Characterization of Maize Genotypes (Zea mays L.) for Resistance to Striga asiatica and S. hermonthica and Compatibility with Fusarium oxysporum f. sp. strigae (FOS) in Tanzania

Striga species cause significant yield loss in maize varying from 20 to 100%. The aim of the present study was to screen and identify maize genotypes with partial resistance to S. hermonthica (Sh) and S. asiatica (Sa) and compatible with Fusarium oxysporum f. sp. strigae (FOS), a biocontrol agent. Fifty-six maize genotypes were evaluated for resistance to Sh and Sa, and FOS compatibility. Results showed that FOS treatment significantly (p < 0.001) enhanced Striga management compared to the untreated control under both Sh and Sa infestations. The mean grain yield was reduced by 19.13% in FOS-untreated genotypes compared with a loss of 13.94% in the same genotypes treated with FOS under Sh infestation. Likewise, under Sa infestation, FOS-treated genotypes had a mean grain yield reduction of 18% while untreated genotypes had a mean loss of 21.4% compared to the control treatment. Overall, based on Striga emergence count, Striga host damage rating, grain yield and FOS compatibility, under Sh and Sa infestations, 23 maize genotypes carrying farmer preferred traits were identified. The genotypes are useful genetic materials in the development of Striga-resistant cultivars in Tanzania and related agro-ecologies.

Striga spp. affect about 100 million hectares of farmland cultivated by resource poor farmers in Africa. Consequently, it affects the livelihoods of over 300 million peoples who depends on the above major grain crops [5,10]. The most important cereal crop in Africa, maize, is exceptionally susceptible to Striga infestations. Low soil moisture Striga seed banks in the soil, prevent new seed production and reduce the spread of Striga to uninfested fields [37]. Host resistance, combined with compatible agronomic practices, may solve some of the problems. Resistant cultivars can reduce both new Striga seed production as well as the Striga seed bank in infested soils in successive seasons [10,38].
Use of resistant varieties to control Striga species is the most effective, economical, and environmentally viable option for resource poor farmers [4,39]. Striga resistance refers to the ability of the host root to stimulate Striga seed germination but at the same time to prevent attachment of the Striga seedlings to its roots, or to kill the seedlings which attach to the roots. Tolerance refers to the ability of the host plant to withstand the effects of the parasitic plants that are already attached, regardless of their number with little yield loss [40,41]. Various studies have revealed that genes conferring resistance to S. hermonthica can been stacked in maize and these can intervene at several points in the pre-emergence stages of the Striga life cycle [38,42,43]. A significant breakthrough was attained by the International Institute of Tropical Agriculture (IITA) in developing maize genotypes with S. hermonthica resistance [38,43]. These genotypes could serve as valuable genetic resource for Striga resistance breeding programs in SSA, including Tanzania.
Striga resistance in maize is expressed in several ways, including low stimulation of Striga seed germination [16,44,45], low haustorial induction [16], avoidance through root architecture (fewer thin branches) [46], escape by early maturity [47], host resistance to Striga attachment [46], and failure to support attached parasites (incompatibility) [16,46,48]. However, the levels of Striga host resistance that have been attained so far in maize are not adequate to counteract high levels of Striga infestation. The current Striga-resistant/tolerant genotypes allow for the flowering and seed set of Striga plants, thus enriching the Striga seedbank in the soil [49][50][51]. Thus, the use of Striga-resistant genotypes combined with a biological control agent and farmers' current agronomic practices may constitute a substantially more effective Striga control strategy.
Biological control denotes the deliberate use of living organisms to suppress, reduce, or eradicate a pest population [52]. The technique is less expensive and more environmentally friendly than chemical control options [53,54]. Prior research has shown that the presence of mycoherbicides in the rhizosphere of susceptible crops reduces the levels of Striga parasitism on the host plant [10,55,56]. Pathogenic isolates of Fusarium oxysporum Schlecht. emend. Synder and Hans f. sp. strigae (FOS) are reported to be efficient in controlling S. asiatica and S. hermonthica infestation in maize and sorghum [7,57]. The biocontrol agent is most effective when combined with Striga-resistant genotypes and other control measures [7,10]. It is reported that the integrated effects of Striga-resistant maize genotypes and FOS reduced Striga emergence by over 90% [57]. Gebretsadik et al. [7] reported up to a 92% reduction in Striga emergence counts when a FOS treatment was applied to Striga-resistant sorghum varieties. Beed et al. [55] reported a reduction of S. hermonthica emergence by 98% and an increase in sorghum yield by 26% following FOS application. FOS can endophytically colonize the root system of the maize host, and from this base, can attack Striga spp. at all growth stages including seeds, seedlings, and flowering shoots, thus affecting the target prior to seed set and crop yield loss, thereby reducing the Striga seedbank [55,58]. Fungi are preferred to other microorganisms as bio-herbicides because they are usually host-specific, attacking only Striga spp. [15,59,60]. Additionally, fungi are highly aggressive, easy to mass produce and are diverse in terms of number of strains available [7,61]. FOS compatible genotypes support no or few Striga plants and produce relatively high yields under Striga infestation. Thus, the use of host plant resistance combined with FOS and sound cultural practices is a viable strategy for enhancing crop yields in Striga infested fields. The development of host plant resistance through breeding is a fundamental component of a sustainable integrated Striga management strategy to minimize yield losses in farmers' fields. A successful maize breeding program depends mainly on the available genetic variation within the germplasm resources [62,63]. Therefore, the aim of the present study was to screen genetically diverse maize genotypes with farmer preferred traits from a range of distinct sources, and to screen these genotypes for resistance to S. asiatica and S. hermonthica, and for FOS compatibility, aiming to develop an integrated Striga control program in Tanzania.

