temperatures inhibit photosynthesis ( Sharkey et al., 2001 ) and the response to high temperatures can vary significantly within a species ( Reynolds et al., 1990 ). High temperatures influenced chloroplast development, chlorophyll biosynthesis, and the
Ritu Dhir, Richard L. Harkess, and Guihong Bi
Mayashree Chinsamy, Manoj G. Kulkarni, and Johannes Van Staden
. Photosynthetic pigment (chlorophyll a, b, and total chlorophyll) content was extracted by homogenizing fresh leaf samples (5 g) of treated and control seedlings in 80% acetone (20 mL) using a homogenizer. The resultant solution was filtered through Whatman No. 1
Nadia Hakam, Jennifer R. DeEll, Shahrokh Khanizadeh, and Claude Richer
Chlorophyll fluorescence (CF) was evaluated as a technique to assess chilling injury of rose (Rosa sp.) leaves exposed to low temperatures. In the more susceptible genotypes, variable fluorescence (Fv) decreased dramatically as the temperature was lowered. In the less susceptible genotypes, Fv was more stable and decreased more slowly as temperature fell. Our results suggest that measurement of CF may provide a rapid method to prescreen genotypes for chilling susceptibility, as required in plant breeding.
G.E. Bell, B.M. Howell, G.V. Johnson, W.R. Raun, J.B. Solie, and M.L. Stone
Differences in soil microenvironment affect the availability of N in small areas of large turfgrass stands. Optical sensing may provide a method for assessing plant N needs among these small areas and could help improve turfgrass uniformity. The purpose of this study was to determine if optical sensing was useful for measuring turfgrass responses stimulated by N fertilization. Areas of `U3' bermudagrass [Cynodon dactylon (L.) Pers.], `Midfield' bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt-Davy], and `SR1020' creeping bentgrass (Agrostis palustris Huds.) were divided into randomized complete blocks and fertilized with different N rates. A spectrometer was used to measure energy reflected from the turfgrass within the experimental units at 350 to1100 nm wavelengths. This spectral information was used to calculate normalized difference vegetation index (NDVI) and green normalized difference vegetation index (GNDVI). These spectral indices were regressed with tissue N and chlorophyll content determined from turfgrass clippings collected immediately following optical sensing. The coefficients of determination for NDVI and GNDVI regressed with tissue N averaged r 2 = 0.76 and r2 = 0.81, respectively. The coefficients of determination for NDVI and GNDVI regressed with chlorophyll averaged r 2 = 0.70 and r 2 = 0.75, respectively. Optical sensing was equally effective for estimating turfgrass responses to N fertilization as more commonly used evaluations such as shoot growth rate (SGR regressed with tissue N; r 2 = 0.81) and visual color evaluation (color regressed with chlorophyll; r 2 = 0.64).
Yuji Yamada, Masayoshi Nakayama, Hiromitsu Shibata, Sanae Kishimoto, and Takashi Ikeda
activities in the fruit of the cultivar Mavras, which are dark purple when immature, and Tequila, which are lilac when immature. We also studied the synchrony between content changes in anthocyanins and both chlorophylls (green pigments) and carotenoids (red
Yiguang Wang, Chao Zhang, Bin Dong, Yaohui Huang, Zhiyi Bao, and Hongbo Zhao
the most important. In addition to the chlorophylls commonly found in green tissues, flavonoids and carotenoids are main pigments determining the colors of plants ( Tanaka et al., 2008 ). Anthocyanins are the most important flavonoids that affect the
Panayiotis A. Nektarios, Ioannis Amountzias, Iro Kokkinou, and Nikolaos Ntoulas
separated from the substrate by rinsing with water. The fresh weight of the aerial plant portion was determined by weighing, and then all plant parts were placed in a drying oven at 70 °C for 4 d to determine leaf and stem dry weights. SPAD and chlorophyll
Eleni Tsantili, Miltiadis V. Christopoulos, Constantinos A. Pontikis, Pantousis Kaltsikes, Chariklia Kallianou, and Michalis Komaitis
for chlorophyll determination, Ca and Mg concentrations, and ≈350 olives per tree were collected for the rest of the fruit measurements. At this stage, all fruits were at the black-ripe climacteric stage. All fruits and leaves collected were
Melek Ekinci, Ertan Yildirim, Atilla Dursun, and Metin Turan
pots were irrigated to field capacity with saline solutions to maintain the level of salinity after transplanting. Leaf chlorophyll reading value. A portable chlorophyll meter (SPAD-502; Konica Minolta Sensing, Inc., Japan) was used to measure leaf
Naoki Yamauchi and Alley E. Watada
Pigments in stored parsley leaves (Petroselinum crispum Nym.) were monitored to determine if degradative products of chlorophyll (chl) differed while under different types of atmosphere. The leaves were stored in a closed container under a stream of humidified air at 20C with or without 10 ppm ethylene and with or without 10 percent oxygen and 10 percent carbon dioxide. Analysis of pigments with HPLC showed that chl a and b decreased sharply with or without ethylene and the decrease was considerably less under CA. Chlorophyll a-1, the oxidized form of chl a, was initially low, and the level decreased slightly with all of the storage conditions. Chlorophyllide was also low, but it increased slightly during storage. Xanthophyll derivatives, which appeared to be the esterified xanthophylls, increased slightly during storage. These results indicate that chl degradation in stored parsley leaves was hastened by ethylene or suppressed by CA condition and the pathway of chl degradation did not appear to be altered by the different storage atmospheres.