canopy generally exhibit adaptations to low light conditions (shade leaves) ( Lambers and Poorter, 1992 ). Sun and shade leaves have additional contrasting characteristics. Sun leaves are able to increase light-saturated photosynthetic capacity by
Leonardo Lombardini, Hermann Restrepo-Diaz and Astrid Volder
Qingqing Duan, Ye Lin, Wu Jiang and Danfeng Huang
and Fujiwara, 2009 ). Kubota and Kozai (1994) found that broccoli plantlets stored in light could preserve their photosynthetic ability. Similar results were also observed in seedlings of Phalaenopsis ( Su et al., 2001 ) and radiata pine ( Mena
Yuya Mochizuki, Saori Sekiguchi, Naomi Horiuchi, Thanda Aung and Isao Ogiwara
supplemental lighting on growth and yield of strawberry ( Hidaka et al., 2013 ; Inada and Matsuno, 1985 ; Shishido et al., 1995 ) and photosynthetic characteristics of strawberry leaf blades ( Ogiwara et al., 2003 ), the manner of enhancing leaf
Thomas E. Marler
Cycas micronesica is an arborescent cycad with sclerophyllous, long-lived compound leaves that are produced in synchronized pulses. The photosynthetic characteristics of leaves in two sequential cohorts of ≈2 and ≈11 months after leaf expansion were determined in this study. Fluorescence yield following 30-min of light exclusion or from leaves engaged in photosynthesis under ambient light was measured throughout several 24-h periods to determine maximum quantum efficiency of PSII photochemistry and quantum efficiency under ambient light. Maximum quantum efficiency was similar for the two cohorts throughout the nocturnal period. Maximum quantum efficiency and quantum efficiency under ambient light declined following exposure to daily direct sun but recovered quickly each afternoon. This daily decline was greater for the older cohort than the younger cohort. Net carbon dioxide assimilation (Pn) was also determined using gas exchange, and light saturated Pn of the older cohort was 75% to 85% of that for the younger cohort during the daily maximum at late morning. Pn of the older cohort increased more slowly in the morning and declined more rapidly in the afternoon than did Pn of the younger cohort. Apparent quantum yield determined by gas exchange was similar for the two cohorts in the absence of extended sun exposure. However, this characteristic declined during midday, and the decline was greater for the older cohort. These results indicate that photosynthetic capacity of older C. micronesica leaf cohorts remains high, and these older leaves may substantially contribute to the plant's overall carbon economy. However, the number of hours during the day in which these older leaves reach their photosynthetic capacity is less than for the younger leaves.
Gang-Yi Wu, Jun-Ai Hui, Zai-Hua Wang, Jie Li and Qing-Sheng Ye
( Zhu et al., 2013a , 2013b ). There are fairly extensive studies on the photosynthetic physiology of thin-leaved Oriental Cymbidium ( Pan et al., 1997 ; Pan and Ye, 2006 ). The photosynthetic characteristics of thin-leaved Oncidium have also been
Qibing Wang and Jianjun Chen*
Ficus benjamina is considered to have a high degree of morphological and physiological plasticity in response to light levels. In this study, leaf area and thickness, specific leaf area (SLA), chlorophyll content, and photosynthetic characteristics of Ficus benjamina `Common'; grown in a shaded greenhouse under four maximum photosynthetic photon flux densities (PPFDs) of 150, 250, 450, or 650 μmol·m-2·s-1 were investigated. Results showed that plants grown under 450 and 650 PPFDs had higher SLA and leaf thickness but smaller leaf areas than those grown under 150 and 250 PPFDs. Total chlorophyll content per unit leaf area decreased as PPFDs increased. Net photosynthetic rates (Pn) increased from 2.7 μmol·m-2·s-1 under 150 PPFD to 5.7 μmol·m-2·s-1 under 450 PPFD, then slightly decreased to 5.5 μmol·m-2·s-1 under 650 PPFD. The highest net photosynthetic rate was not associated with higher intercellular CO2 concentrations (Ci) and stomatal conductance (gs) as plants grown under 250 PPFD had the highest (Ci) (259 ppm) and gs (0.1 mol·m-2·s-1), which suggests that photosynthetic enzymes could play a increasing role under 450 PPFD. Plant quality, however, was not necessarily correlated with the Pn because only those grown under 250 PPFD had appropriate heights, large and dark green leaves, and well-spread branches, and thus were graded higher than plants grown under the other PPFDs. This study shows that fine-tuning production light level is important for high quality Ficus benjamina production.
Chuhe Chen, J. Scott Cameron, Stephen F. Klauer and Paul W. Foote
After anthesis, date of leaf emergence was recorded in fruited plants (F) and deflowered plants (DF) of `Totem' strawberry (Fragaria × ananassa), which were grown in a randomized block design with four blocks in a greenhouse. Two different regression models were fitted to describe leaf emergence rate (LER) after anthesis for F and DF (R2 = 0.826 and 0.916, respectively). The LER of F decreased during the fruit development, and accelerated and exceeded DF after fruit maturity, then both dropped when the growth season was ending.
Physiological and photosynthetic characteristics were measured on leaves from F and DF at green fruit, red fruit, and after fruit maturity stages. Newly expanded leaves had significantly higher gas exchange rates, specific leaf weight, chlorophyll a and b contents but lower a/b ratio than the older leaves both during and after fruit development. They also had higher amplitudes of Ca 693 but lower peaks at Ca 684 and Cb 649 in their fourth-derivative chlorophyll spectra. Leaf chlorophyll a content and CO2 assimilation rate decreased after fruit maturity. Plants at red fruit stage had higher chlorophyll b content than at green fruit and after fruit maturity stages.
The LERs of the second and third leaves emerged after anthesis were most seriously affected by fruit development. They showed greater photosynthetic activity than other leaves in the canopy during fruit development and were thus important to fruit yield.
Jia-yi Wang, Jian-shuang Shen, Mengmeng Gu, Jia Wang, Tang-ren Cheng, Hui-tang Pan and Qi-xiang Zhang
, respectively, and the data of F o and F m both have no significant differences. So, 20 min dark-adaption was used in our research. Data analysis. The design was a one factor (leaf color) complete randomized one with three (photosynthetic characteristics) or
Dawei Shi, Xiaodong Wei, Guoxiang Chen and Yanli Xu
MDA contents also correlated with these parameters, but negatively. No significant correlations were detected between ASA, GSH contents, and senescence parameters. Table 1. Correlations of photosynthetic characteristics, oxidative stress, and
Wook Oh, In Hye Cheon, Ki Sun Kim and Erik S. Runkle
, which includes Korea, the northern half of the United States, and Europe), the mean photosynthetic daily light integral (DLI) can be a limiting factor in the production of many greenhouse crops during the winter and early spring ( Faust, 2003 ). The DLI