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This article presents findings from baseline surveys in 5 states of Nigeria to assess the nutritional outcomes on target groups on attaining the UN Sustainable Development Goal 2. The augmented regression technique was applied to analyze data from a sample of 1642 households with at least 1 child under the age of 5 years (U5) and their mothers or caregivers out of a total of 2500 households that were drawn from the 250 enumeration areas of the Nigeria Bureau of Statistics in the 5 states. The results support the growing evidence base that poverty and household hunger are pervasive. The incidence of poverty highlights inequalities among states. The combination of poverty and hunger was mirrored in the damning extent to which all forms of malnutrition coexisted in children U5, particularly during the second year of infancy and among poor households. Evidence from this study points to poor dietary quality of complementary food rather than other childcare practices as majorly responsible for child malnutrition. Child wellness was positively affected by maternal health-seeking behavior but negatively by the poverty probability index of the household. Notably, maternal health-seeking behavior played a more relevant role in child wellness than mothers’ educational attainment.

Freely nodulating soybean genotypes vary in their phosphorus (P) uptake and P-use efficiency (PUE) in low-P soils. Understanding the genetic basis of these genotypes’ performance is essential for effective breeding. To study the inheritance of PUE, we conducted crosses using two high-PUE genotypes, two moderate-PUE genotypes and two inefficient-PUE genotypes, and obtained F1, F2, BC1 and BC2 populations. The inheritance of PUE was evaluated using a randomized complete block design. A generation mean analysis of phenotypic data showed that PUE was heritable, with complex inheritance patterns and the presence of additive, dominance and epistatic gene effects. Seed P, shoot P, root P, P-incorporation efficiency and PUE were largely quantitatively inherited traits. There were dominance, additive × additive and dominance × dominance gene effects on PUE, grain yield, shoot dry weight, 100-seed weight, root dry weight and shoot dry matter per unit P for populations grown under low-P conditions. Dominance effects were generally greater than additive effects on PUE-related indices. These PUE indices can be used to select P-efficient soybean genotypes from segregating populations.

Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by western corn rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to western corn rootworm larval feeding are currently commercially available. We investigated the genetic basis of western corn rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to western corn rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against western corn rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of western corn rootworm resistance.

The soybean aphid, Aphis glycines, is a pest of soybean in Asia, and it has become a major pest of this crop in North America with large outbreaks that cause significant yield loss. Host-plant resistance is one management tactic being developed against soybean aphid in North America, and resistance may be manifested as antixenosis, antibiosis, or tolerance. In this study, choice tests were conducted to identify antixenosis to soybean aphids in several soybean lines. The soybean lines 'Dowling,' PI 230977, 'Jackson,' 'Cobb' and 'Palmetto' had strong antixenosis to soybean aphid, and lines PI 71506, G93-9223, 'Braxton,' 'Cook,' 'IAC-1,' 'Ripley,' and 'Tie feng 8' were moderately antixenotic. The intermediate level of antixenosis in PI 71506 contrasts with previous results, and suggests biotypic differences in the responses of soybean aphid to this line. Shoot length, shoot width, and seedling dry mass were also measured to test for any association between aphid host choice and plant size. Plant-size parameters varied by soybean line in all tests. However, the relation between aphid host choice and plant-size parameters was generally weak and not consistent across tests, suggesting that other undetermined plant characteristics were important in host selection. The identification of antixenosis in several soybean lines provides soybean breeders and pest management practitioners with additional options for managing soybean aphid through host-plant resistance. Antixenosis may be important on its own, and it may prove be complimentary to the antibiosis mode of resistance by reducing selection on resistance-breaking biotypes of soybean aphid, thereby prolonging the usefulness of plant resistance as a non-chemical means of managing soybean aphid.

Thirteen early-maturing and promiscuously nodulating soybean [Glycine max (L.) Merr.] varieties that belonged to maturity group I developed at the International Institute of Tropical Agriculture (IITA) from 1980 to 1996 were evaluated at two locations in the Guinea savanna of Nigeria in 2001 and 2002 to determine genetic gain in grain yield and associated agronomic traits. The varieties were grown in a randomized complete block design with four replications. Data on grain yield and seven other traits were recorded. The study showed that grain yield potential of the soybean varieties increased from 1117 to 1710 kg ha –1 during two decades of breeding in IITA. The average rate of increase per year per release period (1980–1996) was 24.2 kg ha –1 , which is 2.2%. Fodder yield also showed an annual increase of 22.81 kg ha –1 yr –1 . Recent varieties had better lodging resistance scores of 1.25 to 1.37 in a 1 to 5 scoring scale (1 being resistant and 5 susceptible), shattering resistance scores of 1.6 to 2.7, and improved natural nodulation scores of 3.1 to 3.9. Old varieties had 50% or more pod shattering while the corresponding fi gure for new varieties was around 25%. Old varieties produced few and small nodules, while new varieties had many big nodules although size and number of nodules alone may not necessarily indicate nodule effi ciency in N 2 fi xation. Grain yield showed a positive and highly signifi cant (P ≤ 0.01) correlation coeffi cient (r = 0.75) with fodder yield, implying that high biomass could serve as an indicator of good yielding ability.

The direct effects of three soybean parentages, each represented by an Aphis glycines-resistant and susceptible isoline, on the fitness and performance of two key predators (Orius insidiosus and Harmonia axyridis) were evaluated in the laboratory. Predators were reared from hatch through adulthood in Petri dishes with cut trifoliolate leaves of the designated soybean variety, using eggs of Ephestia kuehniella as surrogate prey to eliminate prey-mediated effects of the host plant. Preimaginal survival and development, sex ratio, adult longevity, fecundity, and size were compared among treatments and a no-plant control. An additional experiment compared life-history parameters of predators caged with soybean versus Ipomoea hederacea (ivyleaf morning glory). Aphid resistance reduced the adult longevity of H. axyridis, but O. insidiosus was unaffected by resistance traits. However, adult O. insidiosus lived longer on soybeans with Group C base genetics than the other soybean varieties. Other parameters were not affected by soybean base genetics or resistance, but both predators generally performed worse on soybean than on I. hederacea or no-plant controls. The results suggest that soybean varietal selection, particularly with respect to A. glycines-resistance, may directly affect biological control agents. Also, implications of the generally poor suitability of soybean for natural enemies are discussed within the context of current crop production practices.

