Incidence of charcoal rot of sorghum and soil populations of Macrophomina phaseolina associated with sorghum and native vegetation in Somalia

Studies were conducted in the Bay Region of Somalia to determine the incidence of charcoal rot in sorghum incited by Macrophomina phaseolina and the soil population of M. phaseolina in sorghum fields and areas of native vegetation. Charcoal rot was detected in 34 of 40 sorghum fields. Incidence (percent sorghum hills with diseased plants) in the four regional districts was 21, 70, 20 and 35% (mean of 15 hills/field and 10 fields/district) for Baidoa, Burhakaba, Dinsoore and Quansadhere, respectively. Soil collected from the 40 sorghum fields and from 40 native vegetation sites (10 in each district) all contained M. phaseolina. Mean soil populations for sorghum fields and native vegetation sites were 25.2 and 2.5 microsclerotia g^–1 soil, respectively. Soil populations of M. phaseolina in sorghum fields were significantly (p=0.05) different from populations in native vegetation sites and ranged from 7 to 107 and 0.1 to 14.0 microsclerotia g^–1 soil, respectively. Incidence of charcoal rot in sorghum was positively correlated with soil populations of M. phaseolina (r=0.53, p= 0.01). Correlation between ratoon failure and disease incidence was also highly significant (r=0.48, p=0.01). Correlation between ratoon failure and soil population of M. phaseolina was not significant (r=0.17, p=0.10). Only one out of 30 seed lots of sorghum grown in the Bay Region contained seed infected with M. phaseolina.     

PCR Amplification，Cloning and Sequencing of RbcL Coding Region in Mesophyll Cell and Bundle Sheath Cell of Sorghum（Sorghum bicolor L．）

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New records of Aphyonidae (Teleostei: Ophidiiformes) from the south-western Atlantic

During austral summer and winter of 2003, three specimens of Aphyonus gelatinosus and one specimen of Barathronus bicolor (Ophidiiformes: Aphyonidae) were trawled off Rio de Janeiro, Brazil.     

两色绿刺蛾危害对毛竹单宁、总酚含量的影响

通过对受害和未受害毛竹枝叶中单宁、总酚含量的测定,分析了两类主要次生代谢物质的差异与两色绿刺蛾危害之间的关系。结果表明：毛竹枝叶中单宁、总酚的含量随着两色绿刺蛾的危害,均呈下降趋势,且显著相关。     

金色补血草花中黄酮类化合物抗氧化活性研究

研究了金色补血草花中黄酮类化合物在大豆油中的抗氧化活性.结果表明:金色补血草花中黄酮对大豆油具有明显的抗氧化作用,且具有剂量效应关系,温度对黄酮类化合物在大豆油中抗氧化性能有一定影响,维生素C、柠檬酸、酒石酸对金色补血草花中黄酮类化合物的抗氧化性能均有协同增效作用.     

Variability of phyllochron, plastochron and rate of increase in height in photoperiod-sensitive sorghum varieties

BACKGROUND AND AIMS: West African sorghum (Sorghum bicolor) varieties are generally highly photoperiod-sensitive, which is a necessary adaptation to the variable onset date of the rainy season and the variable dates of sowing in the savannah zone. Depending on sowing date, plants can produce from 12 to >40 leaves on the main culm, with height varying from 1 m to more than 5 m. The present study aimed to better understand the complex phenology of these variables. METHODS: A 2-year series of monthly sowings of three West African sorghum varieties was conducted near Bamako, Mali. Drought stress was avoided by supplemental irrigation. Rate of initiation of primordia at the stem apex was recorded, together with rate of leaf emergence and increase in plant height. KEY RESULTS: Leaf initiation and appearance rates (plastochron(-1) and phyllochron(-1)) were constant for a given sowing date in cases where less than 20 leaves were produced (generally observed with late sowing dates). In contrast, rates were bilinear for early sowing dates, for which plants produced more than 20 leaves. The secondary rates, which occurred from the 20th leaf onwards, were only half of the initial rate. Plastochron and phyllochron showed large variations among sowing dates, and were correlated with the rate of plant height increase. The initial plastochron and phyllochron were positively correlated with soil temperature and negatively correlated with both day length and day-to-day change of day length prevailing at plant emergence, but these factors explained only half of the variation observed. CONCLUSIONS: Although they belong to different genetic groups and have different height and photoperiod sensitivity, the three varieties studied exhibited similar response patterns of development rates among phenological phases and seasons, with the local landrace showing the greatest variation due to its longer vegetative phase and longer stem internodes. The possible adaptive advantages in African savannah environments of bilinear development rates and the associated limitation in height increase are discussed.     

Characteristics, linkage-map positions, and allelic differentiation of Sorghum bicolor (L.) Moench DNA simple-sequence repeats (SSRs)

Fifty one clones isolated from a size-fractionated genomic DNA library of Sorghum bicolor (L.) Moench, that had been probed with four radiolabeled di- and tri-nucleotide oligomers, were sequenced. Fifty of the clones contained one or more simple-sequence repeats (SSRs) [72% of which were (AG/TC) _n SSRs] and, following analysis of the clones, polymerase-chain-reaction primer sets that amplify 38 unique SSR loci were developed. Genotyping of the 38 loci in 18 sorghum accessions, including the parents of a recombinant inbred (RI) mapping population, revealed polymorphism at 36 of the loci among the 18 accessions and at 31 of the loci (not including null alleles at two loci) between the parents of the RI population. All of the latter 31 loci were mapped. The genotypes at 17-mapped SSR loci were assayed in 190 S. bicolor accessions in order to determine δ* _T , the estimated level of allelic differentiation (the estimated probability that two members of a population, chosen at random and without replacement, differ in allelic composition), at each of the loci. The mean δ* _T value determined for S. bicolor overall was 0.89, the range of mean δ* _T values for ten S. bicolor races was from 0.88 to 0.83, and the range of mean δ* _T values for ten working groups (= sub-races) of the race caudatum, with only two exceptions, was from 0.87 to 0.79. The lowest δ* _T values for six of the loci among the ten race-caudatum working groups ranged from 0.86 to 0.70; thus, the probability that different alleles will be present at one or more of these loci in two accessions chosen at random from a working group is > 0.996 when three of the loci are genotyped, and > 0.9999 when all six of the loci are genotyped. The results of this study confirm that most S. bicolor SSR loci are sufficiently polymorphic to be useful in marker- assisted selection programs and they indicate that the levels of polymorphism at some loci are high enough to allow the vast majority of S. bicolor accessions, even accessions within working groups, to be distinguished from one another by determining the genotypes at a small number, perhaps as few as a half-dozen, SSR loci. Received: 13 September 1999 / Accepted: 2 December 1999     

英罗港红树林昆虫群落及其多样性的研究

用1995～1996年在广西英罗港红树林区取样所得的资料探讨了英罗港红树林昆虫群落及其多样性特点.结果表明,英罗港红树林昆虫种类有195种;主要优势种为黑褐举腹蚁(Crematogaster rogenhoferi)、东京弓背蚁(Camponotus tokioensis)和三条螟蛾(Dichocrocris chorophanta);内滩昆虫群落多样性高于中滩、外滩.潮汐和风暴对昆虫群落多样性的影响是决定群落结构水平的重要因素;内滩、中滩和外滩影响多样性的主要成分是均匀性.