ASHS 2025 Conference

Bacterial endophytes, which live inside plants, could be beneficial by enhancing plant growth, improving stress tolerance, and combating diseases. In a previous study, greenhouse soil-based strawberries inoculated with endophytes exhibited over 60% more root growth. Field strawberry research demonstrated an average marketable yield increase of 15% from a single endophyte (IALR619) across multiple sites. However, high environment variability, resulted in inconsistent yield performance at these field sites. Since greenhouse hydroponics allows the regulation of nutrients and climate variables, it was hypothesized that the addition of growth-promoting bacteria would result in higher yields. In a pilot run, three bacteria and three day-neutral strawberry cultivars were screened. Based on the preliminary results, two endophytes, IALR1379 and IALR619, were tested on the strawberry cultivar Albion using a randomized complete block design (RCBD) with three replications. IALR619 is mainly a biocontrol bacterium with moderate ability to synthesize plant hormone auxin and solubilize insoluble phosphate compounds. IALR1379 has high activity of auxin synthesis, N-fixing, and solubilization of insoluble phosphates. Bato buckets filled with perlite were planted with strawberry bare roots in the Fall of 2024. Each replication or unit consisted of five Bato buckets connected to a single nutrient reservoir, with four plants per bucket. EC and pH were maintained at 1 ± 0.01 and 6 ± 0.01. The treatments included IALR1379 and IALR619 inoculated plants and a non-inoculated control. First bacterial inoculation was done when new leaves appeared, followed by a second treatment applied one month later. Fruits were harvested weekly over nine instances, and the fresh weight of marketable, unmarketable, and diseased fruits was recorded separately. The quality of the fruits was determined by measuring the BRIX index of 4-5 fully ripe fruits. Chlorophyll content was measured using a SPAD meter. The average marketable yield of IALR619-treated plants was 8128 g, while IALR1379 treated plants and control plants recorded 7474 g and 7071 g, respectively. Although these values were not statistically significant, the yield increase of IALR619-treated plants was 14.9% higher compared to the control. SPAD values and BRIX index for different treatments were not significant. The beneficial effects of endophytes are most evident when plants are under stress. This experiment will be repeated in the spring to determine whether endophytes and can help strawberries to tolerate summer heat and achieve higher yields.