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1.
This study aimed to identify the potential allelopathic indigenous rice (Oryza sativa L. ssp. indica) varieties from Bangladesh using a performance study in a weed‐infested field and to assess the extent of allelopathic interference relative to resource competition in a glasshouse experiment. Six varieties – namely, “Boterswar,” “Goria,” “Biron” and “Kartiksail” as the most allelopathic, “Hashikolmi” as weakly allelopathic and “Holoi” as nonallelopathic – were raised following a nonweed control method. The infestation levels of weed species were calculated using Simpson's Diversity Index (SDI), which ranged from 0.2 to 0.56. However, a significant correlation coefficient (0.87, P < 0.001) was obtained from these field data compared with the root inhibition percentage from the laboratory bioassay, and the “Boterswar” variety was the most allelopathic. The interactions between the allelopathic variety “Boterswar,” weakly allelopathic variety “Hashikolmi” and Echinochloa oryzicola via a target (rice)‐adjacent (E. oryzicola) cogrowth culture were determined in a hydroponic arrangement. The relative competitive intensity (RCI) and the relative neighbor effect (RNE) values showed that the crop–weed interaction was facilitation for “Boterswar” and competition for “Hashikolmi” and E. oryzicola in rice/E. oryzicola cogrowth cultures. The allelopathic effects of “Boterswar” were much higher than the resource competition in rice/E. oryzicola cogrowth cultures. The converse was observed for “Hashikolmi.” Moreover, the mineral content of E. oryzicola was severely affected by “Boterswar”/E. oryzicola cogrowth cultures’ exudate solution. Therefore, the allelopathic potential of “Boterswar” variety might be useful for developing the weed‐suppressing capacity of rice, which will likely have a significant influence on paddy weed control.  相似文献   
2.
Drought is a major abiotic constraint for rice production worldwide. The quantitative trait loci (QTLs) for drought tolerance traits identified in earlier studies have large confidence intervals due to low density linkage maps. Further, these studies largely focused on the above ground traits. Therefore, this study aims to identify QTLs for root and shoot traits at the vegetative growth stage using a genotyping by sequencing (GBS) based saturated SNP linkage map. A recombinant inbred line (RIL) population from a cross between Cocodrie and N-22 was evaluated for eight morphological traits under drought stress. Drought was imposed to plants grown in 75 cm long plastic pots at the vegetative growth stage. Using a saturated SNP linkage map, 14 additive QTLs were identified for root length, shoot length, fresh root mass, fresh shoot mass, number of tillers, dry root mass, dry shoot mass, and root-shoot ratio. Majority of the drought responsive QTLs were located on chromosome 1. The expression of QTLs varied under stress and irrigated condition. Shoot length QTLs qSL1.38 and qSL1.11 were congruent to dry shoot mass QTL qDSM1.38 and dry root mass QTL qDRM1.11, respectively. Analysis of genes present within QTL confidence intervals revealed many potential candidate genes such as laccase, Calvin cycle protein, serine threonine protein kinase, heat shock protein, and WRKY protein. Another important gene, Brevis radix, present in the root length QTL region, was known to modulate root growth through cell proliferation and elongation. The candidate genes and the QTL information will be helpful for marker-assisted pyramiding to improve drought tolerance in rice.  相似文献   
3.
