ECOLOGICAL GENETICS OF THE COLONIZING ABILITY OF ROSE CLOVER (TRIFOLIUM HIRTUM ALL.)

Thirteen populations sampled from among the oldest plantings of rose clover (Trifolium hirtum All.), introduced into the California range during the late 1940's, and 12 roadside populations established through natural colonization were compared for their genetic and demographic features. Roadside colonies showed a greater amount of reproductive effort in terms of a larger number of heads per plant and larger calyx, lower rate of seed carryover, higher and more stable plant density, lower seedling survivorship, and earlier flowering. The calyx was more hirsute in roadside collections and remained attached with the seed, a feature accounting for higher germination probabilities on the soil surface or in litter along the roadsides, in contrast to the range where grazing animals would often work the seed into the soil. Outcrossing rates are slightly higher in roadside colonies in which genetic polymorphisms at three marker loci represented as high levels of genetic variability as in the range populations. The colonizing success of rose clover seems to be largely determined by a few and rapid morphological changes and by the retention of some outbreeding and genetic variation. Such joint analyses of genetic and demographic features of colonizing species are needed to support various deductions about the characteristics of “ideal” weeds and colonizers.     

白三叶无性系植物种群整合作用格局的研究

利用酸性品红和＾１４Ｃ－标记光合同化物,分析了在维管系统上的资源运输。在木质部中染料的运输是向顶的,在韧皮部中标记的光合同化物的运输方式与木质部中酸性品红的移动是相反的,具有强烈的基性,定量分析表明,尽管有一些向顶的运输,但向基运输是占绝对优势的,但随着无性系生长时间的不同,运输将会发生改变。一个无性系的变化取决于复杂的整合作用,使它们成为许多半自发的整合生理单位（ＩＰＵｓ）,不同匍匐茎的分枝,就     

THE INFLUENCE OF GROWTH STAGE ON THE RESPONSE OF RED CLOVER (TRIFOLIUM PRATENSE L.) TO GIBBERELLIC ACID

The response of seedling and first harvest year plants of red clover ( Trifolium pratense L.) to treatment with gibberellic acid (GA) at various growth stages is described.
Seedlings sprayed before the seventh leaf stage developed into single-stemmed plants; treatment with GA at the third- or fourth-tiller stage resulted in final stem numbers similar to those of controls. Emergence was earliest, and the number of heads per plant greatest where sprayings were delayed until the third- or fourth-tiller stage.
In first harvest year plants significant increases in the number of heads per stem were obtained with certain treatments, especially those which had two applications of 0.5 mg. GA per plant during the elongation of the first four internodes. This was related in all treatment groups to modifications of the branching pattern, and also to the increased incidence of multiple heading. Earlier emergence resulted from treatment at all growth stages, the effect being maximal where three well-spaced sprayings were applied during active stem extension.     

守宫木种子油的脂肪酸组成（简报）

守宫木种子油的脂肪酸组成（简报）廖学焜,李用华（中国科学院华南植物研究所,广州５１０６５０）ＦＡＴＴＹＡＣＩＤＣＯＭＰＯＳＩＴＩＯＮＯＦＴＨＥＳＥＥＤＯＩＬＦＲＯＭＳＡＵＲＯＰＵＳＡＮＤＲＯＧＹＮＵＳ（Ｌ．）ＭＥＲＲ￥ＬｌａｏＸｕｅｋｕｎ;ＬｉＹｏｎ...     

杉木败育种子及其涩粒物质的研究

杉木种子的涩粒(败育种子)约占种子数的30—70%,涩粒率高是杉木种子发芽率低的根本原因之一。试验表明,立地条件、授粉方式、胚胎发育、光照、涩粒物质及母株的遗传性等都与涩粒的形成有着密切关系。涩粒物质的成分很复杂,其中含萜类物质。还含有多种矿质元素。通过采取多种综合措施,可以有效地提高种子的质量,较大幅度地降低涩粒率。     

OBSERVATIONS ON THE BIOLOGY OF CLOVER ROT

The field behaviour of clover rot in eastern England indicates that infection takes place by ascospores, and not by soil-borne mycelium developing directly from the sclerotia. To support this view, experimental evidence is presented to show that cutting of red clover at the time when the ascospores are being shed, reduces the percentage infection in the following spring.
Ascospore infection of clover causes a 'non-aggressive' spotting which may develop into an 'aggressive' infection. Sclerotinia trifoliorum has been shown to remain viable in non-aggressive spots for at least 16 weeks. Similar symptoms occur when beans are infected with S. trifoliorum var. fabae. Non-aggressive and aggressive infections are two phases of a sequence in time, and not two alternative types of infection dependent on the initial spore load. The occurrence of non-aggressive and aggressive phases in nature explains (1) the observed delay between ascospore discharge and the appearance of obvious disease symptoms, and (2) the seasonal nature of the disease.
Aggressive infection develops only in a saturated atmosphere and within a temperature range of 5–20° C., and its establishment is favoured by a heavy dosage of inoculum. In most seasons humidity is the main 'limiting' factor; over the 18-year period, 1930–47, there is a significant regression between the severity of clover rot and the previous December plus January rainfall.
Crop rotation and autumn grazing check the disease, but the latter must be practised with discretion because, under certain conditions, its effects are more drastic than those of the disease. The only hopeful method of effective control is the breeding of resistant strains of legumes.