Soil seed bank after the application of pre-emergent herbicides during four sugarcane harvests

The objective of this work was to evaluate the effect of the pre-emergent herbicides indaziflam, indaziflam+metribuzin, and diuron+hexazinone on the soil seed bank of a sugarcane crop, during four consecutive harvests. The experimental design was a randomized complete block with four replicates in a split plot. Treatments consisted of doses of the following herbicides: indaziflam, 75, 100, and 150 g a.i. ha(-1); indaziflam+metribuzin, 75 + 960 g a.i. ha(-1); and diuron+hexazinone, 936 + 264 g a.i. ha(-1); besides a clean area, used as a reference. The soil seed bank was analyzed in the 0.00-0.10 and 0.10-0.20-m soil layers. Emerged seedlings were counted and identified, and absolute and relative density, frequency and abundance, as well as the importance value index, were calculated. In the treatments 100 and 150 g a.i. ha(-1) indaziflam, there was a greater reduction in the total seed bank and in the importance value index of species of Poaceae and Asteraceae. The total seed bank, in the 0.10-0.20-m layer, and that of the species Portulaca oleracea, in both evaluated layers, are not affected by the herbicides. The use of pre-emergent herbicides during four consecutive harvests decreases the soil seed bank in the 0.00-0.10-m layer under a sugarcane crop.