M aples F or G ardens , A C olor E ncyclopedia . C.J. van Gelderen and D.M. van Gelderen. 1999. Timber Press, Inc., 133 S.W. Second Avenue, Suite 450, Portland, OR 97204-3527. 294 p. 683 color photos. 2 color maps. $49.95, hardcover
Jeffery K. Iles
Walter Boswell, Bernard Bible, and Suman Singha
Flesh color has been proposed as a maturity index for peaches. The objective of the present study was to determine the effectiveness of this parameter in `Loring', `Jersey Dawn', `Madison', and `Raritan Rose' peach (Prunus persica L. Batsch). Fruit were picked at weekly intervals at three or four harvest dates, with five fruit per cultivar being picked from each of three trees. Flesh firmness and soluble solids were measured immediately following harvest, and CIELAB coordinates (L*a*b*) of blush and flesh color were determined with a Minolta CR-200b calorimeter. There was a highly significant correlation (P < 0.001) between firmness and flesh hue angle for all four cultivars and with flesh chroma especially for the white-fleshed `Raritan Rose'. The correlation values between firmness and blush hue angle were consistently lower. Soluble solids did not consistently correlate with flesh or blush color. Even though blush color influences consumer preference, it was not as good an indicator of maturity as flesh color for the cultivars that we tested.
Mengyang Liu, Yin Lu, Shan Wang, Fang Wu, Jingrui Li, Yanhua Wang, Jianjun Zhao, and Shuxing Shen
Leaf color is largely the result of photosynthetic pigments, primarily chlorophyll (Chl). Chl plays an essential role in light absorption for energy transfer ( Stern et al., 2004 ). The Chl biosynthesis pathway is complex and involves more than 20
Elzette van Rooyen* and Randolph Beaudry
The objective of this study was to evaluate preharvest fertilizer application and postharvest storage temperature and duration as they affect the intensity and stability of color in red and purple potato cultivars during storage. `Michigan Purple', `Dakota Rose', and `Chieftain' were stored at 4 °C and hue angle (h°) was measured weekly. The initial `Michigan Purple' h° of 1.1° changed to 23.2° after 18 weeks of storage (a shift in h° from 350° to 30° changes from purple to red) while the initial hue angle of 18.5° and 34.1° for red-skinned cultivars, `Dakota Rose' and `Chieftain', changed to 27.2° and 43.2°, respectively. Hence, the degree of color shift was greater in `Michigan Purple' although all the cultivars in this experiment underwent significant color change during storage. Hue angle of `Michigan Purple' tubers stored at 4°, 10°, and 20 °C for 8 weeks changed 19.4°, 12°, and 14.2° toward the redder h°, respectively. Thus, the color of `Michigan Purple' tubers changed the least at 10°C. Hue angle of `Michigan Purple' tubers fertilized with 180 lbs/acre slow-releasing nitrogen, 180 lbs/acre nitrogen, 270 lbs/acre nitrogen, and 2.5 lbs/acre poultry manure was measured after 5 weeks at 4 °C. Hue angles were 0.92°, 11.65°, 3.99°, and 1.34°, respectively. The hue of the first three treatments differed significantly from one another, but the hue of the potatoes treated with 180 lbs/acre slow-releasing nitrogen and 2.5 lbs/acre poultry manure did not differ. Preharvest factors like plant nutrition can influence tuber color in storage and `Michigan Purple' tuber color is particularly sensitive to storage temperature.
R.D. Berghage and D.J. Wolnick
Potential consumers were surveyed in the spring of 1996 to gain insight into preferences for flower and leaf color in New Guinea impatiens (Impatiens hawkeri Bull.). Survey participants indicated a preference for bright solid colors, and bicolor flowers. The most preferred solid flower colors were red-violet, and red. The least preferred solid flower colors were pink and blush. Potential consumers ranked bicolor flowers over their solid color counterparts. Red and variegated foliage were preferred to solid green. Foliage with solid red upper or lower surfaces were preferred 2:1 over variegated foliage.
