Efflux, measurement from plant

Figure 6.14 Fluxes of NOs" and NH4+ within rice roots measured by analysing efflux kinetics. Plants were grown on 100 p,M NO3, NH4 or NH4NO3 (i.e. [NOs ] = [NH4+] = 50 xM) for 3 weeks. Efflux kinetics were measured following 60 min exposure of roots to N-labelled solutions of the same composition (data from Kronzucker...

Solomos (14)i in a review of principles of gas exchange in bulky plant tissues suggested that apart from the mathematical complexities, determining the resistance to diffusion of the peel fruits, roots, and tubers from the measurement of the efflux of the inert gas introduces number of uncertainties due to differential diffusion resistant between the skin, fruit surface and the flesh (15). Thus, it cannot be always presumed that the concentration of the metabolically inert gas is uniformly distributed throughout the fruit. 

By measuring the rate of Rb efflux from excised and preloaded cucumber cotyledons, AFM injury was detected at concentrations as low as 10 nM ( ). Also, because AFM has an absolute requirement of light for expression of herbicidal activity, plant tissues can be pretreated in darkness without injury. Then, following light-activation, damage can be detected in relatively short time periods (10 to 15 min) (1 ). We believe these observations are indicative of its primary biochemical mechanism of action. 

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