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1.
A series of near-bottom excess radon profiles was measured in the Indonesian archipelago during the Snellius-II Expedition. The results show considerable variations in structure, 222Rn concentrations and integrated excess 222Rn inventory in the water column. Near-bottom vertical eddy diffusion coefficients vary from 46.4 to 63.6 cm2·s−1 in the basins; they are in general much higher on slopes and sills. The standing crop (the integrated amount of excess 222Rn) ranges from 0.9 to 49.6 dpm·cm−2. 226Radium supported 222Rn concentrations range from 9 to 3888·10−2 dpm·kg−1 Compared to mid-ocean basins the vertical mixing processes of near-bottom water masses in the Indonesian archipelago is fast, especially in the water layer from 50 to 200 m above the bottom, with diffusion coefficients in the order of 10 times higher than in the Pacific Ocean. With the exception of two stations standing crop values were comparable with those found in the Pacific Ocean but higher than those from the Atlantic Ocean. 210Pb analyses show high sedimentation rates, up to 75 cm·10−3·a−1. This does not agree with related standing crops. One explanation can be that erosion plays an important role on the sills and slopes.  相似文献   

2.
Amylose content is a major determinant of the eating quality in rice. To elucidate the allelic diversity at the Waxy (Wx) gene which controls the amylose synthesis, two cultivated strains having opaque endosperms were studied. The gene responsible for opaque endosperms was introduced into the genetic background of the Japonica type of rice by successive backcrosses, and the two near-isogenic lines (NILs) were selected from the B5 generation. The genetic experiments revealed that an allele, Wxop, controls opaque endosperms which show chalky as wx endosperms in spite of the production of amylose. Immunoblotting analysis was carried out to compare the gene expression by using the NILs with 4 different alleles (Wxa, Wxb, Wxop and wx). The level of the gene product bound to starch granules was slightly lower in the NILs with Wxop than that with Wxb, showing a positive correlation with amylose content in the endosperm. Extracts from mature anthers indicated that the gene product was markedly reduced in the NILs with Wxop as well as that with wx, showing an altered expression in the tissue specificity in the Wxop lines. Sequence analysis suggested that the Wxop had been derived from Wxa, independently of the origin of Wxb. The importance of the gene regulation was discussed in relation to diversified phenotypes established during the domestication process.  相似文献   

3.
Resistance at the TM-2 locus in the tomato to tomato mosaic virus   总被引：4，自引：0，他引：4  
T. J. Hall 《Euphytica》1980,29(1):189-197
Summary There are three known tomato mosaic virus (TMV) resistance factors, Tm-1, Tm-2 and Tm-2 2, in the tomato. Tm-2 2 is currently the most widely utilised in glasshouse cultivars. Both Tm-2 and Tm-22 can induce systemic necroses in response to virus infection. These are considered to be hypersensitive resistance reactions in view of the low virus concentrations in affected plants and because sub-inoculation usually fails to infect all plants possessing the same resistance gene. The literature relating to TMV resistance at the Tm-2 locus in the tomato is reviewed.Virulent strains may readily establish when Tm-1 or Tm-2 are used, but Tm-2 2 confers more effective resistance. The possible development of aggressive isolates capable of affecting Tm-2 2/Tm-22 plants is discussed. The establishment of virus types which cause systemic necrosis at normal growing temperatures is considered more likely than widespread infection from fully virulent strain 22 mutants. However, the growing of crops isolated from the TMV reservoirs in the soil considerably reduces the likelihood of even this occurring.  相似文献   

4.
Hordeum chilense is a wild barley species that has a high degree of genetic variability and significant potential for use in plant breeding. To establish a series of trisomics in H. chilense (2n = 14), plants with 2n + 1 chromosome numbers were isolated from the progenies of selfed triploid plants. Based on both fluorescent in situ hybridization with pAs1 and pTa71 repetitive DNA probes and C-banding patterns, seven different trisomics were tentatively identified. Primary trisomic plants were for chromosomes 1Hch, 4Hch, 5Hch, 6Hch and 7Hch. A secondary trisomic carrying a 5HchS-5HchS isochromosome as the extra chromosome and a trisomic for chromosome 3Hch heterozygous for the 3HchS-4HchL and 4HchS–3HchL interchange were identified. The trisomic for chromosome 1Hch cannot be phenotypically distinguished from the diploid. The rest of the trisomic types were distinguishable from the diploid by their morphological characteristics (relatively poor vigour, decreased size and shorter spikes) but they were morphologically indistinguishable from each other. The frequencies of trisomics among the progenies derived from self-fertilization of these aneuploids ranged from 10.7% to 37.5%, with an average frequency of 26.1%. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

