Pre‐ and post‐attachment resistance response of popular western Kenya maize hybrids to parasitism by witchweed (Striga)

Abstract

AbstractStriga hermonthica (Delile) Benth is a root parasitic weed that causes significant crop losses in cereals in the sub‐Saharan Africa. Host resistance is a sustainable management approach; however, Striga resistance in maize is rare. Furthermore, hybrids, preferred for high yield and other agronomic traits are more susceptible than local landraces. We sought to determine the responses of popular maize hybrids against Striga infection using in vitro germination and rhizotron assays. We screened 16 maize hybrids commonly cultivated in Kenya against two common Striga ecotypes (Kibos and Alupe) by measuring their (i) ability to induce the germination of S. hermonthica seeds in an in vitro system (pre‐attachment resistance) and (ii) ability to resist the attachment and establishment of effective parasitism (post‐attachment resistance). Results showed that two maize hybrids H614D and H629 exhibit both pre‐ and post‐attachment resistance comparable to a Striga resistant landrace KSTP'94 used in this study as a resistant check. Other hybrids displayed moderate Striga resistance; DK8031 (pre‐attachment resistance) and Duma43, phb30G19 and WH507 (post‐attachment resistance). Striga virulence, defined as aggressiveness of the parasite—measured by response to germination and host colonisation, was higher for the Kibos ecotype compared to the Alupe ecotype. However, the resistance pattern of maize genotypes remained consistent across the different Striga ecotypes. These results provide a basis for informed decisions on cultivation of various maize hybrids under Striga infestation in western Kenya.