報告書番号

V10032

タイトル（和文）

育苗段階における青色LED照射がサニーレタス苗の品質と定植後の生育に及ぼす影響

タイトル（英文）

Blue LED Light Irradiation of Seedlings Improves Seedling Quality and Growth after Transplanting in Lettuce Plant

概要 （図表や脚注は「報告書全文」に掲載しております）

食の安全・安心，食料自給率向上を背景に植物工場の普及が期待されている．当所では，波長制御が可能な発光ダイオード（LED）を利用した植物工場向けの栽培技術の開発を進めている．野菜や花きの苗は草丈や葉色などの外見でその品質が判断されてきたが、集約化された育苗施設におけるLED光源の利用により，苗に新たな付加価値として機械移植に対応したコンパクト性や環境ストレス耐性等の品質を付与できる可能性がある．そこで，白色蛍光灯（FL），青，赤および青赤LEDを用いてサニーレタスを7日間育苗した後，苗を定植してガラス温室で栽培して光質育苗の影響を調べた．その結果，青LEDを含む光源で光質育苗することで，徒長せずに葉が厚くコンパクトな苗を育成でき，収穫時においても増収効果が得られることが分かった．また，光質育苗は総クロロフィル含量に大きな影響を与えないが，クロロフィル a/b比は青LEDおよび青赤LEDで増加することが明らかになった．光質育苗後の総フェノール含量，カロテノイド含量および抗酸化活性は，赤LEDでは減少したが，青LEDおよび青赤LEDで増加した．抗酸化物質含量の増加は定植後の苗が受ける環境ストレスの緩和に寄与すると考えられた．以上のことから，LEDの活用によりサニーレタスの苗にコンパクト性と環境ストレス耐性を付与でき，収穫時に増収効果が得られる新しい光質育苗技術が提案できた．

概要 （英文）

In this study, we determined the effects of raising seedlings with different light spectra, such as with blue, red and blue+red light-emitting diode (LED) lights, on seedling quality and yield of red leaf lettuce plants. The light treatments we used were applied for a period of 1 week and consisted of 100 umol m-2 s-1 of blue light, simultaneous irradiation with 50 umol m-2 s-1 of blue light and 50 umol m-2 s-1 of red light, and 100 umolm-2 s-1 of red light. At the end of the light treatment, that is 17 days after sowing (DAS), the leaf area and shoot fresh weight (FW) of the lettuce seedlings treated with red light increased by 33% and 25%, respectively, and the dry weight of the shoots and roots of the lettuce seedlings treated with blue-containing LED lights increased by > 29% and > 83% compared with seedlings grown under a white fluorescent lamp (FL). The shoot/root ratio and specific leaf area of plants irradiated with blue-containing LED lights decreased. At 45 DAS, higher leaf areas and FWs were obtained in lettuce plants treated with blue-containing LED lights. The total chlorophyll (Chl) contents in lettuce plants treated with blue-containing and red lights were less than that of lettuce plants treated with FLs, but the Chl a/b ratio and carotenoid content increased under blue-containing LED lights. Polyphenol contents and the total antioxidant status (TAS) were greater in lettuce seedlings treated with blue-containing LED lights than in those treated with FLs at 17 DAS. The higher polyphenol contents and TAS in lettuce seedlings at 17 DAS decreased in lettuce plants at 45 DAS. In conclusion, our results indicate that raising seedlings treated with blue light promoted the growth of lettuce plants after transplanting. This is likely because of high shoot and root biomasses, a high content of photosynthetic pigments, and high antioxidant activities in the lettuce seedlings before transplanting. The compact morphology of lettuce seedlings treated with blue LED light would be also useful for transplanting.

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