5.
The solid load level in the Niger River proved to be subject to distinct seasonal variations, the highest concentration being attained well before peak river discharge.A total of 25.4×109 kg of sediment was flushed into the Atlantic through the drainage system in 1980–1981, representing an upward review of a previous estimate statedin Martins (1982). The specific erosion rate then becomes 20.5·103kg·km−2·y−1, the highest so far measured in Africa.The composition of the transported sediment reflects the chemical disintegration of silicate rocks predominant in the basin.  相似文献   

6.
为探讨HA、金属Cu2+以及活性污泥三者间的相互作用关系,研究了在HA存在下,不同吸附时间、pH值、Cu2+质量浓度以及温度对活性污泥吸附Cu2+的影响,并从热力学、吸附前后活性污泥性状以及红外光谱等角度分析了活性污泥吸附Cu2+机理。结果表明,当活性污泥为2 g/L、HA质量浓度为50 mg/L、pH=6,Cu2+质量浓度为50 mg/L时,经过90 min达到吸附平衡,Cu2+吸附量为45.98 mg/L,吸附率达到91.96%。研究发现,HA可以削弱Cu2+对活性污泥的毒性,活性污泥吸附Cu2+主要依靠氢键力和偶极间力,而多糖类、脂类C-O及苯环C-H等官能团在吸附过程中发挥着主要作用。  相似文献   

7.
M. Q. Yu  J. Jahier 《Plant Breeding》1992,108(4):290-295
Hybrids of Aegilops variabilis (2n = 28, UUSvSv) with the low-pairing type lines of Ae. longissima, Ae. bicornis, Ae. searsii, Ae. speltoides and Ae. umbellulata were obtained. This is the first report of successful hybridization between Ae. variabilis and Ae. searsii. Meiotic analysis of these hybrids showed that the U genome of Ae. variabilis donated by Ae. umbelltilata remained nearly unchanged and Ae. longissima is the possible donor species of the S genome to Ae. variabilis. But the Sv genome and the S1 genome of Ae. longissima are not completely homologous and are structurally differentiated by at least one interchange. According to their levels of homology with Sv through the means of chromosome associations, the four genomes of Sitopsis section species can be classified as follow: Sv? S1 > Sb > Ss > S. The meiotic behaviour of the hybrids between the wheat ‘Chinese Spring’ and the four Sitopsis section species studied has not supported the view that one of the four species is the donor of the B genome of wheat.  相似文献   

8.
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9.
Recent sediment accumulation rates were calculated from downcore 210Pb-excess activity profiles obtained from box cores taken in the Oyster Ground, North Sea. The rates ranged from 0.04 to 0.94 cm·yr−1 with an average of 0.39 cm·yr−1. In the top sediment layer the activities were rather low, the highest being only 1.15 dpm·g−1, and the average value 0.92 dpm·g−1.As shown by X-ray radiographs, downcore variations in texture were small: most samples being homogeneous and lacking primary sedimentary structures. Burrowing was evident in all cores, and most of them had a surface mixed layer of at least 5 cm, below which the 210Pb activity rapidly dropped to background value.Downcore deviations from the logarithmic decrease in 210Pb with depth could generally be attributed to biological disturbance or physical processes causing reworking of the sediment. Only in one core did the 210Pb activity decrease regularly with depth. The activities of 137Cs in this core and another demonstrated recent accumulation rates of 0.44 and 0.88 cm·yr−1, respectively, which are in good agreement with the rates obtained from the 210Pb method in the same cores (viz. 0.37 and 0.94 cm·yr−1). From these sedimentation rates the total amount of mud yearly deposited in the muddy part of the Oyster Ground is estimated to be in the order of 2×109 kg·yr−1, which is 4 to 5% of the total amount of mud yearly deposited in the North Sea.  相似文献   

