Regulation of nutrient uptake, water uptake and growth under calcium starvation and recovery

To analyze the dynamics of growth, water and nutrient uptake, the effects of 1, 3 and 7 d of calcium starvation and the recovery capability during 7 d afterwards were investigated in vegetative tomato plants. Results showed that after only 1 d of Ca-starvation, leaf photosynthesis, leaf expansion and leaf transpiration were already reduced and root growth had stopped completely. Leaf Ca concentration was reduced by a Ca-starvation with the strongest effect in the youngest leaves. When 1 d Ca-starvation period was followed by 7 d of recovery with full-strength nutrient solution, leaf photosynthesis and growth completely recovered. During the recovery period, Ca concentrations in the young leaves increased to higher values than these concentrations in the control plants. During the recovery period calcium uptake showed positive linear relationships with dry-matter increase of the plant as well as with water uptake. Most of the measured Growth parameters showed a strong correlation with the plant Ca concentration, but the relations were not always identical during starvation and recovery. We discuss the role different forms and functions of Ca may play in regulating growth and developmental processes.