Strategic phosphorus (P) application to the nursery bed increases seedling growth and yield of transplanted rice at low P supply

Sustainable phosphorus (P) management in rice production systems requires efficient P application strategies to improve P fertilizer use efficiency combined with the use of P-efficient genotypes that should ideally have reduced grain P concentrations to lower P removal from the system. In this study, the strategic application of a micro-dose of P to the nursery bed was evaluated as a way to improve seedling vigor and P fertilizer use efficiency and overcome potentially reduced seedling vigor associated with low seed P concentration in transplanted rice. In a first experiment established in two fields differing in soil P supply, two rice genotypes (Mudgo and Santhi Sufaid) were grown with and without P application to a P-deficient nursery bed. In a second experiment established in the same fields with the same genotypes, P application to the nursery bed was evaluated in combination with two seed sources differing in seed P concentration. In both experiments, P application to the nursery bed doubled seedling shoot biomass of both genotypes at transplanting time with a 5-fold increase in seedling shoot P content in the first experiment. In the first experiment, P application to the nursery bed increased grain yield by 10–14% in the field with higher soil P supply and 30–40% in the field with lower soil P supply. In the second experiment, P application to the nursery bed increased grain yield by 19–20% in the field with lower P supply only, whereas no effect of P application to the nursery bed on yield was observed at higher soil P supply. We conclude that strategic application of micro-doses of P to the nursery bed can substantially enhance seedling vigor and grain yield of transplanted rice at low P supply.