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Zai Q. Yang, Yong X. Li, Xiao P. Xue, Chuan R. Huang, and Bo Zhang

greenhouses and solar greenhouses are 196 and 313.6 N·m −2 , respectively. Based on Eq. [4], the critical wind speed can be calculated for various zones on surfaces of facilities at different wind direction angles. The wind pressure contours were created using

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Jianlu Zhang and Trevor Ranford

changing, without allowing the reader to understand the r values. To find the key period influencing ‘Royal Gala’ apple size, Zhang and Thiele (1992) created r contour maps that showed the actual r values. They collected and summarized data relating

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Wei Zhou, Xiaoming Wang, Jianhua Chen, Liangming Chen, Zhongquan Qiao, and Huijie Zeng

is indistinctly visible in the nucellus of the aborted ovule, without a cell contour, similar to the characteristics of cells after degeneration. There is no gap in the embryo sac cavity ( Fig. 5H ). In the second category, the egg apparatus structure

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C. Campillo, M.H. Prieto, C. Daza, M.J. Moñino, and M.I. García

at three points chosen at random within the reference rectangle; ( B ) contour method. S is the crop area within the reference rectangle; ( C ) reclassification method. S is the crop area within the reference rectangle. Contour

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Viviana P. Sosa-Flores, Luis A. Valdez-Aguilar, Donita L. Cartmill, Andrew D. Cartmill, Adalberto Benavides-Mendoza, and Antonio Juárez-Maldonado

explore the space area designed ( Table 3 ). The integration of the predictions of each individual model allows the definition of specific areas in the contour plots that include the nutrient solutions on which a threshold optimum response may be achieved

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Jeffrey H. Gillman, Chad P. Giblin, and Gary R. Johnson

Plants that have been grown in containers for a long period of time frequently develop roots that grow in circles, following the contour of the container in which they have been planted. This condition is commonly referred to as “pot-bound.” It is considered common knowledge that if a pot-bound plant is transplanted without any treatment, its roots will continue to follow the contour of the now-removed container. There are, however, a number of transplanting techniques that are intended to reorient the roots in a direction that will be conducive to helping roots to grow out of this potentially harmful situation. These techniques include: butterflying, or slicing the rootball into two halves before planting; scoring, or making inch-deep slices around the rootball at 90° increments and an X-shaped slice across the bottom; or teasing, where roots are manually pulled out of the shape of the container in a direction perpendicular to the stem. Severely pot bound Salixalba and Tiliacordata were treated with one of the three treatments previously listed or as a control and were transplanted into an experimental field and grown for two full seasons. After two seasons, the trees were harvested and the number and size of roots escaping from the pot-bound region were recorded. None of the treatments allowed roots of any size to escape the pot-bound mass more effectively than the control.

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Pamela C. Korczynski, Joanne Logan, and James E. Faust

The daily light integral (DLI) is a measurement of the total amount of photosynthetically active radiation delivered over a 24-hour period and is an important factor influencing plant growth over weeks and months. Contour maps were developed to demonstrate the mean DLI for each month of the year across the contiguous United States. The maps are based on 30 years of solar radiation data for 216 sites compiled and reported by the National Renewable Energy Lab in radiometric units (watt-hours per m-2·d-1, from 300 to 3,000 nm) that we converted to quantum units (mol·m-2·d-1, 400 to 700 nm). The mean DLI ranges from 5 to 10 mol·m-2·d-1 across the northern U.S. in December to 55 to 60 mol·m-2·d-1 in the southwestern U.S. in May through July. From October through February, the differences in DLI primarily occur between the northern and southern U.S., while from May through August the differences in DLI primarily occur between the eastern and western U.S. The DLI changes rapidly during the months before and after the vernal and autumnal equinoxes, e.g., increasing by more than 60% from February to April in many locations. The contour maps provide a means of estimating the typical DLI received across the U.S. throughout the year.

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Steven C Wiest and Edward W. Hellman

Scanning electron micrographs of grape berry surfaces, which resemble mountainscapes, contain a wealth of structural information. A typical statistical characterization of features such as root mean square peak-to-peak spacings, peak density, etc., is readily performed on these images. However, a much richer base of information is accessible by analyzing the images with fractal geometry. Fractal box dimension is a quantitative measure of surface roughness, and varies with the contour at which it is determined in both cultivars `Foch' and `Perlette', suggesting that the surfaces are multifractal structures. Fourier spectral analyses of the surfaces produce a similar conclusion. Thus, the unambiguous quantitative resolution of cultivars on the basis of their wax surface structure looks promising, but requires further work.

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M.S. Tian, A.B. Woolf, J.H. Bowen, and I.B. Ferguson

comments on the manuscript. We also thank Anne Gunson and Stephen Barnett from the Horticulture and Food Research Institute for assistance with contour plot graphical analysis. The cost of publishing this paper was defrayed in part by the payment of page

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Derald A. Harp, Edward L. McWilliams, Michael A. Arnold, and John F. Griffiths

The combination of concrete and asphalt surfaces, large buildings, lack of surface water, and anthropogenic heat inputs result in urban temperatures warmer than surrounding rural areas. This effect is often most pronounced with winter minimum temperatures and may cause changes in local plant hardiness zones. Local minimum temperatures were obtained for the years 1974-96 from the National Climatic Data Center and the Office of the State Climatologist of Texas for all recording stations within the Dallas-Fort Worth, Texas metropolitan area. Data were averaged and analyzed in two groups: 1974-86 and 1987-96. Contour maps were created using Surfer software. The 1974-86 local map had only one major difference from the 1990 USDA Plant Hardiness Zone map, which was the inclusion of 8a temperatures in more western portions of the metroplex. The inclusion of the years 1987-96 resulted in the westward expansion of 8a and a new 8b zone near downtown Dallas. These changes mimic the expansion of suburban development and increased urbanization over the last decade. We propose an updated plant hardiness zone map for this metropolitan area, which should more accurately reflect changes that have occurred since publication of the USDA Plant Hardiness Zone map.