Spatial patterns of radial oxygen loss and nitrate net flux along adventitious roots of rice raised in aerated or stagnant solution

Abstract

Roots of rice (Oryza sativa L.) grown in stagnant de-oxygenated solution contain a 'tight' barrier to radial oxygen loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. It is generally accepted that the barrier to ROL involves anatomical modifications in the apoplast of cell layers exterior to the aerenchyma. A possible drawback of this adaptation is a reduced capacity for nutrient uptake. Whether or not induction of a barrier to ROL influences the capacity of adventitious roots of rice to take up NO3– was determined in the present study, using NO3–-selective microelectrodes. When transferred into O2-free root medium, ROL from positions at 30–50 mm behind the tip of adventitious roots of plants raised in stagnant solution was only 4–6% of the rate from roots of plants raised in aerated solution, indicating the barrier to ROL was induced by growth in stagnant solution. For plants transferred into aerobic nutrient solution containing 0.1 mM NO3–, net NO3– uptake by these root zones, with or without a barrier to ROL, was the same. It is concluded that induction of a barrier to ROL had no effect on the capacity of adventitious roots of rice to take up NO3– from aerobic solution.

Spatial and temporal patterns of net nitrate uptake regulation and kinetics along the tap root of Citrus aurantium

“…Further, the cHATS and iHATS values reflected that reported in whole root system of citrus rootstocks (Sorgonà et al 2005) and for other plant species (Siddiqi et al 1989). Although this spatial uniformity of NNUR was also reported by Colmer and Bloom (1998), Garnett et al (2001) and Rubinigg et al (2002), it contrasted with that reporting either an increase (Lazof et al 1992;Colmer and Bloom 1998;Plassard et al 2002) or a decrease of NO 3 -fluxes from root tip (Cruz et al 1995;Reidenbach and Horst 1997;Hawkins et al 2008).…”

Short-term evaluation of oxygen transfer from rice (Oryza sativa) to mixed planted drought-adapted upland crops under hydroponic culture

“…The seedlings were grown in a plant growth room with a 28/23 °C day/night temperature, a 14 h photoperiod, and a 318 ± 2 μmol m −2 s −1 photosynthetically active radiation (PAR) on the top of the canopy. The PAR value is almost same as those in previous reports to evaluate oxygen release (root respiration) in the laboratories for growing Phragmites australis (Armstrong et al, 2000), O. sativa (Rubinigg et al, 2002), and Zizania latifolia (Nakamura et al, 2013). Pre-germinated rice seeds were sown on a screen mesh and placed on the bottom of each plastic seedling tray compartment (37 × 37 × 46 mm, length × width × height) and then covered with a thin plastic filling to avoid seed drying and light penetration into the root system.…”

Regulation of Root Traits for Internal Aeration and Tolerance to Soil Waterlogging-Flooding Stress

“…Importantly, the greater diffusive resistance across the ROL barrier cells appears not to impede the active uptake of nutrients (e.g. NO 3 2 ; Rubinigg et al, 2002) and might have relatively small consequence for water mass flow (Garthwaite et al, 2006;Kotula et al, 2009b); however, data on these aspects are few, and roots with strongly induced tight ROL barriers should be evaluated for nutrient uptake capacity and for radial hydraulic conductivity.…”