A novel method of supplying nutrients permits predictable shoot growth and root: shoot ratios of pre-transplant bedding plants

BACKGROUND AND AIMS: Growth of bedding plants, in small peat plugs, relies on nutrients in the irrigation solution. The object of the study was to find a way of modifying the nutrient supply so that good-quality seedlings can be grown rapidly and yet have the high root : shoot ratios essential for efficient transplanting. METHODS: A new procedure was devised in which the concentrations of nutrients in the irrigation solution were modified during growth according to changing plant demand, instead of maintaining the same concentrations throughout growth. The new procedure depends on published algorithms for the dependence of growth rate and optimal plant nutrient concentrations on shoot dry weight Ws (g m–2), and on measuring evapotranspiration rates and shoot dry weights at weekly intervals. Pansy, Viola tricola ‘Universal plus yellow’ and petunia, Petunia hybrida ‘Multiflora light salmon vein’ were grown in four independent experiments with the expected optimum nutrient concentration and fractions of the optimum. Root and shoot weights were measured during growth. KEY RESULTS: For each level of nutrient supply Ws increased with time (t) in days, according to the equation {Delta}Ws/{Delta}t=K2Ws/(100+Ws) in which the growth rate coefficient (K2) remained approximately constant throughout growth. The value of K2 for the optimum treatment was defined by incoming radiation and temperature. The value of K2 for each sub-optimum treatment relative to that for the optimum treatment was logarithmically related to the sub-optimal nutrient supply. Provided the aerial environment was optimal, Rsb/Ro{approx}Wo/Wsb where R is the root : shoot ratio, W is the shoot dry weight, and sb and o indicate sub-optimum and optimum nutrient supplies, respectively. Sub-optimal nutrient concentrations also depressed shoot growth without appreciably affecting root growth when the aerial environment was non-limiting. CONCLUSION: The new procedure can predict the effects of nutrient supply, incoming radiation and temperature on the time course of shoot growth and the root : shoot ratio for a range of growing conditions

ECLSS advanced automation preliminary requirements

A description of the total Environmental Control and Life Support System (ECLSS) is presented. The description of the hardware is given in a top down format, the lowest level of which is a functional description of each candidate implementation. For each candidate implementation, both its advantages and disadvantages are presented. From this knowledge, it was suggested where expert systems could be used in the diagnosis and control of specific portions of the ECLSS. A process to determine if expert systems are applicable and how to select the expert system is also presented. The consideration of possible problems or inconsistencies in the knowledge or workings in the subsystems is described

A diagnostic prototype of the potable water subsystem of the Space Station Freedom ECLSS

In analyzing the baseline Environmental Control and Life Support System (ECLSS) command and control architecture, various processes are found which would be enhanced by the use of knowledge based system methods of implementation. The most suitable process for prototyping using rule based methods are documented, while domain knowledge resources and other practical considerations are examined. Requirements for a prototype rule based software system are documented. These requirements reflect Space Station Freedom ECLSS software and hardware development efforts, and knowledge based system requirements. A quick prototype knowledge based system environment is researched and developed

Response of corn yields to nitrogen fertilization and plant population in Missouri, 1961

Cover title."Progress report no. 1"."This report is a joint contribution of the Department of Soils and the Department of Agricultural Economics of the Missouri Agricultural Experiment Station. It is a progress report of Research Project 455, "The Economics of Fertilizer Use on Corn in Missouri."--Page 2

CLIMODE bobber data report : July 2005 - May 2009

This report summarizes direct observations of Eighteen Degree Water (EDW) subduction and dispersal within the subtropical gyre of the North Atlantic Ocean. Forty acoustically-tracked bobbing, profiling floats (“bobbers”) were deployed to study the formation and dispersal of EDW in the western North Atlantic. The unique bobber dataset described herein provides insight into the evolution of EDW by means of direct, eddy-resolving measurement of EDW Lagrangian dispersal pathways and stratification. Bobbers are modified Autonomous Profiling Explorer (APEX) profiling floats which actively servo their buoyancy control mechanism to follow a particular isothermal surface. The CLIVAR Mode Water Dynamics Experiment (CLIMODE) bobbers tracked the 18.5°C temperature surface for 3 days, then bobbed quickly between the 17°C and 19°C isotherms. This cycle was repeated for one month, after which each bobber profiled to 1000 m before ascending to the surface to transmit data. The resulting dataset (37/40 tracked bobbers; more than half still profiling as of January 2010) yields well-resolved trajectories, unprecedented velocity statistics in the core of the subducting and spreading EDW, and detailed information about the Lagrangian evolution of EDW thickness and vertical structure. This report provides an overview of the experimental procedure employed and summarizes the initial processing of the bobber dataset.Funding was provided by the National Science Foundation under Grant No. OCE-0424492

Climate profile for the McCallum Emria study area

March 1981.Includes bibliographical references (page 64)