Effect of B vitamins on lettuce plants subjected to saline stress

The use of water with a high concentration of salts has been increasingly frequent in vegetable production. This reduces the development and productivity of vegetables, raising the importance of the search for techniques to mitigate deleterious effects. In this sense, vitamins have the potential to improve conditions for plant development. The study was conducted to evaluate the effects of the application of B vitamins in lettuce plants submitted to irrigation with saline water. The treatments consisted of Control: irrigated with water and without application of vitamins; NaCl: irrigated with saline solution (50 mM NaCl, equivalent 5.18 dS m-1) and without application of vitamins; NaCl+B1: irrigated with saline solution and application of vitamin thiamine (100 mg L-1); NaCl+B3: irrigated with saline solution and application of vitamin niacin (100 mg L-1). These treatments were applied to two lettuce cultivars, “Pira Roxa” and “Valentina”. Both vitamins increased net photosynthesis when compared to the NaCl treatment. However, only the application of thiamine resulted in a mitigating effect on the losses of plant dry mass accumulation. Thus, the exogenous application of these vitamins alleviates the effects caused by salinity in lettuce plants, reducing stress on photosynthetic mechanisms and increasing photosynthetic activity. In addition, thiamine helps to reduce the deleterious effects of salinity on the accumulation of biomass.