養液栽培イチゴの生育・収量と果実発育に及ぼすカリウム栄養の影響

　Effect of K nutrition on sugar and organic acid concentration in fruit and yield of strawberry cultivars (Fragaria ×ananassa Duch.; Nyoho, Toyonoka, Sachinoka, Asukarubi, Akihime, Tochiotome, and Sagahonoka) was investigated. Nutrient solution (NO3 8, NH4 1, P 1, K 4, Ca 2, Mg 1, SO4 1 ; mM) was modified to contain 0 to 4mM of K by replacing K with Ca and supplied from the beginning of flowering. K in the drainage decreased to a trace level 3 weeks after the beginning of treatment except for 4mM‒K solution. Absorption of NO3 apparently decreased in plants supplied 0mM‒K solution, but little difference was observed among the other 3 solutions. K concentration in petiole decreased linearly with decrease in K concentration in solutions, but there was little difference between the concentrations of leaflet of plants supplied with 4 and 2mM‒K solutions. No difference was observed in concentrations of sugars and organic acids in fruit in primary inflorescence. In the second inflorescence, organic acids and K concentration in fruit linearly decreased with decrease in K in supplied solutions while sugar concentration of fruit decreased significantly only in plants supplied 0mM‒K solution. When 0.5 to 4mM‒K solutions were supplied from 2 weeks after planting, marketable fruit yield was smallest in plants supplied 0.5mM‒K solution followed, by that supplied 1mM‒K solution, and largest in that supplied with 2mM‒K solution. Almost all K supplied with 2mM‒K solution was absorbed by strawberry plants and no difference was observed in quality and K concentration of fruit, yield and plant growth between the plants supplied with 2 and 4mM‒K solutions. It may be suitable to reduce the concentration of K in nutrient solution by half for substrate production of strawberry.

原著論文 (Original paper)