Effect of inoculation with different strains of Azospirillum brasilense on cotton (Gossipium barbadense)

The response of the cotton plant to inoculation with six strains of Azospirillum brasilense was investigated under subtropical conditions in Egypt. Azospirilla populations and activities were increased as a result of root inoculation with liquid inoculum of Azospirillum sp. Highest C2H2 - reduction activities on roots were obtained with strains S631 and Sp Br 14 (means of 216.85 and 209.50 nmol C2H4g-1 root h-1 respectively) while strain M4 gave the lowest activity (mean of 100.8 nmol C2H4g-1 root h-1). Statistical analysis showed that Azospirillum strains 5631, Sp Br 14, E15 and SC22 significantly increased the plant dry weight and nitrogen uptake while inoculation with strains M4 and SE had no significant effect in that respect. © 1987 Springer-verlag.