The effect of red and blue light component on the growth and development of frigo strawberries

The experiments were carried out in 2009 in phytotron chambers and commercial greenhouses of the Lithuanian Institute of Horticulture. The frigo plants of ‘Elkat’ strawberries (Fragaria x ananassa Duch.) were investigated. The frigo sprouts were grown in a phytotron chamber for a month under different light-emitting diode (LED) treatment: sole red (640 nm) light, photosynthetic photon flux density (PPFD) beside leaves of strawberries – 200 μmol m-2 s-1; combination of red (640 nm) with blue (455 nm) light, maintained PPFD was 174.5 and 25.5 μmol m-2 s-1, respectively. The photoperiod of 16 hours and 21/16oC day/night temperature in the phytotron chamber were maintained. After LED treatment, strawberry sprouts were transplanted to a bed mulched by white film in the polythene greenhouse. The spectral quality of light influenced the morphogenesis and diverse physiological responses of frigo plants of ‘Elkat’ strawberry. Development was improved, carbohydrate accumulation and pigment ratio of plants was increased in strawberries grown under red and blue LEDs. Whereas, red LED induced elongation of flowering stem and all plant, and resulted in 1.8 times higher shoot/root ratio. The positive influence of red and blue light treatment on the formation of runners, inflorescence and crown was observed. The fruiting of frigo strawberries ended after 40 days after planting. The treatment of sole red light or combination of red and blue LEDs had no persistent effect on the harvest of frigo strawberries. However, red LED treatment resulted in a smaller size of fruits. It confirms that a mixture of red and blue LED spectral components is necessary for the development of frigo strawberries, likewise for normal plants.