Leaf Photosynthesis Research Articles

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.

Effects of Foliar Application of Magnesium Fertilizer on Photosynthesis and Growth in Grapes

Efforts to increase grape yields have focused on using nitrogen, phosphorus, and potassium fertilizers, often causing unintended magnesium (Mg) deficiencies. To overcome Mg deficiency, different concentrations of MgSO4·7H2O (0, 1, 2, 3, 4 mM) and GABA (2.5 mM), as foliar sprays, were applied during the fruit enlargement and color transition stages. Key physiological parameters such as leaf growth, photosynthesis, and chlorophyll fluorescence were assessed. Interestingly, foliar Mg application increased the key physiological parameters, with the 3 mM treatment (M3) delivering the best improvement. Compared to the control, the M3 treatment increased dry weight and leaf area by 35.9% and 37.2%, respectively. Specifically, the foliar Mg application (M3) improved the photosynthesis (Pn), transpiration (Tr), and stomatal conductance (gs) of leaves when compared to the control. Additionally, the foliar Mg application improved the PSII photosynthetic efficiency, electron yield, and electron transport rates, following the order M2 > M3 > M1 > M0 > M4. This study demonstrated the essential role of foliar-applied Mg, with GABA, in improving grape physiology. Interestingly, the curve-fitting analysis of foliar Mg concentration and grape yield identified 2.14 mM of Mg as the optimal concentration for promoting grape growth.

Response of Alfalfa Leaf Traits and Rhizosphere Fungal Communities to Compost Application in Saline–Sodic Soil

Soil salinization is considered a major global environmental problem due to its adverse effects on agricultural sustainability and production. Compost is an environmentally friendly and sustainable measure used for reclaiming saline–sodic soil. However, the responses of the physiological characteristics of alfalfa and the structure and function of rhizosphere fungal communities after compost application in saline–sodic soil remain elusive. Here, a pot experiment was conducted to explore the effect of different compost application rates on soil properties, plant physiological traits, and rhizosphere fungal community characteristics. The results showed that compost significantly increased soil nutrients and corresponding soil enzyme activities, enhanced leaf photosynthesis traits, and ion homeostasis compared with the control treatment. We further found that the rhizosphere fungal communities were dominated by Sodiomyces at the genus level, and the relative abundance of pathogenic fungi, such as Botryotrichum, Plectosphaerella, Pseudogymnoascus, and Fusarium, declined after compost application. Moreover, the α-diversity indexes of the fungal community under compost application rates of 15% and 25% significantly decreased in comparison to the control treatment. The soil SOC, pH, TP, and TN were the main environmental factors affecting fungal community composition. The leaf photosynthetic traits and metal ion contents showed significantly positive correlations with Sodiomyces and Aspergillus. The fungal trophic mode was dominated by Pathotroph–Saprotroph–Symbiotroph and Saprotroph. Overall, our findings provide an important basis for the future application of microbial-based strategies to improve plant tolerance to saline-alkali stress.

Zinc oxide nanoparticles cooperate with the phyllosphere to promote grain yield and nutritional quality of rice under heatwave stress

To address rising global food demand, the development of sustainable technologies to increase productivity is urgently needed. This study revealed that foliar application of zinc oxide nanoparticles (ZnO NPs; 30 to 80 nm, 0.67 mg/d per plant, 6 d) to rice leaves under heatwave (HW) stress increased the grain yield and nutritional quality. Compared with the HW control, the HWs+ZnO group presented increases in the grain yield, grain protein content, and amino acid content of 22.1%, 11.8%, and 77.5%, respectively. Nanoscale ZnO aggregated on the leaf surface and interacted with leaf surface molecules. Compared with that at ambient temperature, HW treatment increased the dissolution of ZnO NPs on the leaf surface by 25.9% and facilitated their translocation to mesophyll cells. The Zn in the leaves existed as both ionic Zn and particulate ZnO. Compared with the HW control, foliar application of ZnO NPs under HW conditions increased leaf nutrient levels (Zn, Mn, Cu, Fe, and Mg) by 15.8 to 416.9%, the chlorophyll content by 22.2 to 24.8%, Rubisco enzyme activity by 21.2%, and antioxidant activity by 26.7 to 31.2%. Transcriptomic analyses revealed that ZnO NPs reversed HW-induced transcriptomic dysregulation, thereby enhancing leaf photosynthesis by 74.4%. Additionally, ZnO NPs increased the diversity, stability, and enrichment of beneficial microbial taxa and protected the phyllosphere microbial community from HW damage. This work elucidates how NPs interact with the phyllosphere, highlighting the potential of NPs to promote sustainable agriculture, especially under extreme climate events (e.g., HWs).

