History of chicken grazing stunts tomato seedling growth and influences bacterial endophytes isolated from tomato.

Integrated crop-livestock production systems promote resource interchange on the farm. Although crop-livestock integration can increase soil quality and fertility, information on their impact on plant vigor and endophytic bacterial communities is sparce. We aimed to address the impact of chicken-grazed soil (CGS) on tomato ( Solanum lycopersicum ) seedling growth and stem endophytes. We hypothesized that as planting substrate contains higher amounts of CGS, tomato seedlings will have higher biomass and greater bacterial endophyte diversity. Furthermore, endophytes recovered from tomato seedlings grown in planting substrate containing CGS will be similar to those commonly found in plants, and possibly to those associated with animal sources, including chicken manure. To test this hypothesis, two greenhouse trials were conducted where tomato seedlings grew for six weeks in substrates containing different dilutions of CGS. We observed that the greater the amount of CGS, the greater seedling stunting. Bacterial endophytes recovered in these experiments differed by CGS dilution. Bacillus and Paenibacillus were the dominant genera, Bacillus being the only genus present across all treatments. Most recovered isolates were found to be close matches to formerly cultured plant endophytes and soil bacteria. Future directions should focus on identifying mechanisms to ameliorate seedling stunting when grown in CGS.