Field-based evaluation of sorghum for resistance to striga hermonthica under natural infestation

Striga hermonthica is one of the most severe biotic constraints to sorghum production in sub-Saharan Africa, particularly under smallholder farming systems where control options are limited. Host plant resistance remains a key component of sustainable Striga management; however, resistance expression is often influenced by environmental conditions. This study evaluated the agronomic performance and Striga response of six sorghum varieties under natural infestation conditions in southern Niger over two rainy seasons. Four varieties known to be susceptible (El_Tsédaoua, Mota Maradi, MR732, and Sepon82) and two resistant checks (N13 and SRN39) were assessed in a randomized complete block design with three replications. Data were collected on days to flowering, plant height, days to Striga emergence, and Striga density at 45, 60, and 90 days after sowing (DAS). Analysis of variance revealed significant genotypic effects for all traits measured, with year and genotype × year interactions observed for several Striga-related traits. Resistant varieties consistently delayed Striga emergence and maintained lower parasite densities throughout the cropping cycle compared with susceptible varieties. Striga density increased with crop age across all genotypes, although the magnitude of infestation differed markedly among varieties and between seasons. The results highlight substantial variation among the varieties in their response to Striga hermonthica under field conditions and confirm the importance of multi-year evaluation for reliable identification of resistance. This study provides valuable genetic resources for sorghum improvement screening and deployment in Striga-prone environments of the Sahel.