Photosynthesis Rate Research Articles

Comparison of the Photosynthesis, Hydraulic Properties, and Anatomy of Pteroceltis tatarinowii Leaves Between a Limestone and a Cultivated Forest

Pteroceltis tatarinowii Maxim is a famous paper-making tree endemic to China with a wide distribution. Leaves of this tree growing in different habitats show a certain plasticity, which is important for their ecological adaption. Here, the photosynthesis ability, hydraulic properties, and anatomy of P. tatarinowii leaves from a limestone forest (Langya Mountain) and a cultivated forest (Xiaoling Village) in Anhui province were compared. The results showed that leaves from Xiaoling Village had higher net photosynthesis rate and hydraulic conductivity, which were closely related to their higher vein density, stomatal density and palisade tissue thickness than leaves from Langya Mountain. However, lower leaf water potentials at turgor loss point and at 50% loss of conductivity, as well as a higher leaf hardness, for Langya Mountain leaves indicated their higher hydraulic safety and drought resistance than those of leaves from Xiaoling Village. This study reveals a hydraulic trade-off between efficiency and safety for P. tatarinowii leaves growing in distinct habitats. Further studies should include more habitats and different vegetation communities to clarify the ecological adaption so as to provide a scientific basis for the protection of this species.

Carbon accumulation model for simulating 14C radioactivity in Chinese yam grown from a seed bulbil.

Modeling carbon accumulation in crop plants is key to evaluating the transfer of atmospheric 14C into the edible parts of the plants growing near nuclear facilities. Chinese yam 'Nagaimo' (Dioscorea polystachya Turcz.) is a major crop cultivated near a spent nuclear fuel reprocessing plant in Rokkasho, Aomori, Japan. We developed a dynamic compartment model for assessing carbon and 14C accumulation in Chinese yam grown from a seed bulbil in the field. Light and temperature dependence of leaf photosynthesis and temperature dependence of respiration in leaves, stems and belowground parts (tuber and root) were incorporated into the model. Estimated amounts of carbon in the leaves, stems and belowground parts were good agreement with the measured data from the field. Simulation results of 14C accumulation using this model indicated that the accumulation of 14C in belowground parts at the harvest depends on the rate of photosynthesis on the day of exposure.

High-precision prediction of microalgae biofuel production efficiency: employing ELG ensemble method

Microalgae biofuels are considered a significant source of future renewable energy due to their efficient photosynthesis and rapid growth rates. However, practical applications face numerous challenges such as variations in environmental conditions, high cultivation costs, and energy losses during production. In this study, we propose an ensemble model called ELG, integrating Empirical Mode Decomposition (EMD), Long Short-Term Memory (LSTM), and Gradient Boosting Machine (GBM), to enhance prediction accuracy. The model is tested on two primary datasets: the EIA (U.S. Energy Information Administration) dataset and the NREL (National Renewable Energy Laboratory) dataset, both of which provide extensive data on biofuel production and environmental conditions. Experimental results demonstrate the superior performance of the ELG model, achieving an RMSE of 0.089 and MAPE of 2.02% on the EIA dataset, and an RMSE of 0.1 and MAPE of 2.21% on the NREL dataset. These metrics indicate that the ELG model outperforms existing models in predicting the efficiency of microalgae biofuel production. The integration of EMD for preprocessing, LSTM for capturing temporal dependencies, and GBM for optimizing prediction outputs significantly improves the model’s predictive accuracy and robustness. This research, through high-precision prediction of microalgae biofuel production efficiency, optimizes resource allocation and enhances economic feasibility. It advances technological capabilities and scientific understanding in the field of microalgae biofuels and provides a robust framework for other renewable energy applications.

Coral larvae increase nitrogen assimilation to stabilize algal symbiosis and combat bleaching under increased temperature.

Rising sea surface temperatures are increasingly causing breakdown in the nutritional relationship between corals and algal endosymbionts (Symbiodiniaceae), threatening the basis of coral reef ecosystems and highlighting the critical role of coral reproduction in reef maintenance. The effects of thermal stress on metabolic exchange (i.e., transfer of fixed carbon photosynthates from symbiont to host) during sensitive early life stages, however, remains understudied. We exposed symbiotic Montipora capitata coral larvae in Hawai'i to high temperature (+2.5°C for 3 days), assessed rates of photosynthesis and respiration, and used stable isotope tracing (4 mM 13C sodium bicarbonate; 4.5 h) to quantify metabolite exchange. While larvae did not show any signs of bleaching and did not experience declines in survival and settlement, metabolic depression was significant under high temperature, indicated by a 19% reduction in respiration rates, but with no change in photosynthesis. Larvae exposed to high temperature showed evidence for maintained translocation of a major photosynthate, glucose, from the symbiont, but there was reduced metabolism of glucose through central carbon metabolism (i.e., glycolysis). The larval host invested in nitrogen cycling by increasing ammonium assimilation, urea metabolism, and sequestration of nitrogen into dipeptides, a mechanism that may support the maintenance of glucose translocation under thermal stress. Host nitrogen assimilation via dipeptide synthesis appears to be used for nitrogen limitation to the Symbiodiniaceae, and we hypothesize that nitrogen limitation contributes to retention of fixed carbon by favoring photosynthate translocation to the host. Collectively, our findings indicate that although these larvae are susceptible to metabolic stress under high temperature, diverting energy to nitrogen assimilation to maintain symbiont population density, photosynthesis, and carbon translocation may allow larvae to avoid bleaching and highlights potential life stage specific metabolic responses to stress.

Leaf Anatomical Adaptation and Chloroplast Ultrastructure Changes Upon Magnesium Foliar Application of Faba Bean (Vicia faba L.) Grown Under Drought Stress

ABSTRACTBackgroundDrought stress (DS) impedes plant growth and development by impairing the uptake of nutrients, such as magnesium, which is central to many physiological processes, particularly photosynthesis. Leaf application was proposed to be an effective strategy to compensate for inadequate Mg2+ supply from the nutrient solution.AimThe present study is designed to investigate the role of Mg2+ leaf application in ameliorating leaf anatomy and chloroplast ultrastructure changes in faba beans grown under DS.MethodsHydroponically grown plants were subjected to DS under various levels of Mg2+, i.e. sufficient (0.5 mM), deficient (0 mM), and leaf‐application (250 mM). Light and transmission electron microscopy (TEM) were conducted to examine leaf anatomy and ultrastructural changes.ResultsMg2+ deficiency alone and under DS significantly affected plant biomass and photosynthesis. Additionally, sucrose concentration, oxidative stress, and lipid peroxidation were increased. Accordingly, the excessive deposition of photoassimilates in source organs due to the inhibition of phloem loading results in a disruption of the thylakoid structures leading to chloroplast damage. In the current study leaf application of Mg2+ partially ameliorated physiological functions, most notably chlorophyll concentration, photosynthesis and transpiration rate, plant biomass, and preservation of ultrastructure of the chloroplast.ConclusionAlthough the Mg application via roots enhanced drought tolerance, compared to Mg2+ leaf application. However, Mg2+ leaf application was proven to be an efficient strategy in mitigating DS in field trials. Therefore, Mg2+ foliar application should be prioritized for further investigation under relevant environmental stress conditions.

The effects of disease lesions and amoxicillin treatment on the physiology of SCTLD-affected corals

Metrics of coral physiology can be used to identify changes in coral health due to environmental stressors or management actions. One of the most unprecedented stressors to Caribbean corals is the spread of stony coral tissue loss disease (SCTLD), which also resulted in the novel management action of in-water amoxicillin treatments on active disease lesions. Though highly effective at halting lesions and preventing coral mortality, possible unintended consequences of topical application of amoxicillin to coral tissue were unknown. We used in-water instrumentation to measure and compare photosynthesis (P), respiration (R), P/R ratios, and calcification of corals that were visually healthy, actively diseased, and diseased but treated with amoxicillin paste. Measurements occurred across three time points and two species – Orbicella faveolata and Montastraea cavernosa. Across all metrics, treatment type did not cause significant differences, indicating that neither SCTLD lesions nor amoxicillin treatments impacted the physiology of adjacent tissues. There were significant variations among time points, which may have resulted from changes to coral health across the reef, variations due to environmental variables, or other unknown factors. We suggest that physiological metrics could be an interesting way to fate track coral health across short- and long-term timeframes. We also conclude that amoxicillin treatments as a tool to halt SCTLD are not detrimental to respiration, photosynthesis, or calcification rates of adult corals.

