ROOT RESTRICTION AND POTASSIUM AND CALCIUM SOLUTION CONCENTRATIONS AFFECT DRY-MATTER PRODUCTION, CATION UPTAKE, AND BLOSSOM-END ROT IN GREENHOUSE TOMATO

Root restriction has been reported to reduce fruit yield, the incidenc e of blossom end rot (BER) and K concentration in tomato (Lycopersicon esculentum L. 'F121') plant organs. The objectives of the present wor k were to study the effect of root restriction, and combination of K a nd Ca solution concentrations, on greenhouse tomato fruit yield, quali ty and cation uptake, Root restriction reduced total yield but improve d fruit quality by increasing the dry matter concentration and reducin g the incidence of BER. Increasing the K concentration from 5.0 to 10 mmol . L(-1) reduced the marketable yield, due to increased incidence of BER. Root restriction decreased K concentration and K/Ca ratio in t omato plant organs, but had no effect on K uptake rate per unit root f resh weight. Increasing K concentration from 2.5 to 10 mmol . L(-1) in creased the K concentration in plant organs and K uptake rate, but red uced that of Ca, In contrast, increasing Ca concentration in the solut ion had no effect on K concentration in plant organs and K uptake rate , The incidence of BER correlated well with K/Ca concentration ratio i n the leaves, whereas a poor correlation was obtained with K/Ca concen tration ratio in ripe fruit.