Larval corn rootworms (Coleoptera: Chrysomelidae) are soil-dwelling insect pests that damage maize (Zea mays L.) by consuming root tissues, thus lowering grain yield. Little is known about interactions between rootworms and soil bacteria, including potential impacts of maize rhizobacteria, such as entomopathogenic Serratia spp., on subterranean rootworm pests. We used selective growth medium (caprylate-thallous agar, CT) to quantify and isolate Serratia spp. from: (1) bulk soil, (2) roots of four field-grown maize genotypes, half of which were infested with rootworm eggs from a reared colony, and (3) non-diseased, larval rootworms from the same colony. Phenotypic testing and 16S rRNA gene sequencing were used to identify bacteria, including non-Serratia spp., that were successfully isolated on the CT solid medium. We also isolated and identified Serratia spp. associated with non-diseased and diseased Diabrotica adults. Serratia spp. associated with maize roots were more abundant than those associated with bulk soil, where they were undetectable with our methods except for Serratia grimesii. There was no impact of plant genotype on densities of bacteria isolated from maize roots. S. grimesii was frequently associated with maize roots, regardless of infestation with rootworm eggs. Serratia marcescens biotype A4, Serratia plymuthica and several other Enterobacteriaceae genera were also associated with maize roots. Infesting the soil with rootworm eggs enhance the occurrence of two strains of the S. marcescens biotype A1b, with comparable densities of these orange and pink strains within infested roots. However, both strains were associated with larval rootworms from the reared colony, which may indicate that rootworms were introducing these bacteria into infested maize roots. In addition, within larvae the orange strain was significantly more abundant than the pink strain, and was also associated with diseased rootworm adults. Our studies identified specific Serratia strains associated with diseased rootworms that may have potential as biological control agents, and additional Serratia biotypes associated with the maize rhizosphere that, based on the literature, may function as plant growth promoting agents via antagonistic action against plant-pathogenic fungi.

The soybean aphid, Aphis glycines Matsumura, is a pest of soybean [Glycine max L. (Merrill)] in Asia, and its recent establishment in North America has led to large, recurring outbreaks that have challenged pest management practitioners to seek environmentally responsible means for its control. Growth-chamber experiments identified resistance to A. glycines in soybean lines ‘Perrin’; ‘Tracy-M,’ its glabrous near-isoline ‘D88-5328,’ and its densely pubescent near-isoline ‘D88-5272’; ‘D75-10169,’ its glabrous near-isoline ‘D90-9216,’ and a densely pubescent near-isoline ‘D90-9220.’ Tracy-M and D75-10169 were antixenotic to A. glycines in host-selection tests. In no-choice nymphiposition tests, the number of nymphs deposited by A. glycines on D75-10169, Perrin, and Tracy-M did not differ from that on other lines after 24- and 48-h test periods. Under conditions in which A. glycines were free to distribute on plants over a 48-h period, aphids were found primarily on stems and trifoliolate leaves of Perrin, Tracy-M, D75-10169 and a resistant control, ‘Dowling,’ whereas the majority of aphids infesting susceptible lines ‘91B91’ and ‘Davis’ were distributed on unifoliolate leaves. Irrespective of shoot structure, low numbers of A. glycines were found on Dowling compared to other lines. The mean number of days to reproductive maturity for A. glycines did not differ among lines. Aphis glycines produced fewer nymphs during the first 7 d of reproduction on Perrin, Tracy-M, D75-10169 and Dowling compared to Davis, and fewer A. glycines progeny were produced on D75-10169 and Dowling than on 91B91. Results show that Dowling continues to be a strong source of resistance to A. glycines. Perrin, Tracy-M, and D75-10169 have been used as sources of resistance to other insects, and discovery of resistance to A. glycines in these three lines may increase their utility in soybean breeding programs.

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), a pest of soybean, Glycine max (L.) Merr., native to Asia, has recently become a principal pest of this crop in many areas of North America. Insecticides are currently used to manage A. glycines, but host plant resistance is a potential alternative management tool. Tests were conducted to determine resistance to A. glycines among soybean lines. 'Cobb,' 'Tie-feng 8,' and 'Jackson' were resistant to population growth of A. glycines compared with 'Cook' and '91B91,' a susceptible control. Antibiosis was evident in Cobb, Jackson, and Tie-feng 8 from lowered survival of first generation A. glycines, and in Cobb, Jackson, Tie-feng 8, and 'Braxton' from diminished reproduction by first generation aphids. Antixenosis was apparent in Cobb and Jackson during initial infestation of aphid population growth tests, because A. glycines were unsettled and dispersed readily from placement points on unifoliolate leaves. Decreased nymphiposition by A. glycines occurred on Cobb and Jackson, and it may have been caused by antibiotic chemicals in these lines, failure of aphids to settle, or both. Differences in distribution of A. glycines between unifoliolate leaves and other shoot structures suggest that unifoliolate leaves were acceptable feeding sites on 91B91 and Cook, whereas unifoliolate leaves and other shoot structures were roughly equally acceptable feeding sites on Braxton, Tie-feng 8, Jackson, and Cobb. However, Jackson and Cobb had relatively low counts of A. glycines on shoots that may have been due to abandonment of plants by aphids, decreased aphid survival, or both. Results confirm earlier findings that Jackson is a strong source of resistance to A. glycines, and they suggest that Tie-feng 8, Braxton, and especially Cobb are potentially useful sources of resistance.

Soils of many potential soybean fields in Africa are characterized by low levels of biological nitrogen fixation (BNF) activities and often cannot support high soybean yields without addition of inorganic N fertilizers or external application of soybean rhizobia. The most probable number (MPN) technique was used to determine the bradyrhizobial populations that nodulate TGx soybean genotypes (a cross between nonpromiscuous North American soybean genotypes and promiscuous Asian soybean genotypes), cowpea or North American soybean cv. Clark IV, in soils from 65 sites in 9 African countries. The symbiotic effectiveness of isolates from these soils was compared to that of Bradyrhizobium japonicum strain USDA110. The bradyrhizobial population sizes ranged from 0 to 104 cells g−1 soil. Bradyrhizobium sp. (TGx) populations were detected in 72% and B. japonicum (Clark) in 37% of the soil samples. Bradyrhizobium sp. (TGx) populations were generally low, and significantly less than that of the cowpea bradyrhizobial populations in 57% of the samples. Population sizes of less than 10 cells g−1 soil were common as these were detected in at least 43% of the soil samples. B. japonicum (Clark) occurred in higher population densities in research sites compared to farmers’ fields. Bradyrhizobium sp. (TGx) populations were highly correlated with biotic but not abiotic factors. The frequent incidence of low Bradyrhizobium sp. (TGx) populations is unlikely to support optimum BNF enough for high soybean yields while the presence of B. japonicum (Clark) in research fields has the potential to compromise the selection pressure anticipated from the indigenous Bradyrhizobium spp. (Vigna) populations. Bradyrhizobium isolates could be placed in four symbiotic phenotype groups based on their effectiveness on a TGx soybean genotype and the North American cultivar Clark IV. Symbiotic phenotype group II isolates were as effective as B. japonicum strain USDA110 on both soybean genotypes while isolates of group IV were effective on the TGx soybean genotype but not on the Clark IV. The group IV isolates represent a unique subgroup of indigenous bradyrhizobia that can sustain high soybean yields when available in sufficient population densities.