The ‘photosynthetic C1 pathway’ links carbon assimilation and growth in California poplar

Although primarily studied in relation to photorespiration, serine metabolism in chloroplasts may play a key role in plant CO2 fertilization responses by linking CO2 assimilation with growth. Here, we show that the phosphorylated serine pathway is part of a ‘photosynthetic C1 pathway’ and demonstrate its high activity in foliage of a C3 tree where it rapidly integrates photosynthesis and C1 metabolism contributing to new biomass via methyl transfer reactions, imparting a large natural 13C-depleted signature. Using 13CO2-labelling, we show that leaf serine, the S-methyl group of leaf methionine, pectin methyl esters, and the associated methanol released during cell wall expansion during growth, are directly produced from photosynthetically-linked C1 metabolism, within minutes of light exposure. We speculate that the photosynthetic C1 pathway is highly conserved across the photosynthetic tree of life, is responsible for synthesis of the greenhouse gas methane, and may have evolved with oxygenic photosynthesis by providing a mechanism of directly linking carbon and ammonia assimilation with growth. Although the rise in atmospheric CO2 inhibits major metabolic pathways like photorespiration, our results suggest that the photosynthetic C1 pathway may accelerate and represents a missing link between enhanced photosynthesis and plant growth rates during CO2 fertilization under a changing climate.

Optimizing faba bean cultivation: assessing varietal performance in spring and fall

The need to identify specialty crops in Virginia has driven interest in faba beans (Vicia faba L.), which offer potential benefits for crop rotation systems. As a cool-season crop, faba beans can be planted in both fall and spring, providing flexibility in farming schedules. A field study was conducted at Randolph Farm, the Virginia State University Research and Extension Farm, using a completely randomized factorial block design. This study examines the performance of seven faba bean varieties—Ethiopia, NEB247, Aprovecho, EN3, EN47, Windsor and EN45—across three spring (late February, late March and mid April), and three fall (late September, early October and late October) planting dates. Our results demonstrate that both variety and planting date significantly influence the yield and yield components of faba beans. Among the varieties tested, Windsor and EN47 exhibited superior traits across multiple categories, making them preferable for achieving high yields. Conversely, varieties such as EN45, Aprovecho, and NEB247 showed poor performance. Fall planting dates generally resulted in superior growth, yield, and maturity characteristics, underscoring their importance for maximizing faba bean production. We observed that faba beans planted in the fall had 58% more branches, 100% more shoot dry matter, 34% higher 100-seed weight, double the grain yields, and 8% higher harvest index compared to those planted in the spring. To further enhance faba bean production, additional studies are suggested to clarify the physiological relationships between photosynthesis rates and the sink-source dynamics. Furthermore, investigating how planting dates impact the nutrient components of faba beans will provide deeper insights into optimizing their cultivation.

Improvement in photosynthesis under different light intensities is highly linked to domestication stages in cotton.

Domestication has dramatically increased crop size and biomass, reflecting the enhanced accumulation of photosynthates. However, we still lack solid empirical data on the impacts of domestication on photosynthetic rates at different light intensities and on leaf anatomy, and of the relationships of photosynthesis with aboveground biomass. In this study, we measured the photosynthetic rate at three photosynthetic photon flux densities of 2000 (high), 1000 (moderate) and 400 μmol m-2 sec-1 (low light intensity), dark respiration, relative chlorophyll content (SPAD), leaf morphology, and aboveground biomass in 40 wild, 91 semiwild, and 42 domesticated cotton genotypes. The study was replicated for two years (growing years 2018 and 2019). During the first domestication stage (transition from wild to semiwild genotypes), domestication led to higher photosynthetic rates measured under high light intensity, higher SPAD, larger leaf area (LA), and lower leaf mass per unit area (LMA), contributing to greater aboveground biomass accumulation in both study years. During the second domestication stage (transition from semiwild to domesticated genotypes), domestication significantly enhanced photosynthesis under low light intensity and reduced LMA, which were associated with increased aboveground biomass in both study years. In conclusion, photosynthesis improvement at different light intensities has been a gradual domestication phase specific process with the rate of photosynthesis enhanced under high light during the first domestication stage, and under low light during the second domestication stage. We argue that these differences reflect a higher proportion of LA photosynthesizing under low light due to enhanced canopy expansion at the second domestication stage.

