培養液濃度と施用量が高CO2濃度条件下で育てたイチゴ‘さがほのか’の生育・収量と果実品質に及ぼす影響

The effects of supplied amount and strength of nutrient solution were investigated for strawberry (Fragaria×ananassa Duch. cv. Saga-honoka) grown with peat bags in elevated CO2 environment (800-2500 ppm in the day time, November 4 to April 7). Three strengths (L : low-80%, M : standard-100% and H : high-120%) of nutrient solution (N : 8.85, P : 0.85, K : 3.90, Ca : 2.05, Mg : 0.93 mM ; half strength of Ohtsuka A solution) were compared. Around 20% of discharged rate (discharged/supplied amount of nutrient solution) was kept for these 3 plots and 30 to 40% of the rate was kept for additional plot of 80%-solution (L2) by altering the supplied amount of 80%-solution. As almost no nitrate could be detected in drainage of L, nutrient supply was probably insufficient throughout the experiment. Total amount of nitrogen supply was lower than the other 3 plots and leaf area was the smallest after December. Although there was no significant difference in yield and fruit quality, the rate of tip burn affected flowers was lowest in L2 and highest in H. Thus, around 30-40% of drainage rate and 50-60 mS・m−1 of drainage EC may be desirable target values for ‘Saga-honoka’ strawberry grown with peat based substrate.

イチゴ‘さがほのか’を用いて，高CO2濃度条件下(日中800～2500ppm)での栽培における培養液濃度と施用量の影響について検討した．培養液は排液率20%を目標に，大塚Ａ処方を30～50%濃度で適宜変更する慣行区を標準として，濃度をその1.2倍，0.8倍とする高濃度区と低濃度区，さらに低濃度区においては，給液量を1.2倍(排液率35%)とする低濃度多量区を設け，計４処理区とした．排液率20%を目標とした低濃度培養液管理では，12月以降の排液中NO3-Nは検出限界以下であり，栽培期間を通して養分が不足しがちであった．また，全Ｎ施用量も他の３処理区と比較すると少なくなり，１月以降の葉面積が小さくなった．収量・果実品質においては処理区間で有意な差は認められなかったが，チップバーン発生率は，高濃度区で高く，低濃度多量区の発生率が最も低かった．低濃度多量区では，葉面積も大きくなったことから，‘さがほのか’においては，排液率30～40%，排液EC50～60mS・m-1を目標とした低濃度での培養液管理が望ましいといえる．

原著論文 (Original paper)