Photosynthetica最新文献

This study was conducted to assess whether silicon (Si) supply can alleviate the harmful effects of severe salinity in barley (Hordeum vulgare). Plants were grown on non-saline (0 mM NaCl) or saline (200 mM NaCl) nutrient media supplemented or not with 0.5 mM Si. Salinity impacted plant morphology and induced sodium and chloride accumulation within plant tissues. It significantly affected almost all measured parameters. Interestingly, Si supply alleviated salt stress effects on plant morphology, growth (up to +59%), water status (up to +74%), membrane integrity (up to +35%), pigment contents (up to +121%), and the activity of the two photosystems (PSI and PSII) by improving their yields, and by reducing their energy dissipation. Si beneficial effect was more pronounced on PSI as compared to PSII. As a whole, data inferred from the present study further confirmed that silicon application is an effective approach to cope with salinity.

Wide-narrow row maize planting patterns are a popular way to enhance maize yield via improving canopy PAR. To further optimize canopy PAR, we designed an improved wide-narrow row planting pattern (R2) based on the principle of the shortest projection length and the longest illumination of objects on the ground. Compared to the traditional wide-narrow row planting pattern (R1), maize yield increased by about 10% in R2. R2 maize had higher PAR, leaf area index, chlorophyll content, and photosynthetic rates than maize grown in R1. Moreover, compared to maize leaves in R1, the carbon assimilation enzymatic activities were also significantly higher in R2. The higher carbon assimilation enzymatic activity in R2 could account for the increased photosynthetic rate. Thus, the improved wide-narrow row planting pattern could improve photosynthetic performance by enhancing the PAR of the plant canopy, which further promotes the ear number and yield in northeast China.

Parameters representing leaf photosynthetic capacity, namely, the maximal carboxylation rate (V _cmax), maximal electron transport rate (J _max), and triose phosphate-utilization rate (T _p), can vary depending on various factors. The present study investigated diurnal variations in V _cmax, J _max, and T _p of uppermost leaves of soil-grown, well-watered eggplant in a greenhouse based on the simultaneous measurements of leaf gas exchange and chlorophyll fluorescence. The values of net photosynthetic rates and electron transport rates plotted against intercellular CO₂ concentrations were noticeably higher in the morning than in the afternoon. Significant differences were detected among the values of V _cmax, J _max, and T _p obtained at different times of day (08:30, 11:00, 13:30, and 16:00 h). All three parameters tended to decline as the time of day advanced; compared to the values at 08:30 h, V _cmax, J _max, and T _p declined by approximately 15% at 16:00 h. Among the three parameters, T _p appeared to be the most sensitive to time.

Light-induced changes in miRNAs, morphogenesis, and photosynthetic processes in phytochrome-deficient mutant plants grown under different light qualities were studied. miRNA activity in many processes is regulated by phytochromes and phytochrome-interacting factors (PIFs). The reduced content of photoreceptors in phytochrome mutants affects the PIF-microRNA interaction. In plants grown under red light (RL) and white light (WL), the phenotype of phyb mutant was distorted; however, under blue light (BL) conditions, the phyb phenotype was normalized. The photosynthetic rates of both the mutants and wild type were higher under BL than under RL and WL. The expression of most studied miRNAs increased in phyaphyb mutants under BL conditions, which is probably one of the reasons for the normalization of the phenotype, the increase in PSII activity, and the photosynthetic rate. MicroRNAs under BL can partially improve photosynthesis and phenotype of the mutants, which indicates the conjugation of the functioning of phytochromes in miRNA formation.

Semidwarf wheat contributes to significant yield increase worldwide, however, few dwarf cultivars of wheat are cultivated due to grain yield penalty. In this study, a new dwarf wheat Triticum aestivum L., cv. Xiaoyan 101, was investigated to explore its photosynthetic performance and yield potential. In the comparison of the semidwarf wheat cultivars, Jing 411 and Xiaoyan 101, although the first three leaves (including flag leaves) did not differ significantly in both genotypes, Xiaoyan 101 conferred a higher content of photosynthetic pigments and higher photochemical efficiency but had lower contents of hydrogen peroxide and malondialdehyde in lower leaves in the canopy. In addition, the antioxidant enzymes-encoding genes were upregulated while the senescence-associated genes (TaSAG3, TaSAG5, TaSAG7, and TaSAG12) were downregulated in lower leaves in the canopy of Xiaoyan 101. Ultimately, Xiaoyan 101 produced approximate or even higher grain yield than the local semidwarf wheat varieties. Therefore, it is possible to breed dwarf wheat with enhanced photosynthetic activity but without yield sacrifice.

