Effect of planting pattern, time of weed removal and herbicide application on weeddensity and sugar beet (Beta vulgaris L.) root yield

To study the possibility of integrated chemical and non-chemical methods for weeds management in sugar beet, field experiments were conducted in research station of Iranian Research Institute of Plant Protection, Meshkindasht, Karaj, Iran, in 2009 and 2010. Split-split plot arrangement in randomized complete block design with four replications was used. Experimental treatments consisted of three sugar beet planting patterns (including: single rows evenly spaced 50 and 60 cm apart and twin rows spaced 60 cm apart) in main plots, mechanical weed removal stages (in 4-6, 10-12 and 14-16 sugar beet leaf stages) as sub plots and herbicides (including: application of Metamitron and Triflusulfuron-methyl) in sub-sub plots. Only experimental error of total weed biomass and sugar beet root yield were homegeniuos, therefore combined analysis of variance was performed for these two traits. Results showed that single rows spaced 50 cm apart and twin rows had similar weed biomass. The best time for mechanical weed control was 4-6 sugar beet leaf stages, and was more effective when Metamitron was applied in twin rows. Weed removal time had significant effect on sugar beet root yield and higher root yield (37.5 ton.ha-1) was obtained when weeds removed in 2-4 sugar beet leaf stages.