in order to study of nitrogen effect on critical period of weed control in sunflower (helianthus annuus l.) in birjand region, a split plot experiment based on randomized complete block design was conducted with 24 treatments and 3 replications in research farm of college of agriculture of birjand university in 2010. the main factor was three levels of nitrogen (0, 100 and 200 kg.ha-1) and the ...

Effect of weed competition periods on weeds and yield of black seed was studied through field experiments conducted at Agronomic Research Area, University of Agriculture, Faisalabad during winter 2006-07 and 2007-08. Weeds were allowed to compete with the crop for 40, 50, 60, 70, 80 days after sowing and throughout the growth season along with a weed free treatment. The data on weed density and...

in order to determine the critical period of weed control and investigation the effect of periodical control and interference of weeds natural population on yield and yield components of winter canola (brassica napus l. cv. okapi) in west region of tehran an experiment was carried out at research field of tarbiat modarres university, tehran, iran on 2004-5 growing season. fourteen experimental ...

in order to investigate rice competition ability against weeds in direct-seeding and transplanting systems afield experiment was conducted at mahmud abad region of mazandaran province on 2011 growing season. experimental treatments were studied in a split plot factorial design based on randomized complete blocks with three replicates. direct-seeding and transplanting of rice in wet seedbed were...

Stale seedbeds are used by organic growers to reduce weed populations prior to crop planting. Ryemulches, derived from mechanically killed (rolled and crimped) winter rye cover crops, can serve the same purpose for spring-planted organic crops. Both methods can also be employed by conventional growers who face looming problems with herbicide resistant weeds. The objective of this research was t...

evaluation of weed population and their interference on lentil varieties at different sowing date was investigated in a field experiment in khorramabad during 2005-06 growing season. the experimental design was a randomized complete block in factorial arrangement with 4 replications. the experiment had 3 factors including: planting date at three levels (autumn, winter, and spring) weed interfer...

Weed interference in annual cropping systems can be highly variable from year-to-year, as well as spatially heterogeneous. These factors have confounded efforts to develop simple methods for predicting competitive outcomes early in the growing season. A 2-year study was conducted with maize in competition with four annual weed species (Setaria faberi, Abutilon theophrasti, Chenopodium album and...