Search Results
You are looking at 1 - 10 of 27 items for :
- Author or Editor: G.W. Stutte x
- HortScience x
Interactive Image Capture and Analysis System (ICAS) provides for real-time capture of video images using an imaging board and software in a personal computer. Through the use of selective filters on the video input source, images of specific reflective wavelengths are obtained and then analyzed for intensity distribution using interactive software designed for scientific agriculture. Conversion of video cameras into two-dimensional near real-time visual and near infrared (NIR) spectral sensors through the use of filters provides information on the physiological status of the tissue following ICAS analysis. However, caution must be observed to minimize equipment-induced artifacts during image acquisition and analysis.
Abstract
The carbohydrate reserves in plant tissue have been correlated with all phases of plant growth and development. Consequently, several methods have been developed to quantify those reserves. The methods for starch determination are either direct (iodine staining) or indirect (the conversion of starch to sugars by chemical or enzymatic hydrolysis). Chemical methods involve hydrolysis of subunit bonds with either a strong acid or base, and enzymatic methods use catalytic proteins specifically to cleave the subunit bonds.
The relationship between whole canopy and single leaf measurements of gas exchange has not been well documented. Two experiments were conducted in the Biomass Production Chamber at Kennedy Space Center (20-m2 growing area) to compare whole canopy versus single leaf net carbon assimilation rate (Anet) measurement of a stand of tomato (Lycopersicon esculentum Mill. cv. Reimann Philipp) and soybean [Glycine max (L.) Merr. cv. Hoyt]. Both crops were grown under a 12/12 hour photoperiod under HPS lamps at PPF of 800 (mol·m–2·s–1, at 26/22°C (light/dark), and constant 65% RH for 90 days. CO2 concentration was controlled to 1200 (mol·mol–1 during the light cycle. Midday measurements of Anet of single leaves were obtained weekly from upper canopy leaves using a portable photosynthesis system. Whole canopy measurements of Anet were calculated daily from CO2 addition data obtained at 5-minute intervals by the BPC monitoring and control system. Single leaf rates exceeded whole canopy rates prior to full canopy coverage then averaged 0.63 of whole canopy for both species during the period of full canopy coverage. Results suggest that reliable estimates of canopy gas exchange can be obtained from single leaf measurements under relatively constant environment conditions.
An experiment was conducted in the Biomass Production Chamber (BPC) at Kennedy Space Center to examine the effects of using continuously reused nutrient solution in an NFT system to support potato growth in batch and continuous planting scenarios. Tuberization was hastened and plant growth reduced on plants grown in the aged nutrient solution. We have previously reported that the effect is removed when the aged nutrient solution is filtered through activated charcoal. In order to investigate this apparent plant growth regulator response, an in vitro bioassay has been developed that allows for repeatable, small scale, and rapid testing of the tuber-inducing response. The bioassay is a liquid culture system that employs 600-mL Berzelius beakers capped with modified Sun transparent tissue culture bags, a light shield around the root zone, and a polyurethane foam support, which holds a micropropagated potato plantlet. With this bioassay, we have observed the same plant stunting and tuber initiation effects that were previously seen with the aged nutrient solution. The bioassay appears to be sensitive to environmental factors (PPF, photoperiod, and temperature) that influence tuberization. In addition, partially purified preparations of the apparent growth regulators have elicited the tuberization response. Currently, efforts are underway to examine the role of the microbial community associated with the BPC nutrient delivery system on the tuberization response.
Abstract
Growth curves and a developmental index of strawberry (Fragaria × ananassa Duchesne) fruit length and dry weight were obtained for the strawberry cultivar Fern. There was a strong positive correlation between fruit length and the natural logarithm (In) of fruit dry weight. A minimum amount of scatter about the regression line indicated that length may be a useful developmental index. Secondary fruits experienced a 4- to 5-day lag period between pollination and growth, while primary fruits began growing within 24 hr after pollination. Primary and secondary fruits exhibited similar relative growth rates once development began.
