Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short ...Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux （ABS/RC） per PSII reaction center increased with increasing Cu concentration, but the electron transport flux （ET0/RC） decreased. Excess Cu had an insignificant effect on the trapping flux （TR0/RC）. The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than QA-（Ψ0）, the maximal quantum yield of primary photochemistry （φP0）, and the quantum yield of electron transport （φE0） were also observed. The amount of active PSII reaction centers per excited cross section （RC/CS） was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O2 evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side.展开更多
Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence in young fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity (Fv/ Fo), conversio...Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence in young fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity (Fv/ Fo), conversion efficiency of primary light energy (Fv/Fm)of PS II and photochemical quenching (qP) in young fruit of two apricot cultivars. Low temperature enhanced non-photochemical quenching qN, decreasing the quantum yield of photosynthetic electron transfer. The presence of ice nucleating active (INA) bacteria intensified the effects of low temperature, raised the injury temperature threshold from - 4℃ to - 2 - - 3℃. INA bacteria can be a factor to induce frost susceptibility of apricot fruit. The amount of damaged PS I activity center was related to apricot fruit size and cultivar.展开更多
[Objective] This study was to determine the response of Ficus microcarpa L. foliage to polyethylene glycol （PEG） simulated water stress using chlorophyll fluo- rescence imaging technique. [Method] The responses of d...[Objective] This study was to determine the response of Ficus microcarpa L. foliage to polyethylene glycol （PEG） simulated water stress using chlorophyll fluo- rescence imaging technique. [Method] The responses of detached leaves from Ficus microcarpa, Ficus benjamina and Nerium oleander to PEG-6000 simulated water stress were detected, and the chlorophyll fluorescence imaging technique was used to detect and analyze the stress at different spots of a single leaf simultaneously. [Result] The responses of Ficus microcarpa, Ficus benjamina and Nerium oleander to dehydration showed that： ~1~） the maximal photochemical efficiency （Fv/Fm） and non- photo-chemical quenching （NPQ） values were small in the reaction center among different detected spots of leaves, and there were great differences between relative electron transport rate （ETR）, photochemical quenching （qP） and quantum efficiency of PSII photochemistry （（φPSII）; （2） the differences of these parameters were more ob- vious among different spots of water-stressed leaves; （3） the discrete degrees of the species with strong resitances decreased significantly. [Conclusion] This study lays the foundation for the further research on the response of plants to drought stress using chlorophyll fluorescence imaging technique.展开更多
Chlorophyl fluorescence transient from initial to maximum fluorescence （“P”step） throughout two intermedi-ate steps （“J”and“I”） （JIP-test） is considered a reliable early quantitative indicator of stress in...Chlorophyl fluorescence transient from initial to maximum fluorescence （“P”step） throughout two intermedi-ate steps （“J”and“I”） （JIP-test） is considered a reliable early quantitative indicator of stress in plants. The JIP-test is particularly useful for crop plants when applied in variable field environments. The aim of the present study was to conduct a quantitative trait loci （QTL） analysis for nine JIP-test parameters in maize during flowering in four field environ-ments differing in weather conditions. QTL analysis and identification of putative candidate genes might help to explain the genetic relationship between photosynthesis and different field scenarios in maize plants. The JIP-test param-eters were analyzed in the intermated B73 ？ Mo17 （IBM） maize population of 205 recombinant inbred lines. A set of 2,178 molecular markers across the whole maize genome was used for QTL analysis revealing 10 significant QTLs for seven JIP-test parameters, of which five were co-localized when combined＆amp;nbsp;over the four environments indicating polygenic inheritance and pleiotropy. Our results demonstrate that QTL analysis of chlorophyl fluorescence parameters was capable of detecting one pleiotropic locus on chromosome 7, coinciding with the gene gst23 that may be associated with efficient photosynthe-sis under different field scenarios.展开更多
