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Soil application of hydrogels containing rhizobacteria
Hlaváčková, Barbora ; Černayová, Diana (referee) ; Kalina, Michal (advisor)
Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria that can influence plant growth by their mechanisms. In recent years, there has been an increase in the use of these soil-supporting products in the form of biofertilizers to increase yields and improve crop growth in adverse conditions in an environmentally friendly way. The aim of this bachelor thesis was to assess the effect of the external addition of different application forms of PGPR on soil physico-chemical characteristics and on the growth of model plants of lactuca sativa without irrigation restriction in the first case and in the second case under irrigation restricted conditions. A particular strain of Azotobacter vinelandii CCM 289 was selected for the preparation of four forms of PGPR treatments, namely bacterial biomass suspended in PBS, alginate gel without bacterial culture, gel with bacterial culture and lyophilized gel with bacterial culture. The effect of the different treatments was compared with the negative control without the addition of PGPR, as different forms of treatments may achieve different efficiencies of rhizosphere colonization, which in consequence may have different effect on plant growth. To assess the effect of PGPR addition, soil physico-chemical characteristics (moisture content, pH) and growth characteristics of lactuca sativa such as number of leaves, height and width of aerial parts of these model plants were measured during the cultivation experiments. After the termination of the cultivation experiments, the basic growth parameters of the model plants from each treatment such as total plant length, length of aerial parts and roots of the model plants, as well as total weight of each plant and weight of their aerial parts and roots were determined. After drying, the total dry weight of individual plants and the dry weight of the aerial parts and roots were characterized. After drying, root density was analyzed by performing root scans and compared between treatments. Soil extracts from individual treatments after the cultivation experiments were analyzed to assess the effect of PGPR addition on the microbial activity of the soil used in the experiments by plate cultivation using Petri dishes with agar medium, and the average well colour development (AWCD) value determined using the BIOLOG EcoPlate kit. The obtained results were compared between the individual treatments and also between cultivation experiments conducted with different irrigation conditions. Physico-chemical characterization (pH, conductivity) was performed on soil extracts from the drained soils after the cultivation experiments. The amount of organic and inorganic fractions was analyzed on the dried soils of each treatment by TGA. The results were compared with each other and the effect of different forms of external addition of PGPR on the physico-chemical characteristics of the selected soil under conditions without irrigation limitation and under conditions with irrigation limitation during the experiments was assessed.
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