The Growth and Yield Responses ofFragaria ananassato Elevated CO2and N Supply

Abstract

Strawberry plants (Fragaria ananassaDuchesne var. Elsanta) were grown in pots at two concentrations of carbon dioxide (partial pressures of 39 and 56 Pa) and with three rates of nitrogen supply (0.04, 0.4 and 4 mmas nutrient solution) to study their individual and interactive effects on plant growth and fruit yield. Nitrogen deficiency reduced total dry biomass and relative growth rate (RGR), mainly through reductions in leaf area ratio (LAR) and plant N concentration (PNC), although both the net assimilation rate (NAR) and root weight ratio (RWR) increased. Elevated CO2increased the N productivity (NP) but reduced the LAR. High CO2increased the fruit yield by 42% at high N supply and by 17% at low N supply. The CO2yield enhancement occurred through an increase in the flower and fruit number of individual plants. This resulted in an increase in the fruit weight ratio (FWR) of plants at high CO2. Nitrogen deficiency reduced the fruit yield by about 50% through decreases in fruit size, fruit set and the number of fruits. However, N deficiency increased the proportion of total plant dry biomass allocated to fruits. There were no significant interactions between CO2and N supply on yield.