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Many studies have been conducted on maize to study the effect of drought on yield at the flowering stage, but understanding biochemical and photosynthetic response against drought at the seedling stage needs to be well established. Thus, to understand differential changes and interaction of biochemical and photosynthetic parameters at the seedling stage under drought, a greenhouse experiment with twelve maize genotypes under severe drought (30% field capacity) and irrigated (90-100% field capacity) conditions were performed. Drought differentially altered biochemical and photosynthetic parameters in all genotypes. A sharp increase in hydrogen peroxide, malondialdehyde (MDA), and total antioxidant capacity (TAOC) were seen and a positive association between H2O2 and TAOC, and MDA and transpiration rate (E) was observed under drought. Nonphotochemical quenching increased under drought to avoid the photosystem damage. PCA biplot analysis showed that reducing E and increasing photosynthetic efficiency would be a better drought adaptation mechanism in maize at the seedling stage. [ABSTRACT FROM AUTHOR]

To study the light intensity suitable for Bletilla ochracea Schltr., morphology, photosynthetic parameters, and polysaccharide content of seedlings were evaluated under different light intensities. All shade treatments promoted plant growth and net photosynthetic rate while having no significant effect on transpiration rate. The maximum photochemical efficiency and potential photochemical efficiency reached the lowest values under full sunlight. The electron transport rate and photochemical quenching under shade were significantly higher than those under full light, while nonphotochemical quenching was the highest under full light. This indicated that the shade alleviated photoinhibition in summer and improved the utilization of light. B. ochracea could adapt to different light intensities, enhancing photosynthetic efficiency under low light by improving the electron transport and the degree of opened PS? reaction centers, and adapting to high light by increasing heat dissipation. Plant growth, photosynthesis, and polysaccharide accumulation of B. ochracea greatly increased under 76.4% shade. [ABSTRACT FROM AUTHOR]

Active control of photosynthetic activities is important in plant physiological study. Although models of plant photosynthesis have been built at different scales, they have not been fully examined for their application in plant growth control. However, we do not have an infrastructure to support such experiments since current plant growth chambers usually use fixed control protocols. In our current paper, an open IoT-based framework is proposed. This framework allows a plant scientist or agricultural engineer, through an application programming interface (API), in a desirable programming language, (1) to gather environmental data and plant physiological responses; (2) to program and execute control algorithms based on their models, and then (3) to implement real-time commands to control environmental factors. A plant growth chamber was developed to demonstrate the concept of the proposed open framework. [ABSTRACT FROM AUTHOR]

Photosynthetic capacity plays an important role in plant vegetative growth, and is often regarded as a key determinant of adaptability in plant species, including the hybrids. Interspecific hybridizations are common and can easily occur in Buddleja. The F1 hybrid investigated in this study is a newly discovered interspecific hybrid between B. crispa and B. officinalis, and it was found in the Sino-Himalayan region. In this study, the morphological traits, the stoichiometric characteristics and the gas-exchange traits in F1 hybrids and their parents were measured under the cultivation conditions. Buddleja F1 hybrids showed the high leaf mass per area, which was similar to B. officinalis. Although F1 hybrids presented a low light-saturated net photosynthetic rate, they did not reduced carbon cost by increasing the specific leaf area or decreasing the leaf dry mass per unit area. Compared to the parental species, F1 hybrids had low leaf C:N and C:P ratios, C concentration, as well as photosynthetic nitrogen-use efficiency. However, they had a great respiration efficiency through a markedly reduced rate of respiration. Furthermore, F1 hybrids showed similar photochemical efficiency to B. officinalis, which was significantly higher than that in B. crispa. These findings suggest that the F1 hybrids in our study show a high similarity to their parental species in the leaf economic spectrum and photosynthetic capacity. [ABSTRACT FROM AUTHOR]

Low temperature (LT) and low irradiation (LI) are common factors posing a great risk to plants. The study aimed to elucidate the effects of LT and LI and recovery on the photosynthetic apparatus, photoinhibition of PSII, and reactive oxygen metabolism of strawberry seedlings. The results showed that strawberry growth slowed down or even stopped and total chlorophyll content, stomatal conductance, net photosynthetic rate, and maximal quantum yield of PSII photochemistry decreased, while intercellular CO2 concentration increased under LI, LT, and combined stress (LL). Additionally, JIP-test showed that compared to LI or LT stress, LL-stressed plants had lower quantum yields and efficiencies and functional antenna size, and higher reaction center activity. Besides, the contents of hydrogen peroxide and malondialdehyde increased, while the activity of superoxide dismutase, peroxidase, and catalase were significantly inhibited compared with the control. After the stress was relieved, the photosynthesis of LL-stressed plants recovered poorly. [ABSTRACT FROM AUTHOR]

