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DIFFERENTIAL TOLERANCE OF TOO RICE (Oryza sativa L.) CULTIVARS TO DIMETHAMETRYNE
Abstract:
Both the screen house and field trials were conducted at Samaru Zaria (11°11’N 7° 35’E) in the Northern Guinea savanna of Nigeria, to study the tolerance of two selected rice (Oryza sativa L.) cultivars (ITA 257 and Ex-China) to various rates of dimethametryne (herbicide). Dimethametryne (herbicide) was evaluated at 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0kg ai/ha. The result obtained indcated that dimethametryne at low to near medium rates (0.25 – 1.5kg ai/ha) were well tolerated while medium to high rates (2.0 – 4.0kg ai/ha) were observed to be phytotoxic to rice cultivars in both trials. Dimethametryne at 3.0 – 4.0kg ai/ha resulted in total crop loss before 4WAS in the screen house trial. Rice cultivars responded differentially to the various rates of dimethametryne particularly at medium to high rates (2.0 – 4.0kg ai/ha) in the field. ITA 257 was found to be more tolerant to the herbicide rates than Ex-China in both trials resulting in its (ITA 257) least injury, better growth vigour, higher LA/plant, shoot dry weight and paddy yield. Shoot dry weight at 12WAS in the screen house and paddy yield in the field correlated negatively with herbicide injury while these (shoot dry weight at 12WAS and paddy yield) were positively correlated with crop vigour, LA/plant, plant height and tiller number/plant in both trials. No correlation was observed between shoot dry weight, paddy yield and crop emergence in both trials.
DIFFERENTIAL TOLERANCE OF TOO RICE (Oryza sativa L.) CULTIVARS TO DIMETHAMETRYNE
