Effect of Root-Zone Temperature on Growth and （影响神经根带温度对增长和）.pdf

American Journal of Plant Sciences, 2015, 6, 2350-2360 Published Online September 2015 in SciRes. /journal/ajps /10.4236/ajps.2015.614238 Effect of Root-Zone Temperature on Growth and Quality of Hydroponically Grown Red Leaf Lettuce (Lactuca sativa L. cv. Red Wave) * Masaru Sakamoto , Takahiro Suzuki Department of Biological Science, Faculty of Biology Oriented Science and Technology, Kindai University, Wakayama, Japan * Email: sakamoto@waka.kindai.ac.jp Received 13 August 2015; accepted 13 September 2015; published 16 September 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). /licenses/by/4.0/ Abstract Soil temperature influences crop growth and quality under field and greenhouse conditions; however, precise investigation using controlled cultivation systems is largely lacking. We investi- gated effects of root-zone temperatures on growth and components of hydroponically grown red leaf lettuce (Lactuca sativa L. cv. Red Wave) under a controlled cultivation system at 20˚C. Com- pared with ambient root-zone temperature exposure, a 7-day low temperature exposure reduced leaf area, stem size, fresh weight, and water content of lettuce. However, root-zone heating treat- ments produced no significant changes in growth parameters compared with ambient conditions. Leaves under low root-zone temperature contained higher anthocyanin, phenols, sugar, and ni- trate concentrations than leaves under other temperatures. Root oxygen consumption declined with low temperature root exposure, but not with root heating. Leaves of plants