Mixed application of raw amino acid powder and Trichoderma harzianum fertilizer for the prevention and management of apple replant disease

Apple replant disease (ARD) is mainly caused by biological factors, and it severely restricts the development of the apple industry. The use of biological control measures to alleviate ARD is critically important for the sustainable development of the apple industry. The effects of raw amino acid powder and Trichoderma harzianum fertilizer on plant biomass, leaf and root indexes, soil physical and chemical properties, soil enzyme activity, and the soil fungal community were studied under pot and field conditions using Malus hupehensis Rehd. seedlings and grafted trees (Fuji New 2001/M9T337) as experimental materials. We found that the application of the materials significantly promoted plant growth, increased the leaf photosynthesis and chlorophyll content, root respiration rate, root antioxidant enzyme activity, and soil enzyme activity, significantly decreased the number of Fusarium sp. in soil, and significantly increased the abundance of beneficial bacteria. In conclusion, the mixed application of raw amino acid powder and Trichoderma harzianum fertilizer can is an effective method for the prevention and management of ARD.

Nitrogen regulated reactive oxygen species metabolism of leaf and grain under elevated temperature during the grain-filling stage to stabilize rice substance accumulation

Rational additional nitrogen is an important agronomic measure to cope with the adverse effects of warming on rice production. However, the mechanism by which nitrogen mitigated the adverse impact of substance accumulation due to elevated temperature is poorly clarified. Therefore, in this study, a field warming experiment during grain filling and 60kg·ha-1 of additional nitrogen was established. Under elevated temperature, panicle temperature was higher and increased more substantially than leaf temperature. However, nitrogen application did not significantly reduce the leaf, panicle, and canopy temperatures. Additional nitrogen under elevated temperature delayed the decline of chlorophyll, maintained leaf photosynthesis, and prolonged grain-filling period to alleviate the decrease of starch due to warming. Hydrogen peroxide (H2O2) was sensitive to elevated temperature in leaves and grains. However, application of nitrogen under elevated temperature improved the activity of antioxidant enzymes to mitigate the increase of H2O2, resulting in a 30.31% and 45.33% decrease of H2O2 in leaves and grains compared to elevated temperature, respectively. Elevated temperature promoted the expression of heat-responsive genes, especially HSP16.9 and HSP26.7, which were consistently increased in response to warming at 5-30d after flowering. In addition, the expression of HSP16.9 at 5d and 10d after flowering and HSP26.7 at 10d after flowering was further increased with nitrogen application under elevated temperature. Therefore, HSP may be the key regulator of grain response to warming with additional nitrogen under elevated temperature. In conclusion, the relevant results revealed the physiological mechanism of nitrogen to guarantee substance accumulation and provided new ideas for cultivation measures to protect against the likely scenario of global warming.

Genetic variation in leaf photosynthesis and associated traits in elite and landrace-derived genotypes in wheat

Genetic variation in leaf photosynthesis and associated traits in elite and landrace-derived genotypes in wheat

OsSTP1 mediates sucrose allocation to regulate rice responses to different nitrogen supply levels