10.
The paper presents estimates of the relative efficiency (RE) of the 35‐1 (V) and 35‐2 (III) fractional factorial designs. Three variants of each fractional design were generated from a one‐replicated 35 full factorial design applied in field experiments with pea (Pisum sativum L.). Plant height and seed yield were determined in the study. Additional measurements of soil properties (pH, P, K, Mg) and plant traits determined on the alleys between experimental strips, sown with a single cultivar, were performed in regular nets of sampling points. Geostatistical methods were used to estimate the spatial variation of the experimental field. Information on spatial variation was included in the statistical analysis. It was found that in the 35‐1 (V) fractional designs most of the significant effects were the same as in the 35 full factorial design. Information from these two types of design was similar, although there was a distinct tendency to higher values of the coefficient of determination R2 for linear models of the 35‐1(V) designs. The 35‐2 (III) fractional designs were more variable in detecting significant effects. Generally, mean RE was higher in the 35‐2 (III) design than in the 35‐1 (V) design, but at the same time the standard error of the latter one was distinctly lower. It was also demonstrated that in agricultural field experiments factorial fractional designs are a very good alternative to full factorial designs as concerns the estimation of main and two‐factor interaction effects in the case of the 35‐1 (V) designs and main effects in that of the 35‐2 (III) designs. Even if the designs have a highly reduced number of treatments to be tested they are equally or more effective than the original 35 design from which they were generated, provided that the generator is chosen very carefully and the spatial variation of the experimental field is considered in statistical analysis of the experimental data.  相似文献   

11.
We produced 15 dissection lines of common wheat carrying segments of chromosome 1R of wild rye (Secale montanum) (1Rm) by the gametocidal system. Using the 1Rm dissection lines and previously established 24 dissection lines of chromosome 1R from cultivated rye (Secale cereale cv. ‘Imperial’) (1Ri), we conducted cytological mapping of 97 markers that were amplified in the 1Ri addition line. Sixty‐eight of the 97 markers were amplified in the 1Rm addition line. To reveal what structural differentiation occurred in chromosome 1R during domestication, we compared the cytological map of chromosome 1Ri with that of chromosome 1Rm, and also with the previously published cytological map of chromosome 1R from wheat cultivar ‘Burgas 2’ (1RB). There was one discrepancy in marker order in the satellite region between chromosomes 1Ri and 1RB, while there were four discrepancies in marker order between chromosomes 1Ri and 1Rm. These results suggested that during the domestication of rye, some intrachromosomal rearrangements had occurred in chromosome 1R, although this chromosome is regarded as the most stable chromosome in the rye genome.  相似文献   

12.
In July 1984 benthic research was carried out in the Java Sea and around the islands of Madura and Bali.The aim was to describe the structure of the benthic communities in terms of numerical density (numbers of dominant macrofaunal groups and meiofauna per square metre) and biomass (g ashfree dry weight (AFDW) per square metre), and in relation to geographical position and main ambient factors, i.e. water depth, bottom temperature and sediment characteristics.In addition attempts were made to estimate the activity of these benthic ecosystems, and to show their relation to the pelagic.Box-core samples, collected along west-east axis in the Java Sea and in the Strait of Madura, showed relatively poor benthic communities. The average densities of macrofaunal organisms (> 1 mm) did not exceed 250 specimens·m−2; the total biomass was below 1 g AFDW·m−2; small polychaetes and crustaceans were the dominant groups.A number of larger organisms have developed very remarkable adaptations to the muddy environment. Meiofaunal organisms (nematodes being the dominant group) numbered 0.06·106 to 0.46·106 specimens·m−2. In general there is a trend from west to east towards somewhat richer communities. The actual carbon demand of the benthic ecosystem in the area investigated is tentatively estimated at an average of 38 g C·m−2·y−1, which amounts to about 40% of the primary production.Both the very soft fluid-mud bottoms in the central Java Sea and in Strait Madura, and the relatively low amount of energy available for growth, probably prevent the establishment of well developed benthic communities.  相似文献   

