Spraying hydroponic lettuce roots with a suspension concentrate formulation of Bacillus velezensis to suppress root rot disease and promote plant growth

Abstract

Bacillus velezensis was prepared as a suspension concentrate (SC) and sprayed on to the roots of 1-month-old Lactuca sativa, grown in a hydroponic system. In the first experiment using Lactuca sativa (var. Red Coral) with root rot symptoms, a 1% blank with no cells, a 1% SC (1013CFU/ml) and 1% fresh bacterial cells (FC) (1014CFU/ml) reduced the percentage of root tips colonized by the pathogen and increased the fresh shoot weight compared to plants that were not sprayed. In the second experiment with L. sativa (var. Green Oak) using healthy-looking roots, a 1% blank, 10% SC (1013CFU/ml) and 1% FC of the bacterium (1014CFU/ml) reduced the percentage of root tips colonized by Pythium sp. The SC and FC of the bacterium increased the fresh shoot weight, while the blank, the SC and the FC of the bacterium increased the dried weight of the shoot.