The soybean aphid, Aphis glycines Matsumura, is a pest of soybean [Glycine max L. (Merrill)] in Asia, and its recent establishment in North America has led to large, recurring outbreaks that have challenged pest management practitioners there to seek environmentally responsible means for its control. Growth-chamber experiments were conducted to determine and characterize host-plant resistance among several soybean accessions. Soybean plants were first screened for resistance by rating the population growth of A. glycines in two tests. All plants of PI 230977 and 25% of PI 71506 plants were resistant (≤100 aphids per plant) in the first screening test. All ‘Dowling’, PI 71506 and PI 230977 were resistant (≤150 aphids per plant), and 50% of plants of line ‘G93-9223’ were resistant in the second test. Follow-up experiments showed that antixenosis was a modality of resistance based on reduced nymphiposition by A. glycines on Dowling, PI 230977 and PI 71506 in no-choice tests and on fewer numbers of A. glycines on Dowling, PI 230977, PI 71506 and G93-5223 in distribution tests. Antixenosis in Dowling and PI 230977 was stronger in the unifoliolate leaves than in other shoot structures, whereas distribution of A. glycines within plants of PI 71506 and G93-5223 suggested comparable suitability between unifoliolate leaves and other shoot structures of these accessions. Antibiosis to A. glycines was evident as a lower proportion of aphids that reproduced on PI 230977 and from fewer progeny on PI 230977 and Dowling than on 91B91. The number of days from birth to reproduction by A. glycines did not differ among accessions. Results confirmed Dowling and PI 71506 as strong sources of resistance to A. glycines. The levels of antixenosis and antibiosis to A. glycines in PI 230977 and antixenosis to A. glycines in G93-9223 suggest that these accessions may also be valuable to soybean breeding programs as sources of resistance.

Conventional breeding is widely used for modification of various crop and oilseed traits such as fatty acid composition and disease resistance. The effect of these modifications on the nutritionally beneficial bioactive plant components is usually overlooked unless these components are the specific targets for the modifications. The objective of this study was to examine the effect of breeding on nutritionally beneficial bioactive peanut components. The modified peanut lines Tamrun OL 01, Tamrun OL 02, TX977164 and TX977239 were analyzed for their tocopherol, phytosterol, and phospholipid compositions. Sunoleic and Tamrun 96 were the parent lines of these breeding lines. Parent lines were used as controls to examine the compositional changes resulting from breeding. The experimental results indicated that these peanut breeding lines were rich in α-tocopherol. Tamrun OL 01 had the highest total phytosterol content among the peanut breeding lines examined in this study. All the breeding lines were rich in phosphatidylcholine. Although there were some statistical differences in chemical composition among the peanut breeding lines, these variations were within the range reported for traditional peanut varieties.

With limited access to P fertilizers, soybean (Glycine max (L.) Merr.) varieties cultivated in the moist savanna zone of West Africa should use P as efficiently as possible. Field trials were conducted on the effect of P application on grain yield per unit P accumulated (physiological efficiency or PPE), amount of P accumulated in plant biomass per unit P applied in fertilizer (recovery efficiency or PRE), and the amount of grain produced per unit of applied P (yield efficiency or PYE) in soybean. There was greater proportional root proliferation at lower P rates, and at sites where soil test P was low. Physiological efficiency was higher under these conditions. Although a greater proportion of total dry weight was accumulated in the roots of the early and medium (27-28%) compared with the late varieties (22-23%), root dry weight and PPE in the latter were higher. At maturity, PPE was significantly reduced from 245 kg kg−1 with no P applied to an average of 173 kg kg−1 (or by about 29%) with P ap...

Sclerotinia blight, caused by Sclerotinia minor Jagger, has become one of the major limiting factors in peanut (Arachis hypogaea L.) production. The objectives of this research were to evaluate the effects of plant spacing on disease incidence and severity of Sclerotinia blight in peanut research plots, to measure the level of apparent resistance at different seeding rates, and to determine which methods would produce clearest selection criteria in space-planted breeding plots. Four peanut cultivars, Tamspan 90, Southwest Runner, Okrun, and Flavor Runner 458, were evaluated in field plots at four plant spacings (6, 15, 30, and 46 cm) in 2003 and 2004. Increased plant spacing improved sensitivity of disease incidence based determination of cultivar resistance but did not increase mean incidence significantly. Disease severity reached the highest level at the widest plant spacing. Final disease incidence provided excellent differentiation of genotypes with different levels of resistance and required the least amount of labor as compared with other methods of disease assessment.

Several legumes with high biological nitrogen fixation (BNF) potentials have been studied in on-station trials. The processes involved in BNF and the benefits of these species to crop production need to be evaluated using farmers' management practices in farmers' fields. An on-farm trial with 20 farmers was conducted in the northern Guinea savanna (NGS) of Nigeria. The aims were to evaluate the BNF potentials of an improved soybean variety (TGx 1448-2E) and a local variety (Samsoy-2) when inoculated with Bradyrhizobium strains, and of Lablab in farmer-managed and researcher-managed soybean-maize and Lablab-maize crop rotation systems. The level of soil P was generally low with more than 50% of the fields having less than the critical P level. The plant available P content was statistically significantly (P = 0.05) correlated with P in grain (r = 0.60), P in the shoot (r = 0.68), grain yield (r = 0.40) and nodule weight (r = 0.35). Variations in plant parameters (nodulation, shoot dry matter, percentage nitrogen derived from the air [%Ndfa], grain yield, and nutrient uptake) among and within farmers’ fields were attributed to differences in soil fertility and crop management. About 60% of the fields were moderately fertile, sufficient to support legume establishment, while about 30% of the farmers' fields had a low fertility level. For farmers in the study area to benefit from the BNF potentials of the legumes, an external P fertilizer input was necessary as well as suitable crop management practices because all parameters measured in the researcher-managed plots were higher than in the farmer-managed plots.

The chemical composition of five high-oleic peanut lines grown in Oklahoma was examined. Tamrun OL 01, Tamrun OL 02, TX 977164, and TX 977239 were developed using conventional breeding procedures. SunOleic and Tamrun 96 were the parent lines. These lines demonstrated outstanding agronomic characteristics in Oklahoma. The peanut seeds analyzed in this study contained 42 to 49% oil, 25 to 29% protein, 9 to 12% total dietary fiber, about 2% ash, and 5% moisture. The peanut seeds were rich in potassium. Phosphorus and calcium were the two other two major minerals present in all the samples. The proximate compositions of all the breeding lines were within the range of the parent lines except they had 80% (w/w) oleic acid, which was significantly higher than the parent lines. This study indicates that conventional genetic selection for high-oleic concentration does not cause substantial unintentional changes in peanut chemical compositions.

Sustainable resource management is the critical agricultural research and development challenge in sub-Saharan Africa. The accumulated knowledge on soil management gathered over the last 10 years, combined with solid crop improvement and plant health research at farmers’ level, has brought us to a stage where we can now address with confidence the intensification of cereal–grain–legume-based cropping systems in the dry savanna of West Africa in a sustainable and environmentally positive manner. Two sustainable farming systems that greatly enhance the productivity and sustainability of integrated livestock systems have been developed and implemented in the dry savanna of Nigeria. These are: (i) maize ( Zea mays L.)–promiscuous soybean [ Glycine max (L.) Merr.] rotations that combine high nitrogen fixation and the ability to kill large numbers of Striga hermonthica seeds in the soil; and (ii) miflet [ Eleusine coracana (L.) Gaerth] and dual-purpose cowpea [ Vigna unguiculata (L.) Walp.]. Improvement of the cropping systems in the dry savanna has been driven by the adoption of promiscuously nodulating soybean varieties (in particular TGx 1448-2E) and dual-purpose cowpea. The rate of adoption is very high, even in the absence of an efficient seed distribution system. The number of farmers cultivating the improved varieties increased by 228% during the last 3 years. Increased production of promiscuous soybean has been stimulated by increased demand from industries and home utilization. Production in Nigeria was estimated at 405,000 t in 1999 compared to less than 60,000 t in 1984. Economic analysis of these systems shows already an increase of 50–70% in the gross incomes of adopting farmers compared to those still following the current practices, mainly continuous maize cultivation. Furthermore, increases in legume areas of 10% in Nigeria (about 30,000 ha in the northern Guinea savanna) and increases of 20% in yield have translated into additional fixed nitrogen valued annually at US$ 44 million. This reflects, at the same time, an equivalent increase in land-use productivity, and with further spread of the improved crops, there are excellent prospects for additional economic and environmental benefits from a very large recommendation domain across West Africa.

Growing soybean varieties with high residue yield may help to sustain the soil organic matter (SOM) content when recycled. Replicated field trials were conducted in four Guinea savanna sites in Nigeria to study the dry matter partitioning in six soybean genotypes and evaluate them for biomass production. The varieties were early TGx1485-1D and late TGx1670-1F in Trial 1 and early TGx1485-1D, TGx1805-2E and TGx1681-3F, medium TGx1809-12E and late TGx923-2E and TGx1670-1F in Trial 2. On average, the proportion of total dry matter accumulated in soybean plant parts was 42% in grain, 36% in stover, 12% in leaf litter and 11% in roots and nodules. While maturity class had no significant effect on the grain yield of soybean, significantly higher dry matter accumulation of roots and nodules, leaf litter, and stover was observed in medium and late varieties compared with early varieties (P < 0.05). Thus, medium and late varieties would be better able to sustain the SOM content than early varieties when t...

Nutrients of soybean stovers (SBS) from three soybean varieties: TGx 923-2E (SBS1), TGx 1660–19F (SBS2) and TGx 1019–2EN (SBS3) whole plant (WP) and leaf-pruned stem (LPS) were compared, and these SBS (WP and LPS) were offered to West African dwarf sheep to measure voluntary dry matter (DM) intake (VDMI) and apparent crude protein (CP) and cell wall constituent digestibility coefficients. Average DM, CP, ash and cell wall phenolics concentrations in WP were higher than in LPS by 1.53, 33.65, 1.47 and 96.15%, respectively. In contrast, average NDF, ADF, ADL, cellulose and hemicellulose concentrations of LPS were higher than in WP by 1.73, 1.87, 2.93, 1.19 and 1.44%, respectively. Daily DM intake by sheep fed SBS2 (WP; 36.2 g kg BW) was lower (P : 0.05) average intake value of 41.8 kg BW0.75. Corresponding (P > 0.05) average daily CP intake by sheep fed SBS1, SBS2 and SBS3 (WP; 5.1 g kg BW0.75) was higher (P < 0.05) than the CP intake of sheep fe...

Agronomic results indicate that maize grain yields generally are higher when the crop is planted following soybean than in continuous maize cultivation in the moist savanna agroecological zones of West Africa. Many factors have been hypothesized to explain this phenomenon, including enhanced N availability and the so-called `rotational effect'. There is, however, hardly any quantitative information on the residual N benefits of promiscuous soybeans to subsequent cereal crops grown in rotation with soybean. Three IITA promiscuous soybean breeding lines and two Brazilian soybean lines were grown in 1994 and 1995 at Mokwa in the southern Guinea savanna, Nigeria, to quantify the nitrogen contribution by soybeans to a succeeding crop of maize grown in rotation with soybean for two consecutive years, 1996 and 1997 using two methods of introducing 15N into soil (fresh 15N labelling and its residual 15N) and three maize cultivars (including one cultivar with high N use efficiency) used as reference plants. The nodulating soybeans fixed between 44 and 103 kg N ha−1 of their total N and had an estimated net N balance input from fixation following grain harvest ranging from −8 to 43 kg N ha−1. Results in 1996 and in 1997 showed that maize growing after soybean had significantly higher grain yield (1.2 – 2.3-fold increase compared to maize control) except for maize cultivar Oba super 2 (8644-27) (a N-efficient hybrid). The 15N isotope dilution method was able to estimate N contribution by promiscuous soybeans to maize only in the first succeeding maize crop grown in 1996 but not in the second maize crop in 1997. The first crop of maize grown after soybean accumulated an average between 10 and 22 kg N ha−1 from soybean residue, representing 17–33% of the soybean total N ha−1. The percentage 15N derived from residue recovery in maize grown after maize was influenced by the maize cultivars. Maize crop grown after the N-efficient hybrid cultivar Oba Super 2 (844-27) had similar 15N values similar to maize grown after soybeans, confirming the ability of this cultivar to use N efficiently in low N soil due to an efficient N translocation ability. The maize crop in 1997 grown after maize had lower 15N enrichment than that grown in soybean plots, suggesting that soybean residues contributed a little to soil available N and to crop N uptake by the second maize crop. The differential mineralization and immobilization turnover of maize and soybean residues in these soils may be important and N contribution estimates in longer term rotation involving legumes and cereals may be difficult to quantify using the 15N labelling approaches. Therefore alternative methods are required to measure N release from organic residues in these cropping systems.

