Demand-Driven Technologies for Sustainable Maize ... - IITA

et al. (2003) found that tolerant maize following a soybean trap-cropyielded 1580 kg ha -1 of grain and out-yielded farmers’ maize variety bymore than 80%. Carsky et al. (2000) also reported that S. hermonthicaincidence in maize after soybean, compared to maize after sorghum,was signifi cantly reduced from 3.2 to 1.3 emerged plants per maizeplant, resulting in greatly improved grain yields.In addition to host-plant resistance and legume trap-crops, asubstantial amount of research has been conducted on the effect ofsoil fertility on Striga infestation. Infestation is frequently associatedwith low soil fertility (Carsky et al. 2000; Schulz et al. 2003). Improvedsoil fertility conditions are likely to lead to reduced Striga infestation(Debra et al. 1998). The use of grain legumes can contribute to soilN (Carsky and Iwuafor 1999). Sanginga et al. (2001) found that grainyield of maize grown after soybean increased by an average of 25%across two locations. They attributed this to enhanced N availabilityfollowing soybean and other rotation effects, such as the reductionof soil-borne disease organisms. Intercropping, particularly of cerealswith cowpea [Vigna unguiculata (L.) Walp], is a common practice inmany parts of the semi-arid zone of West and Central Africa (WCA).This is because food production is diversifi ed, the risk of crop failureis reduced, and resources for crop growth are utilized more effi cientlythan with sole cropping (Carsky et al. 1994).Intercropping of cereals with legumes has also been proposedas a means of suppressing Striga in the cereal crop (Vernon 1995;Kureh et al. 2000). Most Striga-infested areas have high seed banksof the parasite in the soil. The adoption of control measures that aimat reducing the level of the seed bank, which is a potent source ofStriga inoculum, has to be encouraged. The potentials and benefi cialeffects of intercropping and 1-year legume-cereal rotation for Strigamanagement have been demonstrated under both researcher- andfarmer-managed conditions. Striga control is better when intercroppingand rotation periods are longer. However, farmers seldom grow thesame crop on a piece of land for more than 1 year. Thus, rotationof trap-crops for a long period before growing the host-crop has agreater chance of reaping the benefi ts of long period of rotation.The present study was designed in 2001 by the agronomic groupof the West and Central Africa Collaborative Maize Research Network(WECAMAN) for implementation by member countries. The objectiveswere to demonstrate and promote the adoption of the use of Strigatolerantmaize in rotation with legumes for a longer period. The controlswere maize intercropped with cowpea and continuous sole croppingof Striga-tolerant maize. The expected benefi ts of long-term rotationinclude among others reduction of the Striga seed bank, incidence andinfestation, improvement of soil fertility and improved maize yield.171