Improving the nitrogen use efficiency is an effective way to increase the yield of rice, and maintaining carbon-nitrogen balance is essential for the normal growth and development of rice. To investigate the impact of the sucrose transporter protein OsSTP1 on nitrogen absorption in rice, in this study, we constructed transgenic lines overexpressing the sucrose transporter gene OsSTP1 (OsSTP1-OE1, OsSTP1-OE2) and mutant transgenic lines (osstp1-1, osstp1-2) from the wild type TB309. Further, we conducted a hydroponic experiment with four nitrogen supply levels of free nitrogen (FN, 0 mg/L), low nitrogen (LN, 10 mg/L), normal nitrogen (NN, 40 mg/L), and high nitrogen (HN, 80 mg/L) to study the responses of each line to different nitrogen supply levels during the seedling stage. The results showed that compared with the wild type and mutant lines in the LN group, the OsSTP1-overexpressing lines exhibited significantly increased biomass, root length, and plant height, decreased soluble sugar content in the leaves, and increased soluble sugar content in the roots. The results indicate that the soluble sugars produced by leaf photosynthesis are transported to the roots through the phloem to promote root growth and nitrogen uptake, thus increasing the aboveground biomass. This study has identified that OsSTP1 can affect the long-distance transport of carbohydrates from source to sink to promote root growth, ultimately influencing rice's absorption and accumulation of nitrogen, improving nitrogen use efficiency and providing reference for reducing nitrogen fertilizer application.

Chemical topping enhances the cotton (Gossypium hirsutum L.) yield formation through improving leaf photosynthesis and assimilating the partitioning to reproductive organs

Chemical topping with 1,1-dimethylpiperidinium chloride (DPC) has attracted widespread attention because of its potential to replace manual topping in cotton production. However, the effects of DPC chemical topping remain poorly understood. Therefore, a two-year field experiment (2019–2020) was conducted with two cultivars (DPC-insensitive cultivar Xinluzao 60, C60, and DPC-sensitive cultivar Jinken 1402, C1402), and four topping methods (manual topping (T1), no topping (T2), fortified DPC chemical topping (T3) and DPC chemical topping (T4)) were used as the experimental treatments. Compared with those in T1 and T2, the seed cotton yield and boll weight in both T3 and T4 in C60 and C1402 were greater; the leaf area in T3 and T4 in C60 and C1402 increased on average by 15.6 % 40 days after treatment; the chlorophyll a and a+b contents in T3 and T4 in C1402 increased on average by 8.4 % at 5060 days after treatment; the net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) in T3 and T4 in C60 and C1402 increased on average by 37.5 % 40 days after treatment; the actual photosynthetic efficiency of PSII (φPSII) and relative electron transport rate of PSII (ETR) in T3 and T4 in C60 and C1402 increased on average by 22.5 %, the non-photochemical quenching (NPQ) decreased on average by 26.4 % at 50 days after treatment; and the contents of the soluble sugars, sucrose and starch in T3 and T4 in C1402 significantly decreased on average by 17.3 % at 20 days after treatment; the reproductive organ biomass in T3 and T4 in C1402 increased on average by 15.7 % at 5060 days after treatment. Overall, DPC chemical topping increased the photosynthetic performance of the cotton varieties with different sensitivities to DPC and carbohydrate translocation and was beneficial for increasing the reproductive organ biomass and exploiting the yield potential.

Evaluation of Kabuli Chickpea Genotypes for Tropical Adaptation in Northern Australia

Chickpea is one of the economically important legume crops adapted for winter season production in tropical climates. This study evaluated the physiological, morphological, and biochemical traits of eight Kabuli chickpea genotypes in an Australian tropical environment. The result revealed significant differences between genotypes for seed emergence, plant height, primary shoots, leaf number, leaf area index, gas-exchange parameters, seed yield, carbon discrimination (Δ13C), and natural abundance for nitrogen fixation. Among the tested genotypes, AVTCPK#6 and AVTCPK#19 exhibited late flowering (60–66 days) and late maturity (105–107 days), and had higher leaf photosynthetic rate (Asat) (28.4–31.2 µmol m−2 s−1), lower stomatal conductance (gsw) (516–756 mmol m−2 s−1), were associated with reduced transpiration rate (T) (12.3–14.5 mmol m−2 s−1), offered greater intrinsic water-use efficiency (iWUE) (2.1–2.3 µmol m−2 s−1/mmol m−2 s−1), and contributed a higher seed yield (626–746 g/m2) compared to other genotypes. However, a larger seed test weight (>60 g/100 seed) was observed for AVTCPK#24, AVTCPK#8, and AVTCPK#3. Similarly, a high proportion (45%) of larger seeds (>10–11 mm) was recorded for AVTCPK#24. Furthermore, a higher %Ndfa in AVTCPK#6 (71%) followed by AVTCPK#19 (63%) indicated greater symbiotic nitrogen fixation in high-yielding genotypes. Positive correlation was observed between %Ndfa and seed protein, as well as between seed yield and plant height, primary shoots, leaf count, leaf area index, leaf photosynthesis, stomatal conductance, transpiration rate at pod filling stage, biomass, and harvest index. An inverse correlation between (Δ13C) and iWUE, particularly in AVTCPK#6 and AVTCPK#19, indicates greater heat and drought tolerance, required for high-yielding Kabuli chickpea production in northern Australia.

