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91.
92.
长白山站的研究数据库管理系统翟永华,赵士洞(中国科学院沈阳应用生态研究所110015)Date-BaseManagementSysteminChangbaishanForestEcosystemResearchStation.¥ZhaiYonghua... 相似文献
93.
The sex ratio in final-instar larvae of a birch-feeding, free-living solitary sawfly, Dineura virididorsata, was investigated in Finnish Lapland. The prepupal proportion of females, pooled over ten sites, was 56%, and at four individual
sites the sex ratio was significantly female-biased. Larval survival from egg to prepupae did not differ between the sexes.
This suggests a femalebiased primary sex ratio in the field. The sex ratio varied among the sites but not among host trees
within sites. Contrary to previous results with hymenopterans, we did not find that differences in the sex ratio depended
on forage quality: site-specific or tree-specific sex ratios did not correlate with the average prepupal weight. A literature
search indicated that female-biased sex ratios are also common in other free-living sawflies. We are unable to explain sex
ratios of Dineura virididorsata or other free-living sawflies with existing general models. 相似文献
94.
An important component of the interaction between macroinvertebrates and leaf litter in streams in the extent to which consumers
can differentiate between undecomposed and decomposing leaves. The detritivores Gammarus pulex and Asellus aquaticus fed preferentially on conditioned rather on unconditioned leaf material. Growth in A. aquaticus was significantly reduced when unconditioned leaves were provided, but in G. pulex no significant effect of conditioning on growth was observed. The capacity of G. pulex to tolerate reductions in food quality seems to be a consequence of a compensatory system in which respiration rates change
to compensate for reductions in food quality. In this way a constant growth rate is maintained. Increases in ingestion rates
to compensate for low quality food were not observed. 相似文献
95.
Tradescantia albiflora (Kunth) was grown under two different light quality regimes of comparable light quantity: in red + far-red light absorbed mainly by photosystem I (PSI light) and yellow light absorbed mainly by photosystem II (PSII light). The composition, function and ultrastructure of chloroplasts, and photoinhibition of photosynthesis in the two types of leaves were compared. In contrast to regulation by light quantity (Chow et al. 1991. Physiol. Plant. 81: 175–182), light quality exerted an effect on the composition of pigment complexes, function and structure of chloroplasts in Tradescantia: PSII light-grown leaves had higher Chl a/b ratios, higher PSI concentrations, lower PSII/PSI reaction centre ratios and less extensive thylakoid stacking than PSI light-grown leaves. Light quality triggered modulations of chloroplast components, leading to a variation of photosynthetic characteristics. A larger proportion of primary quinone acceptor (QA ) in PSI light-grown leaves was chemically reduced at any given irradiance. It was also observed that the quantum yield of PSII photochemistry was lower in PSI light-grown leaves. PSI light-grown leaves were more sensitive to photoinihibition and recovery was slower compared to PSII light-grown leaves, showing that the PSII reaction centre in PSI light-grown leaves was more easily impaired by photoinhibition. The increase in susceptibility of leaves to photoinhibition following blockage of chloroplast-encoded protein synthesis was greater in PSII light-grown leaves, showing that these leaves normally have a greater capacity for PSII repair. Inhibition of zeaxanthin formation by dithiothreitol slightly increased sensitivity to photoinhibition in both PSI and PSII light-grown leaves. 相似文献
96.
Improving the mineral reserves and protein quality of maize (Zea mays L.) kernels using unique genes
The effects of the maize genes, o
2 and Mal, on the concentrations of mineral nutrient cations and amino acid levels in mature maize (Zea mays L) kernels of various inbred lines were studied. Previously, the o
2 gene has been used to improve the protein quality and increase the mineral nutrient content of kernels from some inbred lines. Genotypes possessing the Mal (multiple aleurone layer) gene, contain more than one row of aleurone cells in their kernels and this gene enhances the effect of the o
2gene on improving kernel protein quality. Incorporating these genes into the maize genome increased accumulation of several mineral nutrients (including Ca, Mg, Zn, Fe, Mn, Zn and Cu) in some of the experimental lines studied. The physiological basis for this increase of mineral nutrients in the kernels is discussed. The effect of the Mal gene on the kernel amino acid composition and protein quality was also examined. Possibly, these genes could be used in combination in breeding programs to improve kernel quality and nutritional value of maize. 相似文献
97.
