Changes in dry weight and nitrogen partitioning induced by elevated CO2 depend on soil nutrient availability in sweet chestnut (Castanea sativa Mill)

Abstract

The effect of two levels of atmospheric CO2 (ambient 350 ppm, and double, 700 ppm) and two levels of mineral nutrition on dry weight N accumulation and partitioning were examined in two-yr-old chestnut seedlings. Fertilization had a pronounced effect on dry weight accumulation, tree height, leaf area, and plant nitrogent content. Carbon dioxide enrichment significantly increased total biomass by c20%, both on fertilized and on unfertilized forest soil. On the unfertilized soil, only the root biomass was increased, leading to an increase in the root:shoot ratio. On fertilized soil only stem biomass and diameter but not height were increased. Carbon dioxide enrichment significantly reduced N concentration in all organs, irrespective of nutrient availability, but the biomass increase made up for this reduction in such a way that the total N pool per tree remained unchanged. -Authors