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- Author or Editor: Douglas A. Hopper x
Ninety-six uniform plants of each `Russell hybrid' and `Gallery' mix lupines sown 9 June 1995 were randomly assigned to 32 unique treatment combinations. On 14 Dec 1995, plants were either placed in a 17/13°C day/night temperature (DT/NT) greenhouse (COOL) or 22/18°C DT/NT greenhouse (WARM) as controls, or in a constant 4.5°C cooler in the dark for 6, 8 10, or 12 weeks. After cooling, plants were transplanted to #1 nursery cans (2.75 liter) using Sunshine mix #2 and were assigned randomly to the COOL or WARM greenhouse. Greenhouse control plants under natural days were transplanted at intervals similar to cooled plants. Days until visible bud and flowering were analyzed using SAS PROC GLM. Plants receiving long day (LD) flowered 7 to 10 weeks (46 to 70 days) after the start of LD forcing. Buds were visible in 30 to 35 days. Plants receiving natural days (ND) did not flower uniformly unless they were cooled for 12 weeks, yet flowering took longer (8 to 12 weeks) when compared with LD. Unfortunately, LD lighting for the entire forcing period caused excess stretching, so plants finished too tall for quality potted plants. Forcing in a COOL greenhouse delayed flowering about a week compared to the WARM greenhouse.
Height data were collected three times weekly between pinch and flowering to represent `Royalty' rose (Rosa hybrida L.) response to 15 unique treatment combinations of irradiation as photosynthetic photon flux (PPF: 50 to 300 μmol·m-2·s-1), day temperature (DT: 12 to 22 °C), and night temperature (NT: 15 to 25 °C) under constant growth chamber conditions. Combinations were determined according to the rotatable central composite design. A previous full quadratic model approach was compared with a revised approach using a nonlinear Richards function derivative form. This allowed a dynamic change of parameter values for each daily growth iteration by computer. The Richards function assumes nonconstant daily growth rates are proportional to current size; Euler integration enabled additive accumulation of these values. Ratios of the growth constant (k) to the theoretical catabolic constant (m = v+1) caused flexible changes in the growth curve, which were compared with the previous quadratic approach.
Improvements to computer software and advancing technology made it necessary to convert the computer greenhouse simulation model, GHSIM, to a new application for operation across a greater number of platforms. Originally, economics and internal organization compatibility led to use of spreadsheet Quattro Pro. Standard features were relative and absolute references, multiple pages for topic organization, random event generation, and graphing of calculated trends. However, Quattro Pro contained many convenient features, yet proprietory, which were not readily converted: certain formats for graphing trends, recursive formulas, cross page referencing, buttons, macros for dynamic time execution, and floating toolbars that actually changed between old and newer versions (v.5.0 vs. v.7.0). Translation from Quattro Pro v.5.0 to Microsoft Excel 97 produced tedious page by page (worksheet) conversions, loss of buttons and macros, distorted/unreadable graphs, nonexistent toolbars, and, most troubling, obscure problems with recursive execution causing Excel to crash amid nondescript error messages and a core dump. All these were eventually resolved; current efforts seek to reach other platforms, including MacIntosh and the Internet.
One-year-old plants of four cut rose (Rosa hybrida L.) cultivars were grown under either natural or supplemental irradiance for 4 months during the winter in Colorado. Supplemental irradiance with high-pressure sodium (HPS) lamps was supplied at 100 μmol·m–2·s–1 for 10 h each night during off-peak electrical use periods. Total cut flower yield, stem length, and fresh weight of individual flowers were recorded. The number of flowers produced and fresh weight increased for all cultivars under the supplemental irradiance treatment. Flower count, stem length, and fresh weight showed significant differences among the four 4-week production periods; production differences were promoted through pinches of two stems per plant to time for holiday peaks. When production was highest, stem length and fresh weight were lower, most likely due to redistribution of the limited carbohydrate pool during the winter.
One should choose the simplest form of a model as a tool that adequately represents the processes and relationships of interest. ROSESIM was first developed in SLAM II and FORTRAN to run on a mainframe computer, where it had few users and it was cumbersome to learn and use. As use of models on a personal computer (PC) has become more popular for instruction and simulation, ROSESIM was translated first into the American Standard Code for Information Interchange (ASCII) to run in the Beginner's All-purpose Symbolic Instruction Code (BASIC) language in the popular Microsoft Disk Operating System (MS-DOS). As graphical user interface (GUI) Windows applications have gained increased popularity, ROSESIM has been translated into C++ as object-oriented programming (OOP) to run inside Microsoft Windows 3.1. This makes ROSESIM for Windows readily available to virtually every PC user. Features of ROSESIM for Windows are listed and discussed.
