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Field experiments were conducted to evaluate the effect of dates of transplanting (July 31, August 14 and August 28), plant spacing (10 cm x 10 cm, 20 cm x 20 cm and 30 cm x 30 cm) and nitrogen levels (0 kg ha –1, 80 kg ha –1 and 160 kg ha –1) on infestation of rice by African rice gall midge. The experiments were conducted at West African Rice Development Association (WARDA) research farm at Ogidiga near Abakaliki during the 2002 and 2003 farming seasons. The experiments were laid out in split-split- plot in randomized complete block design. The rice variety used for the experiments was ITA 306 a susceptible variety to African rice gall midge. Percentage infestation of rice by African rice gall midge were most severe (47. 5% and 41.32%) on earliest transplanted rice (July 31) irrespective of plant spacing and nitrogen levels for all the experimental years. Similarly rice plants on plots with the least plant spacing (10 cm x 10 cm) had the highest infestation of 40.6% and 33.40 % by African rice gall midge for 2002 and 2003 respectively. Severity of infestation was found to decline with the increasing plant spacing. Percentage infestation increased significantly (P=O.05) with the increasing levels of nitrogen with 34. 3% and 25.75 % infestation recorded in plots treated with 160 kg ha –1. Date of transplanting, plant spacing and nitrogen level significantly influenced the grain yield of rice with highest grain yield of 188.9 g, 307. 9 g and 198. 9 g for the second planting date, 30 cm x 30 cm plant spacing and 80 kg ha –1 nitrogen levels respectively. Keywords: Dates of transplanting, plant spacing, nitrogen levels, African rice gall midge and grain yield, Abakaliki, Nigeria.Journal of Technology and Education in Nigeria Vol. 11 (1) 2006: pp. 7-16 |
