Photomorphogenetic Effects in Different Plant Life Forms

The objective was to evaluate the effect of different combinations of red (R) (638 nm), blue (B) (445 nm) and far-red (FR) (731 nm) light produced by solid-state light-emitting diodes (LEDs) on variation of photosynthetic pigments, non-structural carbohydrates and flowering initiation in different plant life forms, such as radish (Raphanus sativus L. 'Faraon'), carrots (Daucus carota L. 'Garduole 2') and in frigo plants of 'Elkat' strawberries (Fragaria x ananassa Duch.). Before lighting experiments plants, which need vernalization for flowering induction, were grown in particular conditions: strawberry sprouts were held in the refrigerator under -2 degrees C temperature until they were planted, carrots with 9 leaves in rosette were moved from the greenhouse to low temperature (+4 degrees C) chambers for 120 days. Radishes were seeded and grew in lighting conditions. During the lighting experiment plants grew in controlled conditions: total photosynthetic photon flux density generated by LEDs was maintained at 200 mu mol m(-2) s(-1) a photoperiod of 16 h. Three LED treatments were evaluated: R; R+B-10%; and R+B-10%+FR2%. Our results showed that generative development of treated plants depended on light quality. Sole R LED light or combination of R+B conditioned flowering of frigo strawberry plants, whereas the addition of far-red (R+B+FR) was necessary for flowering stem formation in carrots. R or R+B+FR for radish generative development were required. Lower accumulation of non-structural carbohydrates in leaves due to low contents of photosynthetic pigments under R+B was detected, in contrast to strawberry, accumulation of carbohydrates was high. We conclude that (I) spectral quality of light influenced the morphogenesis and diverse physiological responses; (II) flower initiation processes of different plant life forms can be controlled by tailoring the illumination spectrum; (III) plant cultivation was evaluated under phytotron conditions.