Integrative Proteomic and Phosphoproteomic Profiling Reveals the Salt-Responsive Mechanisms in Two Rice Varieties (Oryza Sativa subsp. Japonica and Indica).

Salinity stress induces ionic and osmotic imbalances in rice plants that in turn negatively affect the photosynthesis rate, resulting in growth retardation and yield penalty. Efforts have, therefore, been carried out to understand the mechanism of salt tolerance, however, the complexity of biological processes at proteome levels remains a major challenge. Here, we performed a comparative proteome and phosphoproteome profiling of microsome enriched fractions of salt-tolerant (cv. IR73; indica) and salt-susceptible (cv. Dongjin/DJ; japonica) rice varieties. This approach led to the identification of 5856 proteins, of which 473 and 484 proteins showed differential modulation between DJ and IR73 sample sets, respectively. The phosphoproteome analysis led to the identification of a total of 10,873 phosphopeptides of which 2929 and 3049 phosphopeptides showed significant differences in DJ and IR73 sample sets, respectively. The integration of proteome and phosphoproteome data showed activation of ABA and Ca2+ signaling components exclusively in the salt-tolerant variety IR73 in response to salinity stress. Taken together, our results highlight the changes at proteome and phosphoproteome levels and provide a mechanistic understanding of salinity stress tolerance in rice.

Xylem and Phloem in Petioles Are Coordinated With Leaf Gas Exchange in Oaks With Contrasting Anatomical Strategies Depending on Leaf Habit.

As the single link between leaves and the rest of the plant, petioles must develop conductive tissues according to the water influx and sugar outflow of the leaf lamina. A scaling relationship between leaf area and anatomical traits of xylem and phloem is expected to improve the efficiency of these tissues. However, the different constraints compromising the functionality of both tissues (e.g., risk of cavitation) must not be disregarded. Additionally, deciduous and evergreen plants may have different strategies to produce and package their petiole conduits to cope with environmental restrictions. We explored in 33 oak species the relationships between petiole anatomical traits, leaf area, stomatal conductance, and photosynthesis rate. Results showed allometric scaling between anatomical structure of xylem and phloem with leaf area. We also found correlations between photosynthesis rate, stomatal conductance, and anatomical traits in the petiole. The main novelty is how oaks present a different strategy depending on the leaf habit. Deciduous species tend to increase their diameters to achieve greater leaf-specific conductivity. By contrast, evergreen oaks develop larger xylem conductive areas for a given leaf area than deciduous ones. This trade-off between safety-efficiency in petioles has never been attributed to the leaf habit of the species.

Realizing UV driven microalgae photosynthesis to bio-fix CO2 by spectrum conversion

Microalgae, as efficient photosynthetic autotrophs, hold significant potential for carbon sequestration. However, their photosynthesis is constrained by the selective use of the solar spectrum. To enhance the utilization of natural light energy, a dual functional substrate with ultraviolet (UV) light conversion and microalgae biofilm support was proposed by coating a rare earth complexes phosphor agent onto transparent acrylic in this study. By doing this, UV light could directly drive microalgae biofilm photosynthesis by converting it to red light, resulting in a maximum 2.81 times increase in the carbon fixation rate. The UV conversion substrate increased the electron transport rate of microalgal photosystem II by 58.08%, effectively enhancing the photosynthetic rate and oxygen release, promoting the formation of a porous biofilm structure, and strengthening the material transfer within the biofilm. Additionally, reactive oxygen species (ROS) can cause oxidative stress, affecting cell growth and metabolic activity. With the use of the UV conversion substrate, the levels of ROS and malondialdehyde (MDA) in microalgae decreased by 84.56% and 42.35%, respectively. Consequently, UV-induced damage to microalgae cells was reduced, leading to a 52.52% increase in the photosynthesis rate and achieving UV driven photosynthetic carbon sequestration. This study demonstrated the UV conversion substrate’s effectiveness in reducing UV-induced damage in microalgae and enhancing photosystem activity, showing significant potential for carbon fixation within microalgal biofilms.

