Effect of Concentration of Nutrient Solution on Vegetative Growth and Fruit Yield of Hydroponically Grown Tomato Plants.

Tomato (Lycopersicon esculentum Mill.ev.Ogatazuiko) plants were grown in low concentration (a quarter of the control levels) or control (full strength Yamasaki's tomato solution until 7 weeks, and then 1.5 fold strength).The EC of the low nutrient solution was adjusted daily to avoid deficiency of nutrient supply.There was significant reduction in leaf dry weight, stem dry weight, crop growth rate (CGR) and leaf area index (LAI) of plants grown in low nutrient solution after 6 weeks.These differences were present for the next 9 weeks.There were no significant differences in root dry weight, total number of fruits and early fruit yield, but the total fruit yield from plants grown in low nutrient solution was 32% less than that from the control plants.The relative amount of assimilate in the fruit and the net assimilation rate (NAR) of plants grown in low nutrient solution was significantly greater than the control plants from week 6 to week 12, however, it was less than the control plants at week 15.The concentration of nutrient solution had no effect on the P, Ca and Mg content in leaves, but the N and K content in leaves was significantly lower in plants grown in low nutrient solution than in control plants at week 15.The experiment showed that it is possible to control excessive vegetative growth without the loss of fruit yield by the use of a low concentration of nutrient solution (EC 0.7-0.9dS/m) with the frequent supplementing of N and K after topping.