Showing papers in "Botanical Review in 1946"

Detached leaf culture

Abstract: Detached leaf culture is here defined as the maintaining of leaves in a living condition for various periods after detachment from the plant of which they were once a part. Culture is here used to indicate life or existence as used by Vickery et al. (279) and Mason and Phillis (170) and not to indicate indefinitely continued growth as used by Carrel (41) and White (295), since leaves have apparently never been cultured in the meaning of the word used by Carrel and White. I n detached leaf culture, investigators may be primarily concerned with the development and function of the leaf itself, with some parasite on the leaf, or even with some hyperparasite on a parasite on a leaf. The use of detached shoots is arbitrarily included in this review, but embryo culture is excluded. No claim to completeness of coverage is made, and the writer would appreciate having called to his attention any important publications in the field of detached leaf culture which are omitted from the literature cited for this review. According to Mathuse (171), Madriola in 1652 reported the formation of roots and shoots by detached leaves. In 1754 Bonnet (26) published a book on the function of leaves, in which he reported in some detail many tests with detached leaves. While his interpretations of the functions of leaves are not acceptable to present investigators, his extensive data of the length of life of detached leaves held under various conditions of culture are still valid. Beginning about 1850 detached leaves came to be extensively used in studies of water absorption, transpiration, respiration and photosynthesis. The discovery by Boehm (24) in 1883 that detached leaves in the dark could form starch from sugar solution supplied to their petioles or to leaves floating on the solution was a

Marine algal ecology

Abstract: In 1946 it was suggested (18) that marine algal ecology was at a parting of the ways. In particular it was considered important that there be some co-ordination of nomenclatural problems. The last ten years have seen a considerable advance in this direction, and a number of workers have put forward suggestions for an over-all system of classification. At present there is a tendency towards general acceptance of the classification put forward by the Stephensons (127). Their proposals are certainly applicable to the shores of those parts of the world that have been investigated. As might be expected, there has been some increase in the number of autecological studies, and two or three very important contributions have made their appearance (76, 84, 110). It is expected that more and more such studies will appear because, now that the general pattern of zonation is clear, investigations of individual species should throw considerable light on the causal factors controlling their place in the zonation. There is still a need for ecological studies of muddy bays, sandy shores, mangrove swamps and estuaries. It is true that such areas are not easy to investigate because many of the species are not really identifiable nor are the communities very distinct. Nevertheless, definite algal communities do exist in such habitats, and their study is likely to be rewarding both ecologically and taxonomically. Thus Thompson (140) has described new dinoflagellates that form a maritime sand-dwelling community near low water mark. Day (32, 33, 116) and co-workers have commenced publishing what one hopes will be a series of contributions on estuarine faunas and floras, whilst the present author (21a) has studied the algal flora in a number of representative mangrove and salt marsh swamps within the Auckland province of New Zealand. A number of life-form classifications were proposed between 1905 and 1939, but none of them has since proved generally ac-

Physiology of citrus fruits in storage

Abstract: Refrigerated and frozen storage Concentrating Dehydrating Pickling and fermenting Sugar preservation Miscellaneous Recovery of constituents Disposal of residues and effluents Analytical and composition Nutrition Still another basis for classification might be according to the type of food as: Fruits Vegetables Grains Nuts Spices Meat Fish Dairy products Poultry products Condiments Confections Beverages.

The effect of mineral supply on the mineral concentration and nutritional quality of plants

