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951.
The Lindero membranaceae-Fagetum crenatae association on Mt. Sanpoiwadake, Hakusan National Park, Japan, has been classified
using traditional Braun-Blanquet methods. The association was floristically sub-divided into six communities, all of which
had been included as four subassociations by Hukusima (1982). The resulting table was compared with an analogous community
table derived using computer-based TWINSPAN analysis. This dual approach was shown to provide a fully objective classification
by method, the subjective element in the Braun-Blanquet method thus being substantiated TWINSPAN. Subsequent ordination of
the data using DCA then provided a further degree of objective evaluation allowing any misclassified stand or species to be
re-examined, and at the same time displaying the detailed inter-relationships between all species or stands. 相似文献
952.
953.
A. M. Tomson R. Demets W. L. Homan D. Stegwee H. van den Ende 《Sexual plant reproduction》1988,1(1):46-50
Summary We describe a circadian rhythm in the surface density of receptors that play a dominant role in the mating process of the unicellular green alga Chlamydomonas eugametos.These receptors — called agglutinins — are large glycoproteins extrinsically bound to the membrane of gamete flagella. We found circadian fluctuations in their density. Since inhibition of protein synthesis affected the agglutinin density without a lag period at any time,we conclude that the density was dependent on de novo synthesis and that the fluctuations in density are caused by circadian oscillations in the rate of agglutinin synthesis. This phenomenon evidently underlies the pronounced endogenous rhythm in mating competence that we described previously (Demets et al. 1987). Finally, we speculate on the nature of the time keeping mechanism that is generating these rhythmic events. 相似文献
954.
Masamitsu Wada 《Journal of plant research》1988,101(4):519-528
Chloroplast proliferation was investigated inAdiantum protonemata growing under continuous red light. Cell division is absent when cells are grown under red light. The chloroplast
number increases as the cell length increases, therefore the chloroplasts divide in the absence of cell division. Chloroplasts
in the basal part of the filamentous protonemal cell migrate gradually toward the cell apex, but there is no large net migration
from the tip to the base or vice versa, indicating that chloroplast division takes place in the apical part of the protonemata.
Chloroplast number in the apical 100 μm was maintained at about 200 during cell growth at least over eight days. The chloroplasts
were either dumbbell- or ellipsoid-shaped. Dumbbell-shaped chloroplasts are abundant everywhere in a protonema, ranging from
30 to 50% of the total chloroplasts. The dumbbell-shaped chloroplasts attached to or very close to the plasma membrane seem
to be the ones that are dividing but the dumbbell-shaped ones in the other regions do not divide. These data support the hypothesis
that a signal from the plasma membrane induces the dumbbell-shaped chloroplasts to divide. 相似文献
955.
Process intensity of fixed bed glass sphere culture systems is increased considerably by replacing solid glass spheres with open pore glass spheres. This technique demonstrates the possibility of having a system capable of both volumetric and cell density scale up and being suitable for substrate attached and suspension cells. The yields achieved for a number of attached cell lines (approximately 107/ml) demonstrate an increase approaching one order of magnitude over solid glass spheres (approximately 106/ml). Also suspension cells were successfully entrapped in the open pore structure with similar yields. 相似文献
956.
Detailed examination of a sample plot covered by the Lindero membranaceae-Fagetum crenatae association on Mt. Sanpoiwadake,
Hakusan National Park, revealed a number of correlations between the distribution of subassociations and environmental factors.
The subassociations on the south-facing slopes receive deep snow cover in winter with rapid melting in the spring. They occur
on porous, freely draining soils, typical of the general range of brown forest soils. Conversely, on the north-eastern slopes
there are widespread late-snow patches which delay leaf development and expansion and which provide an abundant water supply
well into early summer. Under these conditions, bleached soil horizons have developed with iron pan formation, resulting in
poor soil drainage, strongly correlated with quite different plant communities. 相似文献
957.
958.
959.
图论在中国慈姑属数量分类研究中的应用 总被引:1,自引:0,他引:1
.黄德世;.钟扬;.陈家宽 《武汉植物学研究》1988,6(4):405-406
慈姑属(Sagittaria L.)是水生单子叶植物泽泻科(Alismataceae)的一个重要属。近年来,陈家宽等对中国慈姑属进行了系统研究。作者应用聚类分析和主成分分析进行了中国慈姑属的数量分类,取得了良好的效果。由于慈姑属分类性状数目较大,因而在压缩后的三维空间中描述分类群间的距离, 相似文献
960.
.钱敏之;.傅萼辉;.徐惠珠;.叶银根 《武汉植物学研究》1988,6(3):267-274
本文针对湖北贝母生产中存在繁殖系数低的问题,研究了单鳞片砂培繁殖对提高鳞茎繁殖率的效果和原理。试验结果表明:1.单鳞片繁殖率为对照种鳞茎的5—9倍,2.低温(2—10℃)预处理4—8周和暗条件培养,能有效地提高子球形成率,促使子球迅速长大,3.植物激素(6-BA、KT、2,4-D)处理,有利于促进鳞片不定芽原基的分化,繁殖率为种茎繁殖的9—11倍;4.单鳞片繁殖的小鳞茎主要发生在鳞片基部的茎盘上,还可发生在鳞片的远轴面上,但不发生在近轴面。 相似文献