13.
Summary A symbiotically defective mutant in Vicia faba is described. This character is controlled by a recessive gene named sym-1. Reciprocal graft experiments indicate that only the root system controls its expression. Depending on the strain of Rhizobium, the root phenotype can be either Fix+ Nod- or Nod-.  相似文献   

14.
烯效唑对杂交水稻温室秧苗形态、生理特性及产量的影响   总被引：2，自引：0，他引：2  
在杂交水稻温室秧苗1 叶1 心期和寄秧15 d 后各喷施1 次50 ～200 mg·L- 1 烯效唑,可使苗高降低,植株干重、分蘖和总根数、白根数增加,茎基部变宽,叶片变宽变短,根系活力增强,叶片的可溶性糖、蛋白质、叶绿素含量及过氧化物酶(POD) 活性、光合速率提高;后期灌浆速率增大,有效穗增加。其中以喷施100 mg·L- 1 处理效果最好,1996 年小区试验比对照增产18-09 % ,1997 年大区对比试验较之对照增产16-20 % 。  相似文献   

15.
钙对水稻苗期光合特性影响及其亚细胞分布   总被引：1，自引：0，他引：1  
为了探明钙对水稻苗期光合特性影响及其在亚细胞分布的分布规律,选用高糙米钙含量品种和低糙米钙含量品种为试验材料,采用水培方法研究了钙对水稻苗期光合特性的影响及其在水稻不同类型品种中的亚细胞分布。结果表明,高钙品种的叶片净光合速率明显强于低钙品种。水稻叶片中钙含量大于根系中钙含量。在各重要细胞器组分中,钙分布表现为细胞壁>核糖体及细胞内可溶物>质体（或叶绿体）>线粒体>细胞核,细胞壁是钙最主要分布场所,细胞核﹑线粒体中分布较少。各细胞器中钙含量随钙处理浓度升高而增加,高钙品种表现更为明显。高钙处理对高钙品种各重要细胞器钙增加明显,推测高钙品种表现出更强的积累钙和耐受高钙胁迫能力。  相似文献   

16.
O. Veisz  H.-J. Braun  Z. Bedő 《Euphytica》2001,119(1-2):179-183
In the first experiments, studies were made on the survival % of fourwinter wheat varieties with good frost resistance and two with poor frostresistance, and on the degree of plant damage after freezing at –14 °C and –16 °C under phytotron conditions. In the secondexperiment the frost resistance of the varieties included in the 9thFacultative and Winter Wheat Observation Nurseries (FAWWON) wasdetermined after freezing in the phytotron at – 15 °C. The scoresgave a good reflection of the variety ranking determined on the basis ofsurvival % and of the different effects of the two freezing temperatures. Onthe basis of the scores, the plants were divided into two groups for eachtreatment and each variety: plants which suffered frost damage (a score of2–3), and plants which suffered no frost damage (a score of 4–5).Twenty plants from each group were raised to maturity in pots. Theyield parameters of plants damaged by freezing at – 14 °C werereduced to a lesser extent than those frozen at –16 °C. Of the eightparameters tested, the reduction in the number of ears per plant andconsequently in the number of grains in the side ears, the grain mass andthe total grain yield, gave the clearest indication of the extent of plantdamage. The results of the second experiment indicated that in some casesthe frost resistance of the varieties could be predicted from the wheatproduction zone (e.g. varieties from Eastern Europe and Nebraska haveexcellent frost resistance), while in other zones winter hardiness and frostresistance depended rather on the country or on the breeding location.  相似文献   

