photosynthesis

摘要： Photosynthesis of organic compounds in coupling with promoted hydrogen evolution under mild conditions of light irradiation is considered as one of the most efficient and promising approach to obtain high purity hydrogen and value-added chemicals concurrently by utilizing green solar energy.Here,we report the synthesis of Ni S nanoparticle-modified Cd S nanorod composites(Ni S/Cd S)as an efficient bifunctional catalyst for the highly selective photocatalytic synthesis of high-value-added product benzaldehyde(BAD)from aqueous solution of benzyl alcohol(BA)under oxygen-free conditions,in accompanying with the efficient hydrogen evolution.The synergetic catalytic effect between Ni S and Cd S is proposed to play an important role in elevating the photo-redox performance.The composition-optimized 30%Ni S/Cd S catalyst affords an extraordinarily high H;generation rate of 207.8μmol h^(-1)and a simultaneous BAD generation rate of 163.8μmol h^(-1)under visible light irradiation,which are respectively 139 and 950 times higher than those of Cd S without Ni S modification.To our knowledge,these are the highest photocatalytic production rates of both H_(2)and aldehyde ever reported on the concurrent photocatalytic of aldehyde synthesis and hydrogen evolution in green aqueous solution.This work provides a highly efficient photosynthesis strategy for the concurrent productions of high-value-added fine chemicals and hydrogen.

摘要： Paphiopedilum dianthum and P.micranthum are two endangered orchid species,with high ornamental and conservation values.They are sympatric species,but their leaf anatomical traits and flowering period have significant differences.However,it is unclear whether the differences in leaf structure of the two species will affect their adaptabilities to temperature.Here,we investigated the leaf photosynthetic,anatomical,and flowering traits of these two species at three sites with different temperatures(Kunming,16.7±0.2°C;Puer,17.7±0.2°C;Menglun,23.3±0.2°C)in southwest China.Compared with those at Puer and Kunming,the values of light-saturated photosynthetic rate(Pmax).stomatai conductance(gs),leaf thickness(LT),and stomatai density(SD)in both species were lower at Menglun.The values of Pmax,gs,仃,adaxial cuticle thickness(CTad)and SD in P.dianthum were higher than those of P.micranthum at the three sites.Compared with P.dianthum,there were no flowering plants of P.micranthum at Menglun.These results indicated that both species were less resistance to high temperature,and P.dianthum had a stronger adaptability to high-temperature than P.micranthum.Our findings can provide valuable information for the conservation and cultivation of Paphiopedilum species.

摘要： Nitrogen(N),phosphorus(P)and potassium(K)are important essential nutrients for plant growth and development,but their functions in energy status remains unclear.Here,we grew Nipponbare rice seedlings in a growth chamber for 20 d at 30°C/24°Cday/night)under natural sunlight conditions with different nutrient regimes.The results showed that N had the strongest influence on the plant growth and development,followed by P and K.The highest nonstructural carbohydrate content,dry matter weight,net photosynthetic rate(Pn),ATP content,as well as NADH dehydrogenase,cytochrome oxidase and ATPase activities were found in the plants that received sufficient N,P and K.The lowest values of these parameters were detected in the N-deficient plants.Higher dry matter accumulation was observed in the K-deficient than in the P-deficient treatments,but there was no significant difference in the ratio of respiration rate to Pn between these two treatments,suggesting that differences in energy production efficiency may have accounted for this result.This hypothesis was confirmed by higher ATP contents and activities of NADH dehydrogenase,cytochrome oxidase and ATPase in the K-deficient plants than in the P-deficient plants.We therefore inferred different abilities in energy production efficiency among N,P and K in rice seedlings,which determined rice plant growth and development.

摘要： Nonstructural carbohydrates(NSC)are indicators of tree carbon balance and play an important role in regulating plant growth and survival.However,our understanding of the mechanism underlying drought-induced response of NSC reserves remains limited.Here,we conducted a long-term throughfall exclusion(TFE)experiment to investigate the seasonal responses of NSC reserves to manipulative drought in two contrasting tree species(a broadleaved tree Castanopsis hystrix Miq.and a coniferous tree Pinus massoniana Lamb.)of the subtropical China.We found that in the dry season,the two tree species differed in their responses of NSC reserves to TFE at either the whole-tree level or by organs,with significantly depleted total NSC reserves in roots in both species.Under the TFE treatment,there were significant increases in the NSC pools of leaves and branches in C.hystrix,which were accompanied by significant decreases in fine root biomass and radial growth without significant changes in canopy photosynthesis;while P.massoniana exhibited significant increase in fine root biomass without significant changes in radial growth.Our results suggested that under prolonged water limitation,NSC usage for growth in C.hystrix is somewhat impaired,such that the TFE treatment resulted in NSC accumulation in aboveground organs(leaf and branch);whereas P.massoniana is capable of efficiently utilizing NSC reserves to maintain its growth under drought conditions.Our findings revealed divergent NSC allocations under experimental drought between the two contrasting tree species,which are important for better understanding the differential impacts of climate change on varying forest trees and plantation types in subtropical China.

摘要： [Objectives]To explore the response characteristics of chlorophyll and photosynthesis in Styrax tonkinensis under different concentrations of copper and cadmium stress and analyze the internal mechanism of the effects of copper and cadmium pollution stress on photosynthesis.[Methods]Taking seedlings of S.tonkinensis as the research object,the response characteristics of chlorophyll and photosynthesis of S.tonkinensis were compared under different concentrations of copper and cadmium.[Results]With the increase of copper and cadmium treatment concentrations,the chlorophyll content first rose and then fell.With the increase of cadmium concentration,the net photosynthetic rate of S.tonkinensis plants increased from decrease to increase,and the stomatal conductance,transpiration rate and intercellular CO_(2) concentration all increased.[Conclusions]Under the stress of different concentrations of cadmium,the photosynthetic characteristics of S.tonkinensis were not obviously inhibited.Copper stress has inhibitory effect on photosynthesis of S.tonkinensis.

摘要： Deficit irrigation is critical to global food production,particularly in arid and semi-arid regions with low precipitation.Given water shortage has threatened agricultural sustainability under the dry-land farming system in China,there is an urgent need to develop effective water-saving technologies.We carried out a field study under two cultivation techniques:(1) the ridge and furrow cultivation model(R);and(2) the conventional flat farming model(F),and three simulated precipitation levels(1,275 mm;2,200 mm;3,125 mm) with two deficit irrigation levels(150 and 75 mm).We demonstrated that under the ridge furrow(R) model,rainfall harvesting planting under 150 mm deficit irrigation combined with 200 mm simulated precipitation can considerably increase net photosynthesis rate(P_(n)),quantum yield of PSII(ΦPSⅡ),electron transport rate(ETR),performance index of photosynthetic PSII(F_(v)/F_(m)′),and transformation energy potential of PSII(F_(v)/F_(o)).In addition,during the jointing,anthesis and grain-filling stages,the grain and biomass yield in the R model are 18.9 and 11.1% higher than those in the flat cultivation model,respectively,primarily due to improved soil water contents.The winter wheat fluorescence parameters were significantly positively associated with the photosynthesis,biomass and wheat production.The result suggests that the R cultivation model with irrigation of 150 mm and simulated precipitation of 200 mm is an effective planting method for enhancing P_(n),biomass,wheat production,and chlorophyll fluorescence parameters in dry-land farming areas.

摘要： 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.

摘要： Although open-central canopy(OCC)is popular in apple(Malus×domestica)orchards in Loess Plateau of China,its relevant photosynthetic mechanisms have not been elucidated.In this study,changes in photosynthetically active radiation(PAR),gas exchange,chlorophyll fluorescence quenching and fruit quality in apple trees were measured in OCC and compared with those in the conventional condensed round and large canopy(RLC).Results showed that light intercepted at different orientations was 44%higher by OCC than that by RLC.The improved light environment within OCC remarkably increased leaf maximum net photosynthetic rate(Pnmax)and significantly decreased stomatal limitation.Under high light,the ratio of photorespiratory rate to gross photosynthetic rate(Pr/Pg)in OCC was higher than that in RLC.Moreover,reversible component in non-photochemical quenching(r(qE))was increased,while irreversible component(r(qI))was decreased in OCC than in RLC.As a result,the fruit quality in OCC was greatly boosted as evidenced by the significantly increased single fruit weight,fruit flesh firmness and fruit soluble solid contents and the sharply decreased fruit titratable acid contents.PAR intercepted by the canopy and the fruit soluble solid contents,leaf Pnmaxor single fruit weight were positively correlated,while PAR or Pnmaxwas negatively correlated with the fruit titratable acid contents.Accordingly,the improved crown light environment and the enhanced leaf photosynthetic performance and photoprotective capacity in OCC led to the boosted fruit quality.

摘要： Sargassum horneri is a foundational species and an important contributor to the fl oating seaweed stock along the northeastern coast of Asia.In this study,benthic and fl oating thalli of S.horneri were collected from Changdao Island(37°54′N,120°43′E),Bohai Bay,China.We conducted an in-situ and an indoor experiment to study the acclimation potential in S.horneri to abiotic conditions at sea surface in autumn and winter.Both benthic and fl oating thalli were cultured in situ for two months(from October to December)at diff erent depths:0 m above sea level(masl)and 3 m below sea level(mbsl),and their growth rate,biochemical content,and photosynthetic performance were compared.During the fi rst month of culture,the relative growth rate of fl oating thalli was 2-fold greater than that of benthic thalli at 0 masl.The photosynthetic rate of most thalli was signifi cantly higher at 0 masl than at 3 mbsl.In the indoor experiments,fl oating and benthic thalli were exposed to high light intensity(400μmol photons/(m^(2)·s)photosynthetically active radiation(PAR))for 21 d,and their photo-acclimation capacities were compared.Under high light intensity,the two types of thalli showed low maximum quantum yield(F_(v)/F_(m))and light utilisation effi ciency(α)but high light saturation point(E_(k)).Floating thalli showed higher photosynthetic rate and photoprotective ability than benthic thalli at high light intensity.The eff ective quantum yield of photosystem II[Y(II)]of both types of thalli recovered after a 6-day treatment with low light intensity(40μmol photons/(m^(2)·s)).These fi ndings suggest that S.horneri is highly acclimated to the sea surface environment,which possibly contributes to its rapid accumulation and long free-fl oating periods at the sea surface.

摘要： Nano-enabled agriculture is an emerging hot topic.To facilitate the development of nano-enabled agriculture,reviews addressing or discussing the applications,knowledge gap,future research needs,and possible new research field of plant nanobiotechnology in agricultural production are encouraged.Here we review the following topics in plant nanobiotechnology for agriculture:1)improving stress tolerance,2)stress sensing and early detection,3)targeted delivery and controlled release of agrochemicals,4)transgenic events in non-model crop species,and 5)seed nanopriming.We discuss the knowledge gaps in these topics.Besides the use of nanomaterials for harvesting more electrons to improve photosynthetic performance,they could be used to convert n IR and UV to visible light to expand the light spectrum for photosynthesis.We discuss this approach to maintaining plant photosynthesis under light-insufficient conditions.Our aim in this review is to aid researchers to learn quickly how to use plant nanobiotechnology for improving agricultural production.