EFFECTS OF LIGHT LEVEL, CO2 ENRICHMENT, AND CONCENTRATION OF NUTRIENT SOLUTION ON GROWTH, LEAF NUTRIENT CONTENT, AND CHLOROPHYLL FLUORESCENCE OF BOSTON FERN MICROCUTTINGS

Abstract

ABSTRACT Boston Fern (Nephrolepis exaltata Schott. “Rooseveltii”) is often propagated in vitro. Microcuttings grow slowly after transfer from in vitro to ex vitro conditions. The aim of this study was to accelerate growth and to improve quality of plantlets by optimization of mineral nutrition, irradiance and CO2 concentration. Two irradiance levels (50 and 150 μmol m−2 s−1), two concentrations of CO2 (350 and 1200 μmol mol−1), and five concentrations of nutrient solution (electrical conductivity: EC 0.3, 0.7, 1.4, 2.1, and 2.8 mS cm−1) were tested. Microcuttings grown at higher irradiance accumulated more leaf fresh and dry weights than microcuttings grown at low irradiance. The higher irradiance level enhanced leaf nitrogen (N), phosphorus (P), and potassium (K) content. Carbon dioxide enrichment enhanced dry weight accumulation and plant height, decreased N and increased K content of leaves. The highest fresh and dry weight of leaves was measured at EC 2.1–2.8 mS cm−1. Leaf N, P, and K content increased with increasing concentration of nutrient solution, leaf calcium (Ca) and magnesium (Mg) concentrations decreased with increasing concentration of nutrient solution. Microcuttings grown under high level of irradiance and high EC had higher chlorophyll fluorescence (F m , F v /F m , S c ) values than those grown under low light and low EC. Quality of propagation material of Boston fern can be significantly enhanced with the best combination of PPFD, mineral nutrition and CO2 enrichment.