Badu-Apraku B.,International Institute Of Tropical Agriculture |
Fakorede M.A.B.,Obafemi Awolowo University |
Gedil M.,International Institute Of Tropical Agriculture |
Talabi A.O.,International Institute Of Tropical Agriculture |
And 6 more authors.
Euphytica | Year: 2015
Two major constraints militating against the achievement of food security in West Africa (WA) are recurrent drought and poor soil fertility. Seventeen early maturing maize inbreds from IITA and CIMMYT were used as parents to produce 136 diallel crosses which were evaluated along with four checks in contrasting environments at four locations for 2 year in Nigeria. The objectives of the study were to (i) examine the combining ability of the lines under drought, low soil nitrogen (low N), optimal and across environments; (ii) classify the inbreds into heterotic groups using the specific combining ability (SCA) effects of grain yield, heterotic group’s specific and general combining ability (HSGCA), the heterotic grouping based on general combining ability (GCA) of multiple traits (HGCAMT) and the molecular-based genetic distance methods; (iii) compare the efficiencies of the four heterotic grouping methods in classifying the inbreds and identifying the best testers; and (iv) examine the performance of the inbreds in hybrid combinations across environments. Sum of squares for GCA of inbreds for grain yield and other measured traits were larger than those of the SCA in all environments. The relative importance of GCA to SCA effects for grain yield and other traits increased from stress to nonstress environments with the additive genetic effects accounting for the major portion of the total genetic variation under all research environments. The HSGCA method classified the lines into three groups and was the most efficient because it had the highest breeding efficiency (40 %) in the test environments followed by the HGCAMT, SNP marker-based and the SCA effects of grain yield methods. Inbred TZEI 19 was identified as the best tester across research environments based on HSGCA method. Hybrids ENT 11 × TZEI 19 and TZEI 1 × TZEI 19 were the most outstanding and should be tested extensively in on-farm trials and commercialized. © 2015, Springer Science+Business Media Dordrecht.
Uyovbisere E.O.,IAR |
Okunola O.J.,Nigerian National Research Institute for Chemical Technology
Electronic Journal of Environmental, Agricultural and Food Chemistry | Year: 2010
The phenomenon of phosphorus adsorption in soils is widespread because of its agricultural importance. Crop yields are often low due to low soil solution P concentration in high P fixing soils. In view of this fact, a study was initiated to determine the P sorption characteristics and derive parameter estimates relevant in the prediction and management of P in major soils of the Nigerian savanna. To achieve these objectives, soils were sampled from 23 locations in 7 mapping units across the Nigerian savanna ecological zones. The soils were characterized and the phosphate sorption isotherms and parameter estimates were determined. The adsorption isotherms for the soils were gentle to steep, covering a wide range of P sorption characteristics. The Langmuir plots gave gentle curves in most cases, indicating that the assumptions on which the model was based were not fully satisfied. The Langmuir parameter estimates varied widely for the soils. The energy coefficient (K) ranged from 0.015 - 11.593ml/μ-1 and was particularly high for soils of the Jos Plateau with appreciable amounts of Fe oxides. The standard phosphate requirement (SRP) ranged from 2.87 - 1021μg/g-1, which implies that P amendment (fertilization) would be necessary for good crop growth in a good number of the soils. The effects of soil properties on P sorption parameters were evaluated. The single factor that influenced P sorption parameters appreciably was Dithionite extractable Fe (Fed). Generally, Fed, pH and CEC explained over 50% of the variation in the sorption parameters in these savanna soils.
OCL - Oleagineux Corps Gras Lipides | Year: 2012
Biodiesel production increases, and each ton of biodiésel produced leads to about 100 kg of glycerol. Because of increasing amount of generated glycerol, but also according to environmental concerns and scarcity of oil, glycerol is considered as one of the top 10 building block chemicals derived from biomass that can subsequently be converted into a number of high value biobased chemicals. Besides the well established sell of purified glycerine to manufacturers of cosmetics and pharmaceuticals, a variety of novel conversion techniques are introduced. This paper provides an overview of the latest biobased compounds produced from glycerol's conversion, and of the lower environmental impact of these new ways of production.
