Foliar biostimulant application on the growth and development of Citrullus lanatus seedlings grown in salinized substrate

Salinity is a process that directly interferes with soil and water quality, compromising agricultural crops. The objective of this study was to evaluate the influence of biostimulant application in mitigating the toxic effects of experimental salt concentrations on watermelon seedlings. Seedling production was carried out using seeds of the watermelon cultivar ‘Crimson sweet’, and the tested treatments were distributed in a 3x2 factorial arrangement. The first factor consisted of three levels of soil salinity with electrical conductivities: 0.6; 2.6; 4.6 dS m-1. The second factor consisted of the presence or absence of biostimulant application. Sowing was carried out in polypropylene containers with a capacity of 300 dm3. Two seeds were sown, and the plants were thinned to one plant per container five days after emergence. Foliar applications of the biostimulant were carried out 7 and 14 days after emergence at a level of 300 mL ha-1. The experimental design was randomized blocks (RBD) with four replications. Watermelon seedlings exposed to salinities ranging from 0.6 to 4.6 dS m-1 showed limited growth and development, evidencing the toxic and harmful effects of salinity on the plants tested during the seedling stage. The biostimulant at the recommended level of 300 mL ha-1 did not show results that could verify the mitigation of substrate salinity or increased growth and development of watermelon seedlings.