HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Loneragan, J. F. Articles by Snowball, K. Search for Related Content PubMed Articles by Loneragan, J. F. Articles by Snowball, K. Agricola Articles by Loneragan, J. F. Articles by Snowball, K.

Phosphorus Toxicity as a Factor in Zinc-Phosphorus Interactions in Plants¹

ABSTRACT

This study examined the hypothesis that accumulation of P to toxic levels in plant tissues may explain reported effects of high P in increasing the Zn requirement of plant tissues. It also examined the contribution of other mechanisms to the complex interaction of Zn and P fertilizers on plant growth.

Three levels of Zn and P fertilizers were applied to a siliceous and a ferruginous sand with low and high capacities to react with P, respectively. Application of P fertilizer induced or enhanced symptoms resembling Zn deficiency in subterranean clover (Trifolium subterraneum L.) in three distinct ways:

1) On the ferruginous sand but not on the siliceous sand, it induced Zn-deficiency by depressing Zn absorption.

2) Where P limited growth, additional P depressed Zn concentrations and induced Zn deficiency in plants by promoting growth thus diluting available Zn supplies.

3) Where P did not limit growth, additional P increased P concentrations to toxic levels producing necrotic symptoms in old leaves and depressing growth.

Where plant tops had high Zn concentrations (> 40µg/g), P toxicity produced nectrotic symptoms in the absence of any of the characteristic symptoms of Zn deficiency. Where plant tops had low Zn concentrations (< 16µg/g), the necrotic symptoms developed in addition to the characteristic Zn-deficiency symptoms of bronzing and chlorosis of old leaves and "little leaf" of young leaves thus strongly enhancing the apparent severity of Zn deficiency. Zn deficiency strongly enhanced P toxicity at the middle and high levels of P application apparently by limiting plant growth and concentrating the available P in plant tissues.

The enhancement of P toxicity by Zn deficiency explains reports that high P increases Zn requirements of plant tissues. It will occur more easily in plants grown in sand and water culture than in plants grown on soils with some capacity to react with P.

¹ Contribution of the Dep. of Soil Sci. and Plant Nutrition, Institute of Agric., The Univ. of Western Australia, Nedlands, Western Australia, 6009. This work was supported by the West Australia Wheat Research Committee.

² Former Associate Professor, former Honors Student, Lecturer and Research Officer, respectively, Dep. of Soil Sci. and Plant Nutrition, Institute of Agric., The Univ. of Western Australia. The senior author is now located at Murdoch Univ., Murdoch, Western Australia, 6153. The second author is now located at CSIRO, Div. of Land Resources Management, Wembley, Western Australia, 6014.

Received for publication December 11, 1978. Accepted for publication March 26, 1979.

This article has been cited by other articles:

				J. J. Wang and D. L. Harrell Effect of Ammonium, Potassium, and Sodium Cations and Phosphate, Nitrate, and Chloride Anions on Zinc Sorption and Lability in Selected Acid and Calcareous Soils Soil Sci. Soc. Am. J., June 2, 2005; 69(4): 1036 - 1046. [Abstract] [Full Text] [PDF]