Response of mutant sorghum (Sorghum bicolor L. Moench) lines to nicosulfuron herbicide

LOMBARDO, L.; BRECCIA G.; GHIONE, C.; FERRANDO ADÍN I.; NESTARES, G.

Córdoba

Simposio; 1st Plant Breeding Symposium; 2021

INTA

OBJECTIVESThe objective of this work was to evaluate the response of mutant sorghum lines to nicosulfuron herbicide through a soil-less bioassay.MATERIALS AND METHODSThe wild-type variety Puka INTA and four resistant candidate M5 lines (M299, M213, M143 and M70), preselected from a field assay, were evaluated. Seeds were sown on plastic pots (55 cm3) filled with a mixture of sand and perlite (2:1). The pots were placed in plastic trays (6 pots by tray) and watered by capillarity with water and different nicosulfuron concentrations (0, 0.1, 0.32, 1, 3.2, and 10 μM). Pots were incubated for 7 days at 25 ± 2 ºC with a 16h photoperiod. The experimental design was randomized with three replications and each replication consisted of 20 plants. After the incubation period, shoots and roots were photographed with a digital camera. Shoot length (SL), shoot green area (SGA), primary root length (PRL) and the longest lateral root length (LRL) were measured from digital images using ImageJ, Easy Leaf Area and RootNav software. Data were analyzed by nonlinear regression, using the package drc within R software. Dose-response curves were adjusted to a log-logistic model of three or four parameters. Comparisons between lines in terms of GR50 values (herbicide dose that inhibited plant response by 50%) were carried out by using approximate t-tests (compParm function of the package drc).RESULTSVariability for herbicide concentrations required to reduce shoot and root growth by 50% (GR50) between lines were observed (Table 1). The M213 line showed the highest estimates of GR50 for SL, SGA and LRL. The resistance factor (RF) of the mutant line M213 was >3.5 for these variables. The M70 line showed the highest GR50 value for LPL.CONCLUSIONSThe bioassay described in this work is a rapid, simple and cost-effective method for screening and characterizing herbicide resistance in putative genotypes. A differential sensitivity to nicosulfuron herbicide was found among the evaluated mutant lines. The highest resistance performance was observed for the M213 mutant line.