Responses Of Photosynthetic Characteristics Research Articles

Responses of Photosynthetic Characteristics, and Agronomic Attributes to Sowing Methods of Winter Wheat

Responses of Photosynthetic Characteristics, and Agronomic Attributes to Sowing Methods of Winter Wheat

Response of photosynthetic characteristics and yield of grape to different CO2 concentrations in a greenhouse.

Due to the enclosed environment of greenhouse grape production, the supply of CO2 required for photosynthesis is often insufficient, leading to photosynthetic downregulation and reduced yield. Currently, the optimal CO2 concentration for grape production in greenhouses is unknown, and the precise control of actual CO2 levels remains a challenge. This study aims to investigate the effects of different CO2 concentrations on the photosynthetic characteristics and yield of grapes, to validate the feasibility of a CO2 gas irrigation system, and to identify the optimal CO2 concentration for greenhouse grape production. In this study, a CO2 gas irrigation system combining CO2 enrichment and gas irrigation techniques was used with a 5-year-old Eurasian grape variety (Vitis vinifera L.) 'Flame Seedless.' Four CO2 concentration treatments were applied: 500 ppm (500 ± 30 µmol·mol-1), 700 ppm (700 ± 30 µmol·mol-1), 850 ppm (850 ± 30 µmol·mol-1), and 1,000 ppm (1,000 ± 30 µmol·mol-1). As CO2 concentration increased, chlorophyll a, chlorophyll b, and carotenoids in grape leaves all reached maximum values at 700 ppm and 850 ppm during the same irrigation cycle, while the chlorophyll a/b ratio was lower than at other concentrations. The net photosynthetic rate (Pn) and water use efficiency (WUE) of grape leaves were the highest at 700 ppm. The transpiration rate and stomatal conductance at 700 ppm and 850 ppm were significantly lower than those at other concentrations. The light saturation point and apparent quantum efficiency reached their maximum at 850 ppm, followed by 700 ppm. Additionally, the maximum net photosynthetic rate, carboxylation efficiency, electron transport rate, and activities of SOD, CAT, POD, PPO, and RuBisCO at 700 ppm were significantly higher than at other concentrations, with the highest yield recorded at 14.54 t·hm-2. However, when the CO2 concentration reached 1,000 ppm, both photosynthesis and yield declined to varying degrees. Under the experimental conditions, the optimal CO2 concentration for greenhouse grape production was 700 ppm, with excessive CO2 levels gradually inhibiting photosynthesis and yield. The results provide a theoretical basis for the future application of CO2 fertilization and gas irrigation techniques in controlled greenhouse grape production.

Response of photosynthetic characteristics and antioxidant system in the leaves of safflower to NaCl and NaHCO3.

Compared with NaCl, NaHCO3 caused more serious oxidative damage and photosynthesis inhibition in safflower by down-regulating the expression of related genes. Salt-alkali stress is one of the important factors that limit plant growth. NaCl and sodium bicarbonate (NaHCO3) are neutral and alkaline salts, respectively. This study investigated the physiological characteristics and molecular responses of safflower (Carthamus tinctorius L.) leaves treated with 200mmolL-1 of NaCl or NaHCO3. The plants treated with NaCl treatment were less effective at inhibiting the growth of safflower, but increased the content of malondialdehyde (MDA) in leaves. Meanwhile, safflower alleviated stress damage by increasing proline (Pro), soluble protein (SP), and soluble sugar (SS). Both fresh weight and dry weight of safflower was severely decreased when it was subjected to NaHCO3 stress, and there was a significant increase in the permeability of cell membranes and the contents of osmotic regulatory substances. An enrichment analysis of the differentially expressed genes (DEGs) using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes identified significant enrichment of photosynthesis and pathways related to oxidative stress. Furthermore, a weighted gene co-expression network analysis (WGCNA) showed that the darkgreen module had the highest correlation with photosynthesis and oxidative stress traits. Large numbers of transcription factors, primarily from the MYB, GRAS, WRKY, and C2H2 families, were predicted from the genes within the darkgreen module. An analysis of physiological indicators and DEGs, it was found that under saline-alkali stress, genes related to chlorophyll synthesis enzymes were downregulated, while those related to degradation were upregulated, resulting in inhibited chlorophyll biosynthesis and decreased chlorophyll content. Additionally, NaCl and NaHCO3 stress downregulated the expression of genes related to the Calvin cycle, photosynthetic antenna proteins, and the activity of photosynthetic reaction centers to varying degrees, hindering the photosynthetic electron transfer process, suppressing photosynthesis, with NaHCO3 stress causing more pronounced adverse effects. In terms of oxidative stress, the level of reactive oxygen species (ROS) did not change significantly under the NaCl treatment, but the contents of hydrogen peroxide and the rate of production of superoxide anions increased significantly under NaHCO3 stress. In addition, treatment with NaCl upregulated the levels of expression of the key genes for superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), the ascorbate-glutathione cycle, and the thioredoxin-peroxiredoxin pathway, and increased the activity of these enzymes, thus, reducing oxidative damage. Similarly, NaHCO3 stress increased the activities of SOD, CAT, and POD and the content of ascorbic acid and initiated the glutathione-S-transferase pathway to remove excess ROS but suppressed the regeneration of glutathione and the activity of peroxiredoxin. Overall, both neutral and alkaline salts inhibited the photosynthetic process of safflower, although alkaline salt caused a higher level of stress than neutral salt. Safflower alleviated the oxidative damage induced by stress by regulating its antioxidant system.

