عنوان مقاله [English]
Lentil is the second most important of legume crops in Iran and is mostly cultivated in the rainfed conditions. Weed competition is a major limitation to lentil production worldwide due to its slow early growth rate, short height, and lack of protective canopy development. Since the level of competition between weeds and crops is highly dependent on nutrient availability, proper nutrient management is considered as a method of weed management. Various aspects of nutrient management such as fertilizer type, application time, amount of application, and form of fertilizer can also change weed interference conditions with crop. It is believed that the application of biofertilizers, while providing environmental security and economic benefits, is a sustainable and beneficial method of plant nutrition and reducing the adverse effects of weeds. In Iran, two herbicides registered for lentil including pendimethalin and promethrin, that both of which are pre-emergence. Applying a single management method alone, in addition weed adaptation, leads to agroecosystem instability. Integrated weed management can increase the efficiency of management methods and also contribute to the sustainability of farming systems. This study was conducted to compare the effects of biological and chemical fertilizers in combination with chemical and mechanical weeding to improve crop yield and management of weeds in lentil farms.
Materials and Methods
The experiment was conducted as factorial based on randomized complete block design with three replications at Research Farm of Ferdowsi University of Mashhad, Iran. Investigated factors included five levels of plant nutrition (inoculation of lentil seeds with phosphorus-releasing bacteria (Phosphorobacter), inoculation of lentil seeds with potassium-releasing bacteria (Potapowerobacter), inoculation of lentil seeds with mycorrhizal fungi, inoculation of lentil seeds with a mixture of Phosphoraverbacter, Potapaverbacter and Mycorrhizal fungi, and application of chemical fertilizers based on soil test results without inoculation with biological fertilizers) and three weed control methods (weeding twice before flowering and pod filling lentil stage, respectively, weed control with pendimethalin as pre-emergence herbicide, and weed control with pyridate as post-emergence herbicide). Lentils were planted at 100 plants m-2 density. Biological fertilizers were sprayed on lentil seeds in lab, before planting. Chemical fertilizer (mixture of potassium sulfate and urea) was distributed at the rate of 50 kg ha-1 in the plots after sowing. Pentimethalin and pyridate were applied with a dose of 3.7 and 1.2 L ha-1, respectively, in 3-4 leaf stage of weeds. Weed sampling was done in three lentil growth stages (flowering, pod filling, and crop harvest) from 0.5 m-2. Matured crops were harvested from 1 m-2 and placed in lab for 48 hours to be dried for biomass and seed yield measurements.
Results and Discussion
The results showed that despite significant weed control, the application of pyridate damaged lentil crop and reduced biomass and seed yield. Pendimethalin resulted in the highest lentil biomass and seed yield and no damage to lentil crop. Among the fertilizers, chemical fertilizer increased weed density and biomass, also increased lentil biomass and seed yield. Among the biofertilizers, Petapowerbacter (potassium fertilizer) showed that the highest yield of lentil (730.8 g m-2), and the biofertilizer mixture resulted in a decrease the yield and biomass of lentil compared to the other fertilizers. Due to the interactions between the control methods and the fertilizers, the highest biomass (800 g m-2) and seed (164 g m-2) yield were obtained in the integration of potassium biofertilizer with pendimethalin.
According to the results of the experiment, application of chemical fertilizer resulted in the highest crop yield and also increased weed density and biomass compared to biofertilizers. Among the biofertilizers, Petapowerbacter, which contains potassium-stabilizing bacteria in the soil, had the best effect on crop yield. However the effects of biofertilizers on weed traits, the lowest density and biomass of weeds were related to mycorrhizal treatment and the other treatments were not significantly different. Among the weed control methods, pendimethalin had the greatest effect on improving crop yield. Although pyridate weed control was better, but caused damage to the crop and yield was decreased. Therefore, according to the results this experiment, we recommend the use of pendimethalin in combination with Petapowerbacter in integrated weed management of lentil.
Zand, E., Baghestani, M.A., Nezamabadi, N., Shimi, P., and Mousavi, S.K. 2017. A Guide Chemical Control of Weed in Iran. Jahad Daneshgahi Mashhad Press. 223 Pp. (In Persian).