DEVELOPMENT OF DELIVERY SYSTEMS FOR INTRODUCING ENDOPHYTIC BACTERIA INTO COTTON

Experiments were designed to evaluate the effectiveness of several met hods for delivering 15 endophytic bacteria into cotton stern and root tissues. The delivery, methods included stab-inoculation of bacteria i nto stems, soaking seeds in bacterial suspensions, methyl cellulose se ed coating, foliar spray, bacteria-impregnated granules applied in-fur row vacuum infiltration and pruned-root dip. The success of delivery w as gaged by recovery of the bacteria from internal plant tissues 2 wee ks after the plants had been grown in a glasshouse potting mix. Follow ing stab-inoculation into sterns or radicles, 10 of the bacterial endo phytes which previously exhibited biological control against fusarium wilt of cotton were successfully re-isolated from > 50% of the plants inoculated; however, this method was labor-intensive, involved woundin g the plant and sometimes reduced plant growth. Four of the other meth ods established,from six to eight of the 15 strains, and, with some st rains, all methods effectively established endophytic bacteria, based on re-isolation of strains from internal tissues 2 weeks after inocula tion. A method was developed which allowed more convenient isolation o f endophytes from a large number of plants. The results suggest that i ntroduction of beneficial endophytic strains into cotton plants could be accomplished by practical methods chosen specifically for each stra in.