Abstract
In order to evaluate the impact of some herbicidal combinations on the physiological growth performance of maize-soybean and herbicidal phytotoxicity this work was undertaken. Therefore, two field experiments were conducted. including four broad-leaved herbicides combined with 3 narrow-leaved herbicides related to different groups differ in their mode of action applied pre- or post-emergence were tested on maize - soybean grown at 2:2 intercropping system. The results showed that all herbicidal combinations controlled broad-leaved weeds better than hand-hoeing at 45 and 75 days from sowing. Pendimethalin at 1.800 kg a.i. ha-1 proved to be the most compatible herbicide in combinations with other herbicides without any antagonistic effect on both crops. The photosynthetic pigments of maize leaves were not adversely affected by the herbicide combinations. However, it shows that an antagonistic effect occurred from the combinations including Metribuzin at 0.336, or Bentazon at 0.864 kg a.i. ha-1. The most severe reduction in chl. a of soybean leaves caused by Pendimethalin at 1.800 kg as pre-em. combined with foliar Bentazon at 0.864 kg a.i ha-1 a post-em. Higher LA or LAI due to better weed control was evident with herbicidal combinations. It was concluded that reducing competition from annual weeds and intercropped maize-soybean through various herbicidal combinations enhanced maize growth, enlarged leaf surface area and dry matter accumulation in leaves and total plants.