Half diallel crosses among ten pure breeding lines of soybean were made in 1997 and 1998 to study the inheritance of pod shattering in soybean. Evaluation for pod shattering among F2 segregating populations was carried out in an oven set at 80 °C for 12 hours. Diallel analysis was carried out to estimate genetic parameters and detect presence of non allelic interaction of genes affecting pod shattering. Hayman's diallel analysis indicated significant variation of Wr + Vr and Wr – Vr over arrays, suggesting epistatic gene action. Similarly results from a joint regression coefficient over replications were significantly (p < 0.05) different from unity and zero, suggesting presence of non allelic interaction of genes. The intercept was positive, suggesting partial dominance for the shattering trait. Both general combining ability (GCA) and specific combining ability (SCA) effects were significant (p < 0.05).

Soybean cultivars capable of nodulating with indigenous Bradyrhizobium spp. have been developed by the International Institute of Tropical Agriculture (IITA) and national programs in Africa in order to avoid artificial inoculation by resource-poor farmers in Africa. The current selection procedure for enhanced N2 fixation is based on an assessment of nodule formation which does not directly quantify the proportions of crop N derived from the atmosphere. We have monitored N accumulation patterns and N2 fixation in nine promiscuous soybean cultivars with different maturity periods, using the 15N dilution technique. Nodule development generally peaked at the early podfill stage for all cultivars except Tgx 1519-1D and Tgx 1447-2D in which it continued to increase. The proportion of crop N derived from fixation (%NDFA) ranged between 51% and 67%, 77% and 84%, and 66% and 73% at full bloom, early podfill, and physiological maturity stages, respectively. Total N accumulation increased in all soybean genotypes with increasing plant age. Significant correlations (P

It has been difficult to explain the rotation effect based solely on N availability in maize-soybean cropping systems in the moist savanna zone of sub-Saharan Africa. Although arbuscular mycorrhizal fungi (AMF) can contribute to plant growth by reducing stresses resulting from other nutrient deficiencies (mainly P) and drought, their role in the maize/soybean rotation cropping systems in the Guinea savanna has not yet been determined. Pot and field experiments were conducted for 2 years using 13 farmers' fields with different cropping histories in two agroecological zones (Zaria, northern Guinea savanna and Zonkwa, southern Guinea savanna) in Nigeria. We quantified the influence of cropping systems and rhizobial inoculation on plant growth, mycorrhizal colonization and diversity of promiscuous soybean and maize grown in rotation. The relationships between these variables and selected soil characteristics in farmers' fields were also examined. Percentage mycorrhizal colonization in promiscuous soybean roots ranged from 7% to 36%, while in maize it varied between 17% and 33%, depending on fields and the previous cropping history. A large variation was also observed for mycorrhizal spores, but these were not correlated with mycorrhizal colonization and did not appear to be influenced by rotation systems. Soybean mycorrhizal colonization was higher (13% increase) in Zonkwa, but not in Zaria, if the preceding crop was maize and not soybean. These differences were related to the soil P concentration, which was positively related to mycorrhizal colonization in Zonkwa but negatively to this parameter in Zaria. The previous crop did not affect mycorrhizal colonization of maize in both locations. Soybean cultivars inoculated with rhizobia had a higher mycorrhizal colonization rate (25%) and more AMF species than maize or uninoculated soybean (19%). Maize grown in plots previously under inoculated soybean also had higher percentage mycorrhizal colonization than when grown after uninoculated soybean and maize. Four AMF genera comprising 29 species were observed at Zaria and Zonkwa. Glomus was the dominant genus (56%) followed by Gigaspora (26%) and Acaulospora (14%). The genus Sclerocystis was the least represented (4%).

A digestibility study was conducted with West African dwarf (WAD) sheep offered four varieties of soybean stovers (SBS) basal diets, TGx 1019-2EN (SBS1), TGx 1448-2E (SBS2), TGx 1660-19F (SBS3) and TGx 932-2E (SBS4) and a growth study with WAD sheep offered three varieties of soybean stovers SBS1, SBS2 and SBS3 incorporated into three diets such that the roughage source in the diet was a 50:50 mixture of stover and hay supplemented with 15% cassava crumb to investigate feed intake, digestibility and body weight change. In Experiment 1, similar ( p >0.05) mean voluntary dry matter intake (VDMI) (37.32±2.19 g kg −1 BW 0.75 day −1 ) observed for sheep fed SBS1, SBS2 and SBS3 was higher ( p −1 BW 0.75 day −1 of SBS4. Crude protein intake pattern was identical to that of N-intake and the similar ( p >0.05) DM mean N-intake (0.68±0.04 g kg −1 BW 0.75 day −1 ) of SBS1, SBS2 and SBS4 was higher ( p −1 BW 0.75 day −1 ) of SBS3, although 0.47±0.02 g kg −1 BW 0.75 day −1 N-retained by sheep fed SBS2 was significantly ( p p p >0.05) mean (61.32±3.08%) CPD value of sheep fed SBS1 and SBS4 while sheep fed SBS3 recorded the least ( p p p >0.05) mean NDFD value (49.02±5.90%) of sheep fed SBS1, SBS3 and SBS4. In Experiment 2, average VDMI of sheep fed diet I (54.58±1.93 g kg −1 BW 0.75 day −1 ) was higher ( p −1 BW 0.75 day −1 ) of sheep fed diets 2 and 3. Similar mean dry matter digestibility (DMD) value (68.25±1.89%) of sheep fed diets 1 and 3 was higher ( p −1 BW 0.75 day −1 ) of sheep fed diet 1 (78.83±2.58) was higher ( p p −1 serum) (46.00±3.13) of sheep fed diet 1 was higher ( p p >0.05) mean value (30.50±3.13) of diets 2 and 3. Also, sheep fed diet 1 recorded growth rate (g day −1 ) (18.68±0.16) which was higher ( p p

