EVALUATION OF SOWING DATE, NITROGEN LEVEL, VARIETY AND HERBICIDE FOR THE CONTROL OF Striga heraionthica (DEL.) BENTH IN SORGHUM (Sorghum blcplor (L) KOENCH)

EVALUATION OF SOWING DATE, NITROGEN LEVEL, VARIETY AND HERBICIDE FOR THE CONTROL OF Striga heraionthica (DEL.) BENTH IN SORGHUM (Sorghum blcplor (L) KOENCH)

Abstract:

A greenhouse study was conducted at the Institute for Agricultural Research, Ahmadu Bello University, Samaru, Zaria (11o11′ N 07°E) in the Northern Guinea Savanna Ecological Zone and two field trials during the 1988 wet season on the commercial farm of Ahmadu Bello University, Mokwa (09°18’N 05′ 04°E) in the Southern Guinea Savanna Ecological Zone to evaluate dates of sowing, nitrogen levels, crop varieties and herbicides for the control of Striga hermonthica in sorghum. Early sowing of sorghum on 23 June, 1988 resulted in more vigorous crop growth and grain yield increase of 64.2% over the late sowing of 14th July. The effect of nitrogen was significant on leaf area per plant at 3 weeks after sowing (WAS) and on grain yield. The effect of variety was significant on leaf area at 8 WAS, Striga score, percentage of Striga – infested sorghum plants, Striga count, head weight, grain yield and the weight of 1000 seeds. Increasing nitrogen from 60kg N/ha to 90kg N/ha increased the grain yield by 21.7%. The most promising variety which supported low number of emerged Striga shoot and produced the highest grain yield was S.35 with 76.5% grain increase over the more susceptible variety L.187, which also had 57.9% lower striga count than variety L.187. Variety ICSV 1007 consitently exhibited the highest level of resistance to Striga hermonthica both in the greenhouse and under field condition as reflected in the number of emerged Striga shoot but its yield was low. Significant interactions between sowing date x nitrogen, nitrogen x variety, sowing date x variety and second order interaction between sowing date x nitrogen x variety on various parameters studied were also observed. Grain yield was negatively iv correlated with Striga count (r = – 0.28). Among the herbicide treatments evaluated, atrazine plus terbuthylazine at 1,25 + 1.25 kg a. kg a.i/ha and diflufenican plus atrazine at 0.40 + 1.00 kg a. i/ha applied pre-emergence alone, respectively increased grain yield by 76.7% and 74.1% over the unweeded control, and 32.8% and 25.3% over two hoe-weedings. Supplementary hoe-weeding apparently encouraged Striga emergence. Grain yield was also correlated with the Striga count (r=s -26) and percentage of Striga infested sorghum plants (r=-0.32*).

EVALUATION OF SOWING DATE, NITROGEN LEVEL, VARIETY AND HERBICIDE FOR THE CONTROL OF Striga heraionthica (DEL.) BENTH IN SORGHUM (Sorghum blcplor (L) KOENCH)