There is a trade-off between leaf structures and photosynthesis physiology. While numerous reports have shown a difference in photosynthesis between Gossypium hirsutum L. (upland cotton) and G. barbadense L. (pima cotton), the potential contribution of leaf structures on this difference was not fully clarified. Here, we investigated the differences in area- and mass-based photosynthetic traits and leaf structures between upland and pima cottons. Our results showed that upland cotton had higher area-based net photosynthetic rate (Parea) than that of pima cotton, which was attributed to the coordination of stomatal conductance (gs), area-based mesophyll conductance (gm-area), and maximum carboxylation rate (Vcmax-area). Parea, gm-area, and Vcmax-area correlated positively with leaf mass per area. But upland and pima cotton had similar mass-based PN (Pmass), gm (gm-mass), Vcmax (Vcmax-mass), suggesting that they have a similar photosynthetic capacity of single cells. Consequently, the higher area-based values in upland cotton were only due to a higher leaf thickness (Tleaf). [ABSTRACT FROM AUTHOR]

Leaf gas exchange and growth responses of three melon cultivars, i.e., Mission, Da Vinci (var. reticulatus), and Super Nectar (var. inodorus) to two irrigation regimes, 50 and 100% crop evapotranspiration (ETc) were investigated under water-limited conditions of southwest Texas. In 2012, deficit irrigation (50% ETc) significantly decreased above-ground biomass, leaf area, leaf number, and specific leaf area, while leaf gas exchange, relative water content, water potential, chlorophyll fluorescence (Fv/Fm), and chlorophyll content (SPAD index) were not affected. However, in the drier year 2011, deficit irrigation significantly reduced net photosynthetic rate (PN) and stomatal conductance (gs). Further, the responses to water deficit varied with cultivars. At 50% ETc, PN and gs were maintained in cv. Da Vinci while decreased in Mission and Super Nectar. Thus, the late maturing cv. Super Nectar appeared to be more sensitive to drought stress, possibly due to the decrease in leaf area and PN. [ABSTRACT FROM AUTHOR]

Climate models predict an increase in atmospheric CO2 concentration and prolonged droughts in some parts of the Amazon, but the effect of elevated CO2 is still unknown. Two experiments (ambient CO2 400 ppm and elevated CO2 ? 700 ppm) were conducted to assess the effect of drought (soil at 50% field capacity) on physiological parameters of Carapa. At ambient CO2 concentration, light-saturated net photosynthetic rate (PNsat) was reduced by 33.5% and stomatal conductance (gs) by 46.4% under drought, but the effect of drought on PNsat and gs was nullified at elevated CO2. Total plant biomass and leaf area production were also reduced (42?47%) by drought. By changing leaf traits, Carapa is able to endure drought, as the consumptive use of water was reduced under drought (32?40%). The improvement of PNsat under elevated CO2 and water stress and the leaf plasticity of Carapa broaden our understanding of the physiology of Amazonian trees. [ABSTRACT FROM AUTHOR]

Increased attention has been paid to effects of coal mining subsidence on the growth of plants. Studying the changes of plants photosynthetic physiology under the disturbance of coal mining subsidence is the basis for understanding dynamic exchanges of plant energy and water at that mining area. The 52302 working face of the Shendong mining area was selected as the experimental site, with Artemisia ordosica, Caragana korshinskii, and Populus spp. as the research targets. Changes in leaf photosynthesis were monitored in plants at a subsidence crack area. We showed collapse cracks decreased soil moisture and caused drought stress. The photosynthetic capacity of leaves was reduced. Compared with plants from the control area, stomatal conductance, photosynthetic CO2 assimilation, and transpiration rate were reduced in all three plant species. The activity of PSII reaction center and electron transport at the donor and acceptor sites significantly decreased. [ABSTRACT FROM AUTHOR]