Evaluation of the Efficiency of Date Seeds as a Carrier of PGPR Inoculants under Different Storage Temperature

Abstract

Two isolates of Plant Growth Promoting Rhizobacteria were used in this experiment, After confirming that these strains belong to Bacillus megaterium and Pseudomonas fluorescence by using agronomic and morphological characteristics, these strains were grown on slants and transferred to liquid broth (NB) in the rotary shaker to prepare mother (starter) culture which contains 31 x 108, 37 x 108 CFU.ml-1 for each strain. Date palm seeds were used as a carrier for these strains, which had two types (the seeds of Rutab dates and the seeds of the molasses date), these strains were mixed with 10 g for each type of date palm seeds and then divided into two groups. The first group was stored at 4° c and the second group was stored at 25° c for 120 days. Survival cells were counted for each microbial combination every 30 days of storage. The results showed the ability of the date seeds material of both types to maintain the density of the bacterial inoculum, whether B. megaterium or P.flourescence throughout the storage period of 120 days. The combination of S3 retained the highest population density of the inoculum cells after 120 days of storage, for both storage grades 4 and 25° c recording log 7.37 and 7.93 CFU/g, While the combination S2 recorded the lowest microbial density of the inoculum cells which was log 6.25 and 6.32 cfu/g. The date seed (al-Rutab, molasses) maintained a constant level of decrease in the numbers of live cells of the Pseudomonas fluorescence (S3, S4) at both storage degrees, the percentage of reduction was 22 and 16% respectively at the end of period storage, as for B. megaterium the combination S1 and S2 were recorded 18 and 30%.