Quantitative and qualitative imaging of plant growth and development in response to environmental factors under greenhouse conditions visualises plant performance on-site and may increase our knowledge of how rapid plants change their growth pattern in relation to environmental stimuli. In the present study a non-invasive plant growth sensor (PlantEye, Phenospex B.V, Heerlen, NL) was tested in analysing changes in diurnal stem elongation patterns and plant height in response to the spectral quality of the light environment. Plants were grown in four different LED supplemental lighting treatments with 0%, 12.5%, 18.5% and 22.5% blue light under greenhouse conditions in winter (18 h day/4 h night). The non-invasive measurements were carried out automatically every four hour with three repetitions, and supported by manual measurements of plant height every third day. A strong linear relation between the non-invasive measurements and manual measurements of plant height was achieved, and a blue-light dose-response showing a decrease in plant height in relation to an increase in blue light was demonstrated. However, the non-invasive plant growth sensor was not able to distinguish between diurnal fluctuations in the rate of stem elongation, and leaf movements, and therefore a further analysis of diurnal variations in leaf angular positions and stem elongation was conducted under greenhouse conditions. Plants were pruned just below the main meristem, and the leaf movements were measured every hour during the following three days showing a clear pattern of upward moving leaves during the afternoon and night, and downward moving leaves during the early hours of the day. These movements were subtracted from the values measured on non-pruned plants grown under the same environmental conditions showing changes in the diurnal stem elongation pattern in relation to day length and environmental conditions. The results are novel in describing a method for measuring diurnal stem elongation in high-resolution on a plant canopy and under greenhouse conditions.
Book of Abstract 7th International Symposium on Light in Horticultural Systems Ishs Lightsym 2012, 2012
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7th International Symposium on Light in Horticultural systems, 2012