Effects of mechanical stress on uptake and distribution of nutrients in barley

Abstract

Roots of barley (Hordeum vulgare, L. v. Salve) exposed to a mechanical stress (pressure) showed morphological and growth changes and differences in nutrient uptake. A model system was used where the roots developed in a nutrient solution in a bed of glass beads, which was compressed by an external pressure of 20 kPa. Pot experiments with compacted sand gave similar results. The main effects of applied pressure were: 1) elongation of roots was suppressed to 30–40% of controls, 2) mean diameter of roots increased, 3) dry matter content of roots increased, 4) N concentration of whole plants decreased, 5) Ca concentration of roots decreased, 6) concentrations of P, K and S were mainly unaffected. The results indicated that the main part of N and P are absorbed by lateral roots but that Ca is taken up by seminal roots. Short term experiments showed that K (86Rb) influx in roots of stressed plants was reduced to 50% of the controls. The corresponding inhibition for SO4 (35S) influx was 20%.