Thylakoid ultrastructural variations in chlorophyll-deficient wheat: aberrations or structural acclimation?

MAIN CONCLUSION: A structural re-modeling of the thylakoid system, including granum size and regularity, occurs in chlorophyll-deficient wheat mutants affected by photosynthetic membrane over-reduction. In the chloroplast of land plants, the thylakoid system is defined by appressed grana stacks and unstacked stroma lamellae. This study focuses on the variations of the grana organization occurring in outdoor-grown wheat mutants characterized by low chlorophyll content and a tendency for photosynthetic membrane over-reduction. Triticum aestivum ANK-32A and Triticum durum ANDW-7B were compared to their corresponding WT lines, NS67 and LD222, respectively. Electron micrographs of chloroplasts were used to calculate grana ultrastructural parameters. Photosynthetic parameters were obtained by modulated chlorophyll fluorescence and applying Light Curves (LC) and Rapid Light Curves (RLC) protocols. For each photosynthetic parameter, the difference Δ(RLC-LC) was calculated to evaluate the flexible response to light in the examined lines. In the mutants, fewer and smaller disks formed grana stacks characterized by a marked increase in lateral and cross-sectional irregularity, both negatively correlated with the number of layers per granum. A relationship was found between membrane over-reduction and granum structural irregularity. The possible acclimative significance of a greater proportion of stroma-exposed grana domains in relieving the excess electron pressure on PSI is discussed.

Effect of copper oxide and zinc oxide nanoparticles on photosynthesis and physiology of Raphanus sativus L. under salinity stress.

The study evaluates the impact of two metal oxide nanoparticles: copper oxide (CuO) and zinc oxide (ZnO) on the growth and physiology of Raphanus sativus L. (radish) under salinity stress. Fifteen days old seedlings of R. sativus were subjected to different concentrations of salt stress (0 mM, 150 mM, and 300 mM NaCl) alone and in interaction with 100 mgL-1 metal oxide nanoparticle treatments (CuO and ZnO NPs via foliar spray) for 15 days. The results confirmed the severe effects of salinity stress on the growth and physiology of radish plants by decreasing nutrient uptake, leaf area, and photosystems photochemistry and by increasing proline accumulation, anthocyanin, flavonoids content, and antioxidant enzyme activities which is directly linked to increased oxidative stress. The foliar application of CuO and ZnO NPs alleviated the adverse effects of salt stress on radish plants, as indicated by improving these attributes. Foliar spray of ZnO NPs was found efficient in improving the leaf area, photosynthetic electron transport rate, the PSII quantum yield, proton conductance and mineral content in radish plants under NaCl stress. Besides, ZnO NPs decreased the NaCl-induced oxidative stress by declining proline, anthocyanin, and flavonoids contents and enzymatic activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaiacol peroxidase (GOPX). Thus, our study revealed that ZnO NPs are more effective and have beneficial effects over CuO NPs in promoting growth and reducing the adverse effects of NaCl stress in radish plants.

Photosynthesis under Environmental Fluctuations: A Challenge for Plants, a Challenge for Researchers.

The ability of plants to cope successfully with environmental fluctuations is a result of their evolution in subaerial environments, where fluctuations in parameters such as temperature, light, and water availability, are the norm and stable states are the exception [...].

Thylakoid membrane appression in the giant chloroplast of Selaginella martensii Spring: A lycophyte challenges grana paradigms in shade-adapted species.

In vascular plants, the thylakoid architecture is dominated by the highly structured multiple membrane layers known as grana. The structural diversity of the thylakoid system among plant species is mainly determined by the adaptation to the growth light regime, according to a paradigm stating that shade-tolerant species are featured by a high membrane extension with an enhanced number of thylakoid layers per granum. In this study, the thylakoid system was analysed in Selaginella martensii Spring, a shade-adapted rainforest species belonging to lycophytes, a diminutive plant lineage, sister clade of all other vascular plants (euphyllophytes, including ferns and seed plants). The species is characterized by giant cup-shaped chloroplasts in the upper epidermis and, quantitatively less important, disk-shaped chloroplasts in the mesophyll and lower epidermis. The study aimed at the quantitative assessment of the thylakoid appression exploiting a combination of complementary methods, including electron microscopy, selective thylakoid solubilisation, electron paramagnetic resonance, and simultaneous analysis of fast chlorophyll a fluorescence and P700 redox state. With a chlorophyll a/b ratio of 2.6 and PSI/PSII ratio of 0.31, the plant confirmed two typical hallmarks of shade-adaptation. The morphometric analysis of electron micrographs revealed a 33% fraction of non-appressed thylakoid domains. However, contrasting with the structural paradigm of thylakoid shade-adaptation in angiosperms, S. martensii privileges the increase in the granum diameter in place of the increase in the number of layers building the granum. The very wide grana diameter, 727 nm on average, largely overcame the threshold of 500 nm currently hypothesized to allow an effