Mineral elements and phytase activity in Pisum sativum grown at different Zn supply levels in the greenhouse

Abstract

Pisum sativum cv ‘Phenomen’ was grown at 1.4–18.0 mmol Zn acetate kg −1 dry soil for 12 and 21 days in a greenhouse to examine the impact of Zn. Results showed that the mineral element status and inter-element relationships were altered even at or below soil and plant Zn levels considered toxic (200–500 mg kg −1 soil and 500 mg kg −1 plant dwt). Cotyledons accumulated Zn, and the overall loss of cotyledon reserve materials and that of K were reduced, but remobilisation of Mg, Ca, Cu, and Mn was enhanced. In vivo total phytase activity correlated negatively with cotyledon dry weight, and N content, but positively with seedling growth. In vitro phytase activity declined at and after day 9, which may point to an age-related factor enhanced by Zn. In the 21-day-old plants, root dry weights were less affected than those of shoots, which were reduced at 3.2 mmol Zn kg −1 and higher soil Zn levels. The N and K concentrations of both shoots and roots, that of P in the roots, and that of Fe in the shoots decreased. Soil Zn reduced the total N, K, P, and Fe contents of entire plants without the shoot-root partitioning being altered, which was concluded to point to direct or indirect effect by Zn on element acquisition. The fraction of shoot Zn decreased with rising soil Zn level. A number of correlations between growth parameters and elements and at inter-element level were altered or inversed, including those of Na and Mn, which were suggested to point to altered or enhanced role for some elements.