evaluation of the effect of planting pattern and weed control on the number of pods, and the number and dry weight of grains per plant in different cultivars of peanut (arachis hypogaea l.)

Introduction: the peanut (arachis hypogaea) is an important edible oil crop that plays a crucial role in strengthening global food and energy security, thereby contributing to sustainable development worldwide (wang et al., 2022). the peanut crop encounters a significant challenge due to the proliferation of various weeds near the plants, particularly during the early growth stages when seedlings emerge 7 to 10 days post-sowing. competing for sunlight, soil space, water, and nutrients, these weeds interfere with pegging and can reduce yields by up to 70% (jat et al., 2011). given the limited peanut cultivation area in the country, implementing agronomic practices such as optimal plant density and planting patterns is essential to enhance yield. in addition to density, the spatial distribution of plants per unit area is highly important, as proper distribution of solar energy and increased absorption can improve crop performance. to maximize sunlight efficiency, an even and sufficient leaf canopy covering the ground is required, achievable by adjusting plant distribution along planting rows (koochaki, 1997؛ haque and sakimin, 2022). based on the points mentioned, the aim of this experiment was to examine the effect of planting patterns and weed management on seed count, pod number, and dry seed weight of in two peanut cultivars under the weather conditions of kermanshah. materials and methods: the experiment was set up as a factorial within a randomized complete block design with three replications, conducted at the razi university research farm in kermanshah, iran, in 1400. the experimental factors were: (1) peanut cultivars, nc2 (north carolina 2) and nc7 (north carolina 7); (2) planting patterns—p1 (50 cm row spacing × 25 cm plant spacing) and p2 (75 cm row spacing × 18 cm plant spacing); and (3) various weed control methods as follows: m1, involving two rounds of hand weeding along with treflan (796 g/ha active ingredient), bentazon (960 g/ha active ingredient), and haloxyfop (75 g/ha active ingredient); m2, including two rounds of hand weeding with treflan (1233 g/ha active ingredient); m3, entailing two rounds of hand weeding with haloxyfop and bentazon; m4, consisting of complete hand weeding every two weeks throughout the growing season; and m5, a weed-infested control maintained throughout the season. at the end of the season, harvesting was done manually when the pods were ripe. from each plot, six plants were randomly selected from the middle of the plot after removing the border rows. the following characteristics were measured: number of seeds per plant, dry weight of seeds per plant, and number of pods per plant. to analyze the variance of the data, sas version 9.4 software was used. mean comparisons were performed using duncan s test at a 5% probability level. results and discussion: the comparison of mean data indicated that seed count per plant in the studied cultivars was influenced by both planting arrangement and weed control treatments. the highest seed count per plant in both cultivars was observed under the full weed control treatment combined with planting pattern p1 (row spacing of 50 × 25 cm). conversely, the lowest seed count per plant, regardless of cultivar type and planting pattern, was recorded in the weed-infested treatment (figure 1). these findings underscore the importance of weed control in boosting seed count and overall yield, as manual weeding can enhance plant performance by reducing competition for nutrients, water, and light. analysis of mean data (figure 2) demonstrated no significant differences among most weed control treatments regarding the impact of planting arrangement on dry seed weight per peanut plant, except in the m4 treatment (manual weeding). in this treatment, dry seed weight per plant increased by 64.80% under planting pattern p1 compared to p2 (figure 2). the closer proximity of plants in p1 minimized intraspecific competition and allowed for optimal use of space. with a row spacing of 75 cm, the increased space between rows appeared to make weeds more tolerable for peanut plants, which may have enhanced the effectiveness of manual weeding in p1. the cultivars exhibited varied responses to the different planting patterns. the highest dry seed weight per plant (22.64 g) in cultivar nc2 was achieved under planting pattern p1 (50 cm row × 25 cm plant spacing). in contrast, under p2 (75 cm row × 18 cm plant spacing), the highest dry seed weight per plant (22.64 g) was recorded in cultivar nc7 (figure 3). according to the mean data comparison (figure 4), the number of pods per plant in the cultivars varied based on planting arrangement and weed management. in cultivar nc2, the highest pod count per plant (53.5) was achieved with planting pattern p1 (50 cm row × 18 cm plant spacing) combined with manual weeding (figure 4). the response of cultivar nc7 differed, with the highest pod count per plant observed under chemical control treatment m2 (treflan alone) and planting pattern p1 (50 cm row × 25 cm plant spacing). overall, pod count per plant was higher in planting pattern p1 compared to p2 (figure 4). a study examining the effect of weed management on peanut growth characteristics demonstrated that all weed control treatments significantly enhanced growth and yield. manual weeding six weeks after sowing increased growth and yield in both peanut cultivars by raising the number of mature pods per plant, seed weight per plant, and 100-seed weight. this improvement may be attributed to positive effects on physiological parameters, such as leaf area index, dry matter accumulation, relative growth rate, net assimilation rate, and crop growth rate (olayinka and etejere, 2015). conclusion: the results indicated that weed control and the selection of an appropriate planting arrangement, particularly pattern p1 (50 × 25 cm spacing), had a positive effect on increasing seed count, pod number per plant, and dry seed weight in peanuts. the cultivar nc2 showed the highest pod count and dry seed weight under manual weeding and planting arrangement p1. these findings highlight the importance of optimizing the combination of weed management and planting arrangement to improve the performance of different peanut cultivars.