Effect of herbicides and intercropping on weeds and yields of maize and the associated intercrops

摘要

Two field trials were conducted at the farm of the University of Agriculture Peshawar, Pakistan in 2014 and 2015, to investigate the effect of intercropping on maize, mungbean, cowpea and sesbania, in which maize was the main crop and the others were intercrops. A two factorial design was used. Factor A comprised of pendimethalin application as pre-emergence and no herbicide application. Factor B consisted of four mono-cropping treatments of Zea mays L. (maize), Vigna radiata (L.) R. Wilczek (mungbean), Sesbania sesban (L.) Merr. (sesbania), and Vigna unguiculata (L.) Walp. (cowpea), along with six intercropping treatments viz. 5 legumes rows and 6 maize rows in combinations i.e. mungbean+maize, cowpea+maize, sesbania+maize, and also 10 legume crops rows and 6 maize rows in combinations mungbean+maize, cowpea+maize, and sesbania+maize. The results indicated a significant influence of the years, the use of herbicide, the treatments of intercropping, and the interaction effect of the herbicide x intercropping on the yields of studied crops which meant that the differences among the observations were statistically significant. For the year effect, the mean yields were higher in 2014; while for the effect of herbicide use, the maize grain yield was higher in pendimethalin applied plots. Stating the effect of intercropping, mungbean grain yield was highest in plots of mungbean mono-cropping and lowest in mungbean: maize intercropping (sown in ratio of 5:6 rows). Cowpea and sesbania biomasses were significantly higher in herbicide plots and also in mono-cropping plots of cowpea and sesbania plots, respectively in 2014 and 2015. The values of the Land Equivalent Ratio (LER) were between 1.40 and 1.49 for all the intercropping treatments, with the highest LER calculated for sesbania-maize intercropping (10:6 rows). Therefore, the herbicide pendimethalin as pre-emergence @1.5 kg ha -1 in maize crop along with intercropping of any of the studied legume crops at the 1:1 row sowing ratio is the best combination for achieving desirable weed control, higher crop yields and greater LERs.