From Petri dish to field: testing Greek lentil accessions for imazamox tolerance

This work aimed to study the intrinsic tolerance of Greek lentil accessions to imazamoxherbicide by combining bioassays, pot and field experiments. Initially, 31 genotypes wereevaluated in Petri dish bioassays for their tolerance to six concentrations of imazamox. Theaverage root length of 10 lentil seedlings/dish at seven days after herbicide application was usedfor non-linear regression analysis and the GR50 values (the amount of the herbicide required for50% root length reduction of the seedlings) were estimated to calculate the resistance ratio (R/S)of each cultivar. The results of the in vitro test clued the selection of nine accessions for furtherstudy in pot experiment, to assess their tolerance to four rates [0 (control), 20, 30, 40 g ai ha-1]of imazamox post-emergently applied at the seven true-leaf stage (V7 stage). Five weeks aftertreatment, the number of survived plants was recorded and the above-ground dry weight wasdetermined in each pot. There was no direct correlation in the results of in vitro test and the potexperiment, suggesting no matching between the two methods. The evaluation of fiveaccessions (cultivars with high commercial interest and accessions sporting tolerance in potexperiment) in field experiment demonstrated different but increased susceptibility toimazamox. Specifically, compared to the untreated control, the imazamox treatments reducedplant growth, delayed flowering and maturity and reduced yield, dry weight, 1000-seed weightand harvest index. Yet the protein concentration was increased in herbicide treatments. Thefindings of the study showed clearly that the evaluated lentil accessions lack genes withresistance to imazamox and different methods have to be used for assessing any potentialtolerance.