Role of arbuscular mycorrhizal fungi in the uptake of phosphorus by micropropagated blackberry (Rubus fruticosus var. brazos) plants

Abstract

The beneficial effects of arbuscular mycorrhizae on plant growth have been often related to the increase in the uptake of no mobile nutrients from the soil such as phosphorus. In this work, the data obtained about the increase of phosphorus by plants extracted from in vitro cultures with mycorrhizae in relation with non-mycorrhizal plants is shown. The mycorrhizal fungi were isolated and propagated from maize cultures. Micro propagation systems for blackberry were used in the Murashige and Skoog medium, varying the hormone concentration according to the growth. Once the plants were developed, they were transplanted into sterile soil and were inoculated with the previously propagated mycorrhizal fungi and finally transferred to a greenhouse. Harvest was made periodically with the objective of making the evaluation of the different agronomic variables and the amount of phosphorus in the aerial parts of the plant was determined by the colorimetric method of blue molybdate. The percent of phosphorus in the aerial part of Rubus fruticosus var. brazos, started to increase since the 30 days of treatment, until it increased an 80% at the end of the assay. This brought more efficiency in the mycorrhized plants to raise the photosynthetic rates in a shorter period of time and to be under a lower stress due to the transplanting process. One of the major effects of mycorrhizal fungi inoculation in plants is the increase of phosphorus absorption ability, by the direct activity of the extramatricial mycelium that allows the exploration of the soil volume. In this way, the mycorrhizal arbuscular fungi make up another chance in the process of getting nutrients for the plants, particularly phosphorus.