Glycinebetaine （Glybet） accumulation, photosynthetic efficiency and growth performance in indica rice cultivated under salt stress and extreme pH stress were investigated. Betaine aldehyde dehydrogenase （BADH） act...Glycinebetaine （Glybet） accumulation, photosynthetic efficiency and growth performance in indica rice cultivated under salt stress and extreme pH stress were investigated. Betaine aldehyde dehydrogenase （BADH） activity and Glybet accumulation in the seedlings of salt-tolerant and salt-sensitive rice varieties grown under saline and acidic conditions peaked after treatment for 72 h and 96 h, respectively, and were higher than those grown under neutral pH and alkaline salt stress. A positive correlation was found between BADH activity and Glybet content in both salt-tolerant （P=0.71） and salt-sensitive （P=0.86） genotypes. The chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids contents in the stressed seedlings significantly decreased under both acidic and alkaline stresses, especially in the salt-sensitive genotype. Similarly, the maximum quantum yield of PSII （Fv/Fm）, photon yield of PSII （ФPSII）, non-photochemical quenching （NPQ） and net photosynthetic rate （Pn） in the stressed seedlings were inhibited, leading to overall growth reduction. The positive correlations between chlorophyll a content and Fv/Fm, total chlorophyll content and ФPSII, and Pn as well as Pn and leaf area in both salt-tolerant and salt-sensitive genotypes were found. Saline acidic and saline alkaline soils may play a key role affecting vegetative growth prior to the reproductive stage in rice plants.展开更多
The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, m...The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate （PN）; chlorophyll a fluorescence （ChlF） characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency （0.125, 0.063, and 0.031 mmol/L P treatments）, whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency （0.016 and 0 mmol/L P treatments）. Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.展开更多
Heat stress occurs frequently in energy-saving sunlight greenhouses(ESSG) at the late growth stage. Three-year delayed cultivation(DC) of the Red Globe cultivar of Vitis vinifera L. was used to clarify the physiologic...Heat stress occurs frequently in energy-saving sunlight greenhouses(ESSG) at the late growth stage. Three-year delayed cultivation(DC) of the Red Globe cultivar of Vitis vinifera L. was used to clarify the physiological mechanisms of short-term heat stress on PSII and subsequent recovery from heat stress. By November, the photosynthetic function had declined and the fall in transpiration rate(E) with heating time increased the possibility of heat damage. In July, the most obvious increase was in the relative variable fluorescence at J point at 40°C, and in November it changed to K point. The 5 min of heat treatment resulted in a significant increase of the relative variable fluorescence at 0.3 ms(W), and after 10 min of heat treatment, the number of reactive centres per excited cross section(RC/CS), probability that a trapped exciton moves an electron into the electron transport chain beyond Q–(at t=0)(Ψ) and quantum yield of electron transport at t=0(φ) decreased significantly(P<0.05), suggesting that the reaction centre, donor and acceptor side of photosystem II(PSII) were all significantly inhibited(P<0.05) and that the thermal stability of the photosynthetic mechanism was reduced. The inhibition of energy fluxes for senescent leaves in November was earlier and more pronounced than that for healthy leaves, which did not recover from heat stress of more than 15 min after 2 h recovery at room temperature.展开更多
To cope with a highly heterogeneous light environment,photosynthesis in plants can be regulated systemically.Currently,the majority of studies are carried out with various plants during the vegetative growth period.As...To cope with a highly heterogeneous light environment,photosynthesis in plants can be regulated systemically.Currently,the majority of studies are carried out with various plants during the vegetative growth period.As the reproductive sink improves photosynthesis,we wondered how photosynthesis is systemically regulated at the reproductive stage under a vertically heterogeneous light environment in the field.Therefore,changes of light intensity within canopy,chlorophyll content,gas exchange,and chlorophyll a fluorescence transient were carefully investigated at the graining stage of maize under various planting densities.In this study,a high planting density of maize drastically reduced the light intensities in the lower canopy,and increased the difference in vertical light distribution within the canopy.With the increase of vertical heterogeneity,chlorophyll content,light-saturated photosynthetic rate and the quantum yield of electron transport in the ear leaf(EL) and the fourth leaf below the ear(FLBE) were decreased gradually,and the ranges of declines in these parameters were larger at FLBE than those at EL.Leaves in the lower canopy were shaded artificially to further test these results.Partial shading(PS) resulted in a vertically heterogeneous light environment and enhanced the differences in photosynthetic characteristics between EL and FLBE.Removing the tassel and top leaves(RTL) not only improved the vertical light distribution within the canopy,but also reduced the differences in photosynthetic characteristics between the two leaves.Taken together,these results demonstrated that maize plants could enhance the vertical heterogeneity of their photosynthetic function to adapt to their light environment;slight changes of the photosynthetic function in EL at the graining stage under a vertically heterogeneous light environment indicated that the systemic regulation of photosynthesis is weak at the graining stage.展开更多
