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One of the main problems in autumn chickpea cultivation is the high density of weeds, which causes a severe reduction in the yield of rainfed chickpeas. The aim of this experiment is to evaluate new pre-emergence and post-emergence herbicides for the control of broadleaf weeds in rainfed chickpea and to study the residual effects of herbicides on rainfed wheat cultivation in crop rotation. This experiment was carried out during the 2021–2023 cropping years in the provinces of Kermanshah, Kurdistan, and East Azerbaijan. The experiment included 11 treatments in 4 replications within a randomized complete block design. The herbicide treatments, applied at commercial rates, included: Application of the following herbicide treatments: flumioxazin (Clean Sheet, 50% WP) at 100 g/ha as pre-emergence, oxyfluorfen (Gol, 24% EC) at 0.7 L/ha as pre-emergence, sulfentrazone (Spartan, 50% WP) at 200 g/ha as pre-emergence, aclonifen (Noagap, 600 SC) at 2 and 3 L/ha as pre-emergence, aclonifen (Noagap, 600 SC) at 0.5, 0.7, and 1 L/ha as post-emergence, flumioxazin at 100 g/ha as pre-emergence + Aclonifen at 0.5 L/ha as post-emergence, flumioxazin (Clean Sheet, 50% WP) at 100 g/ha as pre-emergence and Aclonifen at 0.7 L/ha as post-emergence, Flumioxazin at 100 g/ha as early post-emergence at the cotyledon to 2-leaf stage of weeds, and a hand-weeded control. Thirty days after the post-emergence spraying, the density and dry weight of weeds in each plot were measured and compared with the control. At harvest time, grain yield, chickpea plant height, and chickpea biomass per unit area were measured.
Results showed at Kermanshah, the highest weed control was achieved with the combined pre-emergence flumioxazin and post-emergence aclonifen at 0.5 + 100 (93%) and 0.75 + 100 (96%). At Kurdistan, the same combinations resulted in 71% and 78% weed control, respectively. Additionally, pre-emergence flumioxazin (85%), pre-emergence aclonifen at 3 l/ha (70.5%), and oxyfluorfen (71%) were also effective. At East Azerbaijan, the most effective treatments were the combined flumioxazin pre-emergence and aclonifen post-emergence at 0.5 + 100 (71%) and 0.75 + 100 (88%), early post-emergence flumioxazin (78%), post-emergence aclonifen at 1 l/ha (68%), pre-emergence flumioxazin (66%), and post-emergence aclonifen at 0.7 l/ha (67%). At Kermanshah, the highest chickpea grain yields were observed in the hand-weeded control and in treatments including flumioxazin pre-emergence and aclonifen post-emergence (0.7 + 100), flumioxazin pre-emergence, oxyfluorfen, and aclonifen pre-emergence at 2 and 3 l/ha, with yields of 1519, 1388, 1344, 1387.5, 1409, and 1345 kg/ha respectively. At Kurdistan, the highest yields were in the hand-weeded control (1464 kg/ha) and the flumioxazin pre-emergence + aclonifen post-emergence (0.5 + 100) treatment (1293 kg/ha). At East Azerbaijan, the best yields were seen in the hand-weeded control, flumioxazin pre-emergence and aclonifen post-emergence (0.7 + 100), flumioxazin pre-emergence, and aclonifen applied pre-emergence at 2 l/ha and post-emergence at 0.7 l/ha, with yields of 1040.5, 799, 869, 808, and 979 kg/ha respectively. The results indicated that the combined application of pre-emergence flumioxazin (applied after chickpea sowing but prior to the emergence of chickpea and weeds) and post-emergence aclonifen (applied after chickpea emergence, at the 2–4 leaf stage of broadleaf weeds) at rates of 100 g ha⁻¹ flumioxazin + 0.5 L ha⁻¹ aclonifen provided broader-spectrum control of broadleaf weeds. The efficacy was attributed to the complementary action of flumioxazin in controlling winter annual weeds (Galium tricornutum, Centaurea balsmita, Conringia orientalis, Lamium amplexicaule) and aclonifen in controlling spring annual weeds (Cichorium intybus, Anthmis cotula(. Compared to the application of each herbicide alone, this combination resulted in more effective weed suppression and increased crop yield. This strategy is particularly recommended for fields with high densities of spring-emerging weeds.
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