The Effects of Solid Inocula of Enterobacter cloacae on Grain and Oil Yield of Rapeseed

The objectives of this experiment include determining the appropriate solid medium in terms of bacterial viability, growth improvement, canola oil percentage, as well as determining the amount of oil and type of canola fatty acids in different treatments.   

Methods and Materials:

 Accordingly, this experiment was performed to chek the effect of  a few combination of solid inoculant of bacteria Enterobacter cloacae S16-3 on growth of rapeseeds (Brassica napus L.) cultivar hayola 308. Solid inoculants of this bacterium were prepared using different carriers including: bagasse, peat, hydrochar, biochar, sawdust, perlite and bagasse:perlit, hydrochar:perlit, biochar:perlit, sawdust:perlit (with ratio 1:1 w/w), then after six months, bacteria population was counted and finally the effect of biofertilizers inoculant was checked with rapeseed inoculation in a pot culture. This experiment was conducted in a completely randomized design (CRD) with three replications in greenhouse by considering 10 treatments of solid carriers, a negative control treatment, a positive control containing 100 and 70 percent of NPK. During the growth period, the pots were irrigated at 0.7-0.8 FC and during the growing season the leaf chlorophyll index was measured. At the end of the experiment, plants were harvested and number of seeds per plant were counted, then the silique height, stem diameter, root volume per plant, fresh and dry weight of shoot and root, total fresh and dry weight, silique weight per plant, the weight of one thousand seed were measured. The oil content and fatty acid analysis were measured in seeds using Soxhlet extractor and GC, respectively.  

The results of this study showed that the effect of Enterobacter cloacae in carrier-based formulation (10 formulations) increased the number of seeds per plant, plant height, stem diameter, chlorophyll index, roots volume, fresh and dry weight of shoot and root, weight of silique, total fresh and dry weight and the weight of one thousand seeds. The inoculation effect of solid inocula of Enterobacter on 1000 seed weight was not significant. The results of oil content and fatty acid analysis showed that in all treatments except for peat and bagasse:perlite, oil content increased. GC results indicated that oil quality was affected by bacterial inoculation and bagasse: perlite treatment increased the percentage of oleic acid.  

Based on the experimental findings, the use of Enterobacter in the form of solid carriers improved many agronomic characteristics, increased the percentage of oil and fatty acid of rapeseed. But to finally confirm the effectiveness of this research, in addition to in-vitro and greenhouse experiments, it is better to test their effectiveness in field conditions with different plants. According to the results obtained from the used carriers, hydrocard, biochar-perlite and bagasse-perlite showed better results and are recommended.