Overland transport kinetics of pathogens is controlled, in large part, by soil and vegetation. With an increasing number of concentrated animal operations, there is becoming a greater need to dispose of a vast amount of manure in a single, localized area. Animal manure contains a substantial amount of microbial pathogens, including Cryptosporidium parvum that may pose a threat of contamination of water resources. This study examines the kinetics of C. parvum in overland transport and critical factors involved in the design of best management practices, especially vegetative filter strips, to prevent the transport of harmful pathogens to water bodies. Three soil types were tested (Catlin silt-loam, Alvin fine sandy-loam, Darwin silty-clay), spanning the entire spectrum of typical Illinois soils. A 20-min rainfall event was produced using a small-scale (1.07 m?×?0.66 m) laboratory rainfall simulator over a soil box measuring 0.67 m?×?0.33 m. Each soil type was tested for pathogen transport kinetics with bare surface conditions as well as with smooth brome and fescue vegetative covers. Surface runoff, soil cores, and near-surface runoff were each analyzed for infective C. parvum oocysts using cell culture infectivity assays. Results showed that vegetation greatly reduced the recovery of infective oocysts, in addition to delaying the time to the peak recovery. However, there was no clear evidence of any one vegetation type being advantageous over another. The bare soil experiments resulted in a higher recovery of C. parvum oocysts from the Darwin soil compared to other two soils. Analyses of soil cores show a slightly higher recovery of oocysts in the Catlin soil compared to Alvin or Darwin soils.  相似文献   
4.
Isoxaflutole is a new pre-emergence corn herbicide which controls both grass and broadleaf weeds. Experiments were performed in the laboratory to study the sorption of isoxaflutole in five different soils (Moorhead, MN; East Monroe, CO; Ellendale, MN; South Deerfield, MA; and Chelsea, MI) using the batch equilibration technique. Total initial isoxaflutole solution concentrations for each soil were 0.05, 0.15, 0.3. 0.8, 1.5, 2.0 and 4.0 mg litre−1. Analysis of [ring-14C] isoxaflutole was performed using liquid scintillation counting, and sorption data were fitted with the Freundlich model. Isotherms of isoxaflutole in all the soils were non-linear as depicted by the exponent (n < 1.0), indicating differential distribution of sorption site energies in various soils. Since the isotherms were non-linear the data fit Freundlich's isotherm well, as was indicated by high values of the regression coefficient (r2). The Freundlich sorption coefficient ranged from 0.555 to 50.0 (litre nmg lnkg−1). Multiple regression of the sorption constant, KF against selected soil properties indicated that organic matter content was the best single predictor of isoxaflutole sorption (r2 = 0.999) followed by soil pH (r2 = 0.954). Clay content of the soils did not have a high correlation with KF values (r2 = 0.453), while the sorption of isoxaflutole was not influenced by the Ca2+ concentration in the soil solution. Isoxaflutole sorption increased with an increase in organic matter content of soils. Sorption of isoxaflutole decreased as the soil pH increased from 4.5 to 8.5, which was depicted by the reduction of KF values. Sorption of isoxaflutole to the soils varied with differences in binding energies. At a particular net energy value (E*), the corresponding site energy distribution [F(E*)] values followed the order, Chelsea, MI > Moorhead, MN > East Monroe, CO > South Deerfield, MA > Ellendale, MN. The negative magnitude of Gibbs free energy of sorption (ΔG x) indicates the spontaneity of the given sorption process in the soils from Moorhead, MN; East Monroe, CO and Chelsea, MI. © 1999 Society of Chemical Industry  相似文献   
5.
Gynoecious is an important economic trait of cucumber for determinant of earliness and yield, yet genetic mechanism is not well understood for this trait. The experiment was conducted using F2 mapping population by crossing of PPC-2, a gynoecious and parthenocarpic line with Pusa Uday (monoecious and non-parthenocarpic cultivar). Out of 179 SSR markers screened, 39 markers differentiated the gynoecious and monoecious parents. However, only 17 markers were segregating with F2 mapping population, those were used for genotyping and linkage map analysis and these markers were placed along with F locus on chromosome 6 covering a total distance of 100.4cM. The SSR markers, SSR13251 and UW020605 were found to be closely linked to gynoecious (F) locus at 1.0 and 4.5 cM, respectively. The segregation of F2 population of PPC-2 × Pusa Uday and GPC-1 × Punjab Naveen and test crosses for sex type herein suggested that single dominant gene controlled the gynoecious sex expression in cucumber particularly in gynoecious genotypes PPC-2 and GPC-1. Therefore, the monogenic dominant nature of gynoecious sex identified in the present experiment and SSR markers closely linked to the F locus will be useful in marker-assisted backcross breeding for transfering gynoecious trait into horticulturally desirable varieties.  相似文献   
6.
