EFFECTS OF CO2 CONCENTRATION ON STRAWBERRY - I - PLANT-GROWTH ANALYSIS

Two-week-old strawberry (Fragaria x ananassa Duch. cv. 'Elsanta') plan ts were acclimatized to 300, 450, 600, 750 or 900 ppm CO2 in controlle d environment chambers for 50 days, Elevated CO2 promoted plant growth as indicated by a higher number of leaves, runners and daughter plant s, larger leaf area index and dry mass per unit leaf area, increased t otal length of runners, plant height, canopy diameter, and enhanced da ily growth of leaf area, runner and plant biomass. In contrast, specif ic leaf area and leaf area ratio of the plants decreased with increasi ng CO2 concentration, whereas neither average leaf area nor average ru nner length was significantly affected by CO2 enrichment. When compare d with the 300 ppm CO2 treatment, 600 and 900 ppm CO2-treated plants l ed to a daily increment of 1.6 and 1.9 total leaf area, 1.1 and 1.8 to tal runner length, and 2.5 and 3.9 plant biomass, respectively, Increa sed CO2 concentration from 300 to 600 and 750 ppm markedly accelerated both relative growth rate and net assimilation rate of the plants. Le af weight ratio and root weight ratio were significantly higher, while stem weight ratio was significantly lower above 600 ppm CO2 as a resu lt of proportionally more biomass allocated to leaves and roots than t o stems. Apart from an enhancement of plant growth, the long-term CO2 enrichment boosted vegetative propagation of strawberry plants as well . From an economical point of view, however, it is more efficient to u se elevated CO2 concentrations of up to 600-750 ppm rather than 900 pp m for greenhouse cultivation of strawberry.