Cooperation of acetate regulating and rGO modification of Bi2WO6 for enhancing the H2O2 photosynthesis coupled with selective glucose oxidation

Coupling H2O2 photosynthesis with biomass valorization shows an expansive potential for the storing renewable energy. Here, we prepared a Bi2WO6 (BWO-a/rGO) by acetate regulation and rGO modification of Bi2WO6 during a one-step solvothermal process. Compared with the conventional Bi2WO6, the as-prepared BWO-a/rGO exhibits a significantly enhanced H2O2 photosynthesis rate of 1.864mMg-1 h-1 and an arabinose formation rate of 0.96mMh-1. The addition of manganese acetate and rGO in BWO are indicated to be very effective for regulating the electron density and modifying the carrier migration of BWO, respectively. Thus, boosting both the H2O2 photosynthesis and glucose photo-oxidation to increase the whole reaction efficiency. This work has shown great potential for promoting the practical implementation of BWO in photocatalytic H2O2 synthesis coupled with biomass valorization and provided an effective way for the creation of high-performance chalcogenide photocatalysts.

Water Use Efficiency Characteristics and Their Contributions to Yield in Diverse Sugarcane Genotypes with Varying Drought Resistance Levels Under Different Field Irrigation Conditions

Drought is the major abiotic constraint affecting sugarcane productivity and quality worldwide. This obstacle may be alleviated through sugarcane genotypes demonstrating good water use efficiency (WUE) performance. This study aims to investigate the WUE characteristics of various sugarcane genotypes under different soil water availability levels. Plant and ratoon field experiments were conducted using a split-plot randomized complete block design with three replications. The main plots were assigned three types of irrigation: (1) rainfed conditions (RF), (2) field capacity conditions (FC), and (3) half-available water (½ AW). The subplots consisted of six sugarcane genotypes with varying levels of drought resistance, i.e., KK3, UT13, Kps01-12, KKU99-03, KKU99-02, and UT12. Data on yield, stalk numbers, stalk diameter, height, and WUE were collected throughout the crop cycle for both plant and ratoon crops. For the plant crop, the net photosynthesis rate, transpiration rate, stomatal conductance, and leaf area index (LAI) were recorded during the crop period. In both plant and ratoon crops, the WUE in the RF treatment was lower than in the FC and ½ AW treatments during the drought stress period 4 months after planting (MAP). In the recovery phase, the WUE in the ½ AW treatment fell between the FC and RF treatments. The RF treatment exhibited the lowest WUE compared to the other two water regime treatments at the maturity stage. The drought-resistant genotypes KK3 and UT13 maintained high WUE values throughout both the drought and recovery periods and exhibited outstanding LAIs at 4 and 6 MAP. A significant relationship existed between WUE and LAI during these periods. Moreover, WUE was positively correlated with cane yields and yield components, such as stalk weight, shoot diameter, and height, during recovery and tiller number and height during ripening. Therefore, WUE and LAI are efficient parameters for supporting and maintaining growth and yield during water deficit and recovery phases under rainfed conditions.

