Nutrient Uptake and Partitioning in Modern, Diverse Sesame Cultivars in the Southeastern USA.

Sesame (Sesamum indicum L.) yield response to mineral fertilization has been well-documented, but the temporal dynamics of sesame nutrient uptake and partitioning are poorly understood. Such information is needed to better inform fertilization decisions and improve nutrient use efficiency. The objective of this study was to characterize nitrogen (N), phosphorus (P), and potassium (K) uptake and partitioning among modern, diverse sesame cultivars grown in the Southeastern USA. A two-year field study was just completed in Florida and data from 2015 are presented. Three cultivars (S34, S35, and S39) with variable maturity and branching characteristics were sampled at two week intervals beginning three weeks after planting (WAP) and divided into stem/branch, leaf, flower/capsule, and grain components to determine N, P, and K accumulation. Nutrient uptake was significantly affected by sampling date, but neither cultivar nor cultivar x sampling date interactive effects on nutrient uptake were observed. Nutrient accumulation was minimal through the first month of growth, but increased rapidly from late-vegetative (5 WAP) through early-bloom (7 WAP) stages during which time cultivars accumulated 11 kg N ha-1 day-1, 1.3 kg P ha-1 day-1, and 13 kg K ha-1 day-1. A relatively large proportion of total N (53%), P (61%), and K (46%) was accumulated during reproductive growth. Nutrient content in the flower/capsule component increased by 50 – 70% during the reproductive phase which was likely due to the indeterminate nature of sesame. Harvested grain removed (per ha) approximately 56 kg N, 11 kg P, and 11 kg K, which amounted to harvest indices of 0.34, 0.38, and 0.06, respectively. These results suggest that plant available N, P, and K during late-vegetative and early-reproductive growth may improve nutrient use efficiency by sesame.