The effect of high pH and P on the development of lime-chlorosis in two seedling populations ofEucalyptus obliqua L'Hérit
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Glasshouse experiments have shown that the application of an acidulating agent to a calcareous soil can increase growth and alleviate severe chlorosis in an acidic population ofE. obliqua. In contrast, a calcareous population showed only a slight response to this treatment and maintained adequate growth and a low frequency of chlorosis on both control and treated calcareous soils. Foliar analyses of seedlings of the acidic population showed that alleviation of chlorosis was concomitant with a reduction in the levels of P, Ca and K, and an increase in uptake of Fe. However, the total Fe content of foliage was poorly correlated with the occurrence of severe chlorosis. Although this evidence suggested that the differential susceptibility ofE. obliqua to lime-chlorosis can be reduced by increasing the availability of Fe, the greater concentration of Fe in chlorotic seedlings indicated that lime-chlorosis may also be due to an inactivation of Fe within the plant (i.e. by P).
This hypothesis was partly confirmed by a water culture experiment which showed that a combination of relatively high pH and high external levels of P could induce severe chlorosis in seedlings of the acidic population. In contrast, it appears that the calcareous population has a more efficient mechanism for absorbing Fe and holding it in an available form, even when external concentrations of P are high. It is suggested that plants which have an efficient mechanism for the uptake of Fe at relatively high pH and are less susceptible to the detrimental effects of P have been selected for on these alkaline calcareous soils.
Key wordsCalcareous Eucalyptus obliqua Iron availability pH Phosphorus Soil acidulation
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- 1.Allen S E Ed. 1974 Chemical Analysis of Ecological Materials. John Wiley and Sons, New York, 565 p.Google Scholar
- 3.Anderson C A 1981 The differential susceptibility of three populations ofEucalyptus obliqua L'Hérit. to lime-chlorosis in south-eastern Australia. Ph. D. Thesis, University of Melbourne.Google Scholar
- 7.Biddulph O 1953 Translocation of radioactive mineral nutrients in plants. Kan. Agr. Sta. Rep. 4, 48–58.Google Scholar
- 8.Biddulph O and Woodbridge C G 1952 The uptake of phosphorus by bean plants with particular reference to the effects of iron. Plant Physiol. 27, 431–444.Google Scholar
- 10.Brown J C 1972 Competition between phosphate and the plant for Fe from Fe2+ Ferrozine. Agron. J. 64, 240–243.Google Scholar
- 11.Brown J C and Bell W D 1969 Iron uptake dependent upon genotype of corn. Soil Sci. Soc. Am. Proc. 33, 99–101.Google Scholar
- 12.Brown J C and Tiffin L O 1960 Iron chlorosis in soyabeans as related to the genotype of root stock. II. A relationship between susceptibility to chlorosis and capacity to absorb iron from iron chelate. Soil Sci. 89, 8–15.Google Scholar
- 13.Brown J C, Tiffin L O, Holmes R S, Specht A W and Resnicky J W 1959 Internal inactivation of iron in soyabeans as affected by root growth medium. Soil Sci. 87, 89–94.Google Scholar
- 14.DeKock P C 1955 Iron nutrition of plants at high pH. Soil Sci. 79, 167–175.Google Scholar
- 16.DeKock P C, Hall A and Inkson R H E 1979 Active iron in plant leaves. Ann. Bot. 43, 737–740.Google Scholar
- 18.Federer W T 1955 Experimental Design. MacMillan, New York, 544 p.Google Scholar
- 19.Kashirad A and Marschner H 1974 Effect of pH and phosphate on iron nutrition of sunflower and corn plants. Agrochimica 18, 497–507.Google Scholar
- 20.Ladiges P Y 1976 Mineral nutrition and drought resistance inEucalyptus viminalis Labill. Ph. D. Thesis, University of Melbourne.Google Scholar
- 22.Lowther J R 1980 Use of a single sulphuric acid-hydrogen peroxide digest for the analysis ofPinus radiata needles. Commun. Soil Sci. Plant Anal. 11, 189–199.Google Scholar
- 23.Mengel K and Kirkby E A 1979 Principles of Plant Nutrition, Int Potash Inst, Worblanfen-Bern, Switzerland.Google Scholar
- 24.Okajima H 1975 The physiology of iron and manganese in plants.In The Significance of Minor Elements on Plant Physiology. Eds. H Okajima and I Uritani. pp 1–29, Houng Kun-Luang, Japan.Google Scholar
- 26.Rediske J H and Biddulph O 1953 The absorption and translocation of iron. Plant Physiol. 28, 576–593.Google Scholar
- 28.Sokal R R and Rohlf F J 1969 Biometry: the Principles and Practice of Statistics in Biological Research. W H Freeman and Co., San Francisco, 776 p.Google Scholar