Variabilidade genética e sensibilidade de acessos de Pistia stratiotes ao herbicida glyphosate

Water lettuce (Pistia stratiotes) is one the most important macrophytes, classified as weed and causing serious problems in watercourses in Brazil. The aim of this research was to evaluate the genetic variability of water lettuce and its relationship with this plant's susceptibility to glyphosate. Plant samples were collected in 12 water bodies in different regions in Brazil (Americana-AMC, Cambaratiba-CBT, Curitiba-CRB, Itapura-ITP, Jaboticabal-JBT, Lagoa Santa-LST, Pirai-PRI, Rio Grande-RGD, Rubineia-RBN, Salto Grande-SGD, Santa Gertrudes-SGT and Tres Lagoas-TLG). The accesses were characterized by the use of RAPD markers (Random Amplified Polymorphic DNA), whose unspecific starters allowed the analysis of polymorphic loci, which evidenced the distribution of the accesses into two groups, with high genetic similarity inside the sub-groups, but with high genetic divergence between them. The use of the RAPD technique evidenced the existence of genetic differences between the accesses. Plants growing in plastic pots (5 L) were sprayed with glyphosate at the concentrations of 0.0, 0.6, 1.2, 1.8, 2.4 kg ha-1. Herbicide effects were evaluated on the 7th, 14th, and 21st days after application (DAA) with control note attributions (0% without control and 100% leading to the complete death of the plants). No correspondence was observed between the structure of the access groups by the grouping multi-varied analysis using the RAPD technique and water lettuce susceptibility to glyphosate.