The leguminous tree species Dipteryx odorata (Aubl.) Willd. and Inga edulis Mart. were grown in the field to reforest a degraded area. To investigate the photosynthetic responses and the initial growth of Amazonian fo...The leguminous tree species Dipteryx odorata (Aubl.) Willd. and Inga edulis Mart. were grown in the field to reforest a degraded area. To investigate the photosynthetic responses and the initial growth of Amazonian forest species under fertilization, the study species were subjected to different treatments: T1 = unfertilized-control, T2 = chemical fertilization, T3 = green fertilization and T4 = green and chemical fertilization. D. odorata showed the highest absolute growth rates in height under treatments T4 (10.2 cm·month-1) and T2 (12.2 cm·month-1). I. edulis exhibited the best performance for this same parameter in T4 (23.0 cm·month-1). The highest photosynthesis values (Pn) for both D. odorata (13.1 μmol·m-2·s-1) and I. edulis (20.6 μmol·m-2·s-1) were found in T4. The two species also showed the highest performance index values (PIABS) under T4 (D. odorata = 2.9 and I. edulis = 5.2). Our results suggest that the combination of green and chemical fertilization was the most effective of the four treatments evaluated for improving the photosynthetic performance and the growth of both species during the initial establishment of the species in a degraded area.展开更多
Here, we compared the intrinsic characteristics of 3-day-(newly germinated;<span><span style="font-family:Verdana;">“young”) and 8-week-old (“mature”) fronds of the aquatic plant </span>...Here, we compared the intrinsic characteristics of 3-day-(newly germinated;<span><span style="font-family:Verdana;">“young”) and 8-week-old (“mature”) fronds of the aquatic plant </span><i><span style="font-family:Verdana;">Spirodela</span></i><span style="font-family:Verdana;"> <i>polyrhiza</i></span> </span><span style="font-family:Verdana;">and their sensitivity to paraquat, a toxic herbicide. Endpoints measured were frond area and fresh weight, root length, chlorophyll</span><i><span style="font-family:Verdana;"> a</span></i><span style="font-family:Verdana;"> and</span><i><span style="font-family:Verdana;"> b </span></i><span style="font-family:Verdana;">contents, and chlorophyll</span><i><span style="font-family:Verdana;"> a</span></i><span style="font-family:Verdana;"> fluorescence. Significant differences were detected in the intrinsic physiological traits between young and mature fronds. Young fronds showed higher root length, chlorophyll contents, maximum quantum yield (</span><i><span style="font-family:Verdana;">F</span><sub><span style="font-family:Verdana;">v</span></sub></i><span style="font-family:Verdana;">/</span><i><span style="font-family:Verdana;">F</span><sub><span style="font-family:Verdana;">m</span></sub></i><span style="font-family:Verdana;">), maximal relative electron transport rate (rETR</span><sub><span style="font-family:Verdana;">max</span></sub><span style="font-family:Verdana;">) and saturating photon flux density (PFD), whereas mature fronds exhibited greater frond area and fresh weight. After a 72 h exposure to paraquat, root length and rETR</span><sub><span style="font-family:Verdana;">max</span></sub><span style="font-family:Verdana;"> were identified as the most sensitive endpoints of paraquat toxicity for both frond types, with EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> values of 0.66 and 0.76 μg<span style="font-size:6.5pt;font-family:"background:yellow;">·</span>L</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> for young fronds, respectively, and 5.53 and 2.28 μg<span style="font-size:6.5pt;font-family:"background:yellow;">·</span>L</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> for mature fronds, respectively. Young fronds of </span><i><span style="font-family:Verdana;">S.</span></i><span style="font-family:Verdana;"> <i>polyrhiza</i></span><span style="font-family:Verdana;"> showed significantly higher sensitivity to paraquat than mature fronds. A survey of other studies on paraquat toxicity to </span><i><span style="font-family:Verdana;">Lemna</span></i><span style="font-family:Verdana;"> species revealed that EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> values of paraquat-induced inhibition of root regrowth and rETR</span><sub><span style="font-family:Verdana;">max</span></sub><span style="font-family:Verdana;"> in both stages were the lowest, indicating that these two endpoints were the most sensitive to paraquat. In addition, EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> values of both endpoints of mature fronds of </span><i><span style="font-family:Verdana;">S.</span></i><span style="font-family:Verdana;"> <i>polyrhiza </i></span><span style="font-family:Verdana;">appear to be similar to the current allowable concentrations in drinking water set by the World Health Organization (WHO), indicating that these values may have application for the assessment of toxicity risk of paraquat in aquatic ecosystems.</span>展开更多
