Lead Nitrate in the Germination and Initial Development of Leucaena leucocephala and Peltophorum dubium

The objective of this study was to determine the influence of lead nitrate (Pb(NO3)2) on the germination and initial development of leucaena (Leucaena leucocephala) and canafístula (Peltophorum dubium). The experimental design was a randomized complete block design in a 2x6x4 factorial scheme [two forest species and six Pb(NO3)2 doses], with 4 replicates per treatment, totaling 48 sample units. Statistical analyzes were performed to analyse the variables: tukey test and regression at 5% probability. The experiment was carried out in August 2015, in the botany laboratory of the Pontifical Catholic University of Paraná (PUCPR), Toledo, Paraná, Brazil. The seeds were conditioned to germinate for 14 days in the presence of Pb(NO3)2 treatments in a germination chamber. At the end of 14 days were determined: total germination, chlorophyll content (a, b, total and chlorophyll a/b ratio), lead (Pb) contents in roots and leaves, as well as morphometric variables: shoot length, radicular and collecting diameter. L. leucocephalawas the species that obtained the highest germination index and higher contents of chlorophyll a, b and total. In the species of P. dubium it was found higher levels of lead in the leaves, in the root system and higher chlorophyll a/b ratio. It was concluded that the doses of Pb(NO3)2 influenced the germination of the initial development of L. leucocephala and P. dubium, L. leucocephala being the species that best tolerated the doses administered. Increasing doses of Pb(NO3)2 influenced germination rates and initial development of L. leucocephala and P. dubium at the end of 14 days after sowing. According to the morphometric evaluations and analysis of lead content in roots and leaves, P. dubium was the species that showed the highest sensitivity in the presence of the doses, indicating the higher resistance of L. leucocephala, affirming its use in recovery of contaminated areas.