Germplasm
The study used 56 genetically diverse maize genotypes consisting of 34 landraces acquired from the National Plant Genetic Resources Centre (NPGRC), Tanzania, 18 improved Open Pollinated Varieties (OPVs) from the International Institute of Tropical Agriculture (IITA), Nigeria, and four OPVs from Tanzania Agricultural Research Institute (TARI), Tanzania. The IITA collection included 17 Striga-resistant genotypes and one Striga susceptible genotype which were used as checks. The details of the studied genotypes are presented in Table 1.

Collection of Striga Seeds
Striga seeds were collected from maize and sorghum fields infested with either of the two Striga species or both in the 2016/2017 growing season. The seed of S. asiatica was collected at the TARI-Hombolo Research Centre, Dodoma region and the TARI Tumbi Research Centre, Tabora region, while the seed of S. hermonthica was collected in the Mbutu and Igogo wards, Igunga district, Tabora region. Striga seeds from both species were separately processed, packed, labelled, and stored in the Soil Science Laboratory of TARI Tumbi for further use.

Collection and Inoculation of Fusarium Oxysporum f. sp. Strigae (FOS)
A virulent strain of FOS was used as the biocontrol agent. This was initially isolated from severely diseased Striga plants in sorghum fields in north-eastern Ethiopia [7]. The host specificity and pathogenicity of the FOS isolate on Striga spp. have been previously described by Gebretsadik et al. [7]. The Phytomedicine Department of Humboldt University in Berlin, Germany confirmed the taxonomic identification of FOS [7]. Pure FOS spores are produced and preserved by Plant Health Products (Pty) Ltd., KwaZulu-Natal, South Africa [7]. FOS in a dry powder formulation (supplied by Dr. M.J. Morris of Plant Health Products (Pty) Ltd.) was used to coat the maize seeds before sowing. The 26.8 mg of FOS inoculum was applied to the whole surface of the seed. The specialized hairy structures present at the tip of maize seeds (the pedicel) bind enough FOS inoculum to be effective, without the need for a sticker.

Experimental Procedure
The experiment was established during the 2017/2018 growing season in a screen house facility at TARI-Tumbi Research Centre situated in the Tabora Municipality, western Tanzania. The center is located at 5 • 03 S Latitude and 32 • 41 E Longitude with an altitude of 1190 m above sea level. The experiment was established using a split-plot design, with a FOS treatment being the main plot factor and maize genotypes as the subplot factor. The genotypes were sown in a screenhouse using polyethylene plastic pots (250 mm diameter and 350 mm height) filled with a growing medium consisting of topsoil and sandy soil mixed at a ratio of 6:3. A total of 1680 pots were filled with the growing medium and divided into sets of 336, and two equal sets of 672 pots. The set of 336 pots was not infested with Striga seeds nor treated with FOS (the untreated, uninoculated control). The first set of 672 pots was infested with 30 mg of one-year old S. asiatica (Sa) seeds uniformly distributed at a depth of 30 mm in the growing medium. The second set of 672 pots was infested with 30 mg of one-year old S. hermonthica (Sh) seeds. After 14 days of Striga seed preconditioning, maize seeds were sown in the following order: half of the pots (336) assigned either to Sa or Sh were planted with 2 seeds of the maize genotypes coated with 26.8 mg of FOS powder. The seeds planted in the other 336 pots infested with Sa or Sh were not inoculated with FOS. After emergence, maize plants were thinned to one seedling per pot. Each experimental plot consisted of 2 pots, and these were replicated three times for each treatment. Other agronomic practices used were irrigation, soil fertilization, and weeding. Weeds other than the two Striga species were uprooted manually.