A new dimension of leaf economic spectrum: temporal instability of relationships among genotypes.

Leaf economic spectrum (LES) relationships have been studied across many different plant lineages and at different organizational scales. However, the temporal stability of the LES relationships is largely unknown. We used the wild blueberry system with high genotypic diversity to test whether trait-trait relationships across genotypes demonstrate the same LES relationships found in the global database (GLOPNET) and whether they are stable across years. We studied leaf structure, photosynthesis, and leaf nutrients for 16 genotypes of two wild blueberry species semi-naturally grown in a common farm in Maine, USA, across 4 yr. We found substantial variation in leaf structure, physiology, and nutrient traits within and among genotypes, as well as across years in wild blueberries. The LES trait-trait relationships (covariance structure) across genotypes were not always found in all years. The trait syndrome of wild blueberries was shifted by changing environmental conditions over the years. Additionally, traits in 1 yr cannot be used to predict those of another year. Our findings show that LES generally holds among genotypes but is temporally unstable, stressing the significant influence of trait plasticity in response to fluctuating environmental conditions across years, and the importance of temporal dimensions in shaping functional traits and species coexistence.

Photosynthetic Traits of Quercus coccifera Green Fruits: A Comparison with Corresponding Leaves during Mediterranean Summer

Fruit photosynthesis occurs in an internal microenvironment seldom encountered by a leaf (hypoxic and extremely CO2-enriched) due to its metabolic and anatomical features. In this study, the anatomical and photosynthetic traits of fully exposed green fruits of Quercus coccifera L. were assessed during the period of fruit production (summer) and compared to their leaf counterparts. Our results indicate that leaf photosynthesis, transpiration and stomatal conductance drastically reduced during the summer drought, while they recovered significantly after the autumnal rainfalls. In acorns, gas exchange with the surrounding atmosphere is hindered by the complete absence of stomata; hence, credible CO2 uptake measurements could not be applied in the field. The linear electron transport rates (ETRs) in ambient air were similar in intact leaves and pericarps (i.e., when the physiological internal atmosphere of each tissue is maintained), while the leaf NPQ was significantly higher, indicating enhanced needs for harmless energy dissipation. The ETR measurements performed on leaf and pericarp discs at different CO2/O2 partial pressures in the supplied air mixture revealed that pericarps displayed significantly lower values at ambient gas levels, yet they increased by ~45% under high CO2/O2 ratios (i.e., at gas concentrations simulating the fruit’s interior). Concomitantly, NPQ declined gradually in both tissues as the CO2/O2 ratio increased, yet the decrease was more pronounced in pericarps. Furthermore, net CO2 assimilation rates for both leaf and pericarp segments were low in ambient air and increased almost equally at high CO2, while pericarps exhibited significantly higher respiration. It is suggested that during summer, when leaves suffer from photoinhibition, acorns could contribute to the overall carbon balance, through the re-assimilation of respiratory CO2, thereby reducing the reproductive cost.