Photosynthesis is a process highly sensitive to various abiotic and biotic stresses in plants. Among them, the major abiotic stress, waterlogging, affects the crop's growth and productivity. Under waterlogging, the photosynthetic apparatus of plants was destroyed. Waterlogging reduced chlorophyll content and the net photosynthetic rate. Therefore, this updated review summarized the effect of waterlogging on chloroplast ultrastructure, photosynthetic characteristics, and chlorophyll fluorescence attributes of plant species. By studying various research papers, we found that intercellular concentration of available carbon dioxide in mesophyll cells, assimilation of carbon, and the net photosynthetic ratio declined under waterlogging. The chlorophyll fluorescence efficiency of plants decreased under waterlogging. Thus, the study of photosynthesis in plants under waterlogging should be done with respect to changing climate. Moreover, the recognition of photosynthetic characteristics present in tolerant species will be beneficial for designing the waterlogging-tolerant crop plant in changing environments.

Amaranthus viridis is a functional food due to its antioxidant activity. The aim of this study was to investigate the responses of photosynthesis, growth, and antioxidant properties in A. viridis to nitrogen (N) applications. A. viridis plants were cultivated under low N (LN), medium N (MN), and high N (HN), and harvested at the reproductive phase. The dry mass and plant height of A. viridis plants increased with elevated N, and the dry mass of HN was saturated. Net photosynthetic rate, stomatal conductance, and water-use efficiency in the leaves at HN were strengthened. Meanwhile, under HN, chlorophylls (Chl), their precursors, and degradation intermediates in the leaves were highly accumulated, and the minor route of Chl degradation pathway was induced dramatically. However, 2,2-diphenyl-1-picrylhydrazyl radical-scavenging, ferrous iron-chelating, and reducing power in the extracts were reduced under HN. Conclusively, an appropriate N application balanced the yield and antioxidant properties of A. viridis.

Saline-alkaline stress is one of the most detrimental abiotic stresses that restrict the yield and physiological activity of maize (Zea mays L.). In the present study, maize was planted on saline-alkali land, while 25 mg L^-1 uniconazole (S3307) and 40 mg L^-1 5-aminolevulinic acid (ALA) were sprayed at the stage of nine expanded leaves. Our results showed that both S3307 and ALA applications significantly increased all ear width, volume, and mass in the maturity stage. Both applications also upregulated photosynthetic efficiency via increasing the chlorophyll content, net photosynthetic rate, transpiration rate, and stomatal conductance, as well as reduced the intercellular CO₂ concentration after the silking stage. In addition, both applications upregulated further the antioxidant system via enhancing the activity of antioxidants and contents of soluble protein and sugar, as well as reducing the malondialdehyde content after the silking stage. Thus, both S3307 and ALA applications can improve maize yield in saline-alkali land via enhancing ear morphology and increasing photosynthetic efficiency and antioxidants.

Systematic salt tolerance-related physiological mechanisms in roots and shoots of halophyte Dongying wild soybean have not yet been thoroughly studied. In this study, photosynthesis, modulated 820-nm reflection, chlorophyll a fluorescence, and Na⁺ distribution in cultivated (G _mc) and wild (G _sw) soybean leaves of grafted soybean plants were investigated after NaCl treatment. Results showed that the decreases in photosynthetic rate, performance index, active P₇₀₀ content, and plastocyanin reduction were significantly greater in the G _sw leaves than those in the G _mc leaves. The observed increases in the Na⁺ concentration in the G _sw leaves were likely responsible for the severe decrease in the photosynthetic activity of grafted plants. We suggest that Na⁺ accumulation in G _sw roots, which prevents the transport of Na⁺ from the roots to the shoots, effectively maintains the concentration of Na⁺ at a comparatively low level in the leaves to prevent the destruction of the photosynthetic apparatus by salt.

6-Benzyladenine (6-BA) is an artificial synthetic cytokinin, which plays an important role in regulating plant responses to abiotic stress. This study aimed to investigate the mitigative effect of exogenous 6-BA on photosynthetic capacities and leaf ultrastructure under waterlogging stress using two waxy corn inbred lines. The results showed that waterlogging stress disrupted the photosynthesis of waxy corn seedlings. However, exogenous 6-BA alleviated the inhibition caused by waterlogging stress. Under the waterlogging conditions, 6-BA treatment of plants helped preserve the structural integrity of the chloroplasts and retain higher contents of photosynthetic pigments. It also increased the photosynthetic capacity and promoted the openness of stomatal pores. Moreover, exogenous 6-BA promoted photosynthetic activities and the accumulation of carbohydrates. The results revealed that the detrimental effects of waterlogging stress on maize seedlings can be alleviated by 6-BA via modulating photosynthetic activities.