Responses of photosynthetic characteristics and leaf senescence in summer maize to simultaneous stresses of waterlogging and shading

A field experiment was performed to investigate the physiological mechanism of the simultaneous stresses of waterlogging and shading on leaf photosynthetic and senescence during three growth stages of summer maize. The responses of leaf gas exchange parameters and antioxidant enzyme activities of the summer maize hybrids Denghai 605 (DH605) to waterlogging (W), shading (S), and their combination (W + S) for 6 days at the third leaf stage (V3), the sixth leaf stage (V6), and the tasseling stage (VT) were recorded. Shading, waterlogging, and their combination disturbed the activities of protective enzymes and increased the contents of H2O2 and O2−, accelerating leaf senescence and disordering photosynthetic characteristics. Under waterlogging, shading and their combination, leaf Pn, the photo-assimilates and grain yield was decreased. The greatest reduction for waterlogging and the combined stresses occurred at V3 and that for shading stress occurred at VT. The individual and combined stresses reduced the activities of protective enzymes and inhibited photosynthesis, reducing the accumulation of photosynthetic compounds and thereby yield. Waterlogging and the combined stresses at the V3 stage showed the greatest effect on leaf photosynthetic and senescence, followed by the V6 and VT stages. The greatest effect for shading stress occurred at VT, followed by the V6 and V3 stages, and the combined influence of shading and waterlogging was greater than that of either single stress.

Response of photosynthetic characteristics and non-structural carbohydrate accumulation of Betula ermanii seedlings to drought stress.

We explored the effects of drought stress on photosynthetic characteristics and non-structural carbohydrate (NSC) accumulation of the timberline tree species Betula ermanii in Changbai Mountain with a drought control experiment. The results showed that drought significantly reduced the net photosynthetic rate and stomatal conductance, but increased water use efficiency (WUE) of B. ermanii seedlings. Drought dramatically improved the contents of soluble sugar and total NSC in leaves, barks, stems, and roots of B. ermanii seedlings, but significantly reduced their starch content. The stomatal conductance, photosynthetic rate and WUE decreased rapidly as the drought continued, whereas the contents of soluble sugar, starch and NSC increased and then declined. At the end of the experiment, 90% of the leaves turned yellow, and the ratios of soluble sugar to starch in the stems, barks and roots under the drought treatment were significantly higher than those in the control. These results demonstrated that B. ermanii might be a drought-avoidance species that could reduce water loss by rapidly reducing stomatal conductance and improving WUE under drought stress. B. ermanii might have evolved priority storage strategy to cope with water deficit through improving the content of soluble sugar in organs and increasing the transformation rate between starch and sugar. With the extension of drought stress, seedlings tended to die, since water stress might exceed the threshold of the plant self-regulation capacity. However, the content of NSC in organs did not decrease, suggesting that the death of B. ermanii under drought stress might not be caused by carbon starvation.

Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance

Understanding the physiological processes associated with leaf photosynthetic characteristics and nitrogen (N) assimilation during grain-filling stage are helpful for enhancing nitrogen utilization efficiency (NUtE) of maize. In this study, the leaf photosynthetic and N assimilation parameters in maize, including Zhengdan 958 (ZD958), a low-N tolerance cultivar and Huanong 138 (HN138), a low-N sensitive cultivar under different N rates were examined. Results showed that ZD958 displayed significant increases on grain yield and NUtE than that in HN138. Analyses on the leaf photosynthetic and N assimilation-associated processes indicated that ZD958 had higher leaf N remobilization (Rem N), net photosynthetic rate (Pn) and photosynthetic N use efficiency (PNUE) with respect to those of HN138 during grain-filling stage. In addition, ZD958 was also shown to be higher activities of leaf nitrate reductase (NR), glutamine synthetase (GS), nitrate reductase (GDH) and glutamine synthetase (GAGOT) than those of HN138. The leaf PNUE was significantly positively correlated with NR, GS, GDH, GOGAT suggesting that leaf PNUE and NR, GS, GDH, GOGAT jointly determined the N remobilization efficiency and the leaf N remobilization during post-silking. These results suggested that ZD958 possessed improved PNUE, NR and GS activities in leaves during grain-filling stage that contributes improve grain weights and yield formation capacities upon under low-N conditions. Keywords: low-N, photosynthesis, nitrogen assimilation, nitrogen utilization efficiency, maize DOI: 10.25165/j.ijabe.20201306.5891 Citation: Ji P T, Cui Y W, Li X L, Xiao K, Tao P J, Zhang Y C. Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance. Int J Agric & Biol Eng, 2020; 13(6): 133–143.

Responses of photosynthetic characteristics and growth in rice and winter wheat to different elevated CO<sub>2</sub> concentrations

This study investigated the effects of different elevated CO2 concentrations [ambient CO2 concentration (CK), CK plus 40 μmol mol-1 (T1), CK plus 200 μmol mol-1 (T2)] on photosynthetic characteristics and growth of rice (Oryza sativa L.) and winter wheat (Triticum aestivum L.). The results showed that T2 treatment decreased the net photosynthetic rate and leaf nitrogen content (LNC) but increased the light-saturated net photosynthetic rate of rice. Additionally, T2 treatment increased biomass accumulation and yield in both rice and winter wheat to some extent. T1 treatment, however, had little effect on photosynthetic parameters, LNC, biomass, and yield during the rice and winter wheat growing seasons. The above results suggest that the photosynthesis and growth responses of rice and winter wheat to different CO2 concentrations differed, in general, the increase of CO2 concentrations influenced more photosynthetic performance and growth of C3 plants than lower CO2 concentrations.

Antioxidant enzymes and the mitochondrial alternative oxidase pathway play important roles in chilling tolerance of Haematococcus pluvialis at the green motile stage

During outdoor large-scale cultivation, Haematococcus pluvialis cells, especially at the green motile stage, are frequently exposed to chilling stress in winter. However, the physiological responses and adaptation mechanisms to chilling in H. pluvialis have not been characterized. In order to better understand the chilling tolerance mechanisms of H. pluvialis in the green motile stage, the responses of photosynthetic characteristics and photoprotective mechanisms to chilling were investigated. Chilling stress significantly decreased the activities of key enzymes (ribulose-1,5-bisphosphate carboxylase/oxygenase and NADP glyceraldehyde-3-phosphate dehydrogenase) in photosynthetic carbon assimilation, which would cause the accumulation of excess reducing equivalents and an imbalance of light absorption and energy utilization, leading to more severe photoinhibition. After chilling treatment, there was no induction of cyclic electron flow, non-photochemical quenching, fluorescence emission, or catalase, indicating these factors do not protect H. pluvialis from photoinhibition. However, chilling significantly enhanced the activities of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase), which efficiently dissipated excess electrons generated by photosynthetic linear electron flow (LEF). The malate-oxaloacetate shuttle was activated and the mitochondrial alternative oxidase (AOX) pathway was significantly up-regulated after chilling, indicating the transport of excess reducing equivalents generated by photosynthetic LEF to cytosol and mitochondria and oxidization by the AOX pathway, the mitochondrial non-phosphorylating pathway. As a result, the LEF was not inhibited by negative feedback and the H. pluvialis cells were well protected under chilling stress in the light, with no change in the effective quantum yield of PSII (ΦPSII) and the yield of non-regulated energy dissipation of PSII (ΦNO). The results indicate that antioxidant enzymes and the mitochondrial AOX pathway play important roles in protecting H. pluvialis at the green motile stage against chilling stress.

