Turfgrass root system inoculation and colonization by a mycorrhizal fungus and other symbiotic micro-organisms and evaluation of its effects on green turf cover and growth

Abstract

Efficient use of irrigation water and nutrient uptake is of utmost importance for efficient and sustainable turfgrass management. In the present study, the ability of selected symbiotic micro-organisms to improve the visual quality and growth of turfgrass was investigated. Specifically, three soil inoculants, Trichoderma harzianum T-22, Glomus intraradices (arbuscular mycorrhizal fungus) and Bacillus amyloliquefaciens FZB42 as plant growth promoting rhizobacterium, were applied in order to colonize Festuca arundinacea 'Grande II'. The study was conducted under greenhouse conditions using disinfected 1.7 L pots filled with a sterilized substrate mixture comprising 85% sand, 2% peat and 13% organic soil. Green turf cover (GTC) and dark green color index (DGCI) were determined using digital image analysis. In addition, the weight of the clippings and the root dry weight were determined. Turfgrass cover and color, as determined by digital image analysis, was affected by inoculation treatments. T. harzianum T-22 and B. amyloliquefaciens FZB42 had a positive influence on turfgrass growth, by increasing clipping yield compared with the control. The aforementioned micro-organisms had a positive effect on root development, while the microscopic examination of root samples showed that the turfgrass root system was colonized by T. harzianum T-22 and G. intraradices. In addition, an efficient colonization of the rhizosphere by B. amyloliquefaciens FZB42 and T. harzianum T-22 occurred. Inoculation with strains FZB42 and T-22 improved GTC and DGCI while G. intraradices did not have any positive impact. These positive first results will be used as a basis for a field experiment where the effects of the above three symbiotic micro-organisms on turfgrass drought resistance will be evaluated.