An Excessive K/Na Ratio in Soil Solutions Impairs the Seedling Establishment of Sunflower (Helianthus annuus L.) through Reducing the Leaf Mg Concentration and Photosynthesis

In saline conditions, establishing healthy seedlings is crucial for the productivity of sunflowers (Helianthus annuus L.). Excessive potassium (K+) from irrigation water or overfertilization, similar to sodium (Na+), could adversely affect sunflower growth. However, the effects of salt stress caused by varying K/Na ratios on the establishment of sunflower seedlings have not been widely studied. We conducted a pot experiment in a greenhouse, altering the K/Na ratio of a soil solution to grow sunflower seedlings. We tested three saline solutions with K/Na ratios of 0:1 (P0S1), 1:1 (P1S1), and 1:0 (P1S0) at a constant concentration of 4 dS m−1, along with a control (CK, no salt added), with five replicates. The solutions were applied to the pots via capillary rise through small holes at the bottom. The results indicate that different K/Na ratios significantly influenced ion-selective uptake and transport in crop organs. With an increasing K/Na ratio, the K+ concentration in the roots, stems, and leaves increased, while the Na+ concentration decreased in the roots and stems, with no significant differences in the leaves. Furthermore, an excessive K/Na ratio (P1S0) suppressed the absorption and transportation of Mg2+, significantly reducing the Mg2+ concentration in the stems and leaves. A lower leaf Mg2+ concentration reduced chlorophyll concentration, impairing photosynthetic performance. The lowest plant height, leaf area, dry matter, and shoot/root ratio were observed in P1S0, with reductions of 27%, 48%, 48%, and 13% compared to CK, respectively. Compared with CK, light use efficiency and CO2 use efficiency in P1S0 were significantly reduced by 13% and 10%, respectively, while water use efficiency was significantly increased by 9%. Additionally, improved crop morphological and photosynthetic performance was observed in P1S1 and P0S1 compared with P1S0. These findings underscore the critical role of optimizing ion composition in soil solutions, especially during the sensitive seedling stage, to enhance photosynthesis and ultimately to improve the plant’s establishment. We recommend that agricultural practices in saline regions incorporate tailored irrigation and fertilization strategies that prioritize optimal K/Na ratios to maximize crop performance and sustainability.

Reconciling water-use efficiency estimates from carbon isotope discrimination of leaf biomass and tree rings: nonphotosynthetic fractionation matters.

Carbon isotope discrimination (∆) in leaf biomass (∆BL) and tree rings (∆TR) provides important proxies for plant responses to climate change, specifically in terms of intrinsic water-use efficiency (iWUE). However, the nonphotosynthetic 12C/13C fractionation in plant tissues has rarely been quantified and its influence on iWUE estimation remains uncertain. We derived a comprehensive, ∆ based iWUE model (iWUEcom) which includes nonphotosynthetic fractionations (d) and characterized tissue-specific d-values based on global compilations of data of ∆BL, ∆TR and real-time ∆ in leaf photosynthesis (∆online). iWUEcom was further validated with independent datasets. ∆BL was larger than ∆online by 2.53‰, while ∆BL and ∆TR showed a mean offset of 2.76‰, indicating that ∆TR is quantitatively very similar to ∆online. Applying the tissue-specific d-values (dBL = 2.5‰, dTR = 0‰), iWUE estimated from ∆BL aligned well with those estimated from ∆TR or gas exchange. ∆BL and ∆TR showed a consistent iWUE trend with an average CO2 sensitivity of 0.15 ppm ppm-1 during 1975-2015. Accounting for nonphotosynthetic fractionations improves the estimation of iWUE based on isotope records in leaf biomass and tree rings, which is ultimate for inferring changes in carbon and water cycles under historical and future climate.

Growth and physiology responses of Samanea saman inoculated with arbuscular mycorrhizal fungi in silica post-mining soil media using biodegradable pots

