187 research outputs found
Spectro-polarimetry of the bright side of Saturn's moon Iapetus
Measurements of the polarized reflected sunlight from atmosphereless solar
system bodies, over a range of phase angles, provide information about the
surface structure and composition. With this work, we provide analysis of the
polarimetric observations of the bright side of Iapetus at five different phase
angles, and over the full useful wavelength range (400-800nm), so as to assess
the light scattering behaviour of a typical surface water ice. Using FORS2 of
the ESO VLT, we have performed linear spectro-polarimetric observations of
Iapetus' bright side from 2009 to 2011 at five different phase angles, in the
range from 0.80-5.20^{0}, along with circular spectro-polarimetric observations
at one phase angle. By measuring, with high accuracy (~0.1% per spectral bin
for each Stokes parameter), the spectral polarization of the bright trailing
hemisphere of Saturn's moon Iapetus, we have identified the polarimetric
characteristics of water ice, and found that its linear degree of negative
polarization decreases with increasing phase angle of observation (varying from
-0.9% to -0.3%), with a clear dependence on wavelengths of observation.Comment: Accepted for publication on Astonomy and Astrophysics Journal,
8-Pages and 6-figure
Development of Sorghum (Sorghum bicolor (L.) Moench) Endosperm in Varieties of Varying Hardness
Factors responsible for grain hardness in sorghum are not well understood. Therefore, a study was undertaken to observe differences in the developmental processes of three sorghum varieties which vary in endosperm texture: hard, intermediate, and soft. Grain samples were collected at 5 day intervals beginning at 5 days after half-bloom (DAHB) until physiological maturity (40 DAHB) and prepared for viewing with scanning electron microscopy and transmission electron microscopy.
Comparisons were made between vitreous and floury endosperm portions of each variety and among the three varieties. The major difference between vitreous and floury endosperm was the degree to which the protein matrix was present and continuous. The protein matrix which surrounds the starch granules forms at approximately 20 DAHB. The proportion of cells in the endosperm with a continuous protein matrix corresponds to the proportion of vitreous endosperm in the mature kernel. A similar sequence of development was observed in the hard, intermediate, and soft varieties. however, the harder varieties appeared to develop faster than the softer varieties. Differences between hard and soft varieties were visible as early as 15 DAHB. In the early stages of endosperm development, the hard variety had a higher concentration of protein bodies in the outer endosperm than the softer varieties
Annual report of Sudan cooperative sorghum and millet crop improvement Program (Report No 5, 1981)
Sorghum and Millet are the first and second most important cereal crops, respectively, of the Sudan. Most of the sorghum is grown in the central rainlands where the seasonal precipatationis unpredictable; where as the bulk of the pearl millet in the country is grown in western Sudan where the rainfall is even less reliable...
Inheritance of Resistance to Striga in Sorghum Genotype SRN39
Striga hermonthica (Del.) Benth., a parasitic weed of grasses, causes major yield reductions in the principal cereal crops of semi-arid Africa. Cultivar resistance is the most economic control measure, since adapted, resistant cultivars can be grown without additional input from the subsistence farmer. Information on the genetics of resistance to S. hermonthica is scant. This is partially attributable to the rarity of germplasms which exhibit stable resistance across geographical regions. The objective of this study was to determine if the stable resistance observed in sorghum [Sorghum bicolor (L.) Moench] cultivar SRN39 is heritable. Crosses were made between SRN39 and a susceptible parent, P954063. Parental, F1, F2 and backcross generations were grown in infested pots and development of both host and parasite was monitored. Significant variation among genotypes was observed for both host traits and effects on parasite populations. The F1 did not differ significantly in Striga resistance from the susceptible parent, suggesting recessive inheritance. However, hybrid vigor was exhibited by the F1 which yielded and developed as well as the resistant parent. Broad sense heritability ranged from 0.23 to 0.55 for host traits and from 0.10 to 0.43 for effect of genotypes on the Striga population. Joint scaling tests showed that observed variation in each host or parasite trait consisted of additive and dominance components, suggesting possible progress could be made with appropriate selection scheme
Electronic Voting Service Using Block-Chain
Cryptocurrency, and its underlying technologies, has been gaining popularity for transaction management beyond financial transactions. Transaction information is maintained in the block-chain, which can be used to audit the integrity of the transaction. The focus on this paper is the potential availability of block-chain technology of other transactional uses. Block-chain is one of the most stable open ledgers that preserves transaction information, and is difficult to forge. Since the information stored in block-chain is not related to personally identify information, it has the characteristics of anonymity. Also, the block-chain allows for transparent transaction verification since all information in the block-chain is open to the public. These characteristics are the same as the requirements for a voting system. That is, strong robustness, anonymity, and transparency. In this paper, we propose an electronic voting system as an application of block-chain, and describe block-chain based voting at a national level through examples
Research into Germination of Striga Seed by Sorghum Root Exudates
