Study on The Effects of Controlled Environmental Factors to Nitrate Content in Hydroponic Lettuce (Lactuca Sativa)
Date Issued
2012
Date
2012
Author(s)
Chiang, Yi-Ting
Abstract
Due to climate change and reduced arable land worldwide, the supply of vegetable crops may become inadequate. In response to these uncertainty, plant factory may turn to become a solution. Hydroponic is the main cultivation mode in most plant factory, however, hydroponic often cause over accumulation of nitrate to crops due to nitrogen administration. In this study, we have monitored the accumulation of nitrate in vegetables using various light sources and fertigation strategies. To optimize growing condition for Lactuca sativa (Boston lettuce), three cultivation patterns, static hydroponic, modified nutrient film and rockwool method were used, and three artificial light sources T5 fluorescent white lamp, cold cathode fluorescent lamp (CCFL) and Light emitting diodes (LED) were applied. Lettuce has optimal growth using static hydroponic and LED modes. Further on, 7 days prior to harvest, we used controlled flow of nutrient solution, photoperiod, light intensity and nutrient composition to lower the accumulation of nitrate in plants. The nitrate has 27% reduction but also 21% fresh weight loss been observed. Further application of 16h/8h photoperiod, LED intensity 200 ± 10 μmol/m2 • s, and K/N ratio of 3/2 in Hoagland solution, we observed an optimal growing appearance and 25% reduction of nitrate, coming to 2600 ± 100 ppm. The parameters were then given to other six lettuce cultivars, all cultivars have met the standards of EU regulation in nitrate content.
Subjects
Lettuce
Hydroponics
Artificial lights
Nitrate
Nitrate reductase
SDGs
Type
thesis
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