Physiological unbalances caused by micronutrient excess or deficiency are frequent in plants grown in soilless substrates and there exist no adequate routine method of analysis to assess micronutrient availability in the substrates. Therefore, the efficacy of water extracts (1:1.5 and saturation extract) and DTPA/CaCl2 extract was evaluated to assess micronutrient availability to Eruca sativa L. (arugula) grown in soilless substrates. The experiment was carried out in a greenhouse at Campinas, São Paulo State, Brazil, in a completely randomized design, arranged in a 3x4 factorial, with five replications. The treatments consisted of three substrate types (pinus bark, coir and peat) and four micronutrient concentrations. Substrates were saturated and incubated with nutrient solutions until electrical conductivity became constant. After that, each treated substrate sample was subdivided: one part for chemical analysis and the other to grow arugula plants during 45 days. On the overall, the tested methods were all inefficient to assess Cu, Fe, Mn and Zn availability to arugula. On the other hand, there was a positive correlation between leaf B concentration and B concentration in the different extracts (r>0.98**), independently of the substrate used. The best results were obtained with the saturation extract, but all methods can be used in routine analysis to assess B availability to plants of arugula.
Eruca sativa; substrates; pinus bark; coconut fiber; peat; water extracts; DTPA/CaCl2 method; saturation extract
