Introduction
Garlic (Allium sativum L.) as one of the medicinal plants has an important role in human health. Weeds control is very important to achieve optimal yield in agro-ecosystems. The competitive ability relationship between plant and weeds is determined by the species' biological traits and environmental conditions such as space, light, water, and nutrient availabilities. Fertilizers play a significant role in the competition between crops and weeds in agriculture. Responses of weeds and crops to fertilizer application could be different, but many weeds tend to respond better than crop species to the high availability of nutrients. Also, the kind of fertilizer (chemical and organic) can affect crop-weed competition. Therefore, the purpose of this research was to evaluate interference and weeds control periods in the application of chemical and organic fertilizers on the yield and yield components of garlic in Ramhormoz climate.
 
Materials and Methods
A factorial experiment based on randomized complete block design (RCBD) with three replications was carried out in Ramhormoz during 2019—2020 growing season. The first factor included nutritional management (chemical and organic) and the second factor included 12 treatments of interference and control period of weeds (0, 20, 40, 60, 80, 120 and 160 days). Chemical nutrition management includes the application of urea (46% application preplanting and after emergence) and Triple superphosphate (46% application preplanting) and Organic management, including the application of cattle compost and inoculation with Mycorrhiza.
 
Results and Discussion
The results of analysis of variance revealed that the effect of nutritional management on height of garlic wasn’t significant and on other traits garlic (Bulb diameter, bulb weight, Number of cloves per bulb, Biological yield and yield bulb) and weeds (narrow leaf dry biomass, Broad leaves dry biomass and Total weeds dry biomass) was significant. Periods of Weed Interference and Control weed treatments on all measured traits of garlic and weeds were significant. No interaction effects of nutrition and weed management treatments on the studied traits were observed. There was a significant difference between chemical and organic nutrition management, most of the yield traits and yield components of garlic were higher in organic application than chemical fertilizers. Also, the narrow leaf biomass, broadleaf, and total weeds in chemical application in comparison to organic fertilizers increased by 11.5%, 9%, and 10.5%, respectively. During the interval period for 120 days, garlic yield decreased by 100% and with the increase of control period (control in all growing seasons), bulb yield reached the highest value (3230 g.m^-2). In weed control treatment for 20 days, bulb yield decreased by more than 86% compared to weed control treatment throughout the growing season. It seems that organic fertilizers with gradual release of nutrients could affect the competition of garlic with weeds, and by using organic fertilizers, the dry weight of weeds was less than chemical fertilizers.
 
Conclusion
The results indicated that due to the presence of weeds and the poor competitive ability of garlic against weeds, the field must be controlled for a long time and the use of manure fertilizer for organic agriculture and increasing soil organic matter is recommended.