Showing papers in "Botanical Review in 1969"

Plant root exudates

Abstract: Although the quantities of organic compounds exuding from roots is not large, seldom exceeding 0.4% of the carbon photosynthesized, they do exert a very strong influence on the soil microorganisms and may be significant in affecting plant nutrient availability. There is evidence that exudates from the roots of some plants are toxic to roots of neighboring plants and to the germination of some seeds.

Azolla: Biology and agronomic significance

Abstract: T a x o n o m y and Dist r ibut ion ......................................................................................................................................... 17 Fossil Record ................................................................................................................................................................................. 18 Description and Life His tory ....................................................................................................................................... 19 Physiology ..................................................................................................................................................................................... 2 0

Monoploids and monoploid-derivatives of maize (Zea mays L.)

Abstract: Looking forward, the study and use of monoploids and monoploid-derivatives appears more promising than it has at any time in the past. Of major interest are the cytological and physiological events of monoploid origin. One can hypothesize that precocious division of the egg prior to fertilization or during the initial stages of fertilization sets the stage for development of monoploid sporophytes, and further, that this precocious division results from premature deactivation or inadequate supply of an inhibiting substance present in the microenvironment or normal eggs. These hypotheses are subject to experimental verification. Answering the question whether the haploid sporophyte of maize is ‘truly’ monoploid is important to the understanding of the origin of the species. This is in part a question of semantics, as well as of homologies and homoeologies. It does seem likely that primitive maize or the generic ancestor of maize was an amphidiploid, the chromosomally-doubled product of hybridization of species of the Maydeae and Andropogoneae with a basic genome of five chromosomes. The pattern of crossing-over in monoploid meiosis, if there is a pattern, may provide evidence for homoeologies within the basic set of maize chromosomes. Agronomically, other than in the commercial breeding program for which I was personally responsible, little use has been made of the monoploid method in the development of homozygous diploids. Increased interest in and use of such radical techniques is likely in the future as the challenges of intensified commercial maize culture and of the highly competitive hybrid seedcorn market necessitate an increasingly high degree of responsiveness on the part of the maize breeder.

Implications of allelopathy in agricultural plant science

Abstract: Substances potentially involved in allelopathy are liberated from plants by (a) leaching of foliage by rain, (b) abscission and litter fall, (c) volatilization from foliage, and (d) root exudation. Substances, including metabolites such as mineral nutrients, carbohydrates, amino and organic acids, and growth regulators, can be leached from a wide variety of plants by rain and dew, and the quantity and quality of losses are affected by a great number of both external and internal factors. Materials leached from one plant may have an influence upon the development of the same or other adjacent plants. Plant/plant chemical interactions have been well recognized in commercial agriculture and, in fact, form the basis of many common agricultural practices. They are currently being utilized in modern plant science in the development of bioassay systems for detecting growth regulators, the use of rootstocks to influence the growth and development of scions, in detection and eradication of diseases, and in fruit storage and ripening.

Plant Cell and Tissue Cultures: The Role of Haberlandt

Abstract: The aseptic culture of plant cells and tissues as technique is now well established. Successful development of tissue culture was necessitated by a physiological problem which clearly demanded for its solution some extreme form of isolation of the tissues being studied. Although real success first came with animal tissues, the botanist Gottlieb Haberlandt (1854-1945) (Fig.1) clearly set forth the purposes and potentialities of cell culture after having attempted culture of plant cells. Haberlandt was not entirely successful but foresaw the use of cell culture as an elegant means of studying physiological and morphological problems.

The morphology and toxicology of plant stinging hairs

Abstract: Introduction ................................................................................................................................................................................................... 393 Morphology of stinging hairs ............................................................................................................................................... 394 Urticaceae--Urtlca ............................................................................................................................................................. 394 Girardinia ..................................................................................................................................................... 397 Urera ................................................................................................................................................................. 398 Laportea ........................................................................................................................................................... 398 Euphorbiaceae--Cnidoscolus ........................................................................................................................................ 398 Tragia .................................................................................................................................................... 398 Dalechampia ....................................................................................................................................... 399 Loasaceae---Loasa ...................................................................................................................................................................... 400 Blumenbachia .............................................................................................................................................. 400 Calophora ........................................................................................................................................................ 400 Hydrophyllaceae--Wigandia ..................................................................................................................................... 400 Experimental Morphology .......................................................................................................................................... 401 Toxicology of Stinging Hairs ................................................................................................................................................... 402 Conclusions ................................................................................................................................................................................................... 405 Literature Cited ...................................................................................................................................................................................... 409

The initiation of Xylem differentiation

Abstract: Introduction ..................................................................................................................................................... 201 Ultrastructural Evidence ................................................................................................................................. 202 Lignification .................................................................................................................................................................. 208 Gibberellins ......................................................................................................................................................................... 213 Cytokinins .................................................................................................................................................................... 216 In v i tro Experimcnts .......................................................................................................................................... 218 Inhibitors .................................................................................................................................................................. 225 Physical Factors .......................................................................................................................................................... 230 a) Radiant Energy Effects ..................................................................................................................... 230 b) Geotropic Effects ....................................................................................................................................... 230 c) Pressure Effects ............................................................................................................................................... 231 The Central Role of Auxin ................................................................................................................................. 232 Epilogue .......................................................................................................................................................................................... 235 Acknowledgements ......................................................................................................................................................... 235 Literature Cited ............................................................................................................................................................... 236

Molecular approaches to taxonomy of fungi

Abstract: In view of limitations of current techniques for identifying and classifying fungi, consideration is given to the potential taxonomic value of molecular analysis. Particular attention is paid to macromolecules such as proteins, nucleic acids, and other polymeric components of fungi.

