Compost Tea As Biostimulant: Promoting Tomato Root Development

In the coming years, the application of biostimulants will become a fundamental tool for reducing chemical fertilization in agriculture, increasing the efficiency of soils and crops to face up to climate change conditions. Following this context, we have assessed the effect of garden waste compost tea (CT) in a ratio of 1: 5 (v/v) with water on root morphology of tomato var. Tres Cantos. The studied CT showed relevant content of K2O, N, humic acids and, to a lesser extent, amino acids. Three treatments were proposed: water, optimal tomato Hoagland solution and CT, which were axenically prepared. Tomato seeds were sterilized, germinated and then transferred to the considered treatments. Then, root growth parameters were measured and it was observed that CT promoted primary root length, as well as the number of lateral roots. Moreover, indolacetic acid, indol-3-butyric acid, zeatine, 6-benzyladenine and gibberellic acid concentrations were determined, but they were not detected in any case. Thus, other direct or indirect pathways seem to be involved in CT-mediated tomato root modulation.