Interaction of Silicon and Phosphorus Mitigate Manganese Toxicity in Rice in a Highly Weathered Soil

Abstract

Many researchers have reported beneficial effects of silicon (Si) on plant growth when available phosphorus (P) is low, but the reasons for this are poorly understood. Factorial application of three levels of Si and four levels of P to rice plants grown in Red Ferrosol interacted to increase rice growth and Si and P uptake (P < 0.01). Application of Si with P increased P uptake by <120%. Although Si application affected P uptake, yield increases were more likely associated with reduced manganese (Mn) toxicity, particularly as the P/Mn and P/iron ratios increased with increasing Si application. Further research is necessary to determine if the beneficial effects of Si application on P nutrition occur where adequate P is supplied or is limited to situations where alternate nutritional or disease limitations affect growth.

Keywords:

• Manganese toxicity
• phosphorus
• P/Mn
• P/Fe
• silicon
• rice
• wollastonite

Acknowledgments

We thank L. Lisle for her help with elemental analysis. The first author also thanks G. Lyons, J. Smith, G. McDonald, and M. Cargill for valuable suggestions and critical comments on this manuscript. This work was supported by the University of New England, Australia.