Journal of Soil and Plant Interactions

To investigate the effects of nutrient-solution concentrations of potassium (K) and calcium (Ca), as well as different ratios of K/Ca, on growth and flowering of lisianthus (Eustoma grandiflorum) under soilless culture conditions, a factorial experiment was conducted with two factors including two K levels (300 and 400 mg/L) and three Ca levels (80, 100 and 160 mg/L). Results showed that K= 400 mg/L increased leaf number and plant height by 10% and 5% more than K= 300 mg/L, respectively. But, did not affect shoot or root’s fresh and dry weight. The highest plant height (45.6 cm) was obtained in 100 mg/L of Ca and the highest fresh root weight was observed in 160 mg/L of Ca. The effect of K×Ca interaction was significant on the number of leaves and branches. The highest number of leaves (40.3) was observed in K=400 and Ca=160 mg/L treatment. The interaction effect of Ca×K had significant effect on traits related to flowering. The highest number of flowers (16.4), number of flowering shoots (4.7) and flower diameter (49.5 mm) were observed in K=400 and Ca=100 mg/L or K=400 and Ca=80 mg/L (K/Ca ratios of 4 and 5); while, the flower longevity was the least (10.3 days). The highest flower longevity was observed with K=300 and Ca=100 mg/L. The best nutrient solution treatment for yield and durability of flowers was K=300 and Ca= 80 mg/L (K/Ca=3.7).