Attention is being paid to improving the N2 fixation of promiscuous nodulating soybeans in an attempt to develop sustainable cropping systems in the moist savanna. There is however a dearth of reliable estimates of N2 fixation by these promiscuous soybeans and hardly any quantitative information is available on their residual N benefits to subsequent cereal crops grown in the southern Guinea savanna zone. The15 N isotope dilution method was used to assess symbiotic N2 fixation and response to inoculation and N contribution of three IITA promiscuous and two Brazilian soybean lines grown in the field at Mokwa (southern Guinea savanna) for two years. Rhizobial inoculation increased total N and grain yield of early maturing cultivars IAC 100 and TGX 1456–2E but did not affect the late maturing cultivar TGX 1660–19F. Both fixed N (Ndfa) and N derived from the soil were the major sources of N accounting for 84 and 75 kg N ha-1 or 46 and 43%, respectively, of the plant total N. A line effect was, however, apparent with the late maturing line TGX 1660–19F deriving on the average 126 kg N ha-1 or 52% of plant total N from N2 fixation compared to the early maturing line IAC 100 with 37 kg N ha-1 or 38%. Total N accumulated and amounts of N2 fixed were low during early growth (V2/V3 and R1/R2 stages), but increased rapidly after this period to reach the maximum at R3/R4 and then dropped after R3/R4. The proportion of Ndfa, however, increased with the growing period. At the physiological maturity (R8), N2 fixed accounted for an average of 70% of total N accumulated in the seeds. Roots accumulated about 13% while leaves and stems had 53 and 32% of the entire plant N at R3/R4, respectively. It was estimated after grain removal, that soybean growth led to a net contribution of an average of 18 kg N ha-1 to soil N. However, the N contribution ranged from - 8 to 43 kg N ha-1 depending on the soybean cultivars and inoculation treatment.

Striga hermonthica, an obligate root parasite of grasses, Is one of the most severe constraints to cereal production in sub-Saharan Africa. In the recent past, prior to increased production pressure on land, S. hermonthica was controlled in African farming systems by prolonged crop rotations with bush fallow. Because of increasing need for food and concomitant changes in land management practices, however, these fallow rotations are no longer extensively used. Shorter crop rotations and fallow periods have also led to declines in soil fertility which present a very serious threat to African food production. A sustainable solution will be an integrated approach that simultaneously addresses both of these major problems. An integrated programme that replaces traditional bush fallow rotation with non-host nitrogen-fixing legume rotations, using cultivars selected for efficacy in germinating S. hermonthica seeds, is outlined. The programme includes use of S. hermonthlca-free planting material, biological control, cultural control to enhance biological suppressiveness, host-plant resistance, and host-seed treatments.

The symbiotic performance of promiscuous soybeans depends upon the population size, effectiveness and survival of indigenous or introduced rhizobia in the field. A pot experiment was conducted using soils collected from 13 farmers' fields located in two agroecological zones (northen and southern Guinea savanna) in the moist savanna of Nigeria to determine the relationships between growth response to previous rhizobial inoculation and the indigenous rhizobial populations. At each farmer's field, soil was collected in plots which were planted the previous year (1993) to: (1) maize, (2) soybean cv. Bossier, (3) soybean cv. TGX 1456-2E and (4) soybean cv. TGX 1660-19F. The soybean cultivars TGX 1660-19F and TGX 1456-2E were either uninoculated or inoculated with an enriched population of a mixture of local rhizobial strains. Four test plants: soybean cultivars TGX 1660-19F (slightly promiscuous), TGX 1456-2E (highly promiscuous), Bossier (non-promiscuous) and cowpea (typically promiscuous) were planted in pots containing soils from the above field treatments. Previous inoculation increased shoot dry matter production by an average of 32% over the uninoculated controls in 94 of the 312 (30%) legume inoculations and farmers' field combinations while the indigenous rhizobia were more effective than the introduced ones in 103 combinations (33%) with an average of 20% increase compared to previous inoculation treatments. Previous inoculation increased biomass yield of both promiscuous and non-promiscuous soybean varieties. The response to previous inoculation treatments was farmers' fields dependent and inversely related to the numbers of rhizobia in the soil. Soil rhizobial population ranged from 0 to > 400 cells g−1 soil and response to inoculation often occurred when numbers of indigenous rhizobia were fewer than 10 cells g−1 soil. Numbers of indigenous rhizobia were generally lower or below detection limit in soils previously cropped to maize. These results indicate a relationship between rhizobia cell counts and promiscuous soybean responses, which may be used to indicate under which conditions inoculation will be beneficial to a farmer.

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a major pest of soybean, Glycine max (L.). Merr., that significantly reduces yield in northern production areas of North America. Insecticides are widely used to control soybean aphid outbreaks, but efforts are underway to develop host plant resistance as an effective alternative management strategy. Here, previously identified resistant lines were evaluated in laboratory tests against field-collected populations of soybean aphid and in field-plot tests over 2 yr in South Dakota. Six lines previously identified with resistance to soybean aphid--Jackson, Dowling, K1639, Cobb, Palmetto and Sennari--were resistant in this study, but relatively high aphid counts on Tie-feng 8 in field plots contrasted with its previously reported resistance. Bhart-PI 165989 showed resistance in one of two laboratory tests, but it had relatively large aphid infestations in both years of field tests. Intermediate levels of soybean aphid occurred in field plots on lines previously shown to have strong (Sugao Zairai, PI 230977, and D75-10169) or moderate resistance to soybean aphid (G93-9223, Bragg, Braxton, and Tracy-M). Sugao Zairai also failed to have a significant proportion of resistant plants in two laboratory tests against aphids field-collected in 2008, but it was resistant in laboratory tests with aphids collected in 2002, 2005, and 2006. Overall, results showed that lines with Rag (i.e., Jackson) or Rag1 gene (i.e., Dowling) had low aphid numbers, whereas lines with Rag2 (i.e., Sugao Zairai, Sennari) had mixed results. Collectively, responses of soybean aphid populations in laboratory and field tests in 2008 resembled a virulence pattern reported previously for biotype 3 soybean aphids, but virulence in soybean aphid populations was variable and dynamic over years of the study. These results, coupled with previous reports of biotypes virulent to Rag1, suggest that deployment of lines with a single aphid-resistance gene is limited for soybean aphid management, and that deployment strategies relying on multiple resistance genes may be needed to effectively use plant resistance against soybean aphid.

The success of inland valley crop production in humid and subhumid areas of subSaharan Africa depends on the availability of appropriate crop varieties with some tolerance to excess moisture. Performance of upland crop associations [cassava (Manihot esculenta) + sweet potato (Ipomoea batatas) and cassava + soybean (Glycine max)] was observed in a trial conducted along a small valley toposequence. Groundwater table depth (GWT) was a significant covariate for cassava yield and regression analysis showed that cassava clones of similar yield potential responded similarly and positively to increasing GWT depth (r2=0.77) regardless of associated crop. Sweet potato tuber production was related to GWT depth for variety TIS 9465 (r2=0.47) but not for TIS 8441. Sweet potato was more tolerant of shallow GWT than cassava. Combined cassava and sweet potato tuber production was also positively correlated to GWT depth (r2=0.83). The range of GWT depth to be considered by plant breeders screening cassava and sweet potato varieties for excess moisture in inland valleys should include depths 0.2 to 0.4 m, because those depths were shown to be stressful to these crops.

