Bien que les problèmes technologiques aient été résolu pour le remplacement partiel ou total du blé par la farine de sorgho ou de maïs dans les produits de boulangerie, le succés commercial a été limité. Un travail moindre a été réalisé sur les pâtes composées et les nouilles. Un survol des résultats publiés indique que, sans aucun additif, 30% de sorgho représente le taux d'incorporation maximum possible pour maintenir une qualité culinaire et une couleur satisfaisantes. Une prégélatinisation de 25% de la farine de sorgho avant de la mélanger aux 75% restant, donne de bonnes caractéristiques culinaires mais la couleur n'est pas acceptée par les consommateurs. Une solution intéressante est l'utilisation d'un traitement thermique après le séchage. Ce traitement s'avère efficace appliqué aux spaghetti et aux nouilles fait d'un mélange maïs/blé. A un taux de 70 pour 30 (farine de maïs/semoule de blé), la qualité culinaire a été jugé équivalente à des produits 100% blé. En plus d'un traitement thermique approprié, le choix de la farine (plutôt que de la semoule), une teneur en lipides autour de 1%, et un faible taux de cendres sont nécessaires pour obtenir des pâtes acceptables pour un certain taux d'incorporation

Starch was isolated from the seeds of 3 sorghum cultivars and compared with commercial wheat starch. The amylose content of sorghum starches was in the range of 22.0-27.8%. Sorghum starches had less total lipids than wheat starch (1.66%) but there was no difference between sorghum Milo and Sorghum "100." The water binding capacity of sorghum Dabar did not differ from that of wheat (100%) whereas differences in swelling power were observed, over a range of temperatures, between wheat and sorghum starches except for Sorghum "100" at 70 degrees C. Sorghum starches showed single-step vis- coamylographic curves with pronounced pasting peaks, good pasting stability and good set-back on cooling.

Producers who grow soybean [Glycine max (L.) Merr.] in 3 to and 4-yr rotations with grain sorghum [Sorghum bicolor (L.) Moenchl or other grain crops lack information about the duration of grain yield and soil mineral N benefits of soybean in crop rotations. To determine the 1-, 2-, and 3-yr effects of soybean in crop rotations, an experiment with 8 yr of continuous soybean and grain sorghum, and soybean-grain sorghum and grain sorghum-soybean rotations combined with fertility treatments of control, N (45 kg ha⁻¹ on soybean and 90 kg ha⁻¹ on grain sorghum) and manure (16 Mg ha⁻¹ dry-matter containing 160 to 250 kg available N ha⁻¹) was terminated in 1987. In 1988 and 1989 grain sorghum was grown on all plots without fertilizer to determine the residual effects of previous cropping system and fertilizer regime on soil mineral N, sorghum grain, and stover yield. The experiment was conducted near Mead, NE on a Sharpsburg silty clay loam soil (fine montomorillinitic, mesic, Typic Arqiudoll). Early in the 1988 season plots with soybean as the previous crop had 44 to 50 kg ha⁻¹ more NO₃ -N in the 150-cm soil profile than did plots with continous grain sorghum. Early in the 1989 season, plots where soybean had been grown 2 yr previously had 17 to 23 kg ha⁻¹ more soil NO₃-N than did continous grain sorghum plots, while plots 3 yr after soybean had only 3 to 8 kg ha⁻¹ more soil NO₃-N. The yield of grain sorghum in the first, second, and third year following soybean was 2 to 3, 0.4 to 1.4, and 0.1 Mg ha⁻¹, respectively, greater than the yield of continous grain sorghum. This study indicated that soybean in a crop rotation can contribute to soil NO₃-N and consequently increase sorghum grain yield for 2 yrs if fertilizer N is limiting. Nebraska Agric. Res. Div. Journal Article no. 9434. Research partially funded by USAID Grant no. DAN 1254-G-00-0021 through INTSORMIL, the International Sorghum and Millet CRSP.

Linkage relationships were determined among 85 maize low copy number nuclear DNA probes and seven isozyme loci in an F2 population derived from a cross of Sorghum bicolor ssp. bicolor X S. bicolor ssp. arundinaceum. Thirteen linkage groups were defined, three more than the 10 chromosomes of sorghum. Use of maize DNA probes to produce the sorghum linkage map allowed us to make several inferences concerning processes involved in the evolutionary divergence of the maize and sorghum genomes. The results show that many linkage groups are conserved between these two genomes and that the amount of recombination in these conserved linkage groups is roughly equivalent in maize and sorghum. Estimates of the proportions of duplicated loci suggest that a larger proportion of the loci are duplicated in the maize genome than in the sorghum genome. This result concurs with a prior estimate that the nuclear DNA content of maize is three to four times greater than that of sorghum. The pattern of conserved linkages between maize and sorghum is such that most sorghum linkage groups are composed of loci that map to two maize chromosomes. This pattern is consistent with the hypothesized ancient polyploid origin of maize and sorghum. There are nine cases in which locus order within shared linkage groups is inverted in sorghum relative to maize. These may have arisen from either inversions or intrachromosomal translocations. We found no evidence for large interchromosomal translocations. Overall, the data suggest that the primary processes involved in divergence of the maize and sorghum genomes were duplications (either by polyploidy or segmental duplication) and inversions or intrachromosomal translocations.

Aphid landing rates were monitored with horizontal mosaic green pan traps in monocultures of soybean, Glycine max (L.) Merrill, and in additive mixtures of soybean with dwarf or tall isolines of sorghum, Sorghum bicolor (L.) Moench. Rhopalosiphum maidis (Fitch) colonized sorghum whorls and was the major species caught in pan traps. Weekly aphicide spot applications to sorghum whorls, starting at 36 d after planting, did not suppress R. maidis colonies significantly until after the third application. Landing rates of R. maidis alatae were similar in treated and untreated crop mixtures. The lack of a significant difference may have resulted from immigration of R. maidis alatae from outside the experimental field but inefficient colony suppression may have produced similar results. Mixed cropping reduced landing rates of Aphis gossypii Glover, Aphis helianthi complex, and Lipaphis erysimi (Kaltenbach) on sorghum plants, and R. maidis on soybean plants. Generally, landing rates were equally reduced in the mixtures with tall or dwarf sorghum. The percentage of ground covered by vegetation, which was less in monocultures than in mixtures, proved to be more important than crop height in reducing aphid landing rates. All aphid species landed randomly on soybean and sorghum plants within dwarf sorghum mixtures. However, in tall sorghum mixtures Aphis nerii Boyer de Fonscolombe and A. gossypii preferred to land on soybean whereas Aphis spiraecola Patch landed more often on sorghum. Landing R. maidis alatae did not show a preference for sorghum or soybean in the crop mixtures. Different sensitivities to microclimatic conditions may explain these behavioral patterns.

Sorghum (Sorghum bicolor (L.) Moench] is one of the most important cereal crops in the semi-arid tropics. Grain yields on peasant farms are generally low, insect pests being one of the major factors limiting production. There are over 150 species which damage sorghum crops, of which sorghum shoot fly (Atherigona soccata), spotted stem borer (Chilopartellus), sorghum midge (Contarinia sorghicola), and head bugs (Calocoris angustatus and Eurtystylus immaculatus) are the major pests worldwide. This bulletin describes techniques to screen for resistance under choice (field) and no-choice(cage) conditions, methods of evaluating insect damage, and the sources of resistance to the major pests.