Biomass Production and Phosphorus Use Efficiency in Two Tithonia diversifolia (Hemsl.) Gray Genotypes

Abstract

Little information exists on the phosphorus (P) use efficiency of Tithonia diversifolia under varying levels of soil P availability. This study evaluated biomass production, changes in tissue P concentration, P uptake, and P uptake and utilization efficiencies in a Costa Rican and Colombian T. diversifolia genotype when 0, 0.3, 5, and 30 mg P g−1 were available. Biomass, root length and tissue P concentration increased significantly (P < 0.05) with increasing levels of P availability and with time. Phosphorus uptake (mg plant−1) was significantly higher (P < 0.05) at 30 mg P g−1. Phosphorus uptake (mg P mg−1 Pf) and utilization (mg mg−1 P) efficiencies were greatest at 0.3 and 5 mg P g−1. Differences between genotypes showed that T. diversofilia from Colombia had a significantly higher (P < 0.05) biomass, tissue P concentration, root length, and a more effective uptake and utilization of P when availability of this nutrient was low.