Drought-tolerant Desmodium species effectively suppress parasitic striga weed and improve cereal grain yields in western Kenya

Abstract

AbstractsThe parasitic weed Striga hermonthica Benth. (Orobanchaceae), commonly known as striga, is an increasingly important constraint to cereal production in sub-Saharan Africa (SSA), often resulting in total yield losses in maize (Zea mays L.) and substantial losses in sorghum (Sorghum bicolor (L.) Moench). This is further aggravated by soil degradation and drought conditions that are gradually becoming widespread in SSA. Forage legumes in the genus Desmodium (Fabaceae), mainly D. uncinatum and D. intortum, effectively control striga and improve crop productivity in SSA. However, negative effects of climate change such as drought stress is affecting the functioning of these systems. There is thus a need to identify and characterize new plants possessing the required ecological chemistry to protect crops against the biotic stress of striga under such environmental conditions. 17 accessions comprising 10 species of Desmodium were screened for their drought stress tolerance and ability to suppress striga. Desmodium incanum and D. ramosissimum were selected as the most promising species as they retained their leaves and maintained leaf function for longer periods during their exposure to drought stress conditions. They also had desirable phenotypes with more above ground biomass. The two species suppressed striga infestation, both under controlled and field conditions, and resulted in significant grain yield increases, demonstrating the incremental capability of Desmodium species in striga suppression. These results demonstrate beneficial effects of Desmodium species in enhancing cereal productivity in dry areas.

Recent research progress in combatting root parasitic weeds

“…Furthermore, to expand the push-pull technology to drought-prone areas, climate-adapted push-pull technology using drought tolerant Desmodium spp. and Napier grass (or other grasses) as the intercrop and border crop, respectively, has been developed [141,142,[144][145][146][147]. This improved technology is currently practised by more than 54,000 farmers in East Africa [142] and a higher percentage of women perceived the improved technology as very effective compared to men [146].…”

Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review

“…(generally referred to as Striga) infestations: one 7-year study in Kenya determined that several edible legume species, including crotalaria and groundnut (Arachis hypogaea L.), reduced Striga hermonthica emergence by up to 35% (Midega et al 2014). A more recent study by Midega et al (2017) indicated that drought-tolerant Desmodium [Desmodium uncinatum (Jacq.) DC.…”

Removing constraints to sustainable food production: new ways to exploit secondary metabolism from companion planting and GM

“…This is set to improve further by the introduction of even more drought‐tolerant and insect‐resistant Brachiaria spp. cultivars and newly identified intercrops such as D. incanum …”

“…6 Related signalling in the rhizosphere shows promise for crop protection 7 wileyonlinelibrary.com/journal/ps Figure 1. The push-pull for the control of stemborer moth larval damage to cereals on small holder farms in sub-Saharan Africa is explained in this annotated cartoon, and in the text, 5,9 for the further control of the parasitic weed Striga hermonthica 8,10 and more recently for the fall armyworm. 11,12 This push-pull intervention against the pests and the agro-ecological advantages of plant nutrition and other factors 13 gives three fold cereal yields with no seasonal inputs of fertilizer or pesticide even under climate change stress.…”