Gas exchange in yellow passion fruit hybrids in the Semiarid region

Agronomic characterization and exploitation of the genetic variability in plants of the Passiflora can reveal important genetic resources because the Passiflora species grown under semiarid conditions make important contributions to breeding. The aim of this work was to evaluate the vegetative and physiological characteristics of fifteen yellow passion fruit hybrids in semiarid conditions. The experiment was conducted at IF Baiano – campus Guanambi, Bahia, Brazil. The 15 treatments were 10 genotypes: H09-10; GP09-02; H09-02; H09-14; H09-07; H09-09; FOP09; GP09-03; H09-30; FOP08 from the Active Germplasm Bank of the Genetic Breeding Program of Embrapa Cassava and Fruits, and five commercial hybrids: FB200; FB300; BRS SC; BRGA; BRS Rubi. The treatments were arranged in a randomized block design, with three replications and five observational units per plot. Vegetative characteristics (main branch length, number of functional leaves, number of nodes, and number of flower buds) were measured at full vegetative development, 90 days after transplanting (DAT). Hybrid H09-10 is the earliest in flowering, physiologically more efficient in the morning, closes stomata in the afternoon, regulates transpiration, and has lower leaf temperature, higher photosynthesis rate, and more efficient water use. Gas exchanges and photosynthesis rates, at 300 DAT, vary between hybrids and reading times: photosynthesis is higher in the morning while transpiration is greater in the afternoon. The reduction in carboxylation efficiency is related to non-stomatal factors. Gas exchange variables of the genotypes tend to be directly correlated with the photosynthetically active radiation incident on the leaf

Heat stress and bleaching in corals: a bioenergetic model

AbstractThe coral-dinoflagellate endosymbiosis is based on nutrient exchanges that impact holobiont energetics. Of particular concern is the breakdown or dysbiosis of this partnership that is seen in response to elevated temperatures, where loss of symbionts through coral bleaching can lead to starvation and mortality. Here we extend a dynamic bioenergetic model of coral symbioses to explore the mechanisms by which temperature impacts various processes in the symbiosis and to enable simulational analysis of thermal bleaching. Our model tests the effects of two distinct mechanisms for how increased temperature impacts the symbiosis: 1) accelerated metabolic rates due to thermodynamics and 2) damage to the photosynthetic machinery of the symbiont caused by heat stress. Model simulations show that the model can capture key biological responses to different levels of increased temperatures. Moderately increased temperatures increase metabolic rates and slightly decrease photosynthesis. The slightly decreased photosynthesis rates cause the host to receive less carbon and share more nitrogen with the symbiont. This results in temporarily increased symbiont growth and a higher symbiont/host ratio. In contrast, higher temperatures cause a breakdown of the symbiosis due to escalating feedback that involves further reduction in photosynthesis and insufficient energy supply for $$\hbox {CO}_2$$ CO 2 concentration by the host. This leads to the accumulation of excess light energy and the generation of reactive oxygen species, eventually triggering symbiont expulsion and coral bleaching. Importantly, bleaching does not result from accelerated metabolic rates alone; it only occurs as a result of the photodamage mechanism due to its effect on nutrient cycling. Both higher light intensities and higher levels of DIN render corals more susceptible to heat stress. Conversely, heterotrophic feeding can increase the maximal temperature that can be tolerated by the coral. Collectively these results show that a bioenergetics model can capture many observed patterns of heat stress in corals, such as higher metabolic rates and higher symbiont/host ratios at moderately increased temperatures and symbiont expulsion at strongly increased temperatures.

Photocatalytic Synthesis of Glycine from Methanol and Nitrate

AbstractPhotocatalytic utilization of methanol and nitrate as carbon and nitrogen sources for the direct synthesis of amino acids could provide a sustainable way for the valorization of green “liquid sunlight” and nitrate waste. In this study, we develop an efficient photochemical method to synthesize glycine directly from methanol and nitrate, which cascades the C−C coupling to form glycol, nitrate reduction to NH3, and finally C−N coupling to generate glycine. Interestingly, the involved photocatalytic tandem reactions show a synergistic effect, in which the presence of nitrate is the dominant factor to enable the overall reaction and reach high synthetic efficiency. Ba2+−TiO2 nanoparticles are confirmed as a feasible and efficient catalyst system for the photosynthesis of glycine with a remarkable glycine photosynthesis rate of 870 μmol gcat−1 h−1 under optimal conditions. This work establishes a novel catalytic system for amino acid synthesis from methanol and nitrate under mild conditions. These results also allow us to further suppose the formation pathways of amino acids on the primitive earth, as an extension to proposals based on the Miller‐Urey experiments.