Numerous sea oats (Uniola paniculata L.) plants are transplanted to Northern Gulf of Mexico beaches each year to reduce coastal erosion. To adapt to environmental changes and effectively reduce coastal erosion, genetically diverse sea oats plants with demonstrated plant performance must be used. The objectives of this study were to: (i) identify improved sea oats lines; and (ii) determine the genetic diversity of improved sea oats lines. From 2003 to 2005, 2,000 sea oats lines were evaluated in unreplicated field trials at natural beach sites. In 2005, 75 sea oats lines were selected based upon phenotypic performance. The 75 selected lines and 3 plants of ‘Caminada’, the only commercially available sea oats line, were evaluated in replicated field trials in 2008 and 2010. In 2008, UP01LA-15 K-HB-3092, UP01LA-16S-GP-3138, UP01LA-31-GP-3103, UP01LA-33-GP-1303, and UP01NC-04-HB-3374 had higher (p < 0.05) stem densities than Caminada. In 2010, variation was not detected for any trait measured; lack of significant differences was most likely due to plant stress caused by storm surge one week after transplant. Amplified Fragment Length Polymorphism detected 534 loci for the 75 selected lines and 3 Caminada plants. One hundred eighty one loci were polymorphic; the average polymorphism rate was 34% (range = 25–43%). Polymorphic information content values ranged from 0.15 to 0.41 and averaged 0.29 while Jaccard similarity coefficients ranged from 0.8243 to 0.9794. These findings demonstrate the application of plant breeding techniques to develop genetically different sea oats lines with improved performance for coastal restoration projects in the northern Gulf of Mexico.  相似文献   
7.
Screening of Rice Varieties for Endosperm Storage Proteins   总被引:2,自引:0,他引:2  
A. Bhowmik    T. Omura  T. Kumamaru 《Plant Breeding》1990,105(2):101-105
A total of 118 rice varieties/lines (Oryza sativa L.) from Bangladesh were analyzed for endosperm storage proteins on a single seed basis. The screening was done by observing the profiles of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with standard japonica variety ‘Kinmaze’. Six groups were classified on the basis of the poly-peptide banding patterns. Two-dimensional gel electrophoresis was performed to ensure the SDS-PAGE results in selected varieties. The analysis of extracted protein fractions revealed that one variety had low prolamin and one variety had high glutelin content.  相似文献   
8.
9.
Genetic Resources and Crop Evolution - In several regions of the world, low productivity in this crop is attributed to several factors including poor understanding of the genomic complexity of...  相似文献   
10.
A simple and efficient protocol for direct in vitro shoot multiplication and plant regeneration was established for an important aromatic medicinal plant, Alpinia calcarata. Preinduction of rhizome segments in medium containing 8.8 μM 6-benzylamino purine (BAP) rescued the buds from dormancy in 60% of the cultures. An average of 6.2 shoots were produced from rhizomatous bud explants on Murashige and Skoog (MS) medium supplemented with 5 μM BAP, 10 μM kinetin, and 2.5 μM α-Naphthalene acetic acid (NAA). The mother cultures retained their morphogenetic potential upto four subcultures and a maximum of 1.77-fold increase in shoot multiplication was recorded after the 3rd subculture. Rooting was simultaneously induced during subculture on shoot multiplication medium eliminating an additional step for rooting induction. Rooted plantlets were successfully acclimatized in pots in the greenhouse and subsequently established in the experimental garden without any visible symptoms of wilting and necrosis. The genetic fidelity of regenerated plants was evaluated by adapting to two PCR-based DNA marker techniques, Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR) which detected no variability in the in vitro multiplied plantlets of A. calcarata. This efficient method of clonal multiplication may be useful for commercial scale multiplication, and in situ and ex situ conservation of elite germplasm of A. calcarata.  相似文献   
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