The use of selected mycorrhizae for quality improvement of highbush blueberry (Vaccinium corymbosum L.) plant production

The highbush blueberry culture in Italy is limited by its low adaptability to soil characteristics, the difficulty to find plants of the most interesting varieties, the low rooting ability of some of the main cultivars, and the slow growth and low productivity of young plants propagated by cuttings. Micropropagation proved to be an excellent means to produce many plants in a short period of time and plants with better field performance than those obtained by traditional cuttings: bushier growth habit, increased vigor, number of branches and flowering buds, and yield almost doubled. Preliminary studies on mycorrhization of highbush blueberry with selected fungi showed the role of symbiosis on the growth behavior of young plants. In the present study, the use of two techniques together - micropropagation and mycorrhization – has been investigated in order to improve the production and quality of nursery stock plants, to access a possible reduction in the use of chemicals and to increase the adaptability of highbush blueberry to a wider range of soils. Thus, the aim of this research was to study the effect of selected mycorrhizal fungi inoculated on different varieties of Vaccinium corymbosum propagated in vitro, on the establishment, development and vegetative growth of nursery plants. In comparison to non-mycorrhized plants (control), mycorrhizazion with strains E12 and D IX significantly increased plant growth. However, vegetative growth of the mycorrhized potted plants showed a great interaction between the fungus strain and the cultivar. The different fungi performed differently with each variety as far as total plant growth. The best symbiotic fungi for Atlantic were G2, OMZ and D IX; E12, DIX, LH and HE were the best for Berkeley; OMZ, OME and G1 for Herbert and LH, OME and E12 for Lateblue. The effect of different fungus strains were both on root development and on the growth rate and growth habit of plants. Since the success in the symbiosis between fungus and plant in the field can be influenced by environmental conditions and particularly by the soil, it is very important to study the adaptability of mycorrhized plants in different pedo-climatic environments, assuming that a correct mycorrhiza choice could favor the Vaccinium adaptability to a wider range of environments. Mycorrhized plants were then transferred to the field on different soils for further investigation.