Dose-Response Study to Evaluate Dicamba Tolerance in Selected Wild Tomato Germplasm

Abstract

A greenhouse dose-response study was conducted to determine the tolerance of three wild tomato accessions (TOM199, TOM198, TOM300) in comparison to a commercial cultivar (Better Boy) against the dicamba application at five rates (0, 70, 140, 210, and 280 g ae ha-1) at 14 and 28 days after treatment (DAT). Several physiological traits were evaluated at 0, 1, 3, 5, and 7 DAT. Wild accessions and cultivar were killed at all rates above 70 g ae ha-1 at 14 and 28 DAT, which is why differences between accessions and cultivar were only evident at 70 g ae ha-1. The GR50 (the herbicide rate that causes 50% reduction in dry weight) of Better Boy was 4.4 g ae ha-1 at 28 DAT, and this cultivar was approximately 11-fold more sensitive than wild accessions. At 7 DAT, the levels of H2O2 for wild accessions were lower than Better Boy up to 5 at 70 g ae ha-1 of dicamba. Furthermore, wild accessions showed lower herbicide absorption than Better Boy at all dicamba doses at 1, 3, and 7 DAT. All the three wild accessions expressed tolerance to the dicamba application at the dose of 70 g ae ha-1. At the same time, Better Boy and wild accessions were susceptible to dicamba application at rates of 140, 210, and 280 g ae ha-1.