Abstract: The mineral composition of plants is a function of many factors, such as difference in soils, use of soil amendments or fertilizers, and rainfall and other climatic influences. These factors overlap in their effects or work simultaneously. One factor may influence another. Thus, the effect of climate on the plant is partly direct and partly the result of the development by climatic factors of certain soil characteristics. Differences in these factors will naturally operate to modify the mineral composition of the plant in different ways. For example, it is possible (a) for the mineral composition of two plants of the same variety growing in different soils to be significantly different without there being any important difference in their size or the distribution of their parts, such as leaf, stem or seed head; (b) for the growth (yield) of plants of the same variety to vary in different soils without any important differences in the proportions of the parts of the plants; (c) for two plants of the same variety growing in different soils to have quite different distributions of leaf, stem or head; and (d) for environmental factors to so modify the quantities of plant constituents such as protein, carbohydrate, lignin and cellulose as to influence the percentage distribution of other constituents, as by a deposition of starch with a consequent reduction in the percentage composition of the mineral elements. The properties of two soils may be such as to modify the natural flora and thus to produce plants quite different in mineral composition. The evaluation of the influence of these factors on plant composition is still proceeding, and much valuable information of fundamental importance is being obtained. The nutritional diseases of animals which have been traced to soil characteristics may be divided into two general classes. The first,

Cytology of cereals. II

Abstract: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Euploid Chromosome Aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 Spontaneous Autoploid Aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 Induced Autoploid Aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 Undoubled Interspecific Hybrids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Undoubled Intergeneric Hybrids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 Interspecific Amphidiploids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270 Intergeneric Amphidiploids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Sesquidiploids or Haplo-Diploids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 Triple Hybrids and Bridge Crosses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 Chromosome Morphology and Genom Relationships . . . . . . . . . . . . . . . . . . . 278 Aneuploid and Structural Chromosome Aberrations . . . . . . . . . . . . . . . . . . . 282 Secale cereale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 Speltoids, Compactoids, and Fatuoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 Monosomics, Nullisomlcs,' and Polysomics . . . . . . . . . . . . . . . . . . . . . . . . 286 Other Structural Chromosome Aberrations . . . . . . . . . . . . . . . . . . . . . . . 287 Asynapsis, Desynapsis or Dissociation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 Sterility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 Polyplbidogenic, Etc., Agencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X-rays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Centrifugal Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 Miscellaneous Agencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 Embryo Sac, Embryo, and Endosperm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 Vegetative Grafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 Mitotic Periodicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

Specialization, hybridization, and mutation in the cereal rusts

Abstract: The 50 years that have elapsed since Eriksson’s discovery of physiologic specialization in the cereal rusts have seen notable advances in man’s understanding of these important pathogens. The discovery that theformae speciales or varieties, which were at first regarded as the ultimate units of specialization, were in turn made up of many specialized strains or physiologic races gave a great impetus to the study of the various rusts and, despite the fact that the existence of these physiologic races complicated the problem of developing rust resistant varieties of cereals, served also as a stimulus to greater efforts on the part of the breeders of rust resistant cereal varieties. The discovery of the existence of heterothallism in the rusts made possible studies on the crossing and selfing of the physiologic races of cereal rusts. Such studies have indicated that a great variety of physiologic races may be expected to arise by hybridization and have permitted a much more accurate evaluation than otherwise would have been possible of the significance of the alternate hosts in the production of physiologic races. These studies have also thrown considerable light on the genetics of the rust fungi and have shown that the inheritance of such rust characteristics as pathogenicity and spore color is subject to the same laws that have been found to govern inheritance in higher plants and animals. The writers are indebted to Dr. J. H. Craigie and Mr. I. L. Conners for reading and criticizing the manuscript.

Root diseases of deciduous fruit trees

Abstract: The subject of root diseases of deciduous fruit trees was reviewed by J. S. Cooley in the Botanical Review in 1946 (23). The article which follows is presented as a decennial supplement to Dr. Cooley's review. This article is intended primarily as a review of work in, or closely related to, this field and which has been published during the past decade. Attention here is centered largely upon those fields which have been the focus of investigative attention during this time, rather than upon a broad coverage of both active and inactive aspects of the field. The past decade has not been a period marked by the reporting of new root diseases of major importance. This phase of the treefruit root disease problem was extensively explored and reported upon much earlier. More recent investigations have been in the fields of remedial and preventive measures, manner of infection and spread, the role of environmental factors in disease development, and many other related problems. Attention has also been given to the nematode and virus diseases in this review. The former are logically included, since they are wholly root diseases. The latter are systemic, but rootstocks play an important part in dissemination of some virus diseases. Attention is centered primarily on the root disease problems of the pome and stone fruits as they occur in the United States and Canada. This is not to imply that the root disease problems elsewhere have been treated as essentially different, for they are not necessarily so. The treatment of foreign investigations and of foreign literature is not presented as being comprehensive. References to foreign work regarded as of interest or possible application have been included.

