Evaluation of Sorghum Genotypes Compatibility with Fusarium oxysporum under Striga Infestation

Abstract

Combined use of host resistance and Fusarium oxysporum as a biocontrol agent may provide enhanced management of Striga hermonthica (Delile) Benth. in sorghum [Sorghum bicolor (L.) Moench]. The objective of this study was to identify sorghum genotypes compatible with F. oxysporum and to determine the potential of this biocontrol agent for controlling Striga. Fifty sorghum genotypes were evaluated in the greenhouse in Striga‐infested soils with and without inoculation by F. oxysporum. A supplementary laboratory study was conducted to investigate the growth and proliferation of F. oxysporum in the soil and sorghum roots. Data were recorded on crop growth parameters, Striga incidence and colonization, and the persistence of F. oxysporum in the soil and on plant roots, using samples taken at 45 and 60 d after planting. Inoculation with F. oxysporum significantly shortened days to maturity compared to noninoculated plants. Plant height, biomass, panicle length, and seed yield per plant were higher in F. oxysporum treated pots. Striga emergence was delayed and vigor and overall incidence of the parasite was significantly reduced in Fusarium‐treated pots. The number of Fusarium colony forming units obtained from soil and plant samples were significantly different between genotypes. Three principal components (PCs) contributed to 67.31% of the total variation among the genotypes. Principal component 1, PC2, and PC3 contributed 27, 23, and 18%, respectively, to the total variance. Days to Striga emergence and Striga count and height correlated with PC1 while sorghum panicle length and plant height with PC2 and days to sorghum flowering and maturity with PC3. Thus, 12 promising sorghum lines were identified with farmer‐preferred agronomic traits and with F. oxysporum compatibility. This result is valuable in the development of Striga control in sorghum through integration of host resistance and F. oxysporum inoculation.

Integrated management of Striga hermonthica and S. asiatica in sorghum: A review

“…The biocontrol fungus destroys Striga plants before they penetrate sorghum roots. Recent studies have indicated significant reduction in Striga numbers as well as the number of days to flowering and maturity in sorghum seeds coated with FOS (Rebeka et al, 2013;Mrema et al, 2017a). Use of FOS in Striga management in sorghum fields in East Africa is not yet reported and implemented.…”

“…Therefore, there is a need for integrated management of the parasite through host resistance and application of FOS to enhance production and productivity of sorghum and related cereals affected by Striga.There are no reports of negative effects of FOS on sorghum or related cereal crops. In fact, FOS has been reported to promote the abundance of arbuscular mycorrhizal fungi in the rhizospheres of sorghum resulting in enhanced crop growth and development (Rebeka et al 2013;Mrema et al 2017b). Further, FOS has a very narrow host range, which is restricted to S. hermonthica, S. asiatica and S. gesneroides (Rebeka et al 2013).…”

“…In fact, FOS has been reported to promote the abundance of arbuscular mycorrhizal fungi in the rhizospheres of sorghum resulting in enhanced crop growth and development (Rebeka et al 2013;Mrema et al 2017b). Further, FOS has a very narrow host range, which is restricted to S. hermonthica, S. asiatica and S. gesneroides (Rebeka et al 2013).…”

“…Exploring the mode of gene action and inheritance of candidate Striga resistance genes is imperative to develop promising sorghum genotypes with multiple resistance genes adapted to semiarid environments of sub-Saharan Africa. Saunders (1942), Riches et al (1987), Doggett (1953), Ramaiah (1986), Kiriro (1991), Mabasa (1996), Mohamed (2002), Rebeka et al (2013) Abbasher et al, 1998;Ciotola et al, 2000;Rebeka et al, 2013;Mrema et al, 2017a  Reduces Striga number  Improves sorghum yield  Reduces days to maturity in sorghum Host resistance Low production of germination stimulant,  In expensive …”

“…Resistance break down Lynn and Chang, 1990;Mohamed, 2002;Ejeta, 2007;Rebeka et al, 2013;Mrema et al, 2017b mechanical The method is yet to be commercialized Joel, 2000;Hearne, 2009, Rebeka et al, 2013 (Mohamed, 2002). Several sorghum genotypes that are resistant to Striga had been developed (Table 2) (Riches et al, 1987).…”