This research was undertaken to develop a laboratory assay to permit screening of sorghum lines for low production of sorgoleone, the first germination stimulant of Striga seed to be isolated from host root exudate. Our findings led us to assay for the other substances in sorghum root exudate which control germination of Striga seed. A convenient petri disch assay, described elsewhere, permits host selection for low stimulation of germination. Work to isolate, assay and characterize these compounds is underway at Purdue Universit
Diversity among African Pearl Millet Landrace Populations
Pearl millet [Pennisetum glaucum (L.) R. Br.] is widely grown in
arid to semi-arid regions of Africa. The crop is particularly adapted
to Sahelian West Africa where landraces have evolved in different
ecological niches. These landraces have accumulated interpopulation
diversity that has not been characterized. Evaluation of genetic diversity
is a prerequisite for successful germplasm exploitation through
breeding. The objective of this study was to characterize morphological
and agronomic variability among African landrace populations of
pearl millet. Ten pearl millet landrace populations widely grown in
several African countries and two experimental Fi hybrids were evaluated
at two locations in Niger during the 1989 rainy season. Thirteen
characters (downy mildew [Sderospora graminicola (Sacc.) Schroet]
incidence, days to flowering, primary spike length, peduncle exsertion,
spike girth, flag leaf width, stem diameter, spike number per plant,
non-productive tillers per plant, plant height, spike yield per plot,
grain yield per plot, and 1000-seed weight) were measured on six
replicates of each landrace populations. In the pooled analysis, all
landrace populations were significantly different for one or more of
the characters evaluated. The Niger landrace populations showed
much less variation than the other African landrace populations for
most characters investigated. Ward's cluster and principal component
analyses were used to investigate the nature and degree of divergence
in the landrace populations. The cluster analyses revealed similarities
between Niger and Senegal and between Niger and Nigerian landrace
populations. Four principal components were found to explain 92%
of the total variation. Days to flowering, plant height, stem diameter,
primary spike length, and grain and spike yield per plot were the
major sources of diversity among the landrace populations. These
results could be useful in choosing potentially heterotic pearl millet
populations for intercrossing to develop improved cultivars, synthetics,
and hybrids for use in Afric
Inheritance of Striga hermonthica adaptive traits in an earlymaturing white maize inbred line containing resistance genes from Zea diploperennis
Striga hermonthica can cause as high as 100% yield loss in maize depending on soil fertility level, type of genotype, severity of infestation and climatic conditions. Understanding the mode of inheritance of Striga resistance in maize is crucial for introgression of resistance genes into tropical germplasm and deployment of resistant varieties. This study examined the mode of inheritance of resistance to Striga in earlyâmaturing inbred line, TZdEI 352 containing resistance genes from Zea diploperennis. Six generations, P1, P2, F1, F2, BC1P1 and BC1P2 derived from a cross between resistant line, TZdEI 352 and susceptible line, TZdEI 425 were screened under artificial Striga infestation at Mokwa and Abuja, Nigeria, 2015. Additiveâdominance model was adequate in describing observed variations in the number of emerged Striga plants among the population; hence, digenic epistatic model was adopted for Striga damage. Dominance effects were higher than the additive effects for the number of emerged Striga plants at both locations signifying that nonâadditive gene action conditioned inheritance of Striga resistance. Inbred TZdEI 352 could serve as invaluable parent for hybrid development in Striga endemic agroâecologies of subâSaharan Africa
Sorghums of the Sudan: analysis of regional diversity and distribution
Sorghum [Sorghum bicolor (L.) Moench] is a very important crop in the Sudan serving as a primary source of food, beverage, and total livelihood for millions of people in the country. The crop originated in the Northeast quadrant of Africa, and the Sudan is widely recognized as a major centre of diversity. Although Sudanese sorghum germplasm has been assembled and stored over the last 50 years, careful analysis of this valuable germplasm has not been made. The objectives of this study were to assess phenotypic diversity and compare pattern of distribution among Sudanese sorghum landraces collected from different geographical regions. Phenotypic diversity among landraces was high, as expressed by the large range of variation for mean quantitative traits and the high (0.81) Shannon-Weaver diversity index. Landraces from Gezira-Gedarif tended to be shorter in stature, earlier in maturity and less sensitive to changes in photoperiod. They also had long, narrow and compact panicles that may result from adaptation to low rainfall and early adoption of mechanized farming practices. In contrast, taller and later maturing plant types characterized sorghums from Equatoria, most of which delayed their flowering in response to increased day-length. These sorghums included many genotypes with small and light kernels. Collections from Kassala showed a higher frequency of landraces with kernels that were more difficult to thresh. Landraces from Blue Nile tended to have greater agronomic eliteness with higher proportion of landraces with white kernels, poorly covered and that were easy to thresh. Sorghums from the Upper Nile tended to have loose panicles with poorly covered kernels that may result from adaptation to high rainfall of the Southern region. Although distinct distributions of types were represented by geographical origin, a high level of within-region diversity was present among all Sudanese sorghums
- âŠ