Phosphorus Uptake by Young Citrus Trees in Low-P Soil Depends on Rootstock Varieties and Nutrient Management

Abstract

Because low-phosphorus (P) availability limits citrus growth, rootstocks with a relatively high capacity for P uptake are desirable. An experiment was conducted with trees on Cleopatra mandarin (CM) and Rangpur lime (RL). Treatments consisted of P rates (20, 40, and 80 mg kg⁻¹ of soil) applied in soil layers of 0–0.30 m and/or 0.31–0.60 m, besides an unfertilized control. The P fertilization increased root and shoot growth, and P nutrition was improved as indicated by greater leaf P concentration, P uptake, and P root uptake efficiency (PUE). The P applied in both soil layers improved shoot growth, P uptake, and PUE. Trees on RL took up 23–126% more P and had root systems with greater growth and PUE compared to those on CM. Thus, P uptake by citrus trees in low-P soils can be improved by augmenting the depth of fertilizer application and the use of more adapted rootstocks.

Keywords:

• Fertilizer distribution
• nutrient availability
• phosphorus nutrition
• root growth

Acknowledgments

We thank the São Paulo State Research Foundation (FAPESP) for financial support (process 2007/04634-3). We are also very grateful to James P. Syvertsen from UF/IFAS, Citrus Research and Education Center, USA, for suggestions.