An improved method to measure spatial variation in root respiration: application to the taproot of a young peach tree Prunus persica

This paper presents an improved method to measure the local root respiratio n, by suspending them in a gel which could be sampled using an oxygen micro electrode. The effect of gel type on the oxygen diffusion and on transport of oxygen from the shoot to the root was studied. The local root respiratio n rates were estimated by fitting models for oxygen diffusion and consumpti on to the measured oxygen profile data obtained with the microelectrodes. T he best fits to our experimental data were obtained with a model which desc ribes oxygen radial diffusion, root consumption, and microbial consumption that declines with distance from the root. We applied this method along the taproot of Prunus persica (L.) Batsch. Local respiration level was consist ent with root system respiration rate estimated in other plants of similar age and dimension, as measured by conventional gas chromatography. In accor dance with published results, which have only been reported on primary stru cture respiration, the specific respiration rate was at a maximum in the el ongating apical zone; it then decreased with distance from the root tip up to the root hair zone, where it increased.