In the plant community of chickpeas under the conditions of Bila Tserkva Research Breeding Station NAAS of Ukraine, 15 weed species belonging to 7 botanical families have been identified. In the structure of weed infestation, the dominant were monocotyledonous species (66.2 to 77.8 %) represented by Setaria glauca L. and Echinochloa crus-galli. The highest seed productivity (seeds per plant) was formed by Chenopodium album (24 400), Solanum nigrum (21 300), Persicaria maculosa (6 300), and Polygonum convolvulus L. (8 700).
In chickpea sowings, weeds formed an average of 1575.2 g/m2 of green mass, which is 603.4 g/m2 of dry matter. In the structure of weed biomass accumulation, the leading species was Setaria glauca L., which was quite natural, because it was the most abundant weed species in the experiment. The other species were less numerous. Among them, however, Amaranthus retroflexus L., Chenopodium album, Galium aparine, Solanum nigrum, and Echinochloa crus-galli intensively formed the aboveground biomass. In fact, they ensured the formation of the bulk of weed biomass in the sowings.
The average nutrient removal by weeds per hectare made up 60.5 kg of nitrogen, 41.7 kg of phosphorus, and 69.5 kg of potassium. This significantly exceeds the recommended application rates of mineral fertilizers for chickpea. As a result, a depletion of the plough layer was observed.
Of the studied weed control formulation, herbicide Fabian WG at the application rate of 0.1 kg/ha demonstrated the highest efficiency in the experiment (90.1 %). It combines two active substances, imazethapyr (450 g/kg) and chlorimuron-ethyl (150 g/kg), and effectively controls both annual grass weeds (92.4–95.1 %) and dicotyledonous weeds (82.4–94.0 %) in chickpea sowings. The most effective was the use of this herbicide against Chenopodium album (94.0 %), Galium aparine (89.7 %), Amaranthus retroflexus (86.1 %), and Persicaria maculosa (83.5 %).
Application of herbicides Pivot WS (0.5–0.7 l/ha) and Fabian WG (0.1 kg/ha) allowed to effectively limit the intensity of growth processes in weed plants and, as a result, reduce the amount of biomass accumulation by 4.6 times, to 349.0 and 250.0 g/m2, respectively. Fabian was more effective against grass weeds, decreasing their biomass by 4.3 times to 120.0 g/m2, while against dicotyledonous it was less effective, to 130.0 g/m2. Application of Pivot contributed to the effective reduction of weed biomass, especially in dicotyledonous weed species, up to 219.7 g/m2 compared to the control treatment (without weeds). In the case of the herbicide Racer EC (2.0 l/ha) in chickpea sowings, 115.3 g/m2 of monocotyledonous weeds biomass and 220.7 g/m2 of dicotyledonous weed biomass was formed, which was 5.2 and 4.9 times less than in the control treatment.
In the case of weed control in sowings carried our 15 days following the emergence, the number of weeds was 37.8 plants/m2, green biomass 127.0 g/m2, dry matter of weeds 49.1 g/m2. In the treatment where weeds grew in chickpea sowings for 60 days, the parameters of weed infestation were close to those of control treatment. The number of weeds was 89.8 plants/m2, green and dry biomass were 1453.4 and 561.9 g/m2, respectively.
The presence of weeds in sowings significantly affected the formation of chickpea productivity. Even in the treatment where the weeds were destroyed on the 15th day after the crop emergence, the yield of chickpea seeds decreased by 25.2 % compared to the control treatment. Further delay in the application of control measures leads to even more significant crop losses ranging from 41.9 to 62.3 %.
In conclusion, under the conditions of chernozem soil of the Right-Bank Forest-Steppe of Ukraine, the highest biological productivity of chickpea can be obtained at the seeding rate of 600 000 seeds per hectare with the application of herbicides Fabian WG (0.1 kg/ha) and Bazagran WS (2.5 l/ha).
The production costs of chickpea did not exceed 10 000–11 000 UAH/t, which made it possible to obtain a net profit of 15180 UAH/t in the control treatment), 12820 UAH/t in the treatment with Fabian, 10579 UAH/t in the treatment with Bazagran and 10099 UAH/t with Racer. The profitability ranged from 67 to 130 %. Its maximum value was obtained in the treatment with Fabian (0.1 kg/ha).
Keywords: chickpea, weeds, seed productivity, weed infestation structure, herbicides, efficiency, economic efficiency.