Data Collection
Data were collected based on maize agronomic characters and Striga resistance parameters. The following data were recorded on maize plants: days to 50% anthesis (50% AD) was recorded as the number of days from sowing to when 50% of the plants in a plot shed pollen. The days to 50% silking (50% SD) was recorded as the number of days from planting to when 50% of the plants in a plot produced silks. Anthesis-silking-interval (ASI) was determined as the difference between days to 50% silking and 50% anthesis. The days to 75% maturity (DM) were recorded as the number of days from planting to when 75% of the plants reached physiological maturity [64]. Plant height (PH) was measured from the base of the plant (expressed in cm) to the top of the first tassel branch. Ear height (EH) was measured (cm) from the ground level to the node bearing the uppermost ear. Grain yield/plant (GY) was determined as the weight (g), of the grain from the ears of individual plants after shelling, converted to a constant moisture of 12.5%. Hundred-grain weight was recorded based on a weight (g) of 100 kernels at field moisture content and converted to a constant moisture of 12.5%. The above-ground biomass (AGB) was determined by weighing (g/plant) the above-ground plant parts which included: leaves, stems, and ears. Individual maize plants were cut at the base of the stem.
The following Striga parameters were recorded: Striga emergence counts were recorded at 8 weeks after planting (SEC8) and 10 weeks after planting (SEC10) as the number of emerged Striga plants per genotype. A rating of host plant damage was made at 8 and 10 weeks after planting, denoted as SDR8 and SDR10, using a scale of 1 to 9 as described by Kim [40]. A scale of 1 = normal maize growth with no visible symptoms and 9 = virtually all area scorched, two thirds or more reduction in height, most stems collapsing, no useful ear formed, miniature or no tassel, no pollen production, and dead or nearly dead plant.

Data Analysis
Maize agronomic and Striga parameters were organized in an Excel spreadsheet and subjected to analysis of variance (ANOVA) using the split-plot procedure in GENSTAT 18th Edition [65]. Significance tests were carried out at the 5% probability level. Data on the Striga emergence counts were square root transformed (y = √ (x + 0.5)) before analysis to meet normalization assumptions. Mean separation was performed using Fisher's least significant difference (LSD) test at the 5% probability level. Correlation analysis was conducted separately between FOS-treated and untreated maize genotypes under both Sh and Sa infestation to discern the relationship among maize agronomic traits and Striga parameters. Furthermore, maize agronomic data and Striga parameters from FOS-treated and untreated genotypes were subjected to principal component analysis (PCA) using the mean values of the 56 maize genotypes using the Statistical Package for Social Science Studies (SPSS) Version 24.0 (SPSS, 2017) [66], to group and identify important traits under Striga infestation, with and without FOS treatment.

Effects of FOS on Maize Genotypes and Striga Hermonthica Parameters
Genotypes exhibited highly significant (p < 0.001) differences for all agronomic traits studied under Sh infestation, with and without FOS treatments (Table 2). Furthermore, the test genotypes differed significantly (p < 0.001) for all S. hermonthica parameters studied ( Table 2). The interaction between maize genotypes and FOS was highly significant (p < 0.01) for all the maize traits assessed except hundred kernel weight. The interaction between maize genotypes and FOS showed highly significant (p < 0.001) differences for S. hermonthica resistance parameters such as Sh emergence count at eight weeks after planting (ShEC8) and ten weeks after planting (ShEC10), except for the Sh damage rating at both ShEC8 and ShEC10 (Table 2).