Photosynthetic characteristics of aerial microalga Trentepohlia jolithus during drying and rewetting cycles

Aerial microalga Trentepohlia jolithus is frequently exposed to drying and rewetting cycles. To characterize the adaptive mechanisms allowing survivability of this aerial microalga, the responses of photosynthetic characteristics and photoprotective mechanisms to moderate desiccation (80% and 60% relative air humidity) and severe desiccation (40% relative air humidity) were investigated in T. jolithus grown at 95% relative air humidity. Additionally, the recovery of photosynthetic performance in severe desiccated T. jolithus was monitored after rehydration. In T. jolithus, non-photochemical quenching (NPQ) decreased gradually as the relative air humidity decreased from 95% to 40%, but the actual photochemical efficiency of photosystem II (ΦPSII) remained unchanged until the relative air humidity decreased to 40% under high light, indicating that the photoprotective mechanism NPQ was more sensitive to desiccation than photosynthetic linear electron flow. NPQ was maximally induced even under low light during moderate and severe desiccation. Under high light, excess excitation energy would not be well dissipated by NPQ in the desiccated state. However, a fraction of reaction centers were reversibly down-regulated during moderate and severe desiccation under high light. Inactive reaction centers well protected desiccated T. jolithus against photoinhibition by dissipating excess excitation energy as heat. The linear electron flow was inhibited significantly under severe desiccation. However, activated key Calvin cycle enzymes in severe desiccated T. jolithus promoted the surprisingly rapid recovery of linear electron flow after rehydration. The rapid reaction center recovery of severe desiccated T. jolithus might also favor the fast recovery of linear electron flow after rehydration. Therefore, the reversible down-regulation of reaction centers during desiccation, the maintenance of linear electron flow during moderate desiccation, and the rapid recovery of linear electron flow of severe desiccated algal cells after rehydration might be special adaptive mechanisms that allow T. jolithus to survive in an environment with rapidly changing water availability.

Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance

Understanding the physiological processes associated with leaf photosynthetic characteristics and nitrogen (N) assimilation during grain-filling stage are helpful for enhancing nitrogen utilization efficiency (NUtE) of maize. In this study, the leaf photosynthetic and N assimilation parameters in maize, including Zhengdan 958 (ZD958), a low-N tolerance cultivar and Huanong 138 (HN138), a low-N sensitive cultivar under different N rates were examined. Results showed that ZD958 displayed significant increases on grain yield and NUtE than that in HN138. Analyses on the leaf photosynthetic and N assimilation-associated processes indicated that ZD958 had higher leaf N remobilization (Rem N), net photosynthetic rate (Pn) and photosynthetic N use efficiency (PNUE) with respect to those of HN138 during grain-filling stage. In addition, ZD958 was also shown to be higher activities of leaf nitrate reductase (NR), glutamine synthetase (GS), nitrate reductase (GDH) and glutamine synthetase (GAGOT) than those of HN138. The leaf PNUE was significantly positively correlated with NR, GS, GDH, GOGAT suggesting that leaf PNUE and NR, GS, GDH, GOGAT jointly determined the N remobilization efficiency and the leaf N remobilization during post-silking. These results suggested that ZD958 possessed improved PNUE, NR and GS activities in leaves during grain-filling stage that contributes improve grain weights and yield formation capacities upon under low-N conditions. Keywords: low-N, photosynthesis, nitrogen assimilation, nitrogen utilization efficiency, maize DOI: 10.25165/j.ijabe.20201306.5891 Citation: Ji P T, Cui Y W, Li X L, Xiao K, Tao P J, Zhang Y C. Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance. Int J Agric & Biol Eng, 2020; 13(6): 133–143.

Responses of photosynthetic characteristics to low light stress in ear leaves of high photosynthetic efficiency maize at narrow row of maize-soybean strip in-tercropping system

Responses of photosynthetic characteristics to low light stress in ear leaves of high photosynthetic efficiency maize at narrow row of maize-soybean strip in-tercropping system

干热河谷车桑子光合生理特性对氮磷添加的响应

干热河谷车桑子光合生理特性对氮磷添加的响应

Responses of photosynthetic characteristics in leaves of Physocarpus amurensis and P opulifolius to drought stress

This experiment was conducted to study the responses of photosynthetic gas exchange parameters and the chlorophyll fluorescence parameters in leaves to soil drought. Furthermore, the drought resistance abilities of the endangered native Physocarpus amurensis and the introduced P. opulifolius as well as their differences were studied. The results showed that the leaves of P. opulifolius wilted significantly, while the leaf water content and water use efficiency of the native P. amurensis were higher on the 7th day after soil drought. Soil drought reduced the net photosynthetic rate, stomatal conductance, and transpiration rate in the leaves of the two Physocarpus species, while the observed decrease of P. opulifolius was significantly higher than that of P. amurensis. On the 7th day after soil drought, the intercellular CO2 concentration (Ci) of P. opulifolius was higher than that without drought treatment, while the Ci of P. amurensis was lower than that without drought treatment. The electron transfer rate (ETR) and photochemical quenching coefficient (qP) in leaves of P. amurensis were clearly decreased, while differences of the light energy capture efficiency (Fv'/Fm') in the PS2 reaction center were non-significant. However, Fv'/Fm', ETR, and qP in the lea-ves of P. opulifolius were all significantly decreased to greater extents compared to those in P. amurensis. On the 7th day after soil drought, a non-significant change was observed on the relative variable fluorescence (VJ) at site J of the OJIP curve of P. amurensis leaves, while VJ in leaves of P. opuli-folius was increased. The carbon assimilation ability of P. opulifolius leaves and the sensibility of PS2 function to soil drought were significantly higher than those of P. amurensis. The reduction in the photosynthetic capacity induced by soil drought was mainly due to the limitation of the stomatal factors for P. amurensis, but mainly due to the limitation of the non-stomatal factors for P. opulifolius.