Predatory mites are important components of subterranean food webs and may help regulate densities of agricultural pests, including western corn rootworms (Chrysomelidae: Diabrotica virgifera virgifera). Implementing conservation and/or classical biocontrol tactics could enhance densities of specialist or generalist predatory mites and lead to pest suppression, but first relevant mite species must be identified and their predatory capabilities evaluated. We conducted lab assays to quantify consumption of immature rootworms and oviposition rates of various mite species. Our study indicates that rootworms are a sub-optimal food source for the mite taxa tested. However, all mite species fed upon rootworms to some degree, although consumption by nematophagous Eviphis ostrinus was extremely low. Predators consumed more rootworm larvae than eggs, and mite size was correlated with prey consumption, with larger predators eating more prey. Four mite taxa (Gaeolaelaps sp., S. miles, Gl. americana, and G. aculeifer) had detrimental effects on survival of rootworm larvae, and the latter two species also had negative impacts on densities of pest eggs. Although it is unlikely that any of these mite species by itself has a major impact on rootworm control, the community of generalist soil-dwelling mites may play an important role in regulating immature rootworm populations in the field.

Seven maize, Zea mays L., genotypes selected for native resistance to western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), larval feeding damage (SUM2068, SUM2162, CRW3(S1)C6, NSS1 x CRW3(S1)C6, PI583927, CRW2(C5), and AR17056-16) were evaluated along with three control maize genotypes in the field for plant damage, larval recovery, adult emergence, root size, and root regrowth. Larvae recovered were further analyzed for head capsule width and dry weight and adults for dry weight. All factors evaluated with the exception of adult dry weight varied significantly among maize genotypes. Control genotypes included a highly susceptible hybrid, B37 x H84, a transgenic rootworm-resistant hybrid expressing the modified Cry3A protein (MIR604), and the untransformed modern hybrid with the same genetic background as the MIR604 we used (isoline) as a second susceptible control. In general, the genotypes previously selected for resistance to western corn rootworm larval feeding had less damage, fewer larvae recovered, smaller larvae recovered, and fewer adults recovered than the susceptible controls. SUM2162 was significantly less damaged than all other native sources of resistance. Western corn rootworm larvae recovered from SUM2162 and SUM2068 were significantly smaller in terms of head capsule width and average weight than larvae recovered from all other maize genotypes, indicating that antibiosis is a mechanism of resistance for these two hybrids.

The western corn rootworm, Diabrotica virgifera virgifera (LeConte), is a major pest of maize, Zea mays L., in the United States and Europe, and it is likely to increase in importance as a trend toward increased nonrotated maize favors larger rootworm populations. Options for rootworm management in nonrotated maize in Europe and in nontransgenic “refuge” areas in countries that permit transgenic maize are limited to insecticides. Development of additional options for growers would be helpful. Screening maize germplasm (e.g., landraces, populations, inbreds) for native resistance to western corn rootworm is labor-intensive and is usually conducted on unfinished germplasm and not on hybrid materials. However, we have recently observed that topcrossed (hybrid) materials tend to have reduced western corn rootworm damage. To formally test whether rootworm damage to inbreds and associated hybrids were correlated, we evaluated 25 diverse inbred lines and their B73 hybrids for western corn rootworm damage in seven environments. Overall, hybrids had significantly less damage than inbreds, but unfortunately, the correlation between inbreds and hybrids was not significant. These findings have important implications regarding screening germplasm for western corn rootworm resistance, namely, that inbred materials and perhaps populations should be topcrossed to form hybrid materials before screening for western corn rootworm damage to ensure that valuable sources of resistance to western corn rootworm are not missed during the screening process.

We evaluated 27 prairie grass species thought to be among those dominant 200 yr ago in the northern midwest as larval hosts of the northern corn rootworm, Diabrotica barberi Smith and Lawrence. Maize (Zea mays L.), spring wheat (Triticum aestivum L.), and grain sorghum (Sorghum bicolor L.) were included as controls for a total of 30 species. Twenty pots of each species were planted in a randomized complete block design. Each pot was infested 5 wk later with 20 neonate northern corn rootworm larvae. Two pots within each species and block were assigned an extraction date of 7 or 14 d after infestation. The remaining two pots from each block were used to monitor adult emergence. The percentage of larvae recovered, change in larval head capsule width, and change in average dry weights varied significantly among the grass species. The highest percentage of larvae was recovered from slender wheatgrass, Elymus trachycaulus (Link), and this was significantly greater than the percentage recovered from all other species including maize for the 14-d sample date. Several additional species were also relatively good hosts, in that the percentage of larvae recovered from these species was not significantly different from maize. The average dry weight of larvae recovered was significantly greater for larvae recovered from maize than for larvae recovered from all other species except slender wheatgrass, when the two samples dates were combined. Overall, adults were produced from only 6 of the 28 species evaluated, and no analysis was performed because of the low numbers. The results of this study are discussed in relation to the potential of alternate hosts of northern corn rootworm to serve as a bridge to survival on transgenic maize.

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), a pest of soybean, Glycine max (L.) Merr., native to Asia, has recently become a principal pest of this crop in many areas of North America. Insecticides are currently used to manage A. glycines, but host plant resistance is a potential alternative management tool. Tests were conducted to determine resistance to A. glycines among soybean lines. 'Cobb,' 'Tie-feng 8,' and 'Jackson' were resistant to population growth of A. glycines compared with 'Cook' and '91B91,' a susceptible control. Antibiosis was evident in Cobb, Jackson, and Tie-feng 8 from lowered survival of first generation A. glycines, and in Cobb, Jackson, Tie-feng 8, and 'Braxton' from diminished reproduction by first generation aphids. Antixenosis was apparent in Cobb and Jackson during initial infestation of aphid population growth tests, because A. glycines were unsettled and dispersed readily from placement points on unifoliolate leaves. Decreased nymphiposition by A. glycines occurred on Cobb and Jackson, and it may have been caused by antibiotic chemicals in these lines, failure of aphids to settle, or both. Differences in distribution of A. glycines between unifoliolate leaves and other shoot structures suggest that unifoliolate leaves were acceptable feeding sites on 91B91 and Cook, whereas unifoliolate leaves and other shoot structures were roughly equally acceptable feeding sites on Braxton, Tie-feng 8, Jackson, and Cobb. However, Jackson and Cobb had relatively low counts of A. glycines on shoots that may have been due to abandonment of plants by aphids, decreased aphid survival, or both. Results confirm earlier findings that Jackson is a strong source of resistance to A. glycines, and they suggest that Tie-feng 8, Braxton, and especially Cobb are potentially useful sources of resistance.

