Farmers’ perceptions of sorghum production constraints and Striga control practices in semi-arid areas of Tanzania

The objectives of this study were to investigate constraints affecting sorghum production and farmers' approaches of Striga management in the semi-arid regions of Tanzania. Focus group discussions based on a semi-structured questionnaire and observations following transect walks were used for data collection. Only 35%, 15%, and 10% of the farmers from Igunga, Kishapu, and Meatu districts, respectively, reported growing newly released varieties. The major constraints affecting sorghum production in the study areas included Striga infestation, drought, storage pests, damage by birds, a lack of access to improved varieties, and a lack of access to production inputs, such as fertilizers, insecticides, fungicides and herbicides. Hand weeding, crop rotation, fallowing, intercropping, and organic manure application were the most common practices of farmers for reducing Striga infestations, but most farmers (79.7%) had little knowledge of the best recommended Striga management practices. About 65% of the farmers did not use fertilizers and herbicides for soil fertility improvement and weed management, respectively, creating favourable conditions for Striga infestation. A systematic breeding programme aiming at improving sorghum varieties for Striga resistance, including farmers' preferred traits, should be designed and implemented to increase the adoption of these new varieties by the farmers.     

Screening of sorghum genotypes for resistance to Striga hermonthica and S. asiatica and compatibility with Fusarium oxysporum f.sp. strigae

In the semi-arid areas of Tanzania, yield losses of sorghum [Sorghum biocolor (L.) Moench] due to Striga hermonthica (Sh) and S. asiatica (Sa) infestations are estimated to be 30–90%. The use of resistant sorghum varieties compatible with Fusarium oxysporum f.sp. strigae (FOS), a biocontrol agent of Striga, may supress the weed and enhance the crop productivity. The objective of this study was to screen and select farmer-preferred sorghum genotypes for Sh and Sa resistance and FOS compatibility for resistance breeding under Tanzanian conditions. Sixty sorghum genotypes were evaluated under screen house conditions using Sh- and Sa-infested field soils with controlled seed infestation, with or without inoculation of the sorghum seeds with FOS. Inoculation of sorghum seeds with FOS significantly enhanced sorghum growth and productivity, and supressed Sh and Sa growth and development. There were reductions of 1–4 Sh and Sa plants when sorghum seeds were inoculated with FOS. Overall, we selected 25 promising sorghum lines resistant to Sh and/or Sa, and with FOS compatibility. The selected sorghum lines are valuable genetic resources for the development of Striga management in sorghum through the integrated use of host resistance and FOS inoculation.