Paradoxically, the most luminous things in the cosmos are actually invisible to the naked eye. They are "blazars," mysterious objects that glow not just with visible light—the kind our eyes can see—but with every kind of radiation, from radio waves to gamma rays. At the Boston University Blazar Lab, astronomers Alan Marscher and Svetlana Jorstad and their students are trying to understand how blazars work and where they get their tremendous energy. They think that blazars are powered by supermassive black holes containing the mass of hundreds of millions of suns. But how do black holes—where gravity is so strong that nothing, not even light, can escape—power the brightest objects in the cosmos? That is the puzzle that Marscher, a professor of astronomy in BU's Institute for Astrophysical Research (IAR), and Jorstad, an IAR senior research scientist, are trying to resolve. Add up all the light that comes from blazars and they are the most luminous objects in the universe. But most of this light isn't in a form that we can see. It is spread out through the entire electromagnetic spectrum—the true rainbow that extends far beyond the colors that our eyes can detect and includes radio waves, X-rays, gamma rays, and more. Though some fluke astrophysical phenomena may shine brighter than a blazar for a few minutes or less, blazars keep up the light show for the long haul. Today, astrophysicists have catalogued thousands of blazars. In fact, say Jorstad and Marscher, if we could see the cosmos with gamma-ray eyes, blazars would dominate the night sky. But what are they, and how do they sustain such powerful cosmic fireworks? When the first blazar was discovered in 1962, astronomers were stumped: they did not know what it was and had never seen anything like it. But time and technology, like NASA's Hubble Space Telescope, have yielded some clues. First, astronomers tracked blazars to ancient galaxies located hundreds of millions, or even billions, of light years from Earth. Each of these galaxies, like our own Milky Way, is centered on a supermassive black hole that's engulfed millions of suns' worth of matter. Somehow, researchers think, those behemoth black holes must be firing up the blazars. But even though nearly every galaxy has a supermassive black hole, only a small fraction of galaxies—about one in ten—is an "active" galaxy, radiating a huge amount of energy. And fewer than one in a thousand active galaxies is a blazar. What makes them different? It all starts with the black hole's diet. Black holes gobble up anything that gets too close. When a black hole is "well fed," says Marscher, matter on its way down the gullet will congeal in a pancake-shaped disk centered on the black hole. Friction in the disk heats it up and makes it glow and flicker with ultraviolet and visible light. That explains one part of the mystery—why some galaxies are "active" when others aren't—but something more seems to happen to transform an ordinary active galaxy into a blazar capable of firing off high-energy gamma rays and X-rays. Astronomers think that "something" is a jet: a fire hose of charged particles, magnetic fields, and radiation that shoots out from the top and bottom of the rotating disk. When one of these jets is pointed directly at Earth, our telescopes pick it up as a blazar. "The black hole sucks nearly everything in from its surroundings," says Marscher, "but it creates so much havoc as everything falls in that somehow jets get shot out." When fast-moving electrons near the black hole meet the strong magnetic field inside the jet, they give off a broad spectrum of radiation, from low-frequency radio waves all the way up to high-energy X-rays. Meanwhile, those electrons can also ram into particles of light, called photons, and give them the extra boost of energy to make gamma rays. Which might leave you asking: What, exactly, kicks the electrons up to such high speeds? Astrophysicists are still debating, but many think that the electrons are whorled through a corkscrew-shaped magnetic field that shoots them out at blinding velocity. Marscher compares the effect to cleaning a pipe out with a snake. "If you keep twisting it around, then it will propel in the forward direction," says Marscher. "If the black hole's rotation can wind up the magnetic field enough, that's what propels the jets out at nearly the speed of light." If that hypothesis is right, the twisty magnetic field should leave a characteristic imprint, called polarization, on light coming out of the jet. But isolating that signature is not easy. To do it, Marscher, Jorstad, and a team of international collaborators had to wait for a blazar to discharge a flare—temporary, concentrated emission—that would give them a chance to trace out the shape of the magnetic field. The team started searching for the polarization signal in 2004, and in 2005, they found just what they were seeking: while peering nearly straight down the barrel of the jet of a powerful, flaring blazar called BL Lacertae, they caught the polarization within the flare rotating by one-and-a-half turns, mapping out exactly the spiral shape astronomers had predicted. They presented their results in Nature in 2008. Flares like this one represent "nature doing its most extreme thing," says Marscher, but flares are rare, and catching them in the act requires long-term, dedicated telescope time. Thanks to a partnership between BU and the Lowell Observatory, Marscher and Jorstad have near-continuous coverage of more than three dozen blazars on the Perkins telescope, a 1.8-meter optical telescope near Flagstaff, Arizona, where Jorstad spends about one week each month. When a flare erupts, she quickly notifies the managers of NASA's Swift satellite, which can be rapidly pointed toward the flare source to capture ultraviolet and X-ray readings, and taps into publicly available data from the Fermi Gamma-ray Space Telescope. By scrutinizing differences in the shape and timing of the flare at different wavelengths, she, Marscher, and their colleagues can deduce the physics behind the flare. Marscher and Jorstad also enlist a network of radio telescopes, called the Very Long Baseline Array (VLBA), to zoom in on the flare and take pictures of it as it moves and changes. Because the telescopes that make up the VLBA are located on opposite sides of the Earth, the VLBA can pick out, or "resolve," fine details about 1,000 times