Rice can be cultivated in a range of arable systems, including upland rainfed, lowland rainfed or irrigated, flooded or décrue, and deep water cultivation. These agricultural regimes represent ecosystems controlled to large degree by agricultural practices, and can be shown to produce different weed flora assemblages. In order to reconstruct early rice cultivation systems it is necessary to better establish how ancient rice farming practices may be seen using archaeobotanical data. This paper focuses on using modern analogue phytolith assemblages of associated crop weeds found within cultivation regimes, as well as in wild rice stands (unplanted stands of Oryza nivara or O. rufipogon), as a means of interpreting archaeobotanical assemblages. Rice weeds and sediment samples have been recorded and collected from a range of arable systems and wild stands in India. The husks, leaves and culms of associated weeds were processed for phytolith reference samples, and sediment samples were processed for phytoliths in order to establish patterns identifiable to specific systems. The preliminary results of the phytolith analysis of samples from these modern fields demonstrate that phytolith assemblage statistics show correlation with variation in rice cultivation systems on the basis of differences in environmental conditions and regimes, with wetness being one major factor. Analysis of phytoliths from archaeological samples from contrasting systems in Neolithic China and India demonstrate how this method can be applied to separate archaeological regions and periods based on inferred differences in past agricultural practices, identifying wet cultivation systems in China, dry millet-dominated agriculture of north China and rainfed/dry rice in Neolithic India.
Seed development, especially the relevant regulatory mechanism and genetic network are of fundamental scientific interest. Seed development consists of the development of embryo and endosperm; and endosperm development of rice (model species of monocots) is closely related to grain yield and quality. Recent genetic studies, together with other approaches, including transcriptome and proteomics analysis, high-throughput sequencing (RNA-seq, ChIP-seq), revealed the crucial roles of genetic and epigenetic controls in rice endosperm development. Here we summarize and update the genetic networks involved in the regulation of endosperm initiation, cell cycle regulation, aleurone layer specification, starch synthesis, storage protein accumulation and endosperm size, and the interactions between embryo and endosperm.
Microsatellites were able to retrieve the well-established classification into Indica (isozyme group 1), Japonica (group 6, comprising temperate and tropical forms) and specific groups from the Himalayan foothills including some Aus varieties (group 2) and some aromatic varieties (group 5). They revealed a new cluster of accessions close to, but distinct from, non-Myanmar varieties in group 5. With reference to earlier terminology, we propose to distinguish a group “5A” including group 5 varieties from the Indian subcontinent (South and West Asia) and a group “5B” including most group 5 varieties from Myanmar. In Myanmar varieties, aroma was distributed in group 1 (Indica) and in group 5B. New BADH2 variants were found. Some accessions carried a 43 bp deletion in the 3’ UTR that was not completely associated with aroma. Other accessions, all of group 5B, displayed a particularBADH2 allele with a 3 bp insertion and 100% association with aroma. With the new group and the new alleles found in Myanmar varieties, our study shows that the Himalayan foothills contain series of non-Indica and non-Japonica varietal types with novel variations for useful traits.
The CIMMYT genebank holds about 13,000 wheat lines (from a couple hundred populations) from Mexico that they call “sacramental wheats.” This collection was put together by the late Bent Skovmand, who established the CIMMYT genebank back in the 1970s.
By Climate Central's Michael D. Lemonick: July 2012 was officially not only the warmest July on record, but also the warmest month ever recorded for the lower 48 states, according to a report released Wednesday by scientists at the National Oceanic...
The drought footprint cover 63% of the contiguous states during the hottest month in American history. It's the hottest 12 month stretch (August 2011-July 2012) on record for the lower 48, making it the fourth consecutive month to set a new record (i.e. old record was July 2011-June 2012).The biggest difference from other hot months is the nighttime temperature have been exceptionally high. The most current drought monitor map can be found at: http://droughtmonitor.unl.edu
During the diversification of cultivated rice after domestication, rice was grown in diverse geographic regions using genetic variations attributed to the combination of alleles in loci for adaptability to various environmental conditions. To elucidate the key gene for adaptation in rice cultivars to the northern limit of rice cultivation, we conducted genetic analyses of heading date using extremely early-heading cultivars. The Hd5 gene controlling heading date (flowering time) generated variations in heading date among cultivars adapted to Hokkaido, where is the northernmost region of Japan and one of the northern limits of rice cultivation in the world. The association of the Hd5 genotype with heading date and genetical analysis clearly showed that the loss-of-function Hd5 has an important role in exhibiting earlier heading among a local population in Hokkaido. Distinct distribution of the loss-of-function Hd5 revealed that this mutation event of the 19-bp deletion occurred in a local landrace Bouzu and that this mutation may have been selected as an early-heading variety in rice breeding programs in Hokkaido in the early 1900s. The loss-of-function Hd5 was then introduced into the rice variety Fanny from France and contributed to its extremely early heading under the presence of functional Ghd7. These results demonstrated that Hd5 plays roles not only in generating early heading in variations of heading date among a local population in Hokkaido, but also in extremely early heading for adaptation to northern limits of rice cultivation
This study offers evidence of the robustness of farmer rice varieties (Oryza glaberrima and O. sativa) in West Africa. Our experiments in five West African countries showed that farmer varieties were tolerant of sub-optimal conditions, but employed a range of strategies to cope with stress. Varieties belonging to the species Oryza glaberrima – solely the product of farmer agency – were the most successful in adapting to a range of adverse conditions. Some of the farmer selections from within the indica and japonica subspecies of O. sativa also performed well in a range of conditions, but other farmer selections from within these two subspecies were mainly limited to more specific niches. The results contradict the rather common belief that farmer varieties are only of local value. Farmer varieties should be considered by breeding programmes and used (alongside improved varieties) in dissemination projects for rural food security.
Dear IFPRI Have you managed to turn groundnuts (Arachis hypogea) into a perennial? Or are you confused perhaps by the difference between perennials and nitrogen-fixing legumes, some of which are indeed perennial?
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