عنوان مقاله [English]
Weeds are one of the most important factors in reducing crop yield. Excessive use of herbicides for weed control because of the environmental pollution and ecological damaging effects does not have the necessary sustainability. One of the strategies to reduce the herbicides use in agriculture is use of intercropping systems with cover crops. Additive intercropping of different crop together through create an intense competition micro-ecosystem, provided the conditions that weeds damage would be minimized in these situations. This study was conducted to evaluate the quantitative usefulness of sweet corn-mungbean intercropping and its effect on weed control.
Materials and Methods:
The experiment was conducted as factorial base on randomized complete block design with three replications. The first factor consisted of 6 levels of different cultivation systems (sweet corn and mungbean monoculture, intercropping of 20, 40, 60 and 80 percent of net density mungbeans with sweet corn) and the second factor was two levels of control and lack of weed control. Each plot had a length of 6 meters, including 4 rows by 60 cm distance. In monocultures, sweet corn (8.3 plant m-2 density) with 20 cm plant spacing and mungbean (8.23 plantm-2 density) with 7 cm plant spacing were planted. In intercropping treatments also sweet corn and mungbean were planted on both sides of the heap that plant spacing for sweet corn was 20 cm and for mungbean base on additive intercropping treatment were 8.7, 11.6, 17.5 and 35.8 cm respectively for creation of 80, 60, 40 and 20 percent of mungbean optimal density.
Results and Discussion:
Weed competition reduced 1000 seed weight, seed number per row and canned grain yield of sweet corn by 13.8, 24 and 42.6 percent respectively. The highest (301.7 g) and lowest (281.8 g) of 1000 seed weight of sweet corn were related to intercropping of 20 and 80% optimal mungbean density with sweet corn, respectively. The highest (24.3) and lowest (20.6) of seed number per row of sweet corn were obtained respectively in intercropping of 40 and 80% optimal mungbean density with sweet corn. Compared to monoculture treatment the only intercropping treatments of 40 and 60% mungbean + sweet corn increased the canned grain yield of sweet corn significantly.
Weeds competition and cultivation system had significant effect on 1000 seed weight, pod number per plant, seed number per pod, grain yield, biological yield and harvest index of mungbean. Treatments of 60% mungbean + sweet corn intercropping and mungbean monoculture had the highest (40.8 g) and lowest (37.7 g) 1000 seed weight of mungbean respectively. Intercropping of sweet corn + 20, 40 and 60% mungbean treatments increased number of pods per mungbean plant compared to pure culture significantly. In all of the intercropping treatments relative to mungbean monoculture the seed number per pod was increased. In the absence of weeds, intercropping of sweet corn + 80% mungbean and in the presence of weeds, intercropping of sweet corn + 60% and 80% mungbean had the similar mungbean grain yield (no significant difference) with the mungbean monoculture. Weed competition decreased the 1000 seed weight, pods number per plant and seed number per pod of mungbean about 13, 27 and 15 percent respectively. The highest weed dry weight (802.4 gr m-2) was observed in the pure culture of mungbean without non-significant differences with the sweet corn monoculture.
The lowest weed dry weight (465.9 gr m-2) was observed in the intercropping treatment of sweet corn + 40% mungbean without non-significant differences with other intercropping treatments.
In all of the intercropping treatments the land equivalent ratio was greater than one (LER≥1) and ranged from 1.41to 1.89.
Based on the results of this experiment, additive intercropping sweet corn and mungbean in all of additive mungbean levels had the higher usefulness than monoculture of these species and in all of the intercropping treatments land equivalent ratio was more than one (LER≥1). The best additive intercropping treatment was sweet corn + 40% mungbean.