Effects of Different Cover Crops on Weed Control in Citrus Orchards

In order to investigate the effect of different summer cover crops on weed dynamics, an experiment was carried out based on Randomized Complete Blocks Design with 7 treatments and 3 replications. The experiment was performed at Islamic Azad University of Amol (Komdarreh region) during 2009. Treatments included white bean (Phaseolus vulgaris), red bean (Phaseolus vulgaris), cow pea (Phaseolus vulgaris), pinto bean (Phaseolus vulgaris), mung bean (Vigna radiate), lentil (Lens culinaris), and common pea (Cicer arietinum). Some cover crop and weed parameters such as dry weight of grass and broadleaf weeds in each plot as well as dry weight of cover crops were determined. A cover crop/weed biomass ratio (CCW Index) was applied to determine the efficiency of different cover crops in terms of weed depression. Accordingly, weed growth in cowpea and mung bean plots was greatly reduced (CCWI=10.25 and 4.13, respectively) and lentil could not compete with weeds (CCWI= 0.14) and weeds were dominated in lentil plots. In first stage three cover crops common pea, cow pea and mung bean had the most leaf area but white bean in second stage had the most leaf area among cover crops. In first and second samplings cow pea had the highest dry weight (37.33 and 322.2 gr.m-2) and the least dry weight belonged to mung bean and lentil in second and first sampling, respectively. There was a negative and exponential fit relationship between weed dry weight and cover crop dry weight.