E. H. Roberts

Bio: E. H. Roberts is an academic researcher from University of Reading. The author has contributed to research in topics: Germination & Recalcitrant seed. The author has an hindex of 54, co-authored 135 publications receiving 11487 citations. Previous affiliations of E. H. Roberts include Harper Adams University & Rice University.

The quantification of ageing and survival in orthodox seeds

Abstract: Orthodox seed ageing, survival and longevity are discussed in relation to environmental factors during storage. It is explained why it has been necessary to introduce a new improved viability equation to quantify the relationship between seed longevity and storage environment. This new equation may be applied to predict the viability of seed lots of all cultivars of species after any period under a very wide range of storage environments. Other symptoms of seed deterioration which occur before death are discussed in terms of both the individual and the population. Evidence is presented for a model which represents and quantifies the development of ageing symptoms in seed lots.

An Intermediate Category of Seed Storage Behaviour? I. COFFEE

Abstract: Seeds of four cultivars of arabica coifee (Coffea arabica L.) were tested for germination following hermetic storage for up to 12 months at several different combinations of temperatures between —20 °C and 15 °C and moisture contents between 5% and 10% (wet basis). Most of the seeds from one cultivar withstood desiccation to between 5% and 6% moisture content, a seed water potential of approximately 250 MPa, but those of the remaining three cultivars were much more sensitive to desiccation damage. Moreover, in all four cultivars, seed longevity at cool and sub-zero temperatures, and at low moisture contents did not conform with orthodox seed storage behaviour: viability was lost more rapidly under these conditions than at either warmer temperatures or higher moisture contents. The results confirm that coffee seeds fail to satisfy the definitions of either typical orthodox or recalcitrant seed storage behaviour. These results, therefore, point to the possibility of a third category of storage behaviour intermediate between those of orthodox and recalcitrant seeds. One of the main features of this category is that dry seeds are injured by low temperatures.

Viability of seeds.

Abstract: From prehistoric times man has had a pecial s relationship with seed plants - as a source of food, materials for tools, buildings, clothing and pharmaceuticals, and for ornamenting his surroundings for his own delight (probably in that chronological order which, incidentally, also gives some indication ofthe priorities oflife). Today man's most important staple foods are derived directly from seeds as they have been since neolithic times. (It is a sobering thought, as Harlan* has pointed out, that nothing significant has been added to his diet since then. ) From those times he must have learned to collect, conserve and cultivate seeds; and the accumulated experience has been handed down. This book then is part of an ancient tradition, for here we are still primarily concerned with these skills. Seeds are plant propagules comprised of embryos in which growth has been suspended, usually supplied with their own food reserves and protected by special covering layers. Typically they are relatively dry structures compared with other plant tissues and, in this condi tion) they are resistant to the ravages of time and their environment. But resistant is a relative tenn and seeds do deteriorate: the type, the extent and the rapidity of the deterioration, and the factors which control it are important to agronomists, horticulturalists, plant breeders, seedsmen, seed analysts, and those concerned with the conservation of genetic resources."

Temperature and Organism Size—A Biological Law for Ectotherms?

Abstract: A tool changer is disclosed for automatically removing a working tool after having been used from the spindle of a machine tool such as a vertical milling machine, transferring the used working tool to a rack which stores a plurality of working tools, picking up from the rack another working tool for the next machining operation, transferring such new working tool to the spindle, and operatively mounting such new working tool on the spindle.