Effects of FOS on Maize Genotypes and Striga Asiatica Parameters
The ANOVA revealed highly significant (p < 0.001) differences for all maize agronomic traits studied under Sa infestation, with and without FOS treatment (Table 5). FOS treatment on maize genotypes significantly (p < 0.001) affected the test genotypes and Sa resistance traits. The interactions between maize genotypes and FOS were highly significant (p < 0.01) for all the maize traits studied except for hundred kernel weight. Likewise, the interaction mean squares between maize genotypes and FOS exhibited significant (p < 0.001) differences for the Sa emergence counts at 8 and 10 weeks after sowing (Table 5).  Under Sa infestation, FOS-treated genotypes had higher grain yields than untreated genotypes (Table 6). Mean grain yields in the controls, FOS-treated, and untreated genotypes with Sa infestation were 93.86, 77.07 and 73.80 g/plant, respectively. On average, FOS-treated genotypes under Sa infestation suffered a grain yield reduction of 18%, while untreated genotypes had a 21.4% grain yield loss, compared to the control treatment (Tables 4 and 6). Grain yield performance of some FOS-treated genotypes under Sa infestation surpassed that of the control treatment, including TZA1780 (31.44%), TZA3181 (28.47%), JL21 (11.48%), TZA1782 (10.27%), TZA604 (8.81%), TZA3964 (6.71%) and TZA4165 (6.04%). Conversely, grain yield for TZA1780 under Sa without FOS treatment exceeded that of the control treatment by 7.18%. Grain yield for the genotypes JL03 and JL13 under Sa infestation with FOS treatment are not substantially different from that of the control (Tables 4 and 6). The mean fresh biomass was 190.6 g/plant in the control, 150.9 g/plant in FOS-treated and 143.6 g/plant in untreated genotypes under Sa infestation. The mean above-ground biomass under Sa infestation, with and without FOS application, varied from 60 (TZA3502) to 350 g/plant (TZA1780), and 65 (TZA3502) to 318.30 (TZA1780) g/plant, respectively. The mean plant height was 294.27 cm in the control, 279.56 cm in FOS-treated and 272.64 cm in untreated genotypes, respectively. Plant height was reduced by 5% for FOS-treated genotypes and 7.4% for untreated genotypes, under Sa infestation compared to the control. Based on the number of emerged Sa plants, FOS compatibility and grain quality characteristics, the following genotypes were selected for Striga resistance breeding purposes: TZA4205, TZA1775, TZA3417, TZA4203, TZA1780, TZA4010, TZA4165, TZA4016, TZA2263, TZA3827, JL24, JL22, JL01, JL05, JL08, JL09, JL13, JL15, JL16, JL17, JL18, JL19, and JL20.

Principal Components Analysis (PCA) of the Maize Agronomic Traits and S. hermonthica Parameters under Sh infestation, with and without FOS Treatment
A summary for the rotated component matrix of the PCA, following Varimax rotation with Kaiser Normalization is presented in Table 9 for maize agronomic traits under Sh infestation, with and without FOS treatment. Three principal components were important in allocating traits for both FOS-treated and untreated maize genotypes. From the untreated maize genotypes evaluated under Sh infestation, the first three principal components (PCs) with eigen values greater than 1 accounted for 75.47% of the total variation ( Table 9). The first principal component (PC1) was dominated by four Sh resistance parameters (ShEC8, ShEC10, ShDR8, ShDR10) and explained 28.06% of the total variance relating to Striga infestation. The second principal component (PC2) was highly influenced by four maize agronomic traits (AGB, DM, AD and SD) with high positive loadings explaining 23.77% of the total variation. The third principal component (PC3) was mainly associated with three maize traits (PH, EH and ASI) with high positive loadings, and GYD with a high negative loading, contributing 23.64% of the total variation (Table 9). Likewise, in the FOS-treated genotypes under Sh infestation, three principal components were significant, and explained 74.19% of the total variance in the original data set (Table 9). Sh parameters (ShEC8, ShEC10, ShDR8, ShDR10) were the main contributors of the first principal component (PC1), accounting for 28.9% of the total variation. The second principal component (PC2) was governed by traits such as AGB, AD, DM, explaining 23.85% of the total variance, whereas maize traits such as PH, EH and ASI had high positive loadings into the third principal component (PC3), describing 21.43% of the total variance (Table 9).    asiatica plants (count) recorded ten weeks after sowing, SaDR8-S. asiatica damage rating recorded eight weeks after sowing, SaDR10-S. asiatica damage rating recorded ten weeks after sowing.   50% AD-Number of days from sowing to when 50% of the plants in a plot shed pollen, 50% SD-Number of days from sowing to when 50% of the plants in a plot produce silk, ASI-Anthesis-silking interval, PH-Plant height (cm), EH-Ear height (cm), DM-Days to maturity, GYD-Grain yield/plant (g), HKWT-Weight of 100 kernel (g), AGB-Above-ground biomass recorded as the weight (g) of above-ground plant parts, SaEC8-Number of emerged Striga asiatica plants (count) recorded eight weeks after sowing, ShEC10-Number of emerged Striga asiatica plants (count) recorded ten weeks after sowing, SaDR8-Striga asiatica damage rating recorded eight weeks after sowing, SaDR10-Striga asiatica damage rating recorded ten weeks after sowing. PC1, PC2, and PC3-denote Principal components 1, 2, and 3, respectively.