The RASTA (Radish Assimilation in Spaceflight Testbed Atmospheres) space flight experiment is being designed to evaluate effects of spacecraft environment on carbon partitioning in radish. Carbon dioxide concentration and air temperature effects on radish partitioning are being evaluated to optimize conditions on orbit. Determining effects of these stresses on growth will allow environmental stress effects to be isolated from microgravity effects during the mission. Three cultivars, Cherriette, Cherry Belle, and Early Scarlett Globe, have been grown at 23 °C at 400, 1500 and 10,000 ppm CO2 to determine effects of super-elevated CO2 on growth. Total biomass production was greatest at 1500 ppm CO2, with a decline at 10,000 ppm CO2. Harvest index of all cultivars was also highest at 1500 ppm. `Cherry Belle' and `Early Scarlet Globe' were grown at ambient CO2 under temperatures ranging from 18 to 30 °C. Total biomass production was greatest at 22 °C, with significant declines in total dry mass and harvest index with increasing temperatures. Temperatures less than 22 °C resulted in decrease in total biomass, but partitioning to storage roots was enhanced. (Supported by NASA NCC10-0034)
A series of experiments were conducted to determine the sensitivity of radish to four light alcohols (ethanol, methanol, 2-propanol, and t-butanol) identified as atmospheric contaminants on manned spacecraft. Radish (Raphanus sativus L. `Cherry Bomb' Hybrid II) seedlings were exposed for 5 days to concentrations of 0, 50, 100, 175, 250, and 500 ppm of each alcohol and the effect on seedling growth was used to establish preliminary threshold response values. Results show a general response-pattern for the four alcohol exposures at threshold responses of 10% (T10), 50% (T50) and 90% (T90) reduction in seedling length. There were differences in the response of seedlings to the four alcohols, with the T10 for t-butanol and ethanol (25 to 40 ppm) being 3 to 5× lower than for methanol or 2-propanol (110 to 120 ppm). Ethanol and t-butanol exhibited similar T50 values (150 to 160 ppm). In contrast, T50 for methanol (285 ppm) and 2-propanol (260 ppm) were about 100 ppm higher than for ethanol or t-butanol. Chronic exposures to 400 ppm t-butanol, ethanol or 2-propanol were highly toxic to the plants. Radish was more tolerant of methanol, with T90 of 465 ppm. Seeds did not germinate at the 500 ppm treatment of t-butanol, 2-propanol, or ethanol. There were significant differences in projected performance of plants in different environments, dependent upon the regulatory guidelines used. The use of exposure guidelines for humans is not applicable to plant systems.
To characterize CO2, exchange, potatoes (Solanum tuberosum cv. Norland) were grown for 90 and 105 days in KSC's Biomass Production Chamber, a 116 m-3 closed cuvette, with 0.5 strength modified Hoagland solution using recirculating NFT culture, 12/12 photoperiod, 1000 μmol mol-1 CO2, and approximately 900 μmol m-2 s-1 PPF from HPS lamps. Canopy gas exchange responses to CO, concentration, light intensity, and photoperiod were experimentally determined. CO, exchange showed a linear response to PPF (up to 1100 μmol m-2 s-1 max.) and a light compensation point of about 150 μmol m-2 s-1. Sustained exchange rates of >45 μmol CO2, m-2 s-1 were obtained 50 days after planting. CO2 saturation was approximately 1200 μmol mol-1 CO2 with a compensation point < 100 μmol mol-1. A dark cycle of less than 4 hours resulted in a rapid, continuous decrease in C02 exchange rate which was partially reversed by a 12-hour dark cycle. There was a weak correlation CO2 exchange and leaf starch concentration at the end of the dark cycle.
Proton Density and T2 maps were created throughout the dormant season in `Anna' and Northern Spy′ apple cultlvars. The percentige of oixels with 15-25 ms T2 time increased from 30% in both cultlvars at the beginning of dormancy to 80 and 72% respectively, by the end of dormancy. The conversion in `Anna' was rapid and in `Northern spy was slow. Growth occured only when conversion of bound to free water reached 70% of the total number of pixels. Buds entered into a transitional phase when conversion of water reached 50%. Buds in the transitional phase are willing to respond to treatments aimed to end dormancy. Thus dormancy can be divided into two major part based on the boundness of freeness of water in the bud.
Photoperiod treatments were imposed on potato (Solanum tuberosum L. cv. Norland) grown in the Biomass Production Chamber (BPC) at Kennedy Space Center under HPS lamps (670 μmol m-2s-1 PPF) at 1200 μmol mol-1 CO2. Stand A decreased with dark cycle length, which correlated with the change in leaf starch concentration during the dark cycle, but not absolute starch concentration. A series of growth chamber experiments were performed to characterize the effect of photoperiod and PPF on CO2 assimilation and starch mobilization in single leaves. Plants grown on a 12/12 photoperiod at either low (300 μmol m-2s-1) or high (600 μmol m-2s-1) PPF were subjected to short-term photoperiod treatments of 8/16, 16/8, and 24/0 and diurnal CO2 assimilation rates, CO2 response curves, and leaf starch content were determined. CO2 compensation point was not affected by either photoperiod or PPF. However, Amax (when normalized for PPF) decreased with increasing photoperiod. Anet correlated with the changes in specific leaf weight and starch content during the dark cycle.