Management of insect pests of soybean: effects of sowing date and intercropping on damage and grain yield in the Nigerian Sudan savanna
2004
Sastawa, B.M. | Lawan, M. | Maina, Y.T.
Field trials were carried out during the 2001-2002 cropping seasons at Maiduguri, Nigeria, to determine the effects of defoliation and pod damage by insect pests on grain yield of soybean. The factorial experiments consisted of four sowing dates (31 July, 7, 14 and 21 August in 2001 and 21 and 28 July and 4 and 11 August in 2002), four cropping patterns of millet and soybean (3:1, 2:1, 1:1 and 0:1) and two cropping systems of millet-soybean (MS) and millet-soybean-groundnut-cowpea (MSGC). The number of insect defoliators and pod sucking bugs were significantly higher in soybean sown on 31 July in 2001 and on 28 August in 2002. The numbers of pod sucking bugs were also higher in pattern 0:1 and in MS system than the other patterns and systems in both the 2001 and 2002 cropping seasons. Grain yields were higher in early sown soybean in 2001 but not in 2002. Percentage defoliation was significantly lower in cropping pattern 1:1 over other patterns in 2001 and in pattern 0:1 in 2002. Percentage pod damage was significantly lower in pattern 1:1 than the other patterns in both the years. Percentage defoliation was significantly higher in MS intercrop system than the other system in 2001. In both cropping seasons, grain yields were significantly higher in the MS intercrop system than in the MSGC system.
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