Fall Armyworm Tolerance of Maize Parental Lines, Experimental Hybrids, and Commercial Cultivars in Southern Africa

Abstract

Fall armyworm [Spodoptera frugiperda (J./E. Smith); FAW] is negatively impacting sustainable maize production, particularly in smallholder farming systems in sub-Saharan Africa. Two sets of germplasm (commercial cultivars and experimental hybrids, and local and exotic inbred lines) were evaluated under managed and natural FAW infestation to identify FAW tolerant material with superior grain yield performance. Significant genotypic effects on foliar FAW damage, ear FAW damage, and grain yield were observed. Commercial cultivars were significantly more affected by FAW infestation than experimental hybrids, as evidenced by high foliar and ear damage scores, yet they out-yielded experimental genotypes. The introduced FAW donor lines (CML338, CML67, CML121, and CML334) showed better tolerance to FAW, individually and in hybrid combinations. Local inbred lines, SV1P, CML491, and CML 539, also showed FAW tolerance. Hybrids and open pollinated varieties were more vulnerable to FAW damage at early growth stages, but they grew out of it through the mid to late whorl stages. Inbred lines showed increasing damage as they grew to maturity. Husk cover, ear rot, anthesis date, and plant height were highly correlated with FAW tolerance. The identified local and exotic lines with FAW tolerance will contribute to FAW resistance breeding in southern Africa.

New techniques for breeding maize (Zea mays) varieties with fall armyworm resistance and market‐preferred traits for sub‐Saharan Africa

“…For instance, most introductions of FAW-resistant candidate materials had poor local adaptation, susceptibility to major foliar diseases and less preferred grain colours in SSA (Matova et al, 2022).…”

“…At present, several institutions including CIMMYT, national programmes and private companies have started breeding for FAW resistance in SSA mostly using natural infestation pressure on test candidates. Encouraging results have been reported (Kasoma et al, 2021;Matova et al, 2022). Integrating these breeding efforts with speed breeding techniques such as the DH technology will bring quick ΔGs to most of these breeding initiatives.…”

“…A study in Zimbabwe identified the lines CML334, CML338, CML346, CML121, among other lines as good introductions for use in FAW resistance breeding. Furthermore, these lines have been identified as carrying stable FAW resistance (Matova et al, 2022). Marker assisted backcrossing would be an appropriate solution to avoid linkage drag, and fortunately, large effect QTL have been identified (Womack et al, 2018(Womack et al, , 2020.…”

“…For instance, most introductions of FAW‐resistant candidate materials had poor local adaptation, susceptibility to major foliar diseases and less preferred grain colours in SSA (Matova et al, 2022). Genomic‐assisted selection including MABC is a valuable tool for precision and speed breeding and to reduce linkage drag associated with FAW resistance.…”

“…Local germplasm had not been evaluated for FAW resistance until recently, but new studies have been conducted in Zambia, Kenya and Zimbabwe (Kamweru et al, 2022; Kasoma, Shimelis, Laing, Shayanowako, et al, 2020; Matova et al, 2020). This has delayed progress in the improvement of locally adapted materials for FAW resistance, but now local materials such as CML491 and SV1P have been identified as resistant to FAW (Kasoma, Shimelis, & Laing, 2020; Matova et al, 2022). Hybridization between local lines identified with some resistance or between FAW resistant local lines and exotic donors may create locally adapted materials with enhanced FAW resistance.…”