Response of photosynthetic characteristics and accumulation and distribution of assimilation products in tobacco to different light environments

In order to reveal the photosynthetic characteristics and the mechanism about accumulation and distribution of photosynthetic assimilation products under different light environments, potted tobacco was cultivated in a climate control chamber, there were three light intensity treatments (shading: (400±15)-(500±15) μmol·m-2·s-1; natural light: (800±15)-(1000±15) μmol·m-2·s-1; high light: (1500±15)-(1800±15) μmol·m-2·s-1). The results showed that with the decrease of light intensity, the biomass and root allocation, the net photosynthetic rate (Pn), stomata conductance (gs) and transpiration rate (Tr) were decreased, but the intercellular CO2 concentration (Ci) increased. The maximum net photosynthetic rate (Amax), light saturation point (LSP), light saturation point (LCP) and dark respiration rate (Rd) reached the maximum level under high light condition while the apparent quantum efficiency was higher in low light environment. The effects of light intensity on the absorption, accumulation and distribution of 13C in tobacco were significant, with a reduced proportion of enriched 13C distributed to the root under shading. The changes in the external light environment not only significantly affected the photosynthetic cha-racteristics and biomass accumulation of tobacco leaves, but also the distribution pattern of photosynthetic carbon in tobacco plant-soil system.

Responses of photosynthetic characteristics to low temperature stress and recovery treatment in cotton seedling leaves

Responses of photosynthetic characteristics to low temperature stress and recovery treatment in cotton seedling leaves

Responses of photosynthetic characteristics of Stipa baicalensis to grazing disturbance

Responses of photosynthetic characteristics of Stipa baicalensis to grazing disturbance

Responses of Photosynthetic Characteristics of Winter Wheat Cultivars Released in Different Decades to Water Deficit in North China Plain

In order to understand the reaction and adaption mechanism to water deficit in winter wheat(Triticum aestivum L.) planted in North China Plain,six cultivars(Bima 1 released in the 1950s,Jinan 2 released in the 1960s,Taishan 1 released in the 1970s,Jimai 26 released in the 1980s,Jimai 38 released in the 1990s,and Jimai 22 released in the 2000s) were grown under both irrigated and rain-fed conditions in two successive growing seasons from 2010 to 2012.The photosynthetic characteristics of flag leaf after anthesis and grain yields were compared under two water conditions.The yield of Jimai 22 was significantly higher than that of other cultivars.The increase of yield was along with the significant improvements of photosynthetic rate(P n) and stomatal conductance(G s).Under irrigated condition,Jimai 22 showed increases of 54.4%,39.4%,23.4%,18.9%,and 4.2% in yield,30.0%,15.9%,15.2%,9.8%,and 5.5% in P n,and 46.1%,35.9%,23.1%,7.3%,and 6.6% in G s compared with the previous cultivars Bima 1,Jinan 2,Taishan 1,Jimai 26,and Jimai 38,respectively.Under rain-fed condition,Jimai 22 showed increases of 46.0%,37.6%,21.5%,18.8%,and 3.2% in yield,41.5%,29.1%,19.8%,11.2%,and 6.7% in P n,and 68.4%,48.7%,30.6%,10.7%,and 10.6% in G s compared with the previous cultivars,respectively.Under rain-fed condition,the P n and G s of all cultivars were lower than those under irrigated condition,and these of Jimai 22 showed the least reduction,indicating that Jimai 22 has higher photosynthetic adaptation to water deficiency.However,compared with the irrigated treatment,the rain-fed treatment showed 6.6-11.7% of yield decrease in different cultivars,with the largest reduction percentage in Jimai 22.Therefore,we concluded that the current wheat cultivars in North China Plain have high-yield potential under water-sufficient condition,but they are sensitive to water deficiency,with a relatively strong photosynthetic adaptation to water deficiency.