Acclimatization of ex Vitro Strawberry Plantlets in CO2-enriched Environments and Supplementary Lighting

Abstract

The effect of CO 2 enrichment (CE) and supplemental lighting (SL) on the growth of ex vitro strawberry ( Fragaria × ananassa Duch.) plantlets was studied during acclimatization. Three different concentrations of CO 2 [330, 900, and 1500 ppm (v/v)] and two SL treatments (0 and 150 μmol·s –1 ·m –2 ) were applied. There was no significant interaction between light and CO 2 for root and leaf dry weight and leaf area. CE had no effect on these parameters in the early period following transfer but resulted in significant increases at days 20 and 30. CE had no significant influence on leaf and root relative growth rate (RGR) over the three sampling periods, but had a significant effect on net assimilation rate at a 20- to 30-day period. At the end of the experiment, 900- and 1500-ppm treatments had a significantly higher root and shoot dry weight than the 300-ppm treatment. SL resulted in increased dry weight at 10 days and even greater increases at days 20 and 30. CE was more effective than SL in stimulating root growth, whereas SL increased shoot growth significantly. There was a synergistic effect between CE and SL. The period needed to obtain plants of a similar size to an acclimatized plantlet was shortened by 15 days with 900 ppm CO 2 and SL. At the end of the experiment, SL and CE at 1500 and 900 ppm increased leaf and root dry weight by a factor of 3 and 5 for ‘Honeyoye’ and ‘Kent’, respectively. These increases were less important for SL or CE used alone.