Abstract: The variation of the kinds and the number of microbial biomass in 6 culture media with different proportion of fermented rice husk, corn straw, corn cob, peat and perlite grown with Gerbera jamesoni at different developmental periods was investigated under plastic tunnel conditions. The results showed that biomass of bacteria ranked the first in different medium formulas at different developmental periods of Gerbera jamesoni. The quantity of actinomycetes was the second, and fungus ranked the last. The quantity of bacteria and actinomycetes in the culture medium T1 ( the portion of rice husk, peat and sand was 3∶1∶1) , T2 ( the portion of rice husk, corn straw, peat and sand was 3∶2∶1∶1) and CK1 ( the portion of peat and perlite was 2∶1) reached a peak at leaf flourishing growing stage, and then decreased, rose again at flowering stage, and decreased again remarkably at flower withering stage. The quantity of bacteria and actinomycetes in the culture medium T2 , T1 and CK1 were 10.6 ×106 and 87.2 ×105 , 9.53 ×106 and 35.4 ×105 , 2.87 ×106 and 2.52 ×105 ·g- 1 dry media (DM) , respectively at leaf flourishing growing stage. The quantity of bacteria and actinomycetes appeared the increasing trend in the culture medium T3 ( the portion of rice husk, corn cob, peat and sand was 3∶2∶1∶1) , T4 ( the portion of rice husk, corn straw, corn cob, peat and sand was 2∶1∶1∶1∶1) and CK2 ( soil ) at leaf flourishing growing stage and flower budding stage, and reached a peak at flowering stage, but decreased rap idly at flower withering stage. The quantity of bacteria and actinomycetes in the culture medium T4 , T3 and CK2 were 12.31 ×106 and 48.69 ×105 , 10.74 ×106 and 38.64 ×105 ,2.91 ×106 and 7.75 ×105 ·g- 1DM, respectively at flowering stage. The fungal quantity in different culture medium formulas increased sharply at leaf flourishing growing stage, then decreased, and rose again at flowering stage, and reached a peak at flower withering stage. The fungal quantity at the peak stage in formula T2 was 4.16 ×104 ·g- 1DM which ranked the first; the next was 2.92 ×104 ·g- 1DM in formula T3 , and the least was 0.15 ×104 ·g- 1DM in CK2. Among all the culture media, there appeared less bacteria generally in the culture media with relatively large proportion of rice husk, more bacteria in media with more components and small proportion of rice husk, more actinomycetes in media with large proportion of corn straw, and more fungi in media with large proportion of corn straw or corn cob.

Key words: Gerbera jamesoni, culture media, developmental periods, microorganisms