Anatomy of Seed Plants

Abstract: INTRODUCTION. Internal Organization of the Plant Body. Summary of Types of Cells and Tissues. General References. DEVELOPMENT OF THE SEED PLANT. The Embryo. From embryo to the Adult Plant. Apical Meristems and Their Derivatives. Differentiation, Specialization, and Morphogenesis. References. THE CELL. Cytoplasm. Nucleus. Plastids. Mitochondria. Microbodies. Vacuoles. Paramural Bodies. Ribosomes. Dictyosomes. Endoplasmic Reticulum. Lipid Globules. Microtubules. Ergastic Substances. References. CELL WALL. Macromolecular Components and Their Organization in the Wall. Cell Wall Layers. Intercellular Spaces. Pits, Primary Pit--Fields, and Plasmodesmata. Origin of Cell Wall During Cell Division. Growth of Cell Wall. References. PARENCHYMA AND COLLENCHYMA. Parenchyma. Collenchyma. References. SCLERENCHYMA. Sclereids. Fibers. Development of Sclereids and Fibers. References. EPIDERMIS. Composition. Developmental Aspects. Cell Wall. Stomata. Trichomes. References. XYLEM: GENERAL STRUCTURE AND CELL TYPES. Gross Structure of Secondary Xylem. Cell Types in the Secondary Xylem. Primary Xylem. Differentiation of Tracheary Elements. References. XYLEM: VARIATION IN WOOD STRUCTURE. Conifer Wood. Dicotyledon Wood. Some Factors in Development of Secondary Xylem. Identification of Wood. References. VASCULAR CAMBIUM. Organization of Cambium. Developmental Changes in the Initial Layer. Patterns and Causal Relations in Cambial Activity. References. PHLOEM. Cell Types. Primary Phloem. Secondary Phloem. References. PERIDERM. Structure of Periderm and Related Tissues. Development of Periderm. Outer Aspect of Bark in Relation to Structure. Lenticels. References. SECRETORY STRUCTURES. External Secretory Structures. Internal Secretory Structures. References. THE ROOT: PRIMARY STATE OF GROWTH. Types of Roots. Primary Structure. Development. References. THE ROOT: SECONDARY STATE OF GROWTH AND ADVENTITIOUS ROOTS. Common Types of Secondary Growth. Variations in Secondary Growths. Physiologic Aspects of Secondary Growth in Roots. Adventitious Roots. References. THE STEM: PRIMARY STATE OF GROWTH. External Morphology. Primary Structure. Development. References. THE STEM: SECONDARY GROWTH AND STRUCTURAL TYPES. Secondary Growth. Types of Stems. References. THE LEAF: BASIC STRUCTURE AND DEVELOPMENT. Morphology. Histology of Angiosperm Leaf. Development. Abscission. References. THE LEAF: VARIATIONS IN STRUCTURE. Leaf Structure and Environment. Dicotyledon Leaves. Monocotyledon Leaves. Gymnosperm Leaves. References. THE FLOWER: STRUCTURE AND DEVELOPMENT. Concept. Structure. Development. References. THE FLOWER: REPRODUCTIVE CYCLE. Microsporogenesis. Pollen. Male Gametophyte. Megasporogenesis. Female Gametophyte. Fertilization. References. THE FRUIT. Concept and Classification. The Fruit Wall. Fruit Types. Fruit Growths. Fruit Abscission. References. THE SEED. Concept and Morphology. Seed Development. Seed Coat. Nutrient Storage Tissues. References. EMBRYO AND SEEDLING. Mature Embryo. Development of Embryo. Classification of Embryos. Seedling. References. Glossary. Index.

The ecology of seeds

Abstract: What determines the number and size of the seeds produced by a plant? How often should it reproduce them? How often should a plant produce them? Why and how are seeds dispersed, and what are the implications for the diversity and composition of vegetation? These are just some of the questions tackled in this wide-ranging review of the role of seeds in the ecology of plants. The authors bring together information on the ecological aspects of seed biology, starting with a consideration of reproductive strategies in seed plants and progressing through the life cycle, covering seed maturation, dispersal, storage in the soil, dormancy, germination, seedling establishment, and regeneration in the field. The text encompasses a wide range of concepts of general relevance to plant ecology, reflecting the central role that the study of seed ecology has played in elucidating many fundamental aspects of plant community function.

On the definition of ecological species groups in tropical rain forests

Abstract: The species richness of tropical rain forests creates difficulties for ecological analysis. It may usefully be simplified by defining ecological species groups whose members share characteristics of importance for determining forest structure and composition. Many such classifications have been published, but few are properly explained. The terminology is confused from lack of precise definitions. We propose a simple division of tree species into two groups or guilds, pioneer and non-pioneer (or climax), based on seed germination and seedling establishment. Within each guild there is continuous variation and we recommend arbitrary subdivision by height at maturity. We believe this classification to be applicable in all tropical rain forests.