Silicon Application Contributes to Efficient Gas Exchange in Tomato Plants

The study aimed to analyze the effect of silicon application on tomato crops subjected to different water management conditions. The experiment was conducted in a completely randomized design with two water replacement conditions (60 and 100% of crop evapotranspiration - ETc), four forms of silicon application (no application, full-dose soil application, split soil application and foliar application) with four replicates. When the plants were in the reproductive stage, gas exchange analysis was performed in two periods (critical period before water replacement and after water replacement). The photosynthesis rates, internal CO2, stomatal conductance, transpiration, and instantaneous water use efficiency were determined. The data were subjected to analysis of variance and the means compared by the Tukey test with 5% significance. The application of silicon caused significant variation in gas exchange in tomato leaves, with an increase in rates and an increase in instantaneous water use efficiency. The application of silicon promotes an increase in gas exchange in tomato plants, whether in adequate water conditions or with a deficit in the crop. The application of the element, via soil and foliar, showed a significant increase in gas exchange in tomato plants. The best results were obtained for application via soil, regardless of the water condition or time of evaluation.

Integrating Biofertilizers with Organic Fertilizers Enhances Photosynthetic Efficiency and Upregulates Chlorophyll-Related Gene Expression in Rice

Biofertilizers offer a sustainable method for improving rice growth and productivity, yet their effects on the interaction between plant growth, photosynthetic activity, and gene expression remain under-researched. This study examines how biofertilizer influences rice physiology, focusing on photosynthetic regulation and expression of chlorophyll-related genes. Eight fertilizer treatments were applied: control (CNT), biofertilizer (BF), deactivated biofertilizer (DABF), rice straw (RS), rice straw with biofertilizer (RS+BF), organic fertilizer (OF), organic fertilizer with biofertilizer (OF+BF), and inorganic fertilizer (IOF). Plant height, tiller number, SPAD, NDVI, chlorophyll content, and photosynthesis rates were measured, while gene expression analysis was conducted using RT-qPCR. The OF+BF treatment produced the most significant results, leading to a 31% increase in plant height, a 135% increase in tiller number, and a 42% increase in chlorophyll content (SPAD values) compared to the control. Additionally, OF+BF enhanced photosynthetic efficiency by 74%, with the highest net photosynthetic rate of 48.23 μmol CO2 m−2 s−1. Gene expression analysis revealed that OF+BF upregulated key photosynthesis-related genes, such as OsChlD and OsCHLM, showing a 70% and 90% increase in expression. These findings highlight the potential of integrating biofertilizers with organic fertilizers to sustainably boost rice growth and productivity, contributing to global food security and climate change mitigation.

Physiological Behavior of Rubber Plants (<i>Hevea Brasilliensis</i>) to Different Soil Moisture Conditions

Drought conditions can severely impact rubber (<i>Hevea brasiliensis</i>) plantations, leading to economic loss in Malaysia. The study aimed to assess the impact of varying soil moisture levels on the physiological characteristics of five latex timber clones (LTCs) of rubber, with the goal of identifying the most suitable clone for specific soil moisture conditions. These conditions include (1) field capacity, (2) 75% available water (AW), (3) 50% AW, (4) 25% AW, and (5) wilting point, with the ultimate objective of optimizing cultivation methods and fostering sustainable rubber production in Malaysia. The five clones under investigation include RRIM3001, RRIM2025, RRIM2001, RRIM928, and PB350. Leaf chlorophyll content, stomatal conductance, and net photosynthesis were measured 4 and 8 months after treatment (MAT). The findings indicated significant effects of moisture stress on various physiological attributes, including total chlorophyll content, relative chlorophyll content, stomatal conductance, and net photosynthesis rate. At 4 and 8 MATs, the clones subjected to field capacity exhibited the highest values for these physiological characteristics, followed by those exposed to 75% available water, with the lowest values observed at the wilting point. RRIM3001 consistently exhibited the highest total chlorophyll content, stomatal conductance, and net photosynthesis among the clones at both sampling dates. The highest net photosynthesis was observed in the RRIM3001 clone under field capacity conditions. Furthermore, a significant positive correlation was identified between total chlorophyll and relative chlorophyll contents, as well as between net photosynthesis and stomatal conductance. These findings carry practical implications for water management during the initial growth phase of rubber seedlings and for replanting initiatives in rubber plantations.