EFFECT OF TRAP CROP ROTATION CYCLES ON BROOMRAPE INFESTATION IN FCV TOBACCO

Abstract

Tobacco is one of the common crops that are most seriously affected by broomrapes. Two species that commonly parasitize tobacco are Orobanche cernua and Orobanche ramosa, of which former is being most common in India. Trap crops like blackgram, greengram, sesamum, sunnhemp when grown in broomrape infested fields cause germination of the parasite but not allow the seedlings to establish and reduce the incidence of the parasite in succeeding tobacco. A field study was conducted in FCV tobacco with different trap crops and their rotation cycles at the Central Tobacco Research Institute Research Farm, Katheru, Andhra Pradesh with three trap crops and tobacco during Rabi season for four years. Lower infestation of 1.7 % at 75 days and 14.3% at 100 days was recorded in four year cycle of two year rotation of sorghum preceding two year tobacco. In four year cycle of three year rotation of sorghum preceding one year tobacco, 5.7 % and 14.0% infestation at 75 and 100 days after planting respectively was recorded. In two year rotation of sesamum preceding two year tobacco in four year cycle, 2.7 % and 28 % infestation at 75 and 100 days after planting respectively was recorded. In three year rotation of sesamum preceding one year tobacco in four year cycle, 6% and 19.3% infestation at 75 and 100 days after planting respectively was observed. Infestation and fresh weight of broomrape in tobacco crop was reduced and higher tobacco yields were recorded when tobacco was grown succeeding sorghum and sesamum in two and three year trap crop rotation cycles. Hand pulling for three years also reduced the infestation in monocropped tobacco. Hence, in highly infested fields of Orobanche in tobacco integration of trap crop of sorghum and sesamum rotation for two years with hand weeding for Orobanche management in Vertisols is recommended.