Discussion
The present study identified highly significant differences for all maize agronomic traits and Striga parameters studied under both Sh and Sa infestation, with and without FOS treatments (Tables 2 and 5). This suggests that the test genotypes possess adequate genetic variability from which selection for Sh and Sa resistance breeding could be done. The higher the genetic variation present among the test genotypes, the greater the probability of success for developing new superior Striga-resistant varieties. An effective maize breeding program depends primarily on the available genetic variation within and between the genetic resources [62,63].
The application of the FOS treatment to the maize genotypes significantly (p < 0.001) affected the test genotypes and Striga parameters. The high variability behavior of the test genotypes for all the Striga parameters studied, with and without FOS treatment, could be ascribed to the genetic constitutions and FOS compatibility. Striga emergence count, Striga damage rating, and grain yield under Striga infestation are significant traits for describing the level of resistance of genotypes to Striga infestation [67,68]. The interaction between maize genotypes and FOS was significant (p < 0.05) for all the maize traits studied except for hundred kernel weight. Likewise, the interaction mean squares between maize genotypes and FOS exhibited significant (p < 0.001) difference for Sh and Sa emergence counts at eight and ten weeks after sowing (Tables 2 and 5). This measures the compatibility of the test genotypes with the biocontrol agent, FOS, and thus selections could be made, based on the genotypes individual Striga resistance and their FOS compatibility, under Sh and Sa infestation. Significant interactions between FOS and genotypes suggests the presence of synergistic effects between them for the management of Striga spp. Compatibility between test genotypes and FOS allows the biocontrol agent to colonize the root rhizospheres of the host genotypes, and subsequently to suppress Striga growth and establishment [10,56,57], reducing Striga parasitism to the host plant roots and improving grain yield [7,10,56]. In the present study, FOS-treated genotypes recorded higher grain yields than the untreated genotypes under both Sh and Sa infestation (Tables 3 and 6). The mean grain yield for FOS-treated genotypes under Sh infestation increased by 5.12 g/plant yield relative to the untreated treatment, amounting to 6.80% (Table 3). Likewise, under Sa infestation, FOS-treated genotypes had a mean yield increase of 4.5% (Table 6). These findings agree with those reported by Shayanowako et al. [56] and Venne et al. [57], when studying the effect of FOS on maize genotypes under Sh and Sa infestation, respectively.
Grain yield performance of some FOS-treated genotypes under both Sh and Sa infestation surpassed that of the control treatment. These included TZA3181 (28.47%), TZA1782 (19.07%), JL21 (14.73%), TZA3964 (12.2%), TZA604 (9.11%) and JL25 (10.40%) (Tables 3  and 6). Similar findings have been reported by [10] when screening sorghum genotypes for FOS compatibility under Sh and Sa infestation. This confirms the effectiveness of FOS in enhancing the performance of the test genotypes assessed under Sh and Sa infestation. Furthermore, the present study recorded higher fresh biomass for FOS-treated genotypes compared to untreated genotypes under both Sh and Sa infestation (Tables 3 and 6). Under Sh infestation the following FOS-treated genotypes recorded higher fresh biomass than the uninfested and untreated control treatment: TZA3827 (33.3 g/plant), JL08 (28.3 g/plant), JL05 (31 g/plant) and TZA4203 (26 g/plant) (Tables 3 and 4). Likewise, under Sa infestation, the following FOS-treated genotypes had fresh biomass that surpassed that of the control (uninfested and untreated): TZA3827 (32.5 g/plant), TZA599(30 g/plant) and JL24 (21 g/plant) (Tables 4 and 6). This confirms the effectiveness of FOS in suppressing the Striga spp. and its ability to stimulate plant growth in compatible genotypes. Thus, water, nutrients, and inorganic solutes from the host xylem could be translocated towards the upper plant parts, improving plant vigor, biomass, and consequently grain yield. Studies done earlier on the efficacy of FOS on sorghum genotypes recorded higher fresh biomass on FOStreated genotypes than untreated control under Striga spp. infestation [7,10]. Furthermore, FOS-treated genotypes recorded significantly lower numbers of emerged Striga plants at both eight and ten weeks after sowing. Under Sh infestation, FOS-treated genotypes supported reduced Striga numbers by up to 90.72% (TZA4165) at ten weeks after sowing (Table 3). Likewise, under Sa infestation, FOS was able to reduce the number of emerged Sa plants up to 90.7% (TZA3417) ten weeks after sowing (Table 5). This confirmed the ability of the mycoherbicide to attack Striga