Priming de sementes de Handroanthus heptaphyllus para cultivo em rejeito de mineração de ferro

Abstract

Iron mining is one of the most profitable sectors in the trade balance. However, it causes impacts by removing soil and vegetation cover and contamination of the area, for example, Fe, Mn, Cr, Cd, Pb, Zn, Ni, and Cu. Due to degradation from this activity, reforestation techniques with native tree species, such as Handroanthus heptaphyllus (Ipê-rosa) are important. Seed priming is a low-cost pre-sowing treatment used to improve germination and seedling establishment performance under adverse environmental conditions. Signaling molecules such as priming, such as NO (nitric oxide) and H2O2 (hydrogen peroxide), act on plant growth and development and alleviate the negative influence of abiotic stress by heavy metals. Thus, this work aimed to investigate whether seeds treated with priming in solutions containing NO and H2O2 and their combination would improve the anticipation of germination and the establishment of seedlings in iron mining tailings, to be used in future in recovery techniques. Priming treatments were applied to H. heptaphyllus seeds with the conditions: H2O, 200μM NO, 100μM H2O2 as well as the combination 200μM NO+100μM H2O2. After application, the seeds were cultivated in red oxisol or tailings from an iron mining company from the rupture of the Brumadinho-MG, Brazil, dam in 2019. The results showed that the priming treatments on seeds in ipe-rosa did not affect anticipating the germination when compared to controls on the two substrates, nor oxidative damage, nor changes in the content of the reserves. However, the type of priming showed an effect on Ipê-rosa seedlings. The NO conditioning showed higher Fe and Mn absorption in the tailings, increased the activities of the enzymes of the antioxidant system, while the H2O2 conditioning led to lower absorption of these elements, and both conditioning agents did not damage the photosynthetic apparatus. It can be concluded that NO and H2O2 induced different resistance mechanisms to Fe and Mn in Ipê-rosa seedlings. More in-depth studies with this species can be used for different aspects of the application of priming with NO, which could be used for phytoremediation techniques; and priming with H2O2 can be used for reforestation techniques in impacted areas.