Growth, root adaptations, phosphorus and potassium nutrition of rice when grown under the co-limitations of phosphorus, potassium and moisture

ABSTRACT

Growth of rice when soil phosphorus (P), potassium (K), and moisture are co-limiting is poorly known. An experiment was conducted using two rice varieties [long (LD) and short (SD) duration], two moisture conditions (continuous flooding and top-soil drained after flowering), and five fertilizer treatments (with and without the applications of P and/or K). Phosphorus uptake rate, translocation of P and K from roots, and retranslocation of P and K from senescing leaves were reduced in drained soil compared with flooded condition. LD had greater- root length, root dry weight, specific root length (m g⁻¹), and increased availability of P in soil than SD. Even though LD was better adapted to co-limitations of P, K, and moisture in soil than SD, those adaptive responses were not sufficient to increase the arrested growth, P and K nutrition when P, K and moisture supply was co-limited than their optimal supply.

KEYWORDS:

• Drought
• internal nutrient use-efficiency
• nutrient retranslocation
• plasticity
• uptake

Acknowledgment

Authors appreciate the critical comments given by K. Foster and H. Lambers to improve a previous version of the manuscript.

Funding

The authors appreciate the financial support from the National Research Council, Sri Lanka under the grant NRC-11-179, and technical assistance provided by G. Wijesuriya.