Hybridisation of soybean between susceptible varieties AGS 292 and TGm 737P, and resistant varieties, Duiker, Gc81090-48, Roan and TGx 1448-2E, and intermediate varieties, Kabanyolo 1 and Samsoy 1 , were carried out and the pods assessed for shattering using an oven set at 80oC for 12 hours. The phenotype of F1 populations was closer to the susceptible parents and the distribution of F2 populations was not descrete and could not fit Mendelian ratios. Based on a 1 – 3 scale, the distribution best fitted the 1:3:12 genetic model suggesting genetic control by classical dominant epistasis. The parent offspring regression, suggested a heritability estimate in the narrow sense of 0.79. The average number of segregating genes were 2.01 and 2.06 for F2 and F3 respective generations in six crosses, suggesting that the shattering trait in soybean is conditioned by 2 genes. Key Words: Epistasis, gene number, Glycine max, heritability, progenies RESUME Le croisement du soja entre les varietes susceptibles AGS292 et TGm737P, et les varietes resistantes, Duiker, Roan et TG x 1448-2E, et des intermediares, Kabanyolo1 et Samsoy1, a ete faite et des gousses ont ete evaluees pour l'eclatement en utulisant la methode d'etuve fixee a 80 oC pendant 12 heures. Le phenotype de la population F1 etait presque semblable a celui des parents susceptibles et la distribution de la population F2 n'etait pas discrete et ne correspondait pas au rapport Mandelien. Base sur une echelle de 1 a 3, la distribution repondait au modele genetique 1:3:2 suggerant un controle genetique d' epistasie classique dominante. La regression des descendants des parents a suggere une heritabilite au petit sens de 0.79. Le nombre moyen des genes segregant etait 2.01 et 2.06 pour les progenitures F2 et F3 respectivement dans les six croisements, suggerant que le caractere eclatement chez le soja est controle par deux genes. Mots Cles: Epistasie, nombre de genes, Glycine max, heritablite, progenitures (African Crop Science Journal 8(3) 2000: 203-212)

The size and effectiveness of indigenous rhizobia populations influence the legume yield response to inoculation. Some African soybean varieties (e.g. TGx lines) were developed to nodulate with indigenous Bradyrhizobium spp. as well as B. japonicum ostensibly to eliminate the need for inoculation with B. japonicum. We characterized the bradyrhizobia populations from 70 soils in 9 African countries according to nodulation phenotypes: B. spp. effectively nodulate cowpea, B. spp. (TGx) effectively nodulate TGx soybean and cowpea, B. japonicum nodulates N. American and TGx soybean and cowpea. Populations of B spp.(TGx) and B. japonicum were ≤102 g-1 in 85% and 91% of the soils indicating inoculation should increase soybean yields. B spp.(TGx) and B. japonicum were not detected in 26% and 67% of the soil samples. Population size was not related to soil physiochemical properties but was related to prior management. B. spp.(TGx) and B. japonicum populations≥103 g -1 soil were more frequent at research stations than farmers’ fields and where soybean had previously been grown. Of 258 isolates we made using TGx soybean as a trap host, only 27% were highly effective on TGx soybean. Most of the effective isolates were also effective on N. American soybean. RFLP analysis of 16S rDNA from B. spp.(TGx), B. japonicum, and B. spp. strains showed that most B. spp.(TGx) strains were phylogenetically related to B. spp. Like B. elkanii strains, B. spp.(TGx) strains do not have the nodY gene. Additional genetic analyses, evaluation of cross inoculation with tropical legumes and IAR analysis indicated the B. spp.

Corn rootworms (Coleoptera: Chrysomelidae) are devastating pests of maize (Poaceae: Zea mays L.). Recently, there has been increased interest in biological control of corn rootworms, in part due to their invasion of Europe (Kuhlmann and van der Burgt, 1998; Kuhlmann et al., 2005). One group of parasitoids under investigation for their potential as natural enemies of Diabrotica species are flies in the genus Celatoria (Diptera: Tachinidae) (Kuhlmann and van der Burgt, 1998; Gamez-Virues and Eben, 2005; Kuhlmann et al., 2005; Dequech et al., 2006). Female parasitoids insert eggs containing fully developed first instar larvae directly into adult beetles (Zhang et al., 2003). In North and South America, four Celatoria species attack beetles within Diabrotica and related chrysomelid genera, including: C. compressa Wulp, C. bosqi Blanchard, C. setosa (Coquillett), and C. diabroticae (Shimer) (reviewed in Cabrera Walsh, 2004). Celatoria compressa is found in Mexico, C. bosqi is known from South America, and C. setosa and C. diabroticae are the two species found in North America (O’Hara and Wood, 2004; reviewed in Cabrera Walsh, 2004). Celatoria diabroticae has a widespread distribution across the United States (reviewed in Arnaud, 1978; O’Hara and Wood, 2004) and parasitizes D. virgifera virgifera LeConte, D. undecimpunctata howardi Barber, and D. undecimpunctata undecimpunctata Mannerheim (Arnaud, 1978; reviewed in Cabrera Walsh, 2004). There is little information on the incidence of parasitism of D. barberi Smith & Lawrence by C. diabroticae, although it has been reported in Kansas and Illinois [reported as D. longicornis (Say); reviewed in Chiang, 1973; Fischer, 1983]. To our knowledge, this is the first report of C. diabroticae parasitizing D. barberi in South Dakota.

Host plant resistance is generally included as a means of mitigating production losses in peanut (Arachis hypogaea L.). Testing methods which do not impact yield are of particular value in the development of cultivars. The objectives of this research were to determine the viable seed yield of container-grown peanut plants and the impact of removing the apical dominant shoot on seed set, for use in disease testing. Two resistant cultivars, Tamspan 90 and Southwest Runner, and two susceptible cultivars, Okrun and Flavor Runner 458, were crossed in a diallel to produce F 1 seed. A total of 191 F 1 plants were evaluated in the greenhouse under two treatments, apical shoot removed or not removed, in 2003 to 2005. The mean seed set of the control group (apical shoot not removed) was 12 seed per plant compared with 15 seed per plant when the apical shoot was removed.

(African Crop Science Journal, 1997 5(1): 31-38)