better than the Hubble Space Telescope. In fact, even though the jets are enormous—many light years long, in some cases—they are so far from Earth that the VLBA is the only instrument in the world that can actually see bright spots (technical term: "blobs") moving through the jets. Now, the researchers in BU's Blazar Lab are trying to understand the source of blazars' most energetic gamma ray flares, the blazar equivalent of a baseball pitcher's 100-mile-an-hour fastball. Astrophysicists expected that the gamma rays should all be coming from very close to the black hole at the center of the blazar. But, to everyone's surprise, the BU team found that a major fraction of the gamma rays is coming from a point, light years away. How does such an extreme burst of energy happen so far from the blazar's central engine? The BU blazar team is testing out a variety of ideas using computer models, and they hope to put them to a real-world test soon with the Discovery Channel Telescope, a 4.3-meter optical telescope at Lowell Observatory. Yet the "eureka" moments often belong to the undergraduate and graduate students in blazar lab, who are the first link in the lab's data analysis chain. "They are often the first to tell us when an event—a flare in brightness, change in polarization, or a new 'blob'—appears in the data," says Marscher. "They are in fact directly participating in the exploration of cosmic phenomena." More information: Alan P. Marscher et al. The inner jet of an active galactic nucleus as revealed by a radio-to-γ-ray outburst, Nature (2008). DOI: 10.1038/nature06895
The three-year-old is learning to fend for himself since being found wandering a palm oil plantation, alone and suffering smoke inhalation, at the height of fires last year that razed huge swathes of rainforest in Indonesia's part of Borneo. Otan and the other orphans must build nests, find food and avoid predators—especially man—to prove they're ready to "graduate" and return to the wild, but life in the real world has never been more perilous for these primates. Last month, for the first time in history, Bornean orangutans were declared critically endangered –- one step away from total extinction. Experts warn these majestic tree dwellers—who could once cross Borneo without ever touching the ground—could vanish entirely from the island within 50 years as the ancient rainforest they've inhabited for centuries is felled and burned at alarming speed. "It's heartbreaking," said Ayu Budi, a veterinarian who heads the orangutan health clinic at the International Animal Rescue centre in West Kalimantan province. "When you see them, it's really sad. They're supposed to be with their mothers in the wild, living happily, but they're here." The 101 orangutans under Budi's care –- including the 16 playful infants –- are the lucky ones, rescued near death and nurtured back to health with baby bottles in a tranche of protected forest outside the city of Ketapang. But hundreds of thousands of their kin have died in the past four decades across Borneo, slaughtered by hunters, burned in land-clearing fires or starved to death by habitat loss. Rampant logging and the rapid expansion of commercial-scale paper and palm oil operations across the island has reduced the species's habitat by at least 55 percent in two decades, says environmental group WWF, driving them into ever-closer contact with humans. The result has been wild orangutan populations in freefall. In the mid 1970s, nearly 300,000 of these great apes roamed Borneo. Today, just a third of that number remain. The International Union for the Conservation of Nature—which changed the species's threat level to critical—estimates a mere 47,000 will be left in the wild by 2025. Those working at the coalface are under no illusions that efforts to arrest this decline have not succeeded, said Chris Wiggs, a conservation adviser at IAR's forest outpost in Ketapang. "I think people on the ground working in Borneo have known for a long time that the orangutan situation was pretty desperate," he told AFP, as a wheelbarrow of baby orangutans passed on its way to the nursery. The number of great apes at the centre has grown nearly tenfold since 2009 as ever-increasing amounts of forest is cleared by industry. Two of the school's newest pupils are Vijay and Moli who were found without their mothers near burned land. They are the victims of fire, an annual scourge that's evolved into a major threat to the future of the species. Every dry season across Indonesian Borneo—an island shared with Malaysia and Brunei—fires are illegally lit by land owners to quickly and cheaply clear forest for new plantations. The fires often get out of hand, tearing through forest and smouldering relentlessly on Borneo's compact, carbon-rich peatlands. Last year's blazes were among the worst on record. Fanned by a prolonged dry season, fires tore through 2.6 million hectares (10,000 square miles) of Indonesian forest, laying waste to prime orangutan habitat. The smoke turned skies yellow in Indonesian Borneo and blanketed neighbouring Singapore and Malaysia, forcing schools to shut and causing thousands to fall ill. Conservationists fear a repeat disaster of that scale would ring the death knell for the Bornean orangutan. "I think we're all pretty scared... whether the species can take another hit like that," Wiggs said. This month an Indonesian company linked to the 2015 fires was slapped with a $80 million fine –- a record for slash and burn activities, a spokesman for the environment minister said. Indonesian President Joko Widodo in April proposed a halt on granting new land for palm oil plantations, urging producers of the edible oil to use better seeds to increase their yields. "We need to restore and rehabilitate our peatlands, and fix past mistakes," Sustyo Iriono, the head of the government's conservation agency in West Kalimantan, told AFP. Budi and her colleagues remain optimistic, teaching orangutans like Jack –- a mischievous, attention-seeking seven-year-old—to forage by hiding peanuts and honey inside plastic balls high in the treetops. But she frets her young charge will never get the chance to prove his independence in the wild, as Borneo's lowland forests shrink ever smaller. "I think they still have a chance, but if the forest is gone, it will be difficult," she said. Explore further: Borneo orangutan was shot over 100 times with airgun