Response of LACTUCA SATIVA L. 'baba de verao' exposed to different substrates for laboratory bioassays

Plant bioassays are used to evaluate the biological effect of biotic and abiotic agents and its substrate must be carefully chosen. The objective of this study was to elucidate the effects of four different substrates (filter paper, agar, vermiculite and organic substrate) on the germination and initial growth of Lactuca sativa L. 'Babá de verão'; 30 seeds were used for each treatment, with 3 replicates. After 7 days, the following parameters were evaluated: germination (%G) and emergence (%E) percentages, Germination (GSI) and Emergence (ESI) Speed Index, number of seedlings (NS), fresh biomass (FB), root length (RL) and shoot length (SL). Filter paper and agar were equally satisfactory for %G, GSI and NS; the same was observed for vermiculite and the organic substrate concerning %E, ESI and NS. The parameters FB, RL and SL were higher in the seedlings submitted to vermiculite and lower in the seedlings submitted to filter paper. It is concluded that vermiculite yielded the greatest seedling growth among the tested substrates; however, it does not allow the evaluation of germinative parameters, only emergence. In cases where it is essential to analyze germination parameters and evaluate seedling growth, agar is the most suitable substrate. (author)