Bio efficacy of new herbicides on weed dynamics, yield attributes, yield and weed control efficiency in transplanted rice

A field experiment was conducted during kharif season of 2009 and 2010 at the Agriculture Research Station, Ummedganj, Kota (Rajasthan). The experiment was laid out in randomized block design with 7 treatments comprises of Butachlor 50 EC @ 1.5 kg a.i/ha at 5–7 DAT, Bispyribac Sodium S.C @ 25 g a.i/ha at 15–20 DAT, Bispyribac Sodium SC@ 35 g a.i/ha at 15–20 DAT, Bispyribac Sodium SC@ 50 g a.i/ha at 15–20 DAT, Weed free, (plot at 10 days interval until harvest), Two hand weeding at 20 & 40 days after transplanting and Non weeded control replicated four times. The result revealed that application of Bispyribac Sodium SC@ 50 g a.i/ha at 15–20 DAT produced significantly higher grain yield (56.99q/ha which was at par with Bispyribac Sodium SC@ 35 g a.i/ha at 15–20 DAT. Number of weeds and dry weight of weeds also minimum in these treatments, however the highest grain yield (6.05 & 6.55t/ha) were obtained from weed free treatment in both the years respectively. The increase in yield were about 44 per cent with the application of bispyribac Sodium SC@ 35 g a.i/ha at 15–20 DAT. Significantly lower weed density (9 & 10 no of weeds/m²), weed dry weight,(12.55 &13.69g/m²) weed persistence index (0.03 &0.03)and weed competition index (8.05 &12.55) recorded in the plots where bispyribac Sodium SC@ 35 g a.i/ha at 15–20 DAT were applied in both the years respectively. Significantly higher weed control efficiency (55.81 & 72.75%) and herbicidal efficiency index (2.60 & 2.96) where bispyribac Sodium SC@ 35 g a.i/ha at 15–20 DAT were applied. respectively.