Abstract
Parasitic weeds belonging to the Orobanchaceae family are a menace in Sub-Saharan African (SSA). Specifically, the two witchweeds from the genus Striga, S. hermonthica and S. asiatica, are jointly responsible for land abandonments and cereal yield reductions in the SSA. Factorial experiments involving fourteen maize genotypes and two levels of Striga asiatica infestation (infested and noninfested) were conducted under pot and laboratory experiments at the Department of Plant Production Sciences and Technologies, University of Zimbabwe, during the 2014/2015 season. A 14 × 2 factorial pot experiment was arranged in a 7 × 4 α-lattice design replicated four times, whereas the laboratory agar gel was arranged in a complete randomized design with four replications. Results revealed significant differences ( p < 0.05) for S. asiatica and genotype main effects for the recorded traits. S. asiatica-infested genotypes had lower biomasses than noninfested ones. However, the University of Zimbabwe bred hybrids such as Ax31, Ax28, Ax7, and Ax32 had similar plant heights and stem, leaf, and cob biomass across the two Striga levels unlike the local checks, particularly SC513, SC537, and SC637, under Striga infestation. Moreover, these genotypes also had the least Striga germination percentage and furthest germination distance indicating that they are resistant/tolerant to Striga asiatica. The University of Zimbabwe bred hybrids, using Striga hermonthica resistance from the International Institute of Tropical Agriculture, exhibited resistance/tolerance to Striga asiatica compared to local checks. Therefore, these varieties could offer a better and viable Striga spp. control option to farmers in both S. hermonthica and S. asiatica endemic areas.
Highlights
In Africa, many smallholder farmers are seriously facing weed problems in their maize production systems, especially parasitic weeds
Significant differences (p < 0.05) in leaf biomass were recorded for individual genotypes such as SC513 between S. asiatica infested and noninfested levels (Figure 2)
The University of Zimbabwe hybrids bred from Institute of Tropical Agriculture (IITA) S. hermonthica resistant varieties proved to be resistant and tolerant to S. asiatica compared to local checks. is is not surprising as IITA and partner organizations such as CIMMYT have been rigorously working towards the breeding of Striga resistant varieties derived from wild maize relatives, which are naturally resistant to S. hermonthica [49]
Summary
In Africa, many smallholder farmers are seriously facing weed problems in their maize production systems, especially parasitic weeds. Mabasa [4] reported Striga asiatica as the most prevalent of the Striga species in southern Africa with particular reference to Zimbabwe whereas S. hermonthica is more prevalent in the west and east of Africa, causing serious damage and crop yield reductions [5,6,7]. Germination stimulants known as strigolactones released by host crops such as maize are responsible for Striga spp. germination, Advances in Agriculture parasitizing the plant through haustoria formation [11, 13, 14]. Studies have shown that S. asiatica has occupied more than 50 million hectares allocated to cereal production in Africa, causing a problem of food insecurity among smallholder farmers [16, 17]
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