Positive response of seedlings from an old-growth grassland to soil quality improvement

Stress tolerance is the predominant strategy among the plant species that colonize the Brazilian rupestrian grassland (Campo rupestre) and is a response to edaphic conditions involving specific morphological and physiological adaptations. Motivated by the need to increase the efficiency in the production of seedlings, we experimentally evaluated whether these plant species are naturally limited in terms of optimum development and if they could have their survival and growth increased when cultivated under enhanced nutrient and water conditions and reduced iron concentration. To experimentally test this hypothesis, we cultivated seedlings of nine plant species in six distinct substrates for 150 days. The percentage of seedling survival had great variation among species (ranging from 40 to 100% survival). Eight out of the nine studied species showed higher growth and higher biomass accumulation as well as greater investment in aerial parts when grown in nursery or organic substrate (up to 10 times greater than the control treatment). This study provides evidence that these species also present reversible adjustment to cope with the poor soil conditions and are able to improve their performance in more fertile soils. Thus, seedling production for the restoration of ironstone rupestrian grasslands can be more efficient.