Arbuscular mycorrhizal fungi (AMF) and biodegradable pots are environmentally friendly and enhance plant growth in adverse soil conditions. These studies explored AMF interactions and biodegradable pots in physiology, growth, and the uptake of nutrients in Samanea saman seedlings. The present research interactive effects of biodegradable pots with different compositions and raw material sizes with and without AMF inoculation on S. saman grown in silica post-mining soil media. Results indicated AMF inoculations significantly improved leaf chlorophyll content, photosynthetic rate, heights, diameters, biomass, as well as nutrient absorption of S. saman as compared with non-inoculated plants in biodegradable pots. AMF and biodegradable pots composed of 15% used newspaper, 70% compost, 5% cocopeat, and 10% rock phosphate showed the best results and increased the leaf chlorophyll content, photosynthesis rate, height, diameter, and total biomass of the plants by 161.1%, 208.7%, 263.6%, 118.1%, and 269.9%, respectively, compared to biodegradable pots composed only of used newspaper. Additionally, uptake of the nutrients nitrogen, phosphate, potassium, and magnesium increased by 365%, 800%, 369%, and 250%, respectively. By the fourteenth week after transplanting, the C/N ratio of the organic pot decreased significantly. Thus, AMF and biodegradable pots containing compost and rock phosphate interact positively and enhance the growth of S. saman under adverse soil conditions. These findings suggest that biodegradable pots containing compost and rock phosphate show potential as more environmentally friendly replacements for plastic bags (polybags) as growth medium containers for seedling production.

Acclimation Unifies the Scaling of Carbon Assimilation Across Climate Gradients and Levels of Organisation.

The temperature dependence of carbon assimilation-from leaf photosynthesis to ecosystem productivity-is hypothesised to be driven by the kinetics of Rubisco-catalysed carboxylation and electron transport. However, photosynthetic physiology acclimates to changes in temperature, which may decouple temperature dependencies at higher levels of organisation from the acute temperature sensitivity of photosynthesis. Here, we integrate relative growth rate theory, metabolic theory and biochemical photosynthesis theory to develop a carbon budget model of plant growth that accounts for photosynthetic acclimation to temperature. We test its predictions using a novel experimental approach enabling concurrent measurement of the temperature sensitivity of acute photosynthesis, acclimated photosynthesis and growth rate. We demonstrate for the first time that photosynthetic acclimation mediates how carbon assimilation kinetics 'scale up' from leaf photosynthesis to whole-plant growth. We also find that existing models of photosynthetic acclimation are unable to predict features of growth rate responses to temperature in our system.

Knockdown of Adenosine 5'-Triphosphate-Dependent Caseinolytic Protease Proteolytic Subunit 6 Enhances Aluminum Tolerance in Peanut Plants (Arachis hypogea L.).

Aluminum (Al3+) toxicity in acidic soils reduces root growth and can lead to a considerable reduction in peanut plants (Arachis hypogea L.). The caseinolytic protease (Clp) system plays the key role in abiotic stress response. However, it is still unknown whether it is involved in peanut response to Al3+ stress. The results from this study showed that Adenosine 5'-triphosphate (ATP)-dependent caseinolytic protease proteolytic subunit 6 (AhClpP6) in peanut plants was involved in the Al3 stress response through its effects on leaf photosynthesis. The AhClpP6 expression levels in the leaf and stem significantly increased with the Al3+ treatment times. Knockdown AhClpP6 peanut lines accumulated significantly more Al3+ when exposed to Al3+ stress, which reduced leaf photosynthesis. Furthermore, in response to Al3+ treatment, knockdown of AhClpP6 resulted in a flattened shape of chloroplasts, disordered and flattened thylakoid, and accumulating more starch grains than those of the wild-type (WT) peanut lines. Taken together, our results suggest that AhClpP6 regulates Al3+ tolerance by maintaining chloroplast integrity and enhancing photosynthesis.

Water controls the divergent responses of terrestrial plant photosynthesis under nitrogen enrichment

