Response of open-grown wrapper tobacco to different weed control methods, nitrogen fertilization and row arrangements

Results of the study showed that in both single and double row arrangement, pendimethalin produced the highest level of crop injury that persisted up to 30 DAT [days after transplanting]. Thiobencarb and butachlor injured tobacco until 15 DAT. A slight injury was also observed on cultural method. Excellent weed control against all kinds of weed was observed from cultural method. Rottboellia cochinchinensis L.F. and Amaranthus spinosus L. were effectively controlled by pendimenthalin while butachlor effectively controlled A. spinosus L. and Ageratum conyzoides L. Thiobencarb was not able to control any of the weed species. In double row arrangement, plant height was increased by weedfree, cultural methods, pendimethalin fb HU [followed by Hilling-up] 30 DAT and butachlor fb HU 30 DAT. Number of leaves, leaf area and breadth index were increased by weedfree, cultural and pendimethalin fb HU 30 DAT. In single row arrangement, all agronomic characters were increased by weedfree and cultural method. Thus, high yield of 2.04-2.09 t/ha and 1.79-1.9 t/ha was produced from weedfree and cultural method, respectively. Pendimethalin fb HU 30 DAT produced a yield of 1.48 and 0.92 t/ha in double and single row arrangement, respectively. The application of 40 kg N/ha increased plant height, leaf area, number of leaves and consequently total yield. Breadth index increased at 80 kg N/ha in double row and 40 kg N/ha in single row arrangement. Days to flower was reduced at 40-80 kg N/ha. In both single and double row arrangement, weedfree, cultural method and pendimenthalin fb HU 30 DAT increased percentage of binder leaves causing a decrease in the percentage of filler leaves. A small percentage of wrapper leaves was also produced from these three weed control treatments. Nitrogen did not affect percentage of wrapper, binder and filler leaves in double row arrangement. However, in single row arrangement, the application of 80 kg N/ha increased percent binder leaves while 80-120 kg N/ha decreased percent filler. Percent nicotine was not affected by weed control in single and double row arrangement