evaluation the effects of wheat residues and day or night tillages on weed community and yield of sc 704 corn cultivar (zea mays l.)

wheat residues management and modification in tillage time are among suggested practices in weed control. to evaluate the effects of wheat residues and tillage time on weed dry matter and leaf area, corn dry matter and corn grain yield, a study was conducted at darab agriculture and natural resource college, shiraz university during growing season of 2008-2009. this experiment was conducted in a split plot arrangement based on randomized complete block design with four replications. tillage time was considered as main plot at two levels of plowing at day time and during the night and residue rates were sub plot at four levels; 0 (control), 25%, 50% and 75% of left wheat residues (3 t.ha-1). the results showed that the tillage time had significant effects on corn dry matter and corn grain yield and also on weed dry matter. the highest grain yield and dry matter of corn and the lowest weed dry matter was obtained from night tillage treatment. the final number of common lambsquarter (chenopodium album l.), foxtail (setaria spp.) at night tillage treatment was 38.6 and 22% lower than that of day tillage, respectively. these differences were significant at 5% probability level. final number and dry matter of weed, were reduced significantly (p≤0.01) by using wheat residues. the interactive effects of tillage and crop residue on measured traits were not significant. it was concluded that to achieve the highest grain yield of corn and to suppress the weed on the similar agro-climatic conditions, night tillage and application of 50% of wheat residues might be recommended.