HOUSTON: Mars had a surface environment that supported liquid water about 3.5 billion years ago, according to a study of river deposits spread across the red planet.
A region of Mars named Aeolis Dorsa contains some of the most spectacular and densely packed river deposits seen on the planet, researchers said.
These deposits are observable with satellite images because they have undergone a process called “topographic inversion,” where the deposits filling once topographically low river channels have been exhumed in such a way that they now exist as ridges at the surface of the planet, they said.
With the use of high-resolution images and topographic data from cameras on orbiting satellites, B T Cardenas and colleagues from the Jackson School of Geosciences in the US identified fluvial deposit stacking patterns and changes in sedimentation styles controlled by a migratory coastline.
They also developed a method to measure river paleo- transport direction for a subset of these ridges.
Together, these measurements demonstrate that the studied river deposits once filled incised valleys. On Earth, incised valleys are commonly cut and filled during falling and rising eustatic sea level, respectively.
Cardenas and colleagues conclude that similar falling and rising water levels in a large water body forced the formation of the paleo-valleys in their study area.
Cross-cutting relationships are observed at the valley- scale, indicating multiple episodes of water level fall and rise, each well over 50 metres, a similar scale to eustatic sea level changes on Earth, researchers said.
The conclusion that such large water level fluctuations and coastline movements were recorded by these river deposits suggests some long-term stability in the controlling, downstream water body, which would not be expected from catastrophic hydrologic events, they said. (AGENCIES)
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RESEARCH-BAJRA-GENE
Gene map reveals how bajra survives extreme heat, drought
NEW DELHI, Sept 19:
Scientists, including those from India, have decoded the genome of bajra and discovered how the crop survives high temperatures and drought, a finding that may help boost production of other cereals in light of the impending global climate change and food crisis.
Rising temperatures and frequency of extreme climate events like heat waves in many parts of the world will lead to a drop in major staple crop production, researchers said.
A global team of 65 scientists from 30 research institutions decoded and sequenced the bajra (or pearl millet) genome and revealed critical coping strategies.
The analysis has led to a better understanding of the ability of this dryland cereal to survive soaring temperatures of over 42 degrees Celsius and its exceptional drought tolerance.
The discovery published in the journal Nature Biotechnology may help develop climate adaptation strategies in other important food crops.
This research co-led by the International Crops Research Institute for Semi-Arid Tropics (ICRISAT) in Telangana, BGI- Shenzhen in China and the French National Research Institute for Sustainable Development (IRD), used the latest innovations in DNA sequencing and analysis.
The team identified new genetic tools like molecular markers related to drought and heat tolerance, as well as other important traits.
The findings may boost efforts to improve this crucial staple food for millions of people in arid and semi-arid Africa and Asia in particular, researchers said.
Pearl millet is a nutritious drylands cereal, rich in protein, fibre and essential micronutrients like iron, zinc and folate.
Nutrition studies have shown that this cereal has the potential to fight iron deficiency, the most widespread micronutrient deficiency and major cause of anaemia, affecting health and development of a third of global population.
Pearl millet is grown on about 27 million hectares worldwide and is a daily food for more than 90 million people, among the most vulnerable in arid and semi-arid Africa and Asia.
It is also an important source of fodder for millions of farms. However, pearl millet yields have remained low over the last six decades, as this cereal is mainly grown in poor soil conditions without irrigation, minimal and no fertiliser and other agricultural inputs.
Investment in genetic research for this crop has been inadequate and breeders had limited genetic information to develop high yielding superior varieties and hybrids that respond to farmers’ constraints, researchers said.
“Most cereals like rice or maize cannot support temperatures over 30 to maximum 35 degrees Celsius when they start forming their grain, whereas pearl millet will fill its grain in air temperatures of up to 42 degrees,” said Professor Rajeev Varshney from ICRISAT, who coordinated the Pearl Millet Genome Sequencing Consortium.
“We have found that compared to other cereals like wheat, rice or maize, pearl millet has a more diverse repertoire of genes for natural wax proteins, which act as thermal protection for the plant,” said Varshney.
Such heat resistance is crucial as climate experts forecast further heat waves in years to come.
With the new biotechnology methods, we can foresee the transfer of such heat and/or drought tolerance to other important food cereals in a near future.
“This research will lead to delivery of high yields of pearl millet in farmer fields in the marginal environments in Africa and Asia,” said David Bergvinson, Director General of ICRISAT.
“Identifying better genes for heat tolerance in pearl millet can also help other crops like wheat, rice and maize become more climate change ready, showing the importance of investing in so called ‘orphan’ or neglected crops,” Bergvinson said. (AGENCIES)
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