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- Author or Editor: C. Stevens x
Digitized photographic images of turf plots composed of bermudagrass, buffalo grass, tall fescue, and zoysiagrass were taken at a height of about 150 cm with a 28-mm lens. Fast Fourier transforms of these images were performed, and a radial plot of the power spectrum was obtained from each image. Hurst plots (log frequency vs. log intensity) were used to subtract “background” from the power spectra, so peaks would be more evident. The peak of the power spectrum occurs at the average spacing between leaves (more precisely, between areas of the canopy that reflects a significant amount of light) and defines the characteristic dimension. Zoysiagrass had the lowest characteristic dimension, while tall fescue had the highest. The width of the power spectrum is indicative of the variability of the characteristic dimension within the canopy. The minimum characteristic dimension (occurring at the highest frequency) was less than 1.7 cm, whereas all the other species had about the same minimum characteristic dimension of ≈1.9 cm. The maximum characteristic dimension was greatest for fescue (6.9 cm), followed by buffalo grass (3.8 cm), bermudagrass (3.3 cm), and zoysiagrass (2.8 cm). These results indicate that the characteristic dimension can be a useful tool for discriminating between turfgrass species in digitized images.
A system for the digital analysis of photographic prints of turfgrass plots is being developed. The 3-year-old turfgrass plots included Meyer zoysiagrass, Midlawn bermudagrass, Prairie buffalograss and Mustang tall fescue. The plots were photographed by a camera with a small dual bubble level on the camera back and a 28-mm-wide angle lens. Photographs were digitized with flatbed scanners. The images can then be analyzed in a variety of ways. For example, a series of photographs were taken from mid-Sept. through late Oct 1995 and spectral analysis of the resultant digital images were made. The initial RGB (red-greenblue) format of the images was converted to HSI (hue-saturation-intensity) for analysis. The results indicate, obviously, that hue changed from 104 (i.e., green) to 75.7 degrees (i.e., brownish) between the beginning and end of Oct. 1995. Similarly, intensity changed from ≈0.12 to ≈0.16 during the same time period, indicating that the images became darker over time. These phenomena were observed in all four species examined. However, the saturation value evoked a significant species * date interaction. The three warm-season species showed a decrease in saturation, while Mustang had no significant decrease during Oct. Spectral as well as textural analysis are likely the two most useful techniques in the digital analysis of turfgrass plots. Examples of both will be presented.
Seed vigor has a very subtle effect on the productivity of greenhouses producing vegetable transplants, celery, cauliflower, lettuce, etc. and on todays highly mechanized automatic or semi-automatic transplanting operations. As greenhouse production technology moves from traditional bare root to plug/tray growing systems and as automatic and semi-automatic transplanting operations increase in number, the impact of poor seed vigor is realized.
Measures to mitigate the impact of poor seed vigor in the nursery are: Seed density grading; increased growing cycle in the nursery, hand culling or replanting. Measures to mitigate the impact of poor seed vigor in automatic transplanting operations: increase the number of people following the planter to replace poor vigor plants; use hand fed transplanters.
The process of ice formation in media at container capacity was followed by sectioning the frozen medium and determining solute content in each sample using sodium fluorescein as a tracer. H2O apparently moved from the bottom and central interior regions of the container medium to the sides of the container. The phase in which movement occurred is unknown. Fluorescein moved down from the top and central interior regions to the bottom and sides of the container. The final distribution of fluorescein should indicate the location of the majority of liquid H2O due to the exclusion of solutes by ice. In the partially frozen state the greatest amount of liquid water therefore occurs near the container sides – a region normally occupied by a large proportion of the root system.
Early season vegetative development of grapevines was studied in the year after imposing three cropping levels to mature `Seyval' vines in the field or establishing two light levels to potted `DeChaunac' vines growing in the greenhouse. Heavily cropped `Seyval' vines (averaging 90 buds, 15.8 kg fruit per vine over the previous two growing seasons) had 85% fewer count buds and 31% fewer non-count (latent) buds than lightly cropped vines (averaging 25 buds, 9.7 kg fruit per vine). The rate of leaf area expansion was reduced on heavily cropped vines. Covering `DeChaunac' vines in the greenhouse with 80% shade from bloom onwards reduced the leaf area per shoot in the year after treatment by reducing both the rate of leaf appearance and the rate of leaf expansion. The leaf at node four from the base of the shoot had the greatest area on both shaded and control vines; however, the area was reduced 33% on shaded vines. Data from the greenhouse experiment were used to model the effect of leaf size at the transition from sink to source on total source leaf area per shoot. Prior to bloom the total source leaf area per shoot was increased when individual leaves became sources earlier, i.e., at a lower percent of their final size. Whether a leaf became a source at either 30%, 50%, or 80% of its final size had little effect on total source leaf area per shoot after bloom. The proportion of source to sink leaf area at bloom was greater than 90% for both slow- and rapidly growing shoots (those on shaded and control vines, respectively). Expansion of grapevine leaves was reduced by heavy cropping and low light levels in the previous year, greatly reducing the source leaf area per shoot.
Fresh-market basil is becoming a viable greenhouse commodity in Colorado. Marketing pressures and profit advantages also encourage the production of certified organic produce. The research objectives were to determine the length of time basil plants were productive in the greenhouse and to compare the production of fresh-market basil grown with three root zone systems and two fertilizer treatments. The three systems were hydroponic rockwool slab culture, hydroponic perlite raised bed culture, and hydroponic peat/perlite/compost bag culture. The two types of hydroponic fertilizer treatments were an inorganically formulated nutrient solution and an organic solution consisting of fermented poultry compost, hydrolized fish emulsion, and soluble kelp. The plants were harvested once per week and fresh weight was determined. During the 2nd and 3rd months of harvest, productivity from the plants treated with the organic fertilizer was greatest in the perlite system. However, productivity from the plants treated with the traditional fertilizer was greatest in the bag mix and rockwool systems.
Fresh-market sweet basil (Ocimum basilicum) is in high demand from specialty produce markets and commercial restauranteurs. Many consumers are also demanding produce that has been organically grown. Three hydroponic media systems were evaluated twice over two years, rockwool slabs, perlite frames, and commercial sphagnum peat/perlite/compost medium, where the bag was laid flat on the bench. Plants grown in these systems were fertilized with nutrient solutions derived from either organic or conventional, saltbased fertilizer sources. Few differences in yield were detected between basil plants grown in the commercial medium with either fertilizer source. Total yield from plants grown in perlite with the organic fertilizer was 22% greater in the first study and 100% greater in the second study than those for plants grown with the conventional fertilizer. Plants grown in rockwool with the conventional fertilizer were 17% more productive in the first study and 46% more productive in the second study than those grown with the organic fertilizer. Taste test panelists (69%) could discern differences between samples from organically and conventionally grown basil plants, yet no preferences were shown.
During 1995, 33 poinsettia cultivars were evaluated for Colorado greenhouse production conditions. Plants were supplied by the Paul Ecke Poinsettia Ranch, Fischer Geraniums USA, Oglevee, and Mikkelsens. At the end of the production period, Colorado greenhouse growers were invited to an open house and asked to judge the cultivars for plant, bract, and cyathia quality. As rated by the 24 growers, the best red cultivars in overall performance were `Freedom Red', `Nutcracker Red', `Cortez', and `Bonita', respectively. The best pink cultivars in overall performance were `Nutcracker Pink', `Maren', and `Flirt', respectively. The best white cultivars in overall performance were `Nutcracker White' and `V-17 Angelika White', respectively. The best novelty cultivars in overall performance were `Puebla' and `Monet', respectively.