Abstract Quantifying leaf photosynthetic response to nitrogen (N) deposition under contrasting water conditions is important for reliably modelling terrestrial carbon and water cycles, a topic that has not been well understood. Here, we analysed 737‐paired observations from 102 publications to assess the response of 11 leaf photosynthesis‐related properties to N addition under different water conditions. Our research includes global experiments, with 19 conducted in the field and 83 in greenhouses. Treatments without water reduction were classified as ‘no water change’, while those with reduced water or precipitation causing physiological drought were categorized as ‘drought’. We found that, compared to the control group, N addition significantly increased leaf photosynthetic rate (Pn; 20.9%), leaf transpiration (E; 8.3%) and stomatal conductance (gs; 14.1%). However, the decrease in Pn (−11.6%), E (−24.7%) and gs (−23.9%) under the combination of N addition and drought indicated that N addition could not offset the negative effects of drought. Furthermore, N addition significantly enhanced water‐use efficiency (WUE) by 19.8% under no water change conditions and by 21.1% under drought conditions. Within plant functional groups, herbaceous species exhibited greater susceptibility to N addition than woody species, especially under drought conditions. The observed patterns of increase in Pn with longer experimental duration and WUE with higher N rate under drought conditions showed that plants would gradually adapt to long‐term water stress in the context of N deposition. Furthermore, our results showed that drought could strengthen the correlations between leaf photosynthetic properties. Lastly, our study demonstrated that N addition and drought significantly impacted leaf nitrogen content and SPAD, respectively, and further affected gs, Pn and WUE. Synthesis. Our results emphasize the crucial role of water conditions in shaping the response of leaf photosynthesis to nitrogen (N) enrichment and also acknowledge the significance of leaf functional traits in regulating the dynamics of leaf photosynthetic processes.

Leaf Area Index, Photosynthesis and Chlorophyll Content Influences Yield and Quality of Nanasaheb Purple Seedless Grapes under Semi-arid Condition

Canopy management practices in grapes are crucial for achieving high-quality production. The study was conducted with different treatments of number of leaves above the bunch (10, 12, 14, 16, and >16 leaves). Significant variation was recorded on photosynthetic activity, yield and quality of Nanasaheb Purple Seedless grape variety. The increase in leaf number enhanced total leaf area and photosynthetic capacity while, it had negative impact on bunch weight, berry size and total soluble solids (TSS). Retaining 10 leaves above bunch with leaf area of 1980.00 cm2 /bunch resulted in maximum bunch weight (450.20 g), 50-berry weight (250.13 g) and yield/vine (13.60 kg) while, minimum bunch weight (400.00 g), 50-berry weight (222.30 g) and yield/vine (11.22 kg) were observed by retaining >16 leaves above the bunch. However, retaining 10 leaves above the bunch on a shoot with leaf area/shoot (2475.00 cm2), leaf area/vine (59400.00 cm2), leaf area/bunch (1980.00 cm2) and leaf area/g berry weight (4.36 cm2/g) were sufficient to obtain good quality production in Nanasaheb Purple Seedless grape variety spaced at 9 feet X 5 feet distance.

Instantaneous growth: a compact measure of efficient carbon and nitrogen allocation in leaves and roots of C3 and C4 plants.

Elucidating plant functions and identifying crop productivity bottlenecks requires the accurate quantification of their performance. This task has been attained through photosynthetic models. However, their traditional focus on the leaf's capacity to uptake CO2 is becoming increasingly restrictive. Advanced bioengineering of C3 plants has made it possible to increase rates of CO2 assimilation by packing photosynthetic structures more densely within leaves. The operation of mechanisms that concentrate CO2 inside leaves can boost rates of assimilation while requiring a lower investment in carboxylating enzymes. Therefore, whether in the context of spontaneous plants or modern manipulation, considering trade-offs in resource utilization efficiency emerges as a critical necessity. I've developed a concise and versatile analytical model that simulates concurrent leaf and root growth by balancing instantaneous fluxes of carbon and nitrogen. Carbon is made available by leaf photosynthesis, encompassing all types of biochemistries, while nitrogen is either taken up by roots or remobilized after senescence. The allocation of leaf nitrogen between light or carbon reactions was determined using a fitting algorithm: growth maximisation was the only reliable fitting goal. Both the leaf nitrogen pool and the root-to-leaf ratio responded realistically to various environmental drivers (CO2 concentration, light intensity, soil nitrogen), replicating trends typically observed in plants. Furthermore, modifying the strength of CO2 concentrating mechanisms proved sufficient to alter the root-to-leaf ratio between C3 and C4 types. This direct and mechanistic one-to-one link convincingly demonstrates, for the first time, the functional dependence of a morphological trait on a single biochemical property.