報告書番号

V09036

タイトル（和文）

省エネルギー植物生産技術の開発(2)－レタス養液栽培における培養液濃度と生育との関係－

タイトル（英文）

- Relationship between concentration of nutrient solution and lettuce growth in hydroponic culture-

概要 （図表や脚注は「報告書全文」に掲載しております）

園芸施設利用時に排出される温室効果ガスの削減のために、電気式ヒートポンプを熱源とした技術の開発などが求められるようになってきた。一方、レタスなどの葉菜類の養液栽培において、安定して生産するために比較的高濃度の養液を用いる場合が多い。しかし、この養液に含まれる肥料の合成の際には大量の温室効果ガスを排出することが知られている。従って、温室効果ガス排出削減や外部環境への影響の低減のために低濃度の養液で栽培する方法の開発が望まれる。本研究は、レタスの湛液式栽培を用いて、レタスを栽培するには、培養液をどの程度までならば、低濃度にすることができるのかを明らかにするとともに、レタスの生育を阻害する養分条件を明らかにすることを目的に行った。その結果、標準的な養液処方の30％程度の濃度の養液で栽培ができることが明らかとなった。

概要 （英文）

The leafy vegetables such as lettuce are produced hydroponically using the Deep Flow Technique (DFT) and NFT in Japan. A comparatively high density solution is often used to produce vegetables stably (EC=1.2-3 dS/m). In these cultivation methods, it is necessary to exchange the nutrient solution to the new one, when the control of EC and pH becomes difficult or after the harvest of vegetables. The consequent waste water is large amount so that reducing the concentration of the nutrient solution is needed to protect the environment. In this study, we measured EC, PH, the concentration of Ca, Mg, K, PO4, NO3, NH4 in the nutrient solution, and amount of the absorbed solution and the growth of lettuce plants to determine the optimal concentration of each element as low as possible. Lettuce plants grown in the nutrient solution diluted from 0.2 to 1.0 times (EC = approx. 1.3 ds/m) were harvested approximately 21 day after transplanting to the DFT system. There was no or little difference of the growth and the amount of the absorbed fertilizer among the plants grown in the solution diluted 0.6, 0.8 and 1.0 times. The plants grown in diluted solution at 0.4 times and below grew somewhat small and K and PO4 were almost absorbed. No NH4 remained in the nutrient solution, irrespective of the dilution magnification. The concentration of Ca and Mg in the each solution was almost constant. The next experiment was carried out to test the hypothesis that fortification of the diluted solution with K and PO4 leads plant growth normally. The growth of lettuce plants grown in the solution diluted 0.4 times, supplemented with K and PO4 was comparable to that grown in the regular solution, indicating the possibility of reducing the concentration of the nutrient solution without the growth defect.

報告者

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