RHIZOSPHERE OXIDATION IN RICE - AN ANALYSIS OF INTERVARIETAL DIFFERENCES IN OXYGEN FLUX FROM ROOTS

The polarographic technique (Armstrong 1967) has been found suitable for the detection of significant intervarietal differences in oxygen diffusion from rice roots. All the evidence obtained supports the thesis that intervarietal differences in oxygen diffusion rate occur and the varieties tested may be arranged in order of increasing oxygen flux as follows N 36 < N 22 < N 29 < N 32 < Yubae. The lowest oxygen flux rates are found in those varieties (N 22 and N 36) susceptible to Akagare disease of rice while the flux rates of varieties resistant to Akagare (N 29 and N 32) are higher. On the basis of these results one would also expect Yubae to be resistant to Akagare. The results are discussed with reference to previous work which has shown the oxidising activity and carbohydrate exudation properties of rice roots to be similarly correlated with resistance or susceptibility to Akagare. Attention is drawn to what it is felt are the shortcomings in existing techniques for measuring the oxidising activity of roots. It is suggested that with certain provisions the polarographic technique may he found useful in any effort to build up high oxidising power into the new plant type proposed for the tropics. Copyright © 1969, Wiley Blackwell. All rights reserved