17.
In situ sediment denitrification rates were determined in the major areas of deposition of the North Sea, using the acetylene block technique. In addition, nitrous oxide profiles of the water column were determined. Nitrous oxide production generally occurred in the photic zone possibly due to nitrification; and throughout the water column in the German Bight region. Consumption at depth was possibly due to reduction in the anoxic microzones of faecal pellets, concentrated at the thermocline. Saturation of surface waters was 102.2% compared to 130.3% in the German Bight region. Calculated flux of nitrous oxide to the atmosphere was 9.5 × 106 kg yr−1, over half of which was produced in the German Bight.Sediment denitrification rates varied through three orders of magnitude; the highest value of 150 μmol m−2 d−1 was recorded in the Norwegian Trench. Nitrous oxide production by the sediments was low (1.1 μmol m−2 d−1 max.), and was undetectable at half of the sites. Sediment nutrient profiles exhibited porewater nitrate concentrations exceeding that of the overlying water suggesting that denitrification was fuelled by nitrification, which, in turn was related to other environmental variables. A significant positive relationship existed between in situ denitrification rate and the nitrate content of the upper sediment. Extrapolation of the rate to the total area of deposition in the North Sea suggests that denitrification is responsible for a minimum loss of 7.5–12% of the total annual nitrogen contaminant input.  相似文献   

18.
The dwarf safflower mutant ‘Enana’ has been developed from the cultivar ‘Rancho’ by chemical mutagenesis. The objective of the present research was to study the inheritance of plant height in crosses between ‘Enana’ and ‘Rancho’. Plants of both lines were reciprocally crossed and the F1, F2 and F3 generations were obtained. The evaluation of plant height in the F2 generation suggested the presence of a single locus controlling this trait. This was confirmed after the evaluation of 164 F2:3 lines, which revealed an F2 segregation fitting a 1:2:1 (dwarf: intermediate: standard) ratio. The locus was designated Dw. As the mutated allele was partly dominant over the wild‐type allele, the proposed genotype for ‘Rancho’ was dw dw, whereas that for ‘Enana’ was Dw Dw. Furthermore, a partial cytoplasmic effect on plant height was detected, with the heterozygote Dw dw being about 6 cm taller when ‘Rancho’ was used as female.  相似文献   

19.
新陆早42号体细胞胚发生和植株再生   总被引：3，自引：2，他引：1  
 以新陆早33号为对照研究新疆主栽品种新陆早42号的体细胞胚胎发生。研究表明,所用4种激素组合均能有效诱导愈伤组织,但二者仅在经过IBA 1.0 mg·L-1+KT 0.5 mg·L-1和2,4-D 0.1 mg·L-1+KT 0.1 mg·L-1两种激素组合诱导初生愈伤后,才能胚胎发生。新陆早42号在IBA 1.0 mg·L-1+KT 0.5 mg·L-1培养基上46 d就开始胚胎发生;新陆早33号则不能直接胚胎发生,需继代到MSBP培养基上培养48 d才有胚胎发生。经2,4-D 0.1 mg·L-1+KT 0.1 mg·L-1组合培养的愈伤均需要继代到MSBP培养基上培养才能胚胎发生,新陆早42号和新陆早33号胚胎发生的最早时间分别是71 d和81 d。胚性愈伤在铺有滤纸的MSBF培养基上分化成胚并发育成再生植株。新陆早42号在140 d有根系发育良好的能嫁接植株（株高 7～8 cm）,而新陆早33需180 d。即成功建立了新陆早42号的再生体系,且其胚胎发生能力和再生能力均优于对照。  相似文献   

20.
枣棉间作条件下棉花密度对棉花光合特性及产量影响   总被引：3，自引：0，他引：3  
在枣棉间作条件下,通过设置不同的棉花种植密度(13.5万、18.0万和22.5万株·hm-2),研究了密度对棉花光合作用及产量的影响。结果表明,间作棉花形态、荧光参数和光合特性受到枣树的显著不利影响,表现出明显的边行负效应。随着枣棉间距离的增加,不利影响减小,SPAD值、光系统II的实际光化学效率(ΦPSII)和净光合速率(Pn)显著增加;随着密度增加,间作棉花LAI和干物质质量显著增加。密度为18万株·hm-2的间作棉花的光系统II的实际光化学效率(ΦPSII)、净光合速率(Pn)、蒸腾速率(Tr)和产量显著高于13.5万株·hm-2和22.5万株·hm-2。在枣棉间作复合系统中,适当增加枣棉间距可以减轻枣树对棉花的不利影响,而较高的棉花密度也有利于棉花高产。  相似文献   

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