Research focused on alternative methods to control Western flower thrips (Frankliniella occidentalis Pergande), encompassing chemicals from varying classes, parasitic nematodes, microbial insecticides, and physical/mechanical deterrents. Chemical spray applications were applied weekly for 4 to 6 weeks. Experiment 1 made comparisons between fenoxycarb (Precision), bifenthrin (Talstar), and entomopathogenic nematodes (Biosafe). Experiment 2 compared abamectin (Avid), spinosyn A and D (Spinosad), azadirachtin (neem extract: Margosan-O), and diatomaceous earth (a physical control aimed at deterring pupation). Experiment 3 compared Spinosad, fipronil, and two microbial insecticides (Naturalis-O and Mycotrol). The number of thrips counted in flowers after treatments had been applied indicated that the strict chemical treatments (Avid, Spinosad, fipronil) provided quick knockdown and overall longer-term population control. Microbial insecticides, diatomaceous earth, and nematodes maintained populations at a lower level than the control, but were not as effective as strict chemical controls. Margosan-O, Precision, and Talstar controlled populations at medium levels. For periods when populations may cycle upward, more potent chemicals could be used (Spinosad, fipronil, and Avid) while still avoiding problems associated with more toxic chemicals.
Stock plants of two perennial species (Penstemon and Dianthus) were grown in either a warm (16C NT) or cool (10C NT) greenhouse under either natural-day (ND) or long-day (LD) continuous-lighting treatments. Black plastic curtains were placed between the treatments from 1600 to 0800 hr. Starting Apr. 1994 through Jan.1995, the number of cuttings produced and the number of flowering shoots per plant were recorded at ≈3-week intervals. Preliminary analysis shows significantly more cuttings were produced by Dianthus in a warm vs. a cool greenhouse under both ND and LD photoperiods. Penstemon showed only a slight trend toward more cuttings produced in a warm greenhouse. Conversely, Dianthus produced fewer flowering stems in ND as compared with LD conditions in the warm house, due mainly to a greater proportion of stems remaining vegetative in the ND photoperiod. No significant differences in number of flowering stems of Penstemon occurred between any of the treatment combinations.
Four cut rose cultivars (`Royalty', `Samantha', `Sonia', and `Gabriella') were exposed to supplemental radiation for 2 years of production at the W.D. Holley Plant Environmental Research Center (PERC) at Colorado State Univ. and 1 year at Jordan's Greenhouse (cultivars Royalty and Kardinal). At PERC the house was divided into two treatments: l) natural light, and 2) supplemental radiation at ≈100 μmol·m–2·s–1 (750 fc) from 1000-W high-pressure sodium (HPS) lamps for 10 h each night. Jordan's had a third treatment of supplemental radiation at ≈50 μmol·m–2·s–1 (400 fc). Nutrient solution recirculation was tested with one bench in each of the treatments. Each rose was counted and measured for stem length and fresh weight. At PERC, all the cultivars showed no significant differences in the weekly number of flowers produced or the total flower fresh weight when grown under nonrecirculation vs. recirculation of nutrient solution. From 1993 results, grade A production for 60 `Royalty' plants increased from 455 flowers under natural conditions to 522 flowers under lighted conditions over 7 months, a 97-flower increase (21%) due to lighting.
An interactive simulation model of plant growth must be flexible to accept specific crop equations from the user. ROSESIM functions as a dynamic plant growth model based on `Royalty' rose (Rosa hybrida L) response to 15 unique treatment combinations of photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT) under constant growth chamber conditions. Environmental factors are assumed constant over an entire day. Coefficients are read from an external ASCII file, thus permitting coefficients from any linear, quadratic, or interaction terms to be input into ROSESIM up to a full quadratic model form. Nonsignificant terms are given a coefficient of zero. ROSESIM has been restructured into Borland C++ object oriented program (OOP) code to execute in the Microsoft Windows 3.1 operating environment. This enables ease of operation in the user friendly graphical user interface (GUI) provided with most IBM personal computers (PC). The user chooses a set of environmental conditions which can be altered after any selected number of days, allowing conditions to be changed and modeled daily for interactive comparison studies.
Growth predictions derived from data collected in controlled-environment chambers would be expected to differ from growth responses observed in variable greenhouse conditions. ROSESIM was developed as a dynamic plant growth model based on `Royalty' rose (Rosa hybrida L.) response to 15 unique treatment combinations of photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT) under constant growth chamber conditions. Regression coefficients for growth equations are read from an external ASCII file, thus permitting coefficients up to a full quadratic model form. Calibration coefficients (CC) were added to ROSESIM to enable predictions to be altered proportionally to permit improved prediction of specific growth characteristics. Numerator and denominator values for CC are adjustable for the first 10 days (initial) growth equations, subsequent growth until anthesis equations, and for the prediction of anthesis. Validation studies were used to set CC values; this enables the model based on growth in controlled environment chambers to be systematically calibrated on site to fit actual growth measured at a specific greenhouse location.