Photoperiod and light spectrum effects on growth, pigment and ascorbic acid content of Lactuca sativa cv. Fire Red under controlled growth environment
2018
Ngilah, E. I. | Tsan, F. Y. | Yap, B. K.
The application of Light Emitting Diodes (LEDs) in agricultural sector has become popular in recent years. LEDs can even be used in total absence of natural sunlight in raising indoor vegetables and ornamental plants. Appropriate light spectral regions must be studied according to crop species or varieties, especially for plants with high commercial values. The present experiment was conducted to determine the effects of monochromic LED of Red (R) and Blue (B), and their combinations at 1:1, 1:2 and 2:1,at 18 W and 240 V, on production of Lactuca sativa cv. Fire Red in controlled laboratory environment in total absence of natural light. EachLED irradiation treatment was assigned as sub plot with photoperiods (PPs) ranging from 12 h to 18 has main plots in a split plot design to study their combined effects on growth, pigment and ascorbic acid (AA) contents of this attractive red colour vegetable. Seedlings in moist jiffy blocks at one week after sowing were transferred to polyvinyl chloride (PVC) troughs of 5 cm diameter containing quarter strength Hoagland solution at electrical conductivity ranging from1,100 to 1,300 μS/cm and pH 6-7. Plants were grown with nutrient film technique at a distance of approximately 8 cm below LED. Results obtained showed that R was not appropriate forgrowing this vegetable while analysis of variance indicated that plants irradiated with B gained the greatest plant height at five weeks at harvest, but these plants had the lowest number ofleaves. Highest fresh weight (FW) as marketing attribute of this vegetable was obtained with 18 h PP. When combined 18 h PP with BR or 2BR, it was the best for production of L. sativa cv. Fire Red with the highest anthocyanin content.
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