Competitive relationships among herbaceous grassland plants

Abstract: The present state of the art of grassland competition is one of imminence rather than eminence We know many fragments and bits of information, but heretofore have been unable to unite all of what we do know into an integrated system

Further studies of drought resistance in woody plants

Abstract: This publication is an extension of the 1956 review of drought resistance in woody plants. The more important recently used terms are listed and defined. Summaries of reports of drought effects on forest trees are presented in tabular form. Frost-drought is discussed as an important factor in the limitation of woody plants’ geographical ranges. The role that droughts play in the initiation of tree diseases is considered, especially in the light of new evidence from studies of diebacks-declines of forest trees. Interactions between soil moisture and transpiration are discussed as well as ways to control transpiration in large stands. Also considered are drought experiments with tree seedlings and symptomatology of drought injury. The means by which woody plants survive drought (excluding ephemerals) are discussed.

Disorders of carbohydrate metabolism of apples (Watercore, internal breakdown, low temperature and carbon dioxide injuries)

Abstract: Introduction .......................................................................................................................................................................................... 169 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Watereore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Internal Breakdown .......................................................................................................................................................................... 175 Low Temperature Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 Carbon Dioxide Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 Multiple Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 Possibility of Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

Biochemical systematics and fungi

Abstract: In the foregoing paragraphs I have discussed in outline several areas where biochemistry has been able to make a positive contribution to fungal taxonomy. The review is not intended to be exhaustive, but rather to alert classical fungal taxonomists to the contribution biochemists may make to their specialty. The number of species studied, although still very small compared with the number of species described, is steadily increasing, and it is therefore expected that comparative biochemistry will in the future play an increasingly important role in fungal taxonomy.

Experiments on the culture of isolated plant cells

Abstract: I~ To my knowledge ~7,81, no systematically organized attempts to culture isolated vegetative cells from higher plants in simple nutrient solutions have been made. Yet the results of such culture experiments should give some interesting insight to the properties and potentialities which the cell as an elementary organism E~ [Elementarorganismus] possesses. Moreover, it would provide information about the inter-relationships and complementary influences to which cells within a multicellular whole organism are exposed. As early as 1898, I had performed a number of such culture experiments with artificially isolated plant cells. Originally, it was my intention to pursue these experiments on a large scale, testing the behavior of ceils from different kinds of tissues in different kinds of solutions. Other work prevented this plan from being carried out. Since my sensory

The respiration of tissues infected by virus

Abstract: Introduction 372 Respiration Rate of Tissues Infected by Virus .372 Respiration Rate following Infection .372 Respiration Rate of Tissues Systemically Infected by Virus .374 Respiration Rate of the Local Necrotic Lesion Host. 375 Substrate Concentration and Respiration in Virus-Infected Tissues .376 Carbohydrates .377 Organic Acids .378 Non-Protein Nitrogen.378 Virus-Induced Changes in Substrate Concentration in relation to Respiration 379 The Effect of Virus Infection on the Activity of Enzymes from the Host-Plant . 379 Embden-Meyerhoff Parnas Pathway Enizymes .380 Pentose Phosphate Pathway Enzymes .380 Tricarboxylic Acid Cycle Enzymes .380 Oxidases, Peroxidases, and Catalase in Virus-Infected Tissues .381 Pathways of Carbohydrate Catabolism in the Virus-Infected Plant .384 Rate-Limiting Reactions of Respiration in Virus-Infected Tissues .386 Conclusions. 388

Chemical control of flowering

Abstract: The existence of flower-forming substances has a reasonably firm foundation, although none of the substances responsible have yet been isolated. The studies which have been performed on the alteration of flowering behaviour by the application of various chemical substances have helped to elucidate the internal mechanism of control of flowering to a marked degree. The purpose of this review is not to list various substances that have been applied from time to time to modify flowering. Rather an attempt has been made to discuss some relevant information of chemical modifications which have elucidated the problem of flowering. The problem of chemical control, including a number of specialized treatments such as auxins, gibberellins, purines, pyrimidines, and steriods, requires some critical survey. The entire study of auxin effect on flowering is complex. Auxins have been shown to be useful in modification of flowering through the manifestations of either their enhancing (21, 20, 30) or inhibitory effects (19). It is not the intent of this review to discuss the auxin physiology of control of flowering. It is interesting to find from the work of Leopold and Guersney (17) that the auxin effect of flowering is not specific. They found that chemical vernalisation may be accomplished by thiamine thus indicating the auxin action in chemical vernalisation is not a specfiic one. In those cases where auxin is effective when applied alone, it can be argued that the internal environment is sensitive, being limited from flowering expression by active growth rate. An induced depression on active growth rate by externally applied auxin will sometimes initiate flowering. The following discussion will mainly center on the recent stadies of gibberellins, pyrimidines, purines, and steroids. The only inorganic substance that has been reported to influence flowering is cobalt. Experiments of Salisbury (24, 25) indicate the possibility of an involvement of endogenous sulfhydryl groups in the timing reaction of flowering. Attempts will be made to indicate the extent to which gibberellin and cther natural hormones can be linked to the control of flowering on a chemical basis.