報告書番号

U01009

タイトル（和文）

青色光の夜間補光がサニーレタスの着色と成長に及ぼす効果

タイトル（英文）

Effects of supplementary lighting of blue-light during the night on anthocyanin synthesis and growth of red-leaf lettuce (Lactuca sativa L.)

概要 （図表や脚注は「報告書全文」に掲載しております）

サニーレタスの温室水耕栽培では、アントシアニン含量の低下による着色不足が問題となっている。青色光を夜間に12時間補光すると、アントシアニン含量は60μmol/㎡/s以上の補光強度で増加し、露地栽培とほぼ同じ着色を得るには120μmol/㎡/sの補光強度を必要とした。地上部の乾物重は補光強度に従って増加し、乾物率と葉厚は60μmol/㎡/s以上で増加した。120μmol/㎡/s条件下で補光の長さの影響を調べたところ、6時間以上で着色し、長時間ほどアントシアニンの含量、地上部の乾物重と乾物率および葉厚が増加した。また、連続補光、120分毎および30分毎の間欠補光を比較したが、アントシアニン含量と地上部の乾物重には有意差は認められなかった。以上の結果から、青色光の夜間補光を120μmol/㎡/sの補光強度で6時間以上行うことで着色と成長を促進し、徒長を抑制する効果が得られることが明らかになった。

概要 （英文）

Poor coloration due to low anthocyanin content in leaves has often happened in hydroponic red-leaf lettuce (Lactuca sativa L.). Our previous study suggested that supplementary lighting of blue light improves the coloration by increasing anthocyanin content. In this study, effects of blue light supplementation during the nighttime on the coloration and growth were examined to develop practical methods for improving quality of red-leaf lettuce by hydroponics in a greenhouse. Effect of light intensity on anthocyanin level was examined in red-leaf lettuce. The lettuce was grown under sunlight during the daytime and was exposed to blue light from 18:00 to 6:00 (12 hours) for 7days. The anthocyanin level increased linearly with 60 μmol／㎡／s or more and reached a plateau with 160 μmol／㎡／s. The coloration obtained at 120 μmol／㎡／s was comparable to that produced in the field. The growth of lettuce was also enhanced by the increase of light intensity. The dry matter rates and thickness of a leaf were increased with 60 and 120 μmol／㎡／s of blue light.Effect of lighting duration on anthocyanin level and growth was examined in the lettuce under 120 μmol／㎡／s of blue light. The anthocyanin level increased with 6 hours and the highest value was obtained at 12 hours. Under 120 μmol／㎡／s of blue light condition, at least 6 hours continuous irradiation was necessary to improve the coloration. At that time, the longer the lighting duration was extended, the greater the growth of lettuce could be seen such as the dry weight, dry matter rates, and thickness of a leaf. The anthocyanin content and/or the dry weight were not affected by the irradiation pattern, continuous and 30 and 120 minutes intermittent lighting, under the condition of 120 μmol／㎡／s of blue light for totally 6 hours. It was concluded that 120 μmol／㎡／s of irradiation of blue light for more than 6 hours in nighttime was enough to improve coloration and growth in a greenhouse hydroponic red-leaf lettuce.

報告者

キーワード