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61.
62.
Summary Somatic embryogenesis was initiated from immature embryos on Murashige-Skoog (MS) medium plus 2 mg.l-1 2,4-dichlorophenoxyacetic acid, 2% sucrose and 0.6% agarose. Somatic embryos were isolated and regenerated into whole green plants on MS medium devoid of 2,4-D. These regenerants were previously demonstrated to differ in their mitochondrial DNA organization. In order to estimate their characteristics three progenies of short-term culture regenerants and three progenies of long-term culture regenerants were analyzed and compared to the parental line. These somaclones obtained from the wheat variety Chinese Spring were evaluated for variation of 13 agronomic and morphological quantitative characters in comparison to the parental line. Significant variation was observed for plant height, spike length, main tiller diameter, between the somaclones regenerated from long-term culture and their parent. Differences were observed to increase with the duration of culture, leading to a significant modification of the structure of the plants. Several changes occurred during the somatic tissue cultures, but to a lesser extent than has previously been described in the literature. 相似文献
63.
Summary Significant genetic variation in CO2 assimilation rate (A), stomatal conductance (g), and A: g ratio, which are indicators of intrinsic differences in productivity and water use efficiency (WUE), has been demonstrated in grain sorghum [Sorghum bicolor (L.) Moench] hybrids. The primary objective was to determine the possible parental influence on the components of the A: g relationship in sorghum hybrids across a range of water supplies. Thirty F1 hybrids resulting from a 6 × 6 diallel crossing pattern constituted the genetic material. Field experiments were conducted using four water supply treatments established through differential irrigation. Carbon assimilation rate (A), g, and leaf water potential (w) of individual leaves were monitored every 15 to 20 days. Genetic analyses revealed that general- and specific-combining ability effects were evident for A. However, reciprocal and maternal effects were more important in governing the A-g and A-w relationships. Since the maternal effects were the major determinants in causing reciprocal differences, A can be improved by selecting specific female parents to exploit cytoplasmic factors or physiological characteristics of this parent. Substantial genetic variation in the A-g relationship resulting from significant genetic control of A offers the opportunity to impose selection for high A and stability of A, which might directly contribute to whole plant WUE and productivity in grain sorghum.Abbreviations A
carbon assimilation rate
- g
stomatal conductance to water vapor
- GCA
General Combining Ability
- SCA
Specific Combining Ability
- WUE
Water Use Efficiency 相似文献
64.
Claudio E. Rafanelli Gianna L. Petriconi Henry M. Papee 《Water, air, and soil pollution》1979,12(3):283-294
Our earlier research on the photochlorination of some organics suspended in solutions of aqueous Cl? codissolved with anionic NO x ? is extended to systems comprising either bromides or iodides, and NO 3 ? . It is found that the bromide-containing systems follow, under both artificial UV and sunlight, overall reaction patterns quite similar to those of chlorides although the rate term which stands for the bromination of organics is larger and directly proportional to light intensities. Solutions containing iodides also follow a similar overall pattern but the first rate term is now proportional to the square of light intensity. However, they react liberating detectable amounts of iodine which thereafter attack the hydrocarbon. This excess of elementary iodine is thus found to be either dissolved in or adsorbed by the organic; it furthermore also dissolves and becomes complexed in the aqueous phase. 相似文献
65.
Margaret A. Wheeler L. Slade Lee Robert J. Henry 《Genetic Resources and Crop Evolution》2001,48(5):483-497
Potamophila parviflora, a wild relative ofdomestic rice, is endemic to the north-eastern river systemsof New South Wales, Australia. It is the only member of the genus,and is habitat specific. Several new sites were found, mostly in theUpper Clarence catchment. Florets of P.parviflora were found to be 86%female-only, while 14% contained mature malereproductive parts, which occurred more often in the middle sectionof the panicle. Pollen was found to be necessary for the developmentof mature fruits. RAPD data showed that there is very little geneticvariation between individual plants, or between differentpopulations. An embryological study showed several irregularities inmegasporogenesis and megagametogenesis. No tetrads were observed inmegasporogenesis and the ovule is vacuolate at the megaspore mothercell stage. Megagametogenesis proceeded rapidly, nuclei within theovule were sometimes not spherical and varied in size, and sometimesthe antipodal cells doubled in number with a corresponding halving insize of the nuclei. Chromosome number varied between 2n = 24and 2n = 25, between and within populations. These resultsindicate that P. parvifloracould be a diplosporous apomict of the Antennaria type, althoughfurther works are required to provide conclusive proof. 相似文献
66.
Horvatovich P Miesch M Hasselmann C Delincée H Marchioni E 《Journal of agricultural and food chemistry》2005,53(15):5836-5841
The 2-alkylcyclobutanones (2-ACBs) are formed from triglycerides by irradiation treatment and may be used as markers for this type of food processing. This paper describes a detection method for the analysis of monounsaturated alkyl side chain 2-ACBs, which is formed upon irradiation from monounsaturated fatty acids which frequently are the most abundant fatty acids in foods. The estimated radioproduction yields of the cis-2-(dodec-5'-enyl)-cyclobutanones (cis-2-dDeCB) and the cis-2-(tetradec-5'-enyl)-cyclobutanones (cis-2-tDeCB) were 1.0 +/- 0.5 and 0.9 +/- 0.2 nmol.mmol(-1) precursor fatty acid.kGy(-1), respectively, being similar to that of saturated 2-ACBs. The stability study of the s- and mu-2-ACBs in poultry meat samples irradiated at 10 kGy and stored for 3-4 weeks at 4 degrees C and 25 degrees C showed that these compounds undergo some transformation, their amounts being reduced by about 50%. These storage losses did not depend on the saturation state of the alkyl side chain. The EI-MS detection limit of 2-tDeCB is 3 times higher (0.6 pmol) than that of 2-dodecylcyclobutanone (0.2 pmol). Consequently, when the oleic acid content of the analyzed food exceeds the content of palmitic acid by a factor of 3, it would be of an advantage to apply 2-tDeCB as a marker for detection of the irradiation treatment. 相似文献
67.
Plant species-level research that comprises inventories, impact studies and monitoring is necessary if plant resources are to be harvested sustainably by human populations living adjacent to protected areas in sub-Saharan Africa. This research assessed the extraction of plant products from two montane forest ecosystems, Uzungwa Scarp Forest Reserve (USFR) and Bwindi Impenetrable National Park (BINP), East Africa. In USFR, data from vegetation sampling and interviews with local people were used to understand the ecological and socio-economic aspects of non-timber forest product (NTFP) harvesting. The densities of eight commonly harvested tree species, most of which were used as building poles, were approximately 2.4-4.5 times lower in disturbed versus undisturbed habitats across all four sites in USFR. Interviews with 91 women and 54 men suggested that most species were harvested for medicinal uses (57 species) and building purposes (50 species). In BINP, the liana Loeseneriella apocynoides (Apocynaceae), is harvested for basketry weaving. Evidence suggested that the liana was harvested in both protected and unprotected areas of BINP. Data collected suggested a negative impact on this species in an unprotected versus a protected area, with stem diameters larger than 1 cm significantly more abundant in the protected area. This study reveals that harvesting of NTFPs occurs even in these two protected forest areas, and that over-exploitation not only threatens species of high-demand, but could also alter forest structure and composition. Management practices that encourage the monitoring of sustainable harvesting levels of species and promote alternative plants for the same uses should be considered as part of conservation strategies. 相似文献
68.
Soil and plant samples were collected from chlorotic plantations of Grand fir (Abies grandis) and Douglas-fir (Pseudotsuga menziesii) in Winter, 1989. The soils had been amended in 1981 with an average of 300 dry Mg ha?1 of municipal sewage sludge. The sludge amendment resulted in an N application rate of approximately 8000 kg ha?1. Foliage analysis indicated a severe Mg deficiency (0.25 g kg?1 in sludge-treated vs. 0.93 g kg?1 in untreated area) might be the cause of chlorosis. No other nutrient showed concentrations in the deficient or toxic ranges. Trace metal levels in foliage were elevated significantly for Ni, Cd and Cr in sludge-treated sites, but not toxic levels. Soil samples taken to a depth of 1.4 m indicated the potential for soil acidification (up to 0.9 pH unit) in soil surface horizons. In addition, exchangeable Ca, Mg and K may have been depleted in surface horizons. Exchangeable Al and Fe were greater in the surface of sludge-treated sites. These observations and the loss of much of the nitrogen added during the sludge amendment indicated that nitrification and cation leaching was likely the mechanism for acidification and depletion of exchangeable cations. Fertilization of the plantation with MgSO4 or dolomitic limestone was carried out in Spring 1990. New foliage collected in June, 1990 was non-chlorotic and significantly higher in Mg concentration than unfertilized foliage (1.1. vs. 0.7 g kg?1, respectively). Results of this study indicate that it is important to assess the potential for initiating a nutrient deficiency due to secondary effects of sludge application in forest systems. 相似文献
69.
Claudio E. Rafanelli Gianna L. Petriconi Henry M. Papee 《Water, air, and soil pollution》1978,9(4):403-412
The dissipation of chemical elements from ash basin effluent was determined by use of neutron activation analysis of sediment, water, plant, invertebrate, and vertebrate samples taken from successive sites through the drainage system. Samples were tested for concentrations of 40 elements for a 12 mo period. Three different modes of dissipation were found. The major mechanism for removal of chemical elements from effluent was sedimentation into the benthic sediment. All biota had greater concentrations of chemicals than did water, with invertebrates having slightly higher levels than did plants and vertebrates. Ten elements were more concentrated in at least one biotic group than in the sediment. Concentrations of six elements in the drainage system exceeded the EPA recommended limits for surface waters. The observed modes of dissipation in this aquatic system emphasize the necessity for stable biotic communities present to permit cycling of chemical elements. 相似文献
70.
Bockelée-Morvan D Biver N Moreno R Colom P Crovisier J Gérard E Henry F Lis DC Matthews H Weaver HA Womack M Festou MC 《Science (New York, N.Y.)》2001,292(5520):1339-1343
The gas activity of comet C/1999 S4 (LINEAR) was monitored at radio wavelengths during its disruption. A runaway fragmentation of the nucleus may have begun around 18 July 2000 and proceeded until 23 July. The mass in small icy debris (=30-centimeter radius) was comparable to the mass in the large fragments seen in optical images. The mass budget after breakup suggests a small nucleus ( approximately 100- to 300-meter radius) that had been losing debris for weeks. The HNC, H2CO, H2S, and CS abundances relative to H2O measured during breakup are consistent with those obtained in other comets. However, a deficiency in CH3OH and CO is observed. 相似文献