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 Title: Effect of airflow and carbon dioxide on growth, yield, and gas exchange of lettuce Author(s): Chen, Guang-Yau Stanley Doctoral Committee Chair(s): Spomer, L. Art Department / Program: Crop Sciences Discipline: Crop Sciences Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Agronomy Biology, Plant Physiology Abstract: Romaine lettuce (Lactuca sativa var. longifolia L.) was grown hydroponically inside a walk-in growth chamber (Conviron, PGW36) with two levels of airflow (0.36 and 2.50 m$\rm\cdot s\sp{-1})$ at different atmospheric CO$\sb2$ concentrations (350 and 700 $\rm\mu mol\cdot mol\sp{-1}).$ A combination of metal-halide and high-pressure sodium lamps was used to provide 30 mol$\rm\cdot m\sp{-2}$ photosynthetic photon flux (PPF) per day with a 12-hour photoperiod at the rate of 660 $\rm\mu mol\cdot m\sp{-2}\cdot s\sp{-1}.$ Air temperature was maintained at 22$\sp\circ$C and relative humidity at 70% for both day and night. Nutrient solution pH was kept at 5.7 with nitrate as the sole nitrogen source. Growth analysis was carried out at 3-day intervals and gas exchange rate of both single-leaf and whole-plant was measured with a modified portable photosynthesis system (LI-COR, LI-6200 PPS). A microcomputer-based data acquisition and process control system was developed to maintain CO$\sb2$ concentration and monitor environmental condition in each of the four runs of this experiment.Results from this study indicated that CO$\sb2$-enhancement can greatly increase the growth and yield of lettuce by increasing RGR shortly (1.3 days) after the treatment was applied. It created bigger plants while it kept them at the same physiological age with equal leaf number per plant as those grown under low CO$\sb2$ environment. In contrast, higher airflow decreased lettuce yields by producing smaller plants with fewer leaves per plant than under lower airflow. The delay of growth and development caused by higher airflow was estimated to be 1.3 days, while RGR remained the same throughout the rest of growth.The results of this study confirm that airflow is an important environmental factor, which should be controlled or characterized in every experiment. There should exist an optimal range of airflow for plants growing under unique environments. In order to promote the maximum crop growth and yield under a particular controlled environment, the timing and duration of CO$\sb2$-enrichment and control of airflow need to be considered. Issue Date: 1996 Type: Text Language: English URI: http://hdl.handle.net/2142/21203 ISBN: 9780591471984 Rights Information: Copyright 1996 Chen, Guang-Yau Stanley Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9737070 OCLC Identifier: (UMI)AAI9737070
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