عنوان مقاله [English]
To study the critical period of weeds competition with sugar beet and determine the duration that the crop can tolerate the weeds, a field experiment was carried out at Esfahan Agicultural Research Center, in Kabotarabad-Esfahan during 1999-2000. The experiment conducted in RCB Design with 14 treatments and four replications. The treatments included control throughout the growth season (as a check), till and after 4, 6, 8, 10, 12 and 14 weeks from crop emergence together with no weed control during the whole growing season. The result showed that the weeding until four weeks after planting had a positive effect on root yield and sugar yield. The results also indicated that there was a critical period for weed control between 4-21 weeks after planting ( WAP).There was a significant interaction between the plant density and establishment with the period of weed control. There was no critical period for sugar content, Na, K and NO3. This study showed that the best period for weed control in Baran(Esfahan) would be 4-21 WAP.