Growth dynamics of maize (Zea mays L.) and weeds in response to different nitrogen levels and weeding intervals

摘要

Maize yield is very low in Khyber Pakhtunkhwa compared to Punjab-Pakistan and advance countries of the world. Weed and improper nutrients is one of the reason for low yield. Field study was carried out for the management of weeds and nutrients (Nitrogen) in 2014 and was repeated in 2015. An open pollinated maize variety “Azam” was used in the experiment. Four nitrogen levels (N 0 =0, N 1 =100, N 2 =150, and N 3 =200 kg ha -1 ) and seven weed periods (W 0 =Weed free throughout season, W 1 =15 DAS (days after sowing), W 2 =30 DAS, W 3 =45 DAS, W 4 =60 DAS W 5 =75 DAS, W 6 = weed allowed for whole period). In all sub plots weeds competed with maize for the above mentioned days and were then kept free for the rest of duration through regular hand weeding. Experimental data illustrated highest plant height (220 cm), grain yield (6268 kg ha -1 ) and biological yield (10189 kg ha -1 ) from the plots treated with N @ 200 kg ha -1 . Furthermore, plots which were kept weed infested throughout the season caused severe yield losses to maize crop. However, weed competition beyond 60 days after sowing caused no significant reduction in yield. So it is recommended that weeding should be done before 30 days after sowing having nitrogen @ 200 kg ha -1 for enhancing grain yield in maize crop.