Estimating regional carbon stocks and spatially covarying edaphic factors using soil maps at three scales 总被引:2,自引:1,他引:1
Most estimates of regional and global soil carbon stocks are based on extrapolations of mean soil C contents for broad categories
of soil or vegetation types. Uncertainties exist in both the estimates of mean soil C contents and the area over which each
mean should be extrapolated. Geographic information systems now permit spatially referenced estimates of soil C at finer scales
of resolution than were previously practical. We compared estimates of total soil C stocks of the state of Maine using three
methods: (1) multiplying the area of the state by published means of soil C for temperate forests and for Spodosols; (2) calculating
areas of inclusions of soil taxa in the 1:5,000,000 FAO/UNESCO Soils Map of the World and multiplying those areas by selected
mean carbon contents; and (3) calculating soil C for each soil series and map unit in the 1:250,000 State Soil Geographic
Data Base (STATSGO) and summing these estimates for the entire state. The STATSGO estimate of total soil C was between 23%
and 49% higher than the common coarse scale extrapolations, primarily because STATSGO included data on Histosols, which cover
less than 5% of the area of the state, but which constitute over one-third of the soil C. Spodosols cover about 65% of the
state, but contribute less than 39% of the soil C. Estimates of total soil C in Maine based on the FAO map agreed within 8%
of the STATSGO estimate for one possible matching of FAO soil taxa with data on soil C, but another plausible matching overestimated
soil C stocks. We also compared estimates from the 1:250,000 STATSGO database and from the 1:20,000 Soil Survey Geographic
Data Base (SSURGO) for a 7.5 minute quadrangle within the state. SSURGO indicated 13% less total soil C than did STATSGO,
largely because the attribute data on depths of soil horizons in SSURGO are more specific for this locality. Despite localized
differences, the STATSGO database offers promise of scaling up county soil survey data to regional scales because it includes
attribute data and estimates of areal coverage of C-rich inclusions within map units. The spatially referenced data also permit
examination of covariation of soil C stocks with soil properties thought to affect stabilization of soil C. Clay content was
a poor predictor of soil C in Maine, but drainage class covaried significantly with soil C across the state. 相似文献
98.
Bayesian analysis of linkage between genetic markers and quantitative trait loci. I. Prior knowledge 总被引:8,自引:0,他引:8
I. Hoeschele P. M. VanRaden 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,85(8):953-960
Summary Prior information on gene effects at individual quantitative trait loci (QTL) and on recombination rates between marker loci and QTL is derived. The prior distribution of QTL gene effects is assumed to be exponential with major effects less likely than minor ones. The prior probability of linkage between a marker and another single locus is a function of the number and length of chromosomes, and of the map function relating recombination rate to genetic distance among loci. The prior probability of linkage between a marker locus and a quantitative trait depends additionally on the number of detectable QTL, which may be determined from total additive genetic variance and minimum detectable QTL effect. The use of this prior information should improve linkage tests and estimates of QTL effects. 相似文献
99.
Combinations of different light quality and fluence exposure times were investigated for their effects on in vitro growth of the woody plant Spiraea nipponica. An interaction was demonstrated between different levels of benzyladenine (BA) used for in vitro propagation and the specific light regimes investigated. This relationship was affected by the length of exposure to either white or red/FR light and the time of transfer from one fluence rate to another. In all instances exposure to red/FR light resulted in more extensive growth than under white light. Thus explants cultured under 0.25 and 0.4 mg l-1 of BA exhibited high shoot proliferation rates when transferred, after 4 weeks of low photon fluence red/FR light, to higher fluence white light for a further week. The proliferation rates obtained were higher than any white light treatment including that with the highest BA level of 0.5 mg l-1. In addition, the combination of red/FR light exposure with a white light stage of higher fluence improved proliferation at lower exogenous BA levels. 相似文献
100.
Federica Rossi Rita Baraldi Osvaldo Facini Bartolomeo Lereari 《Plant Cell, Tissue and Organ Culture》1993,32(2):145-151
The morphogenic effect of different light wavelengths on in vitro rooting of Prunus insititia GF655-2 in relation to the presence of napthaleneacetic acid (NAA) in the culture medium was investigated. Results of experiments in which plantlets were rooted in NAA enriched medium showed that the presence of auxin induced rooting even in the dark after an initial lag period. Illumination of the cultures with Red light was as effective in promoting rooting as treatment with 0.5 M NAA; Red was more active in stimulating rooting in the short term than was NAA. The pattern of root formation resulting from the addition of NAA appeared to dominate development under White, Blue and Far Red treatments. Although it was possible to correlate the rooting response to the phytochrome photoequilibrium induced by the light treatments used, there arises a possible interference of specific Blue absorbing photoreceptors.Abbreviations B
Blue
- FR
Far Red
- HIR
High Irradiance Response
- Pfr
active (far-red absorbing) form of phytochrome
- Ptot
total phytochrome
- R
Red
- W
White
- NAA
-naphtaleneacetic acid
- BA
benzyladenine
- IAA
indole 3-acetic acid 相似文献