Articles
COLORATION AND GROWTH OF RED LETTUCE GROWN UNDER UV-RADIATION TRANSMITTING AND NON-TRANSMITTING COVERS
Article number
761_28
Pages
221 – 225
Language
English
Abstract
Production of red lettuce for salad mixes in Hawaii is primarily out-of-doors in the drier, leeward sides of the islands.
Because the newer acrylic-polycarbonate hard covers transmit only small amounts of UV-radiation (which is essential for anthocyanin production), we experimented with a new ethylene-tetrafluoroethylene copolymer film (F-Clean), which transmits more than 90% of visible light and UV-radiation, for possible use in red lettuce production in high rainfall areas.
Four cultivars of red lettuce, Natividad – Red Lollo Rossa, Dark – Lollo Rossa, Aruba – Red Oak Leaf, and New Red Fire – Red Grand Rapids, were grown in static hydroponic solution under each of the two levels of light and three UV-radiation environments.
Lettuce plants with the most coloration and lowest head weight were produced out-of-doors with 100% UV-radiation.
All of the lettuce produced under the non-UV-radiation transmitting, acrylic-polycarbonate cover had the least coloration and largest head weight.
All were mostly green.
Lettuce grown under the UV-radiation transmitting, F-Clean film with an additional layer of 50% aluminized shade screen were intermediate in color and head weight.
The coloration of all the red lettuce studied appeared similar to Dark – Lollo Rossa, where the anthocyanin, cyanidin 3-(6-malonyl) glucoside is present.
UV-radiation appears to be the most important factor in coloration of red lettuce.
Even with the additional layer of 50% shade, daytime temperatures were 4 to 6°C higher in the F-Clean house than in the acrylic-polycarbonate house.
Yet, the cooler acrylic-polycarbonate house, which had little UV-radiation, produced green red lettuce with little coloration.
Because the newer acrylic-polycarbonate hard covers transmit only small amounts of UV-radiation (which is essential for anthocyanin production), we experimented with a new ethylene-tetrafluoroethylene copolymer film (F-Clean), which transmits more than 90% of visible light and UV-radiation, for possible use in red lettuce production in high rainfall areas.
Four cultivars of red lettuce, Natividad – Red Lollo Rossa, Dark – Lollo Rossa, Aruba – Red Oak Leaf, and New Red Fire – Red Grand Rapids, were grown in static hydroponic solution under each of the two levels of light and three UV-radiation environments.
Lettuce plants with the most coloration and lowest head weight were produced out-of-doors with 100% UV-radiation.
All of the lettuce produced under the non-UV-radiation transmitting, acrylic-polycarbonate cover had the least coloration and largest head weight.
All were mostly green.
Lettuce grown under the UV-radiation transmitting, F-Clean film with an additional layer of 50% aluminized shade screen were intermediate in color and head weight.
The coloration of all the red lettuce studied appeared similar to Dark – Lollo Rossa, where the anthocyanin, cyanidin 3-(6-malonyl) glucoside is present.
UV-radiation appears to be the most important factor in coloration of red lettuce.
Even with the additional layer of 50% shade, daytime temperatures were 4 to 6°C higher in the F-Clean house than in the acrylic-polycarbonate house.
Yet, the cooler acrylic-polycarbonate house, which had little UV-radiation, produced green red lettuce with little coloration.
Authors
R. Shioshita, J. Enoka, D.K. Aiona, M. Wall
Keywords
Latuca sativa L., anthocyanin, head weight, ethylene-tetrafluoroethylene copolymer
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