Unfortunately, particular attention has not been paid to the production of this plant in Iran and one of the challenges of alfalfa production is the presence of weeds.
Weed interference can suppress alfalfa yield and impact stand densities Weeds also alter the composition of the forage, increasing drying time and reducing palatability of the alfalfa. In this study, an experiment was conducted to evaluate the effect of weed interference in different densities of alfalfa on yield and some morphological traits of alfalfa, forage crop, as factorial and based on a randomized complete block design with three replications in two cuttings during 2013-14 crop years. The experimental treatments were weed interference and non-interference in two levels (hand weeding and non-hand weeding) and plant density in four levels (20, 40, 60 and 80 stems per square meter). The results obtained in two cuttings in the third year of established alfalfa showed that the weeds caused quantitative and qualitative reduction in alfalfa.
Alfalfa in the second cutting had better growth compared to the first cutting, so that the plant produced the highest fresh and dry yield in the second cutting.
Weed non-interference increased the levels of superior morphological traits of alfalfa, such as fresh and dry yield, and number of leaves per plant. The test results indicated contamination of alfalfa farms with a wide range of weeds. The research findings in the study area showed significant effects of plant density and weed control on the alfalfa yield. This plant in suitable sowing density, in addition to producing high yield and ash content, could better use the resources and conditions in comparison with weeds and could significantly outreach superior morphological traits. Thus, according to the importance of forage plants, it is scientifically recommended that suitable cultivation density to be on the agenda of alfalfa farmers in the study and other regions in the country to achieve maximum yield as well as to minimize herbicide use.