Effects of ammonium and calcium on lisianthus growth

Abstract

The objective of the present study was to determine the influence of ammonium (NH4 +) (0% and 50% of total nitrogen, N) in combination with calcium (Ca) on the growth of lisianthus (Eustoma grandiflorum) in perlite cultures. Ammonium significantly improved leaf area, stem diameter, flower buds, and chlorophyll content (SPAD index) while increasing levels of Ca resulted in decreased leaf area, and chlorophyll contents. Application of NH4 + increased dry weight (DW) of stems, leaves and flowers with a reduction in root DW. In contrast, increased Ca caused a decrease in DW of all plant parts, except flowers. Decreased photosynthesis in NH4 + -fed plants was associated with a decrease in magnesium (Mg) and potassium (K) uptake, and an increase in phosphorus (P) and sulfur (S) uptake. The potentially deleterious effect of this nutrient imbalance was counteracted by allocating more K and Mg to the shoot and flowers. The ability of lisianthus to shift the allocation of nutrients to sensitive plant parts may explain the tolerance of this species to high NH4 +. Ammonium was associated with decreased peroxidase and catalase activities, suggesting that plants were under oxidative stress. Plants typically respond to high NH4 + nutrition by decreasing the uptake of Ca; however, in our study, increasing Ca and NH4 + resulted in increased Ca uptake, reaching toxic concentrations in shoot tissues.