Rhizobium as Potential Biofertilizer of Eruca Sativa

Eruca sativa , commonly known as rocket salad, is one of the leading leafy vegetables, belonging to the Brassicaceae family that include other species of agricultural importance, such as broccoli, cabbage, cauliflower, and mustard, amongst others. It is widely cultivated and consumed, being its popularity due to its peculiar flavour and nutritional value. On the other hand, to maintain agricultural production, the indiscriminate use of chemical fertilizers, pesticides, and herbicides results in damage to soil and biodiversity reduction and may result in adverse health effects. An effective alternative is the use of biofertilizers based on plant growth-promoting rhizobacteria (PGPR). In this study, we evaluated the use of a Rhizobium sp. strain as biofertilizer for E. sativa , performing different assays to demonstrate its potential. According to the obtained results, the partial sequencing of 16S rRNA gene classified this strain into the genus Rhizobium. This strain is not able to solubilize phosphate under in vitro conditions. However, this strain was an excellent producer of indole-3-acetic acid (IAA) and its precursors. Moreover, this strain produced siderophores in a low concentration. In vitro inoculation of E. sativa plants with this strain resulted in a significative increase of the number of secondary roots at 6 and 8 days post-inoculation compared to the uninoculated treatment. Therefore, our results support the possible inclusion of this strain of Rhizobium sp. in formulations as potential biofertilizer for E. sativa crops.