Effects of Rye (Secale cereale) and Berseem Clover (Trifolium alexandrinum) cover crops management on the growth indices in common bean (Phaseolus vulgaris) at the presence and absence of weeds

To evaluate the effect of different cover crops management on the trend of growth indices of common bean (Phaseolus vulgaris) during the growth season in the presence and absence of weeds, an experiment was carried out as a factorial experiment based on the randomized complete block design with three replications in 2012-2013 growing season at the research farm of the Faculty of Agriculture, Ferdowsi University of Mashhad. Experimental factors were type of cover crops in three levels of erseem clover (Trifolium alexandrinum L.), rye (Secale cereale L.) and intercropping of berseem clover+ rye (50:50), in two levels of seeding rate (recommended density and additive density), and three levels of mulch managements including herbicide+ mulch (cover crops killed by glyphosate and left the dead mulches on the soil surface), harvest+ mulch (cut the live cover crops and left them on the soil surface) and harvest (cut the cover crops and carried them out of the field). Results indicated that all treatments had significantly effects on the total weed density and dry weight and the maximum value of all growth indices. According to this, the LAI of common bean at chemical control (4.68), hand- weeding (3.96) and additive density of clover + rye with herbicide + mulch were the highest and total weed density and dry weight in this treatment, were the lowest. According to the results, the TDM at mentioned treatments were 747.43, 708.49 and 719.77 g.m-2 and had the highest values. In cover crop treatments without herbicide application, remaining the cover crop residue was better than removing cover crop from soil surface. In addition, CGR (g.m-2.day-1) and RGR (g.g-1.day-1) of common bean had the similar trends to LAI and TDM. It was concluded that the additive density of clover + rye with herbicide+mulch was the best combination to achieve to highest values of common bean growth indices.