Google Scholar
- 5.Brar M S and Sekhon G S 1976 Interaction of zinc with other micronutrients cations. I. Effect of copper on zinc65 absorption by wheat seedlings and its translocation within the plant. Plant and Soil 45, 137–143.Google Scholar
- 6.Brown J C, Ambler J E, Chaney R I and Foy C D 1972 Differential responses of plant genotypes to micronutrients.In Micronutrients in Agriculture. Eds. J J Mortvedt, P M Giordano and W L Lindsay. Soil Sci. Soc. Am., Madison, Wisc. pp 389–418.Google Scholar
- 7.Dittmer H J 1937 A quantitative study of the roots and root hairs of winter rye plants. Am. J. Bot. 24, 417–420.Google Scholar
- 8.Fleming A L and Foy C D 1982 Differential response of barley varieties to iron stress. J. Plant Nutr. 5, 457–468.Google Scholar
- 10.Graham R D 1981 Absorption of copper by plant roots.In Copper in Soils and Plants. Eds. J F Loneragan, A D Robson and R D Graham. Academic Press, Sydney, Australia. pp 141–160.Google Scholar
- 12.International Rice Research Institute 1977 Annual Report for 1976. pp 97–104.Google Scholar
- 13.International Rice Research Institute 1978 Annual Report for 1977. pp 124–125.Google Scholar
- 14.Lineweaver H and Burk D 1936 The determination of enzyme dissociation constants. J. Am. Chem. Soc. 56, 658–666.Google Scholar
- 15.Schmid W E, Haag H P and Epstein E 1965. Absorption of zinc by excised barley roots. Physiol. Plant, 18, 860–869.Google Scholar
- 16.Snedecor G W 1948 Statistical Methods Applied to Experiments in Agriculture and Biology. Iowa State College Press, Ames, Iowa. 485 p.Google Scholar
- 17.Takahashi D T 1968 Zinc deficiency — varietal differences. Hawaiian Sugar Planters' Assoc. Expt. Sta. Ann. Rpt. 1968, 17–18.Google Scholar
- 18.Wallace A 1981 Some physiological aspects of iron deficiency in plants. J. Plant Nutr. 3, 637–642.Google Scholar