LAUSR

ABSTRACT To assess the effects of ozone (O3) on uptake and utilization of nitrogen, phosphorus, and potassium nutrients in rice for planning rational fertilization under projected O3 elevation. Two hybrid indica cultivars were exposed to ambient and elevated O3 (E-O3) under a free-air O3 enrichment system. E-O3 differently affected the accumulation and distribution of biomass, and the absorption and distribution of nutrients between cultivars. These effects were related to rice cultivar and nutrient type. E-O3 led to significantly decreased partial factor productivity and grain production efficiency (GPE) of nitrogen in both cultivars; however, the effects of E-O3 on GPEs of phosphorus and potassium varied with cultivar. Responses of nutrients harvest indices between cultivars to E-O3 were adverse. Differences between cultivars and elements should be considered when examining E-O3 potentially affecting the nutrient dynamics for the purpose of reducing the amount of fertilizer applied in paddy systems to decrease potential environmental pollution.