Symbiotic fungi in nature Finnish peat moss promote vegetative growth in rabbiteye blueberry cuttings

Abstract

In nature conditions, mutualization of ericaceous plant (Ericaceae) roots with mycorrhizal fungi or other soil symbiotic fungi improves efficiency on nutrient uptake and tolerance to heavy metal stress. Effects of ericoid mycorrhizal fungi (EMF) or dark septate endophyte (DSE) colonization have been evaluated in highbush blueberry (Vaccinium corymbosum) but remained unclear in rabbiteye blueberry (V. virgatum Ait.). In this study, callused cuttings of ‘NTU-104’ rabbiteye blueberry were grown in substrate containing either sterilized (SP) or unsterilized (UP) nature Finnish peat moss as a fungal inoculum. Vegetative growth, fungal colonization frequency (Cf) and intensity (Ci), substrate pH and electrical conductivity (EC), and plant nutritional elements were assessed. Sterilization did not completely exclude fungi resources in the peat moss and colonization of EMF and DSE was found in both SP and UP substrate types. Regardless, UP treatment resulted in greater total Cf (69.3%) and Ci (9.91%) than those of SP (41.49% and 6.17%, respectively). In either substrate type, both Cf and Ci of DSE were greater than those of EMF. Plants in UP treatment produced more shoots (2.33), number of leaves (76.33), greater total leaf area (494.18 cm2), and shoot length (121.78 cm) than in SP substrate (1.67, 24.17, 116.13 cm2, and 30.22 cm, respectively). Fresh weights of roots, shoots, and leaves in UP plants were significantly greater (7.57, 9.64, and 15.25 g, respectively) than in SP plants (1.29, 2.62, and 3.08 g, respectively). Dry weights of roots, shoots, and leaves in UP plants were also significantly greater (4.34, 2.37, and 4.51 g, respectively) than in SP plants (0.67, 0.47, and 0.90 g, respectively). Concentrations of phosphorous and magnesium in roots and potassium in shoots were increased in UP plants while other nutritional elements remained consistent. Contents of all nutritional elements were increased in UP plants due to greater dry weight. After the establishment of the transplants, pH and EC of both substrate types were in the optimal range for blueberries but significant lower pH while higher EC were measured in UP substrate. The results indicated that using nature Finnish peat moss as a symbiotic fungi inoculum was capable of establishing symbiotic fungal colonization and promoting rooting and vegetative growth in rabbiteye blueberry cuttings.