Introduction: Determining the appropriate timing for weed control is one of the important objectives in integrated weed management systems. This is one of the main topics in research related to crop plants. The critical period of weed control is an example of achieving such goals, known as the weed-crop competitive period. Because during this period, the maximum interference of weeds with crop plants does not necessarily occur, but it is considered the best time for weed control. Sugar beet, a plant with low competitive ability during the emergence growth stage (low initial growth rate during the emergence phase until thinning), weak growth potential, and a relatively long period from emergence to full leaf development, is well known. Therefore, the long-term presence of weeds due to the low height of sugar beet will seriously reduce yield.
Materials and methods: The experiment was conducted in the agricultural research farm of West Azerbaijan in 2019 in a randomized complete block design with four replications in two groups: weed control and weed interference treatments, where control and weed interference treatments were conducted 14, 28, 42, 56, 70, 84, and 175 days after emergence. The data were analyzed using the GLM procedure, and mean comparisons were also performed using the least significant difference method in the SAS software.
Results: The results showed that the highest sugar percentage, extractable sugar content, molasses sugar, extractable sugar yield, and extraction coefficient were obtained in complete control and interference treatments up to 14 days, and the lowest values of these traits were obtained in control treatments up to 14 days after emergence. While the maximum gross sugar yield was in the 28-day interference treatment and the minimum was in the control treatment up to 14 days. The results also showed that the highest percentage of nitrogen and sodium was in the 14 and 28-day interference treatments, and the lowest nitrogen percentage was in the 70 and 84-day control treatments. According to the Gompertz and logistic models for the effect of weeds on extractable sugar yield, non-pure sugar yield, and root yield, the effect of weeds is significant within 7 and 15 percent defined time intervals.
Conclusion: In general, the results indicated that the effect of interference and control periods on most of the studied traits was significant. In such a way that increasing the interference period had reducing effects, while increasing the control periods had increasing effects on the studied traits. |
