非循環式の閉鎖型養液栽培システムを用いたトマト促成長期栽培における培養液濃度管理法(栽培管理・作型)  [in Japanese] A Dynamic Control of Concentration of Nutrient Solution for a Long-Term Forcing Culture of Tomatoes in a Closed Hydroponic System(Crop Production & Cropping Type)  [in Japanese]

養液栽培による環境への負荷を軽減するために開発した非循環式の閉鎖型養液栽培システムにおいて,トマト促成長期栽培における培養液濃度(給液EC)管理法について検討した.培養液には改良処方(NO_3-N:NH_4-N:P:K:Ca:Mg:S=7.0:0.2:2.1:5.6:2.9:1.0:1.1me・L^<-1>)を用いた.促成長期区の給液量および窒素施用量は定植後から増加し10月中旬に最大値をとり,その後12月中旬まで減少した.12月中旬からは促成区とほぼ同様な推移を示し,給液量は3月下旬まで,窒素施用量は2月上旬まで増加傾向であった.培地内溶液濃度は促成長期区では促成区と同等かやや高めに推移したが,施用培養液濃度を超えて集積する成分は認められなかった.このような培地内溶液濃度の推移から促成長期区における給液ECの管理は,定植から12月上旬までか1.2dS・m^<-1>,その後2月上,中旬まで1.4dS・m^<-1>,以後低下させ4月上旬に1.0dS・m^<-1>とする管理が適することが示唆された.

Control of the concentration of nutrient solution for a long-term forcing culture (LTFC) of tomatoes was studied in a noncirculating closed hydroponic system that was developed in order to decrease the load on the environment. An improved nutrient solution (NO_3-N : NH_4-N : P : K : Ca : Mg : S = 7.0 : 0.2 : 2.1 : 5.6 : 2.9 : 1.0 : 1.1 me・L^<-1>) was applied in both LTFC and normal-term forcing culture (NTFC). Nutrient solution and nitrogen supplied in LTFC increased immediately after planting and reached a maximum in mid-October, then decreased until mid-December. Thereafter, the trends of nutrient solution and nitrogen supplied were similar in both LTFC and NTFC, i.e. nutrient solution and nitrogen supplied tended to increase until late March and early February, respectively. Concentration of solution within the substrate toward greater fluctuation in LTFC, but there was no ingredient that markedly exceeded the concentration of the nutrient solution applied. It was suggested that adequate levels of EC in the supplying nutrient solution would be 1.2 dS・m^<-1> from planting until early December, increased to 1.4 dS・m^<-1> then lowered in February to 1.0 dS・m^<-1>.