عنوان مقاله [English]
Sweet corn (Zea mays L. var. saccharata) is an important crop, grown over 2,000 hectares in Iran. The consumption demand for sweet corn in its fresh form or as a processed crop has contributed to a significant increase in its cultivation in recent years. Sweet corn is susceptible to weed competition for nutrients, moisture, and light interception. Herbicides labeled for use on sweet corn are limited. Chemical control can be very important because of the low efficiency and cost effectiveness of mechanical or other methods of weed control. Hence, it is necessary to provide information about the sulfonylurea herbicides and suitable doses. Sulfonylureas such as nicosulfuron, rimsulfuron, and foramsulfuron are effective group of herbicides for annual and perennial weed control in maize. These herbicides provide a new chance for weed management in maize. Their mode of action occurs through inhibiting acetolactate synthase (ALS), thereby interfering with the production of branched-chain amino acids, leucine, isoleucine, and valine. The objectives of this experiment were to evaluate the effect of different doses of sulfonylurea herbicides on weeds control and growth and yield of sweet corn.
Materials and Methods
In order to evaluate the effect of different doses of sulfonylurea herbicides on weeds control and growth and yield of sweet corn (KSC403su), a field study carried out during 2015 growing seasons at the Agricultural College of Shiraz University. The experiment was conducted in a randomized complete block design with 4 replications. Treatments included different doses of nicosulfuron (1.5, 2 and 2.5 l ha-1), foramsulfuron + idosulfuron (1, 1.5 and 2 l ha-1) and acetochlor (4.5, 5 and 5.5 l ha-1) herbicides and weed free and weedy control. The number and dry weight of aboveground weeds parts were harvested within three fixed 1 × 1 m quadrats in every plot, separated by species, enumerated, oven-dried at 75 °C for 48 h, and then weighed. Then, percent weed density and dry weight reductions were measured. The traits included ear length, ear diameter, ear number per plant, row number per ear, grain number per row, grain number per ear and canned grain yield. Data were analyzed using SAS v. 9.1 software (SAS Institute 2003). When significant differences were observed among treatments, mean comparisons were made using Duncan's multiple range tests (P < 0.05). Correlation coefficients between different traits were also calculated.
Results and Discussion
Results showed that the canned grain yield, 1000 grain weight and number of grain per ear were reduced by weeds up to 73, 33 and 60%, respectively. The highest dry weights reduction obtained were of redroot pigweed (Amaranthus retroflexus) (75.8 and 59.5%), lambsquarters (Chenopodium album) (49.84 and 38.76%), barnyard grass (Echinochloa crus-galli) (58.37 and 40.85%) and bindweed (Convolvulus arvensis) (60.56 and 55.06%), so that applying of nicosulfuron )2.5 l ha-1) and foramsulfuron + idosulfuron (2 l ha-1) herbicides caused reduction in total dry weight of weeds in comparison with weedy treatment, and canned seed yield increased by nicosulfuron )2.5 l ha-1) and foramsulfuron + idosulfuron (2 l ha-1) herbicides in comparison to the acetochlor. Acetochlor was the weakest treatment in the reduction of weed density and dry weight. The highest canned grain yield (8.00 and 7.03 t ha-1), number of row per ear (12.00 and 11.50), number of grain per row (25.00 and 24.75), number of grain per ear (299.00 and 285.50) and 1000 grain weight (325.06 and 308.44 g) were obtained in nicosulfuron )2.5 l ha-1) and foramsulfuron + idosulfuron (2 l ha-1) herbicides, respectively. Positive correlation was found between canned grain yield and 1000 grain weight (r = 0.83, p<0.05) and number of grain per ear (r = 0.96, p<0.05). Applying nicosulfuron showed a high efficiency as compared to the foramsulfuron + idosulfuron and acetochlor for weed suppression.
It can conclude that nicosulfuron at 2.5 l ha-1 showed the best performance for weed control, especially broadleaved weeds and were associated with the maximum sweet corn canned grain yield. Therefore, due to the restricted use of herbicide in sweet corn, the herbicide used in this experiment is not created serious injury in sweet corn at the recommended rate while effectively controlling weeds. Hence, utilization of this herbicide could be a favorable option in contemporary weed control programs for local or regional sweet corn growers.
We would like to thank the School of Agriculture, Shiraz University for their support, cooperation, and assistance throughout this research.