Zongyu Li, R. Karina Gallardo, Vicki A. McCracken, Chengyan Yue, Ksenija Gasic, Gregory Reighard, and James R. McFerson
disease, caused by the fungus Monilinia fructicola , which causes significant losses to the southeastern U.S. peach crop ( Schnabel et al., 2010 ) and the fruit quality attributes of size and fruit color (blush). Although the development of resistance to
Anusuya Rangarajan and Betsy Ingall
Interest in the production of the specialty vegetable radicchio (Cichorium intybus L. var. silvestre Bisch.) has increased among vegetable growers in the northeastern United States due to the popularity and consumption of premixed prepared salads. Growing environments with moderate daytime temperature and high light level have been associated with dense, deep red heads. Production problems include the low percentage of plants producing marketable heads and labor costs associated with hand-weeding. Traditional bareground culture was compared with several colored mulches (white, silver, red, black, and blue) for their effects on head formation, size, yield, and color of two Italian cultivars. Field studies were conducted in Freeville (upstate), N.Y., in 1997 and 1998. The percentage of heads harvested ranged from 32% to 82% over the 2 years of experiments and was lowest in black and red plastic mulch treatments. Yields were significantly higher, heads larger, and harvest earlier for plants grown over silver and white mulch compared to the control and other mulch treatments in 1998. In addition, average head weight was greater in all mulch treatments except blue when compared with the control. Cultivar differences were measured for the number and weight of heads, the percent bolting and marketable heads, and head color in 1998. Air and soil temperatures varied significantly around these mulches; however, these differences in microclimate had no effect on head color quality. Despite relatively moderate temperatures in upstate New York, radicchio responded positively to mulches that lowered average soil temperatures (white and silver) compared with the other treatments.
W.C. Lin, J.W. Hall, and A. Klieber
A video-imaging technique, using commercial software to process images obtained at 550 nm, was established to estimate chlorophyll content of cucumber fruit disks. The chlorophyll content of excised disks was extracted, determined, and regressed on the video-image grey level. They were linearly related. The change in grey level of the whole visible image accurately indicated the change of green color during fruit development on the vine and the loss of green color after 1 week of storage at 13C. The relationship of the chlorophyll content on grey level was quadratic for three imaging methods: 1) average grey level of the five disks; 2) average grey level of the whole cucumber image; and 3) average grey level of central one-third of the whole cucumber image. Chlorophyll content was most highly correlated to the grey level of the disks themselves (residual SD = 6.74 μg·cm-2), but this sampling technique was destructive. Both one-third of the fruit image (SD = 9.25 μg·cm-2) and the whole image (SD = 9.36 μg·cm-2) provided satisfactory precision. For simplicity, whole-fruit imaging is suitable for estimating fruit chlorophyll content and for quantifying fruit green color intensity. Potential use of this technique in product sorting and shelf life prediction of long English cucumbers is discussed.
Renata Koyama, Ronan Carlos Colombo, Wellington Fernando Silva Borges, João Pedro Silvestre, Ibrar Hussain, Muhammad Shahab, Saeed Ahmed, Sandra Helena Prudencio, Reginaldo Teodoro de Souza, and Sergio Ruffo Roberto
’)] × ‘BRS Linda’. This new hybrid seedless grape is tolerant to downy mildew, the main grape disease in subtropical humid areas, requiring fewer fungicide applications. However, their slightly pinkish clusters show color deficiency when cultivated in warm
Meredith R. Blumthal, L. Art Spomer, Daniel F. Warnock, and Raymond A. Cloyd
Flower color preference of western flower thrips [WFT (Frankliniella occidentalis) (Thysanoptera: Thripidae)] was assessed by observing insect location after introduction into chambers containing four different colored flowers of each of three plant species: transvaal daisy (Gerbera jamesonii), matsumoto aster (Callistephus chinensis), and chrysanthemum (Dendranthema ×grandiflorum). Preference was based on the number of WFT adults found on each flower 72 hours after infestation. Significantly higher numbers of WFT were found on yellow transvaal daisy and yellow chrysanthemum. When these accessions were compared in a subsequent experiment, WFT displayed a significant greater preference for the yellow transvaal daisy. Visible and near infrared reflectance spectra of the flowers used in the study were measured to determine the presence of distinct spectral features that would account for the relative attractiveness of the flowers. Likewise, the reflectance spectra of three commercially available sticky cards (blue, yellow, and yellow with a grid pattern) that are used to trap or sample for WFT were compared to those of the flowers to determine any shared spectral features that would support observed WFT flower color preference. The observed similarity between the yellow transvaal daisy and yellow sticky card reflectance spectra supports the hypothesis that flower color contributes to attractiveness of WFT. In particular, the wavelengths corresponding to green-yellow (500 to 600 nm) seem to be responsible for attracting WFT. These findings also indicate that yellow sticky cards may be more appropriate in sampling for WFT than blue sticky cards. Although further research is needed, under the conditions of this study, yellow transvaal daisy appears to be a potentially useful trap crop for WFT.