spp. at different growth stages before emergence and flowering. The reduction of Striga number in FOS-treated maize genotypes was reported earlier in field and pot experiments [56,57]. FOS reduces Striga spp. though complete digestion of Sh and Sa seedlings inside the host and clogging of vessels of emerged Striga plants by hyphae, causing wilting and subsequent death of Striga plants [69]. The present study noted some cases where there were few or zero emerged Striga plants, as well as wilting of emerged Striga plants in some of FOS-treated pots, suggesting the efficacy of FOS in infecting Striga seeds, seedlings, and shoots. Comparable observations have been reported before in field and pot experiments involving maize and sorghum treated with FOS [10,70]. Some FOS-treated genotypes (TZA604, TZA3952, TZA4064 and JL01) under both Sh and Sa infestation supported an increased number of emerged Striga plants at eight and ten weeks after planting, suggesting FOS incompatibility. Some Striga-resistant genotypes excrete exudates that are inhibitory to fungal growth, rendering them FOS incompatible [57]. Conversely, FOS compatible maize genotypes release exudates that activate virulence genes of the Striga mycoherbicide to efficiently suppress the parasite [56]. FOS is highly host-specific, and it may be more compatible with some maize genotypes than others [60,71,72].
In the present study, secondary traits such days to 50% anthesis, days to 50% silking, anthesis-silking-interval, plant height, and ear height under Sh and Sa infestation, revealed significant and positive correlations with Striga parameters after FOS treatment (Tables 7  and 8). This suggested that selection of one trait may simultaneously improve the other under FOS treatment. It has been reported that secondary traits play a significant role in the selection for improved grain yield under Striga infestation [73]. The studied Striga parameters of Striga emergence counts at eight and ten weeks after planting, and Striga damage rating at eight and ten weeks after planting were highly significant and positively correlated among each other. This suggests that selection for one trait may improve the performance of another simultaneously. Therefore, either of these parameters could serve as a selection criterion for the evaluation of genotypes for Striga resistance [41].
Principal component analysis performed on the mean values of each trait, identified the most important traits that accounted for most of the variance in the data set (Tables 8 and 9). Striga emergence count and Striga host damage rating at eight and ten weeks after sowing were the most significant traits, which accounted for the highest proportion of the variance in the data set. These traits were loaded in the first principal component (PC1) under both Sh and Sa infestation, with and without FOS treatment. Comparable results have been reported earlier in sorghum study involving FOS treatment [7]. Maize traits such as above-ground biomass, days to 50% anthesis, and days to maturity formed the second-best linear combinations of traits and were loaded in the second principal component (PC2) under both Sh and Sa infestation with and without FOS application. The traits grouped by the principal components, reflected significant relationships with Striga parameters under the Pearson correlation matrix, while Striga traits had strong positive correlations with each other. This suggests their usefulness in discriminating between the genotypes and should be considered during evaluation for Striga resistance [56]. The strong negative loading found on grain yield per plant was expected because as Striga thrives, it causes damage to the host, thereby reducing grain yield.

Conclusions
The application of FOS to maize genotypes under both S. hermonthica and S. asiatica infestation enhanced the resistance of the test genotypes to Striga and significantly reduced the number of emerged Striga plants and the levels of Striga-induced host damage, and subsequently improved grain yield of many test genotypes, compared to the untreated ones. The study demonstrated the value of combining host plant resistance, farmers compatible cultural practices and FOS for integrated Striga control in maize in Tanzania. Additionally, the study identified 23 genotypes with variable resistance, high grain yield, farmers preferred traits and FOS compatible for a Striga resistance breeding program in Tanzania. Development and deployment of Striga-resistant and FOS compatible crop genotypes is a fundamental component of an integrated Striga management strategy in Striga infested agricultural lands. However, the identified maize genotypes need to be evaluated in multiple field conditions after FOS treatment to substantiate the findings recorded in the screen house.  Data Availability Statement: All data generated or analyzed during this study are included in the present article.