RESPONSE OF TOMATO TO INOCULATION WITH SINGLE AND MULTI-STRAIN INOCULANTS OF DIFFERENT BACTERIAL SPECIES

摘要

Three pot experiments were conducted on tomato (Lycopersicon esculentum Mill) cv. Castle Rock during the growing seasons of 98/99, 99/2000, and 2000/2001 to test its response to inoculation with selected single or multi mixed strains in comparison with the uninoculated control. In the first season (1998/1999), with the exception of P. fluorescens, all single inoculation treatments with the selected strains A. chroococcum strain (5) and (11), A. lipoferum and B. polymyxa produced significant or highlysignificant increases in shoot and root fresh and dry weights of tomato plants. Inoculation with either of A. chroococcum strains No. 5 or 11 scored the highest shoot and root dry weights, number of branches and fruit yield per plant. The mixed co-inoculation treatments with double of the selected strains showed superior effects on plant growth and yield in two cases: first when A chroococcum strain No. 11 was mixed with B. polymyxa and second when A. chroococcum strain No. 5 was mixed with Azospirillum lipoferum. In the second and third seasons, 1999/2000 & 2000/2001, the results of the single inoculation treatments showed similar trends to those recorded in the first season. Also, fruit yield in both seasons was significantly increased by single inoculation with A. chroococcum and B. polymyxa as well as by co-inoculation with their mixture. The increases in fruit yield per plant in the second season were 55%, 63% and 39%, respectively for the above inoculation treatments compared with the uninoculated control. In the third season, the corresponding values were 36%, 28.0%, 36% respectively. Also, in the third season co-inoculation of A. chroococcum plus Azospirillum lipoferum increased fruit yield by 55.5% compared with the uninoculated control. In general, the results of the three seasons showed that the mixed inoculation treatments, except those with P. fluorescens, were usually more promotive than the single inoculation treatments. It is also indicated that co-inoculation of P. fluorescens with either A. chroococcum or Azospirillum lipoferum prevented their promotive effect.