Enhanced blackberry production using Pseudomonas fluorescens as elicitor

This report shows for the first time the ability of Pseudomonas fluorescens N21.4 to trigger the secondary metabolism of blackberries, Rubus fruticosus, in the field. Blackberries are an excellent source of bioactive compounds as compared to other marketable berries. Biotic elicitation with plant growth-promoting rhizobacteria has been proposed to improve biomass production and to trigger secondary metabolism. However, most reports that support this statement involve controlled, in-door experiments, not real field conditions under continuous environmental changes. Furthermore, most investigations are carried out using model plants. Strain P. fluorescens N21.4 has been able to trigger secondary metabolism of plant species. Therefore we studied P. fluorescens ability to increase blackberry fitness, fruit quality, and protection against natural pests under field conditions. P. fluorescens N21.4 was delivered in the root or shoot system of blackberry plants along its entire production period, evaluating fruit quality and yield. Our results show an average increase up to 800 g per plant in total production, directly related to the increase in flowering buds. Protection against Spodoptera littoralis in inoculated plants was similar to control plants, hence contributing to increase in yield. Fruits from inoculated plants showed significant increases of up to 3 °Brix, total phenolics of up to 18 %, and flavonoids of up to 22 %. We conclude that P. fluorescens N21.4 enhances plant defense and fruit quality together with an increased productivity as compared to current management practices, already obtaining high yields with economic profit.