Desenvolvimento, anatomia e nutrição de Mimosa acutistipula var. ferrea, Solanum crinitum e Zea mays sob doses de ferro

Abstract

The exploitation of natural resources is increasing due to the growth and development of the world population. The mining activity causes, directly or indirectly, environmental impacts, occurring in most cases the suppression of native vegetation, which is still little studied. In general, these plants are found in environments with high levels of Fe in the soil. Due to lack of studies with native species, this work has the objective of analyzing the effect of Fe doses on two species that are present in the flora on the ferruginous canga, Mimosa acutistipula var. ferrea and Solanum crinitum, and to compare with a Zeamays (maize) agricultural species, aiming the viability of the plants for vegetation again and to analyze how the development will be towards a genetically improved species to absorb, grow and produce in the high avail ability of nutrients. In order to carry out this work, two different types of soil, Latosol (with low Fe content) and canga soil (with high Fe content) we used, from a completely randomized experimental design, consisting of seven treatments with three replicates. The applied Fe doses were, 0, 50, 100, 200, 400 and 800 mg kg and natural ferruginous canga soil as additional control. The evaluation of the germination in the pots was carried out for forty five days for the native canga species and twenty days for the maize. After one hundred and twenty days of cultivation for Mimosa acutistipula var. ferrea and Solanum crinitum and sixty days for maize, the evaluation of plant eight, root size and stem thick ness of the plants was carried out. The plant parts were taken to the laboratory, the anatomical alterations were verified, the histochemical test for the identification of the Fe and, afterwards, the macro and micro nutrients contents in the shoot and roots were quantified. The results showed that M. acutistipula var. ferrea develop dup to the dose of 200 mg kg, Solanum crinitum developed until the dose of 400 mg kg, while the maize developed in all doses of Fe applied. The study showed that Fe influenced the germination and development of the plants, because the increase in Fe doses, the lowest was the germination and development index of the plants. There was also an effect of Fe doses on the anatomy of leaves and roots, with thickening of the epidermis and mesophyll in the intermediary doses and reduction of these tissues in the higher doses of Fe. This result was observed mainly for the diameter of the roots. Fe also influenced the nutrient contents, in the leaves and roots, however, varying the contents depending on the species. The three species cultivated in canga soil presented low development, which may be related to the low availability of nutrients. The results showed that the plants cultivated at the lowest Fe doses presented higher development than the plants cultivated at the higher doses, this may be due to the fact that the Fe, although be an essential element for the plants, at the higher doses it became toxic causing nutrition, physiological and anatomical changes.