Weed dynamics, growth and yield of rapeseed canola in response to trifluralin efficacy under rainfed conditions
2003
Majid, A. | Nawaz, N. | Hazara, R. | Yousaf, M. | Baig, D. (National Agricultural Research Centre, Islamabad (Pakistan). Oilseed Programme)
Rapeseed canola (Brassica napus L.) has recently been introduced in Pakistan and it is becoming popular among the barani farming community in Pothwar region of the country. Heavy weed infestation is one of the factors limiting crop production in the barani areas. Pre-emergence herbicides are generally recommended for weed control in rapeseed crops because post- emergence herbicides are of very limited efficacy. Response of weed dynamics (weed density + biomass), growth and yield of canola to trifluralin as pre-planting herbicide was investigated in the field under barani conditions of the Pothwar region of Pakistan in 1998-99 and 1999-00. Trifluralin was used with four application rates. The broad-leaf and grasses were observed to be the major weeds in the experiment area. Application of trifluralin at the rates of 1.5 liters (L) active ingredient (a.i) ha-1 and 2.0 L a.i ha-1 significantly affected the total weed dynamics (density + biomass) of rapeseed canola during both growing seasons. The broad-leaf weed flora was controlled more effectively by trifluralin than other weed species. Application of trifluralin at the rate of 1.5 L a.i ha-1 resulted in maximum seed yield of 1968 kg ha-1 that was significantly higher than rest of the application rates during 1999-00 crop season. Similarly, in 1998-99, the highest seed yield of 1776- kg ha-1 was also produced by 1.5-L a.i trifluralin ha-1 but it remained at par with 1.0-L a.i. trifluralin ha-1. The 1000-seed weight and seed yield of canola of 1999- 00 crop season was 2.9 and 2.7% higher than that of 1998-99, respectively. The highest application rate of trifluralin (2.0 L a.i ha-1) decreased seed yield of canola by 27% and 35% over the rate of 1.5 L a.i ha-1 in 1998-99 and 1999-00, respectively. Thus, rapeseed growers can earn higher economic return by growing canola through better weed management by using trifluralin at the rate of 1.5 L. a.i ha-1 as pre-plant incorporation a day before crop sowing.
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