The Copaifera langsdorffii Desf. seedlings, popularly known as “copaiba” or diesel tree, present a natural occurrence in the riparian forests of the Brazilian Cerrado, however, not much is known about their capacity...The Copaifera langsdorffii Desf. seedlings, popularly known as “copaiba” or diesel tree, present a natural occurrence in the riparian forests of the Brazilian Cerrado, however, not much is known about their capacity to recover from flooding, particularly when the focus is on their establishment and use in programs for the recovery of degraded areas near watercourses and subject to flooding. The objective of this study was to evaluate over time the recovery of the efficiency of the photosynthetic apparatus and the antioxidant activity of C. langsdorffii seedlings flooded during different periods. The pots with the seedlings were placed in a plastic tank and submerged with water, and were removed from the flood condition every 21 days (0, 21, 42, 63 and 84 days), and evaluated every 30 days (0, 30, 60, 90 and 120 days). The seedlings tolerated the flooding for up to 42 days, recovering after suspension of this condition. Seedlings flooded for 63 and 84 days showed lower recovery capacity after flooding, independently of the evaluation period. Under these conditions, lower efficiency of the photosynthetic apparatus, gas exchange, photo assimilate production and seedling quality were observed.展开更多
基金supported by the National Natural Science Foundation of China (No. 40676079, 40976078)the National Key Technology R&D Program (No.2008ZX07211-003)
文摘Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux （ABS/RC） per PSII reaction center increased with increasing Cu concentration, but the electron transport flux （ET0/RC） decreased. Excess Cu had an insignificant effect on the trapping flux （TR0/RC）. The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than QA-（Ψ0）, the maximal quantum yield of primary photochemistry （φP0）, and the quantum yield of electron transport （φE0） were also observed. The amount of active PSII reaction centers per excited cross section （RC/CS） was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O2 evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side.
文摘Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence in young fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity (Fv/ Fo), conversion efficiency of primary light energy (Fv/Fm)of PS II and photochemical quenching (qP) in young fruit of two apricot cultivars. Low temperature enhanced non-photochemical quenching qN, decreasing the quantum yield of photosynthetic electron transfer. The presence of ice nucleating active (INA) bacteria intensified the effects of low temperature, raised the injury temperature threshold from - 4℃ to - 2 - - 3℃. INA bacteria can be a factor to induce frost susceptibility of apricot fruit. The amount of damaged PS I activity center was related to apricot fruit size and cultivar.
基金Supported by the Major Program for the West Action Projects of the Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX2-XB2-08)the Science-Technology Foundation of Zealquest(ZQFD200705)~~
文摘[Objective] This study was to determine the response of Ficus microcarpa L. foliage to polyethylene glycol （PEG） simulated water stress using chlorophyll fluo- rescence imaging technique. [Method] The responses of detached leaves from Ficus microcarpa, Ficus benjamina and Nerium oleander to PEG-6000 simulated water stress were detected, and the chlorophyll fluorescence imaging technique was used to detect and analyze the stress at different spots of a single leaf simultaneously. [Result] The responses of Ficus microcarpa, Ficus benjamina and Nerium oleander to dehydration showed that： ~1~） the maximal photochemical efficiency （Fv/Fm） and non- photo-chemical quenching （NPQ） values were small in the reaction center among different detected spots of leaves, and there were great differences between relative electron transport rate （ETR）, photochemical quenching （qP） and quantum efficiency of PSII photochemistry （（φPSII）; （2） the differences of these parameters were more ob- vious among different spots of water-stressed leaves; （3） the discrete degrees of the species with strong resitances decreased significantly. [Conclusion] This study lays the foundation for the further research on the response of plants to drought stress using chlorophyll fluorescence imaging technique.
基金supported by research grants 073-0731674-1673,073-0731674-0841 and 073‐0730463-0203 from Ministry of Science,Education and Sports,Republic of Croatia
文摘Chlorophyl fluorescence transient from initial to maximum fluorescence （“P”step） throughout two intermedi-ate steps （“J”and“I”） （JIP-test） is considered a reliable early quantitative indicator of stress in plants. The JIP-test is particularly useful for crop plants when applied in variable field environments. The aim of the present study was to conduct a quantitative trait loci （QTL） analysis for nine JIP-test parameters in maize during flowering in four field environ-ments differing in weather conditions. QTL analysis and identification of putative candidate genes might help to explain the genetic relationship between photosynthesis and different field scenarios in maize plants. The JIP-test param-eters were analyzed in the intermated B73 ？ Mo17 （IBM） maize population of 205 recombinant inbred lines. A set of 2,178 molecular markers across the whole maize genome was used for QTL analysis revealing 10 significant QTLs for seven JIP-test parameters, of which five were co-localized when combined＆amp;nbsp;over the four environments indicating polygenic inheritance and pleiotropy. Our results demonstrate that QTL analysis of chlorophyl fluorescence parameters was capable of detecting one pleiotropic locus on chromosome 7, coinciding with the gene gst23 that may be associated with efficient photosynthe-sis under different field scenarios.
基金supported by the National Center for Genetic Engineering and Biotechnology (BIOTEC) (Grant No. BT-B-06-RG-14-4502)partly funded by the International Atomic Energy Agency (IAEA) (Contract No. 12998/R0)
文摘Glycinebetaine （Glybet） accumulation, photosynthetic efficiency and growth performance in indica rice cultivated under salt stress and extreme pH stress were investigated. Betaine aldehyde dehydrogenase （BADH） activity and Glybet accumulation in the seedlings of salt-tolerant and salt-sensitive rice varieties grown under saline and acidic conditions peaked after treatment for 72 h and 96 h, respectively, and were higher than those grown under neutral pH and alkaline salt stress. A positive correlation was found between BADH activity and Glybet content in both salt-tolerant （P=0.71） and salt-sensitive （P=0.86） genotypes. The chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids contents in the stressed seedlings significantly decreased under both acidic and alkaline stresses, especially in the salt-sensitive genotype. Similarly, the maximum quantum yield of PSII （Fv/Fm）, photon yield of PSII （ФPSII）, non-photochemical quenching （NPQ） and net photosynthetic rate （Pn） in the stressed seedlings were inhibited, leading to overall growth reduction. The positive correlations between chlorophyll a content and Fv/Fm, total chlorophyll content and ФPSII, and Pn as well as Pn and leaf area in both salt-tolerant and salt-sensitive genotypes were found. Saline acidic and saline alkaline soils may play a key role affecting vegetative growth prior to the reproductive stage in rice plants.
基金supported by the project of the National Natural Science Foundation of China (No. 31301243)a project funded by the Priority Academic Program Development of Jiangsu higher education institutions (PAPD)+1 种基金the research foundation for introduce talents of Jiangsu university (13JDG030)the brainstorm project on social development of Guizhou Province (SY[2010]3043)
文摘The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate （PN）; chlorophyll a fluorescence （ChlF） characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency （0.125, 0.063, and 0.031 mmol/L P treatments）, whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency （0.016 and 0 mmol/L P treatments）. Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.
基金supported by the National Natural Science Foundation of China(31660585)the Experimental Station for Scientific Observation of Fruit Trees in the Northwest of China(10218020)the earmarked fund for China Agriculture Research System(CARS-30-21)
文摘Heat stress occurs frequently in energy-saving sunlight greenhouses(ESSG) at the late growth stage. Three-year delayed cultivation(DC) of the Red Globe cultivar of Vitis vinifera L. was used to clarify the physiological mechanisms of short-term heat stress on PSII and subsequent recovery from heat stress. By November, the photosynthetic function had declined and the fall in transpiration rate(E) with heating time increased the possibility of heat damage. In July, the most obvious increase was in the relative variable fluorescence at J point at 40°C, and in November it changed to K point. The 5 min of heat treatment resulted in a significant increase of the relative variable fluorescence at 0.3 ms(W), and after 10 min of heat treatment, the number of reactive centres per excited cross section(RC/CS), probability that a trapped exciton moves an electron into the electron transport chain beyond Q–(at t=0)(Ψ) and quantum yield of electron transport at t=0(φ) decreased significantly(P<0.05), suggesting that the reaction centre, donor and acceptor side of photosystem II(PSII) were all significantly inhibited(P<0.05) and that the thermal stability of the photosynthetic mechanism was reduced. The inhibition of energy fluxes for senescent leaves in November was earlier and more pronounced than that for healthy leaves, which did not recover from heat stress of more than 15 min after 2 h recovery at room temperature.
基金supported by the National Natural Science Foundation of China (31571576)the Strategic Priority Research Program of Chinese Academy of Sciences (XDA26040103)。
文摘To cope with a highly heterogeneous light environment,photosynthesis in plants can be regulated systemically.Currently,the majority of studies are carried out with various plants during the vegetative growth period.As the reproductive sink improves photosynthesis,we wondered how photosynthesis is systemically regulated at the reproductive stage under a vertically heterogeneous light environment in the field.Therefore,changes of light intensity within canopy,chlorophyll content,gas exchange,and chlorophyll a fluorescence transient were carefully investigated at the graining stage of maize under various planting densities.In this study,a high planting density of maize drastically reduced the light intensities in the lower canopy,and increased the difference in vertical light distribution within the canopy.With the increase of vertical heterogeneity,chlorophyll content,light-saturated photosynthetic rate and the quantum yield of electron transport in the ear leaf(EL) and the fourth leaf below the ear(FLBE) were decreased gradually,and the ranges of declines in these parameters were larger at FLBE than those at EL.Leaves in the lower canopy were shaded artificially to further test these results.Partial shading(PS) resulted in a vertically heterogeneous light environment and enhanced the differences in photosynthetic characteristics between EL and FLBE.Removing the tassel and top leaves(RTL) not only improved the vertical light distribution within the canopy,but also reduced the differences in photosynthetic characteristics between the two leaves.Taken together,these results demonstrated that maize plants could enhance the vertical heterogeneity of their photosynthetic function to adapt to their light environment;slight changes of the photosynthetic function in EL at the graining stage under a vertically heterogeneous light environment indicated that the systemic regulation of photosynthesis is weak at the graining stage.
基金the National Institute of Amazonian Research(MCTI-INPA)for logistical supportCAPES and CNPq for fellowships and funding for this research
文摘The leguminous tree species Dipteryx odorata (Aubl.) Willd. and Inga edulis Mart. were grown in the field to reforest a degraded area. To investigate the photosynthetic responses and the initial growth of Amazonian forest species under fertilization, the study species were subjected to different treatments: T1 = unfertilized-control, T2 = chemical fertilization, T3 = green fertilization and T4 = green and chemical fertilization. D. odorata showed the highest absolute growth rates in height under treatments T4 (10.2 cm·month-1) and T2 (12.2 cm·month-1). I. edulis exhibited the best performance for this same parameter in T4 (23.0 cm·month-1). The highest photosynthesis values (Pn) for both D. odorata (13.1 μmol·m-2·s-1) and I. edulis (20.6 μmol·m-2·s-1) were found in T4. The two species also showed the highest performance index values (PIABS) under T4 (D. odorata = 2.9 and I. edulis = 5.2). Our results suggest that the combination of green and chemical fertilization was the most effective of the four treatments evaluated for improving the photosynthetic performance and the growth of both species during the initial establishment of the species in a degraded area.
文摘Here, we compared the intrinsic characteristics of 3-day-(newly germinated;<span><span style="font-family:Verdana;">“young”) and 8-week-old (“mature”) fronds of the aquatic plant </span><i><span style="font-family:Verdana;">Spirodela</span></i><span style="font-family:Verdana;"> <i>polyrhiza</i></span> </span><span style="font-family:Verdana;">and their sensitivity to paraquat, a toxic herbicide. Endpoints measured were frond area and fresh weight, root length, chlorophyll</span><i><span style="font-family:Verdana;"> a</span></i><span style="font-family:Verdana;"> and</span><i><span style="font-family:Verdana;"> b </span></i><span style="font-family:Verdana;">contents, and chlorophyll</span><i><span style="font-family:Verdana;"> a</span></i><span style="font-family:Verdana;"> fluorescence. Significant differences were detected in the intrinsic physiological traits between young and mature fronds. Young fronds showed higher root length, chlorophyll contents, maximum quantum yield (</span><i><span style="font-family:Verdana;">F</span><sub><span style="font-family:Verdana;">v</span></sub></i><span style="font-family:Verdana;">/</span><i><span style="font-family:Verdana;">F</span><sub><span style="font-family:Verdana;">m</span></sub></i><span style="font-family:Verdana;">), maximal relative electron transport rate (rETR</span><sub><span style="font-family:Verdana;">max</span></sub><span style="font-family:Verdana;">) and saturating photon flux density (PFD), whereas mature fronds exhibited greater frond area and fresh weight. After a 72 h exposure to paraquat, root length and rETR</span><sub><span style="font-family:Verdana;">max</span></sub><span style="font-family:Verdana;"> were identified as the most sensitive endpoints of paraquat toxicity for both frond types, with EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> values of 0.66 and 0.76 μg<span style="font-size:6.5pt;font-family:"background:yellow;">·</span>L</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> for young fronds, respectively, and 5.53 and 2.28 μg<span style="font-size:6.5pt;font-family:"background:yellow;">·</span>L</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;"> for mature fronds, respectively. Young fronds of </span><i><span style="font-family:Verdana;">S.</span></i><span style="font-family:Verdana;"> <i>polyrhiza</i></span><span style="font-family:Verdana;"> showed significantly higher sensitivity to paraquat than mature fronds. A survey of other studies on paraquat toxicity to </span><i><span style="font-family:Verdana;">Lemna</span></i><span style="font-family:Verdana;"> species revealed that EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> values of paraquat-induced inhibition of root regrowth and rETR</span><sub><span style="font-family:Verdana;">max</span></sub><span style="font-family:Verdana;"> in both stages were the lowest, indicating that these two endpoints were the most sensitive to paraquat. In addition, EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> values of both endpoints of mature fronds of </span><i><span style="font-family:Verdana;">S.</span></i><span style="font-family:Verdana;"> <i>polyrhiza </i></span><span style="font-family:Verdana;">appear to be similar to the current allowable concentrations in drinking water set by the World Health Organization (WHO), indicating that these values may have application for the assessment of toxicity risk of paraquat in aquatic ecosystems.</span>
文摘The Copaifera langsdorffii Desf. seedlings, popularly known as “copaiba” or diesel tree, present a natural occurrence in the riparian forests of the Brazilian Cerrado, however, not much is known about their capacity to recover from flooding, particularly when the focus is on their establishment and use in programs for the recovery of degraded areas near watercourses and subject to flooding. The objective of this study was to evaluate over time the recovery of the efficiency of the photosynthetic apparatus and the antioxidant activity of C. langsdorffii seedlings flooded during different periods. The pots with the seedlings were placed in a plastic tank and submerged with water, and were removed from the flood condition every 21 days (0, 21, 42, 63 and 84 days), and evaluated every 30 days (0, 30, 60, 90 and 120 days). The seedlings tolerated the flooding for up to 42 days, recovering after suspension of this condition. Seedlings flooded for 63 and 84 days showed lower recovery capacity after flooding, independently of the evaluation period. Under these conditions, lower efficiency of the photosynthetic apparatus, gas exchange, photo assimilate production and seedling quality were observed.