The relation of weather to fungus diseases of plants. II

Abstract: The present review is intended as a supplement to that published in this periodical in 1935 (58), and for that reason much of the previous general introduction to the subject is omitted. It is necessary to explain that the literature on this subject, considered in its widest scope, is so extensive, being approximately one tenth of all mycological and phytopathological papers, that it is desirable to restrict this supplementary review to fungus diseases, chiefly of agricultural and horticultural crops. Any serious paper on crop diseases almost always has some reference to weather relations or to one or more aspects of this subject, while purely mycological papers frequently include some study of the relation of weather factors to the life cycle of the organism involved. Nevertheless, much of this material is incidental to the main research, and as a result such literature finds small space in the present review. A comprehensive picture of the research on this subject carried out in the last decade is gained from the literature which exclusively deals with one or other aspects of the subject. From the point of view of general training, it is satisfactory to note that many textbooks now deal with this subject in some detail (248). It will be appreciated that in order to understand the complex relation of weather as a whole with the epidemiology of economic crop diseases, the separate component parts of the weather must be analysed in some order. In the following pages will be set out the effects of the weather factors on the production, survival, spread and germination of spores and other structures of fungi and on the initiation and progress of the epidemics they cause.

Preventing plant disease introduction

Abstract: A discussion of the prevention of foreign plant-disease introduction constitutes in reality merely a special treatment of the broader subject of disease dissemination-an attempt to view the larger field from one small angle, so as to present and interpret the conditions, relations and limitations of this larger field in terms of the human needs and peculiar interests of a given country or area. Such discussion has value only because human society has a certain confidence in its own collective intelligence and power, whereby it is encouraged to attempt a bold control of the natural world for its own benefit. Human intelligence recognizes that in spite of the universal and imposing dispersal pressure developed in all pathogens as a requisite for survival, their dissemination is everywhere checked, limited or prevented by natural means and in various ways, and recognition of these weaknesses arouses the hope, even the conviction, that with adequate knowledge and carefully directed effort a national group might be able to interfere successfully with undesirable dispersal and control its own activities so as to prevent the establishment of destructive foreign pathogens in its homeland. Stripped to bare essentials this situation represents a primal struggle between species. On the one hand are ranged a host of parasitic forms of life, numerous, successful, often advantageously specialized, always blindly surging toward new territory by virtue of a tremendous dispersal pressure, but unable to overcome certain obstacles and limitations. Matched against these is a human society, endowed with intelligence, capable of effective organization, furnished with vast means of accomplishment, but not yet fully aware of its threatened interests, and only partially awake to the character of its enemies. The struggle between these two unlike antagonists is continuously in progress and its eventual outcome lies far in the long future. Because of this uncertain present situation it seems helpful to review the elements in the problem of plant-disease introduction from the restricted viewpoint of our own country, in the hope of

Cytoplasmic inclusions of the plant-like flagellates. II

Abstract: The past ten years have witnessed the first applications of two important instruments, the phase-contrast microscope and the electron microscope, to the investigation of cytological problems in phytoflagellates. One interesting development, from investigations with the electron microscope, is the emergence of more or less characteristic structural patterns for mitochondria. It is reasonable to hope that such observations may soon make it possible to resolve various cases of disputed or mistaken identity involving mitochondria and other inclusions. In addition to the increasing application of electron microscopy, the period just passed has yielded a variety of other data on the inclusions of phytoflagellates.