A Comparison of Weeds Interference at different planting densities, on Nutritional Value of Alfalfa (Medicago Sativa L.)

Alfalfa as a forage crop constitutes the largest area of planting in the world as Iran, and it plays an important role in feeding livestock due to its high protein content. One of the challenges of alfalfa production is the presence of weeds Alfalfa are particularly susceptible to weed competition because they are not vigorous competitors and weeds emerging shortly after seeding can reduce alfalfa success.The alfalfa growth stage is considered as the most important factor influencing the composition and nutritional value of forage. The need for structural tissues will rise by ageing the plant, resulting in increased contains of main structural carbohydrates (such as cellulose and hemicellulose) and lignin. Protein content decreases by ageing the plant; therefore, there is an inverse relationship between the protein content and fiber in a plant species. Moreover, the levels of inorganic elements, potassium, calcium, phosphorous and other micronutrients will be reduced by raising plant age, parallel to reduced total forage ash. In addition to the quantitative damages, the nutritional value of forage for feeding livestock will also decrease, which unfortunately has not been the subject of attention. In this study, an experiment was conducted to evaluate the effect of weed interference in different densities of alfalfa on nutritional value 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 increased the nutritional value of alfalfa in terms of nutrient elements, proteins and factors such as ADF, Ash, CF, NDF.

Keywords:

Weed , ADF , Ash , CF , NDF