Effect of Brassica campestris var. toria as a catch crop on Orobanche aegyptiaca seed bank

Field studies were conducted in two naturally Orobanche-infested fields at Nawalparasi district in Nepal for 2 years to evaluate the effectiveness of tori (Brassica campestris var. toria) plant as a catch crop for the reduction of Orobanche aegyptiaca pers. seed bank. For this, two successive crops of tori were grown in the same fields each year; the first crop was planted in the usual sowing date (third week of October) and it was harvested in the third week of January, when the crop was fully matured. The second crop was planted as catch crop immediately after the harvest of the first crop. Catch crop plants when 1-month-old (early flowering stage) were harvested as green vegetables. The reduction of Orobanche seed bank by the first crop was 20.9% in 1997/98 and 26.2% in 1998/99, and the reduction due to the second crop (catch crop) was 33.35% in 1997/98 and 27.95% in 1998/99. These values were significantly high compared with that of fallow plots. Optimum density of tori plants required for the significant reduction of Orobanche seed bank was found to be about 140/m(2) that equals 2.1 g of tori seeds sown/m(2). (C) 2002 Elsevier Science Ltd. All rights reserved.