TITLE:
Effect of Root-Zone Temperature on Growth and Quality of Hydroponically Grown Red Leaf Lettuce (Lactuca sativa L. cv. Red Wave)
AUTHORS:
Masaru Sakamoto, Takahiro Suzuki
KEYWORDS:
Root-Zone Temperature, Anthocyanin, Red Leaf Lettuce, Hydroponics, Drought Stress
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.6 No.14,
September
16,
2015
ABSTRACT: Soil temperature influences crop growth and quality under field and greenhouse conditions;
however, precise investigation using controlled cultivation systems is largely lacking. We investigated
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. Compared
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 treatments
produced no significant changes in growth parameters compared with ambient conditions.
Leaves under low root-zone temperature contained higher anthocyanin, phenols, sugar, and nitrate
concentrations than leaves under other temperatures. Root oxygen consumption declined
with low temperature root exposure, but not with root heating. Leaves of plants under low rootzone
temperature showed hydrogen peroxide production, accompanied by lipid peroxidation.
Therefore, low temperature root treatment is suggested to induce oxidative stress responses in
leaves, activating antioxidative secondary metabolic pathways.