Relationship among irrigation-media regimes and plant growth

Summary Factors limiting growth in media culture are oxygen, nutrients and water. These factors are dependent on particle diameter, nutrient solution composition, and irrigation frequency. This study evaluated combinations of trickle irrigation frequencies and particle sizes of media on the growth ofChrysanthemum morifolium Ramat. irrigated with a complete nutrient solution. Plant height, fresh weight, dry weight, and flower diameter were used to measure growth. Media used were: coarse incinerated anthracite refuse, fine incinerated anthracite refuse, and soil material from the B21 horizon of Gatesburg sand. Irrigation frequencies were: once per day, four times per day at 4-h. intervals, and constantly during the 13 daylight hours. Fine incinerated anthracite refuse irrigated constantly and every 4 hours produced chrysanthemums with significantly greater height, fresh weight and flower diameter than other treatments, whereas Gatesburg sand irrigated daily resulted in less growth than other treatments. Excess water held in finer textured media causes oxygen deficiency and substandard growth. Authorized for publication November 5, 1973 as paper no.4561 of the Journal series of the Pennsylvania Agr. Exp. Sta., University Park, Pa. 16802. The authors gratefully acknowledge support from The United States Agency for International Development (U.S.A.I.D.), through a 211 (d) grant to the Agronomy Department at The Pennsylvania State University. The information and conclusions in this paper do not necessarily reflect the position of AID or the U.S. Government. Research Assistant, Associate Professor of Floriculture, Associate Professor of Soil Genesis and Morphology, and Associate Professor of International Agronomy, respectively.     

Response ofPinus resinosa ait. Plantations to potassium fertilization on a potassium-deficient site

Summary Using deviations of the cumulative height growth due to fertilization treatments from the linear finite difference curve of untreated red pine trees in plantations, it was noted that: 1) large-sized trees responded in height growth to fertilization in the year following treatment while the medium and small trees took two years to respond; 2) medium-size trees responded to fertilization similar to large trees, but to a lesser magnitude; and 3) small trees are further suppressed by fertilization due to growth responses in the large medium trees.Contribution of the Silviculture Department, State University College of Forestry at Syracuse University, Syracuse, New York 13210.The authors are, respectively, Professor of Silviculture, Tokyo University of Agriculture and Technology and Visiting Professor of Silviculture, State University College of Forestry at Syracuse University, 1966–67; Forester, Continental Can Co., Augusta Division, Georgia; Professor of Silviculture, State University College of Forestry at Syracuse University.     

A far-reaching career

An interview with Stephen A. Felt, DVM, MPH, DACLAM, DACVPM, Attending Veterinarian, Assistant Professor, Department of Comparative Medicine, Associate Director, Veterinary Service Center, Director, Laboratory Animal Medicine Residency Program, Stanford University, Stanford, CA.     

Bacterial rhodopsins: evolution of a mechanistic model for the ion pumps

Walther Stoeckenius received a MD degree at the University of Hamburg, Germany in 1950. After 18 months of clinical work as an intern, he began postdoctoral work on the development of pox viruses at the Institute for Tropical Medicine in Hamburg using mainly electron microscopy techniques. After two years he moved as Assistant Professor to the Department of Pathology at the University of Hamburg and became Docent for Pathology in 1958. In addition to teaching and routine pathology work, he continued to use electron microscopy to explore the fine structure of cells and developed an interpretation of the triple-layered appearance of membranes in electron micrographs in terms of molecular structure and the chemistry of osmium tetroxide fixation. In 1959 he obtained a position as Research Associate in Keith Porter's laboratory at Rockefeller University. This was changed after a few months to Assistant Professor and he stayed there, later as Associate Professor, for eight years. The work on membrane structure continued, and a model was developed that described the membrane as a lipid bilayer with embedded protein domains. In efforts to isolate such domains, the purple membrane and bacteriorhodopsin were discovered. In 1966, the lure of California became irresistible and Dr. Stoeckenius accepted a professorship at the University of California at San Francisco. The work on bacteriorhodopsin continued there with the emphasis changing from electron microscopy to spectroscopy and biochemical techniques. He is now Professor Emeritus there in the Department of Biochemistry and Biophysics and the Cardiovascular Research Institute.     

Differential foliar responses of northern hardwoods to fertilization

A 70-year-old thinned northeastern Fagus-Betula-Acer stand in the Adirondack Mountains of northern New York was fertilized with varying combinations of N, P, K, and lime in the spring of 1976.Betula alleghaniensis Brit.,Acer saccharum Marsh.,Acer rubrum L., andFagus grandifolia Ehrh. foliage was collected in the autumn for 1974 through 1977 and analyzed for foliage areas and weights, and levels of ash, N, P, K, Ca, Mg, Mn, Na, Fe, Zn, Al, Cu, and Co. Comparisons are made within species and among treatments, expressed as concentrations on a dry weight basis. Elemental composition is examined to determine the differential foliar responses to fertilization.Contribution of State University of New York College of Environmental Science and Forestry, Syracuse, New York, 13210.The authors are Graduate Research Assistant, Director of Huntington Forest, Technical Research Assistant, and Professor of Forest Soil Science (now deceased), SUNY, respectively.     

Seasonal correlations of specific leaf weight to net photosynthesis and dark respiration of apple leaves

Specific leaf weight (SLW), net photosynthesis (P _n ), and dark respiration (R _d ) of apple leaves were monitored for an entire growing season. Leaves were sampled from the canopy interior and periphery to provide a range of SLW. Leaf P _n was linearly correlated with SLW until mid-August, when P _n began to decline. During September the relationship between SLW and P _n was a quadratic. Leaf R _d and SLW were linearly correlated throughout the season. Leaf P _n and R _d were significantly correlated through most of the season, but the relationship was not always linear. Specific leaf weight appears to be a reliable index of the previous light environment of a leaf, but use to estimate P _n is probably limited to the first half of the season, because of increased variation after mid-August.Former Graduate Research Assistant (presently Assistant Professor, Department of Horticulture and Forestry, Rutgers University, Cook College, New Brunswick, NJ 08903, USA) and Associate Professor, respectively.     

The epiphytology of spearmint rust in Indiana

Summary Field studies indicated that subterranean aecia ofPuccinia menthae Pers. are of little significance in the initiation of spearmint rust infection in undisturbed fields. Also, wild or escaped mints do not appear to be of significance. The primary source of inoculum comes either from fields that are not fall plowed or from infected rhizomes or transplants during spring planting. Temperatures during May appear to be critical in the development of rust epiphytotics. The predominant race of the pathogen occurring in Indiana corresponds to Race 1.Respectively, former graduate research assistant, Department of Botany and Plant Pathology, Purdue University, presently Assistant Plant Pathologist, University of Arizona, Mesa Branch Experiment Station, Mesa, Arizona; and Associate Plant Pathologist, Department of Botany and Plant Pathology, Purdue University, Lafayette, Indiana. Journal paper 2691. The authors thank Dr.M. J. Murray, A. M. Todd Company, Kalamazoo, Michigan, for species ofMentha used as race differentials. This research was supported, in part, by funds provided through the Mint Industries Research grant.