Introduction: Pea cultivation is vital to the agricultural systems of the Mediterranean region. In addition to providing important nutrition for both humans and livestock, peas help maintain soil fertility, especially in arid areas worldwide. Weeds pose a significant challenge to agriculture because they compete with crops for essential resources like water, nutrients, light, and space. In developing countries, grass interference greatly reduces crop yields, leading to substantial losses. The herbicide Imazethapyr can be used either as a pre-sowing soil treatment or both before and after legume emergence to effectively control this problem. In Iran, which is characterized by arid and semi-arid climates with limited rainfall, careful planning and strategic resource management are crucial to minimize production losses during dry periods. To address these challenges, improving seed germination and early seedling establishment while optimizing soil moisture use is essential. Seed priming is an effective technique that enhances germination rates, ensures uniform emergence, supports seedling growth, and promotes key developmental stages such as vegetative growth, flowering, seed filling, and tillering in various crops.
Materials and Methods: A field experiment was conducted from 2014 to 2015 to examine the effects of chickpea seed priming and imazetapyr herbicide on weed control, yield, and its components in chickpeas, arranged factorially within a randomized complete block design with three replications. The main factor was seed priming (primed and non-primed), while the secondary factor involved applying imazetapyr herbicide at doses of 250, 500, 750, and 1000 cc, combined with two weeding treatments. Each plot measured 3 × 8 meters, with row spacing of 60 cm and a planting density of 45 seeds per square meter. To assess weed density and relative abundance across the entire field, each plot was split lengthwise into two sections: the upper section, serving as an unsprayed control, and the lower section, which received the treatment. Weed density and relative abundance were evaluated by placing two 5 cm × 5 cm squares in the unsprayed part of each plot. Spraying was done with a MATABI model backpack sprayer fitted with a calibrated nozzle, applying 300 liters of water per hectare. Pre-planting herbicides were incorporated into the soil using a sander, and pre-emergent treatments were applied immediately after planting Arman chickpeas. Weed density and dry weight were measured fifteen and thirty days after the last spraying by sampling from two 0.5 × 0.5-meter boxes in each plot. The data were analyzed using SAS (9.1) software via analysis of variance. Means were compared using Duncan's multiple range test at a significance level of 5%.
Results and Discussion: The highest herbicide efficacy at 15 days after spraying (DAS) on weed dry weight (67.14%) and weed density (71.37%) was related to treatments (Imazethapyr 1000 cc + non-priming and Imazethapyr 250 cc non-priming). In addition, the highest herbicide efficacy at 30 DAS on weed dry weight (87.37%) and weed density (91.8%) belonged to treatments (Imazethapyr 500 cc + priming and Imazethapyr 750 cc + non-priming). The results indicated that the tallest (27.5 cm) and the shortest (12.9 cm) chickpea plant height were associated with the priming + weeding and non-priming +1000 cc herbicide treatments, respectively. The highest yield (873 kg. ha^-1) and 100-seed weight (26.8 g) were attributed to the weeding priming treatment. In this experiment, Imazethapyr effectively controlled weeds; however, its adverse effects caused slow growth, severe phytotoxicity, and a reduction in chickpea seed yield. Therefore, it is recommended not to use this herbicide under rainfed conditions.
Conclusion: Studies have shown that the use of the herbicide imazethapyr is highly effective in controlling weeds in chickpea fields. Specifically, increasing the concentration of this herbicide leads to a significant reduction in weed density, especially 15 and 30 days after spraying. One of the notable findings of this research was the positive effect of seed priming combined with the application of 1000 cc of imazethapyr. This combination resulted in a 94% reduction of annual weeds. In terms of yield, the treatment of seed priming along with hand weeding produced the best results in seed production, and the highest 100-seed weight was also observed in this treatment. This indicates that hand weeding, as a complementary method, can help improve chickpea yield. However, the use of high doses of imazethapyr alone, due to phytotoxic effects, caused a decrease in yield and yield components of chickpea. Therefore, it is recommended to use a dose of 500 cc per hectare as the optimal dose for this herbicide.