The effect of ectomycorrhizal Pisolithus tinctorius (Pt) infection was studied on the growth and photosynthetic characteristics of Pinus densiflora seedlings grown at ambient (360 µmol mol-1, AC) and elevated (720 µmol mol-1, EC) CO2 concentrations. After 18 weeks, Pt inoculation had led to significantly increased dry mass and stem diameter of P. densiflora at both CO2 concentrations, relative to non-inoculated seedlings. Moreover, EC significantly increased the ectomycorrhizal development. The phosphate content in needles inoculated with Pt was about three times higher than without inoculation at both CO2 concentrations. The PAR saturated net photosynthetic rates (Psat) of P. densiflora inoculated with Pt were clearly higher than for control seedlings at both CO2 concentrations, and the maximum net photosynthetic rate (PN) at saturated CO2 concentration (Pmax) was higher than in controls. Moreover, the carboxylation efficiency (CE) and RuBP regeneration rate of the PN/Ci curve for P. densiflora inoculated with Pt were significantly higher than for non-inoculated seedlings at both CO2 concentrations, especially at EC. The water use efficiency (WUE) of seedlings inoculated with Pt grown at EC was significantly raised. Allocation of photosynthates to roots was greater in Pt inoculated pine seedlings, because of the enhanced activity of ectomycorrhiza associated with seedlings at EC. Moreover, PN of non-inoculated seedlings grown for 18 weeks at EC tended to be down regulated; in contrast, Pt inoculated seedlings showed no down-regulation at EC. The activity of ectomycorrhiza may therefore be enhanced physiological function related to water and phosphate absorption in P. densiflora seedlings at EC. and D. S. Choi ... [et al.].
The response of stomatal parameters of four rice cultivars to atmospheric elevated CO2 concentration (EC) was studied using open top chambers. EC brought about reduction in stomatal conductance and increase in stomatal index, size of stomatal guard cells, stroma, and epidermal cells. Such acclimation helped the regulation of photosynthesis to EC. These changes in stomatal characters made rice cultivars adjustable to EC environment. and D. C. Uprety ... [et al.].
The effect of elevated CO2 on ovemight malate accumulatíon in the CAM epiphyte Tillandsia ionantha and the CAM terrestrial species Crassula arborescens was compared. Both species showed an increase in nocturnal accumulatíon of malate with increasing CO2 concentrations. This study is the first to show an increase in nighttime malate accumulatíon with increasing levels of CO2 at near-ambient concentrations in a CAM plant. The results indicate that some CAM plants can respond to increasing levels of CO2 in the atmosphere, potentíally leading to an increase in productívity.
Gas exchange and chlorophyll (Chl) fluorescence were measured on young mature leaves of rose plants (Rosa hybrida cvs. First Red and Twingo) grown in two near-to-tight greenhouses, one under control ambient CO2 concentration, AC (355 µmol mol-1) and one under CO2 enrichment, EC (700 µmol mol-1), during four flushes from late June to early November. Supply of water and mineral elements was non-limiting while temperature was allowed to rise freely during daytime. Leaf diffusive conductance was not significantly reduced at EC but net photosynthetic rate increased by more than 100 %. Although the concentration of total non-structural saccharides was substantially higher in the leaves from the greenhouse with EC, ΦPS2 (quantum efficiency of radiation use) around noon was not significantly reduced at EC indicating that there was no down-regulation of electron transport. Moreover, CO2 enrichment did not cause any increase in the risk of photo-damage, as estimated by the 1 - qP parameter. Non-photochemical quenching was even higher in the greenhouse with EC during the two summer flushes, when temperature and photosynthetic photon flux density (PPFD) were the highest. Hence rose photosynthesis benefits strongly from high concentrations of atmospheric CO2 at both high and moderate temperatures and PPFD. and L. Urban ... [et al.].
Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic rate, apparent quantum yield, maximum carboxylation rate, and photosynthetic electron transport rate, were significantly different between cultivars due to elevation and positively correlated with leaf nitrogen per area. Moreover, the seasonal gas exchange of the two cultivars showed variations due to elevation, particularly during the warmer seasons. Therefore, elevation affects the photosynthetic performance of these mango cultivars.
The use of Jatropha curcas oil as a source of biofuel has been well-explored. However, the physiological and growth studies of J. curcas have received considerably lesser attention. In this study, leaf gas exchange measurements and leaf nitrogen content were determined for four varieties of J. curcas, grown in the field or in pots. Based on stable carbon isotope analysis (δ13C) and
gas-exchange studies, J. curcas is a C3 sun plant and the range of leaf photosynthetic rates (or CO2 assimilation rates, PNmax) were typically between 7 and 25 μmol(CO2) m-2 s-1 and light saturation generally occurred beyond 800 μmol(quanta) m-2 s-1. Higher rates of leaf photosynthesis were generally obtained with the mature leaves. In addition, increased foliar PNmax were recorded in potted J. curcas variety Indiana with increasing nitrogen (N) nutrition levels. These plants also showed greater growth, increased leaf N content, higher maximum CO2 assimilation capacity (PNhighCO2) and chlorophyll (Chl) content, indicating the potential of optimizing the growth of Jatropha by varying fertilizer nutrient levels. A rapid assessment for leaf N using a nondestructive and portable Chl meter had been established for J. curcas. This approach will allow repeated sampling of the same plant over time and thus enable the monitoring of the appropriate levels of soil fertility to achieve good Jatropha plantation productivity. High N nutrition improved the overall plant oil yield by increasing the total number of fruits/seeds produced per plant, while not affecting the intrinsic seed oil content. and J. W. H. Yong ... [et al.].
Leaf tissue of azalea cultivars was treated with fluoride by floating leaf discs on Solutions or by allowing KF to enter intact leaves via stem segments and petioles. In each čase, the photosynthetic rate was more strongly influenced by KF than the respiration rate or content of chlorophyll were.
The present study was conducted to determine the effect of exogenous application of brassinolide (BR) on Leymus chinensis grown under shade, i.e., control (100% natural light), mild shade (70% natural light), and moderate shade (50% natural light). Shade substantially enhanced the plant growth, synthesis of photosynthetic pigments, photosynthetic efficiency, and chlorophyll (Chl) fluorescence attributes of L. chinensis as compared with control. The order of increase was mild shade > moderate shade > natural light except Chl content, where the order of increase was moderate shade > mild shade > natural light. Likewise, application of BR resulted in further exacerbation of plant height, plant fresh and dry mass, but less in case of Chl and carotenoids contents, gas-exchange characteristics, and Chl fluorescence attributes. The results conclude that shade significantly enhanced plant growth through alterations in physiological attributes of L. chinensis, while, application of BR may not further improve the plant growth under shade., A. J. Yang, S. A. Anjum, L. Wang, J. X. Song, X. F. Zong, J. Lv, A. Zohaib, I. Ali, R. Yan, Y. Zhang, Y. F. Dong, S. G. Wang., and Obsahuje bibliografii
On the first day after foliar application, chitosan pentamer (CH5) and chitin pentamer (CHIT5) decreased net photosynthetic rate (PN) of soybean and maize, however, on subsequent days there was an increase in PN in some treatments. CH5 caused an increase in maize PN on day 3 at 10-5 and 10-7 M; the increases were 18 and 10 % over the control plants. This increase was correlated with increases in stomatal conductance (gs) and transpiration rate (E), while the intercellular CO2 concentration (Ci) was not different from the control plants. PN of soybean plants did not differ from the control plants except for treatment CH5 (10-7 M) which caused an 8 % increase on day 2, along with increased gs, E, and Ci. On days 5 and 6 the CHIT5 treatment caused a 6-8 % increase in PN of maize, which was accompanied by increases in gs, E, and Ci. However, there was no such increase for soybean plants treated with CHIT5. In general, foliar application of high molecular mass chitin (CHH) resulted in decreased PN, particularly for 0.010 % treated plants, both in maize and soybean. Foliar applications of chitosan and chitin oligomers did not affect (p > 0.05) maize or soybean height, root length, leaf area, shoot or root or total dry mass. and W. M. Khan, B. Prithiviraj, D. L. Smith.
The effect on traits of photosynthesis and water relations of assimilate demand was studied in olive tree that has strong alternate bearing. The diurnal and seasonal leaf gas exchanges, area dry mass, and saccharide and chlorophyll (Chl) contents were measured by comparing shoots with fruit of "on-trees" (heavy fruit load) with shoots without fruit on both "on-trees" and "off-trees" (light fruit load). In spite of large seasonal and diurnal differences, leaf net photosynthetic rate (PN), stomatal conductance (gs), sub-stomatal CO2 concentration (C1), transpiration rate (E), and respiration rate (RD) were not significantly influenced by fruit load or by the presence or absence of fruit on the shoot. An only exception was at the beginning of July when the one-year-old leaves on shoots with fruit had slightly higher PN and E than leaves on shoots without fruit. Water content, Chl and saccharide contents, and area dry mass of the leaf were not substantially influenced by the presence/absence of fruit on the shoot or fruit load. Hence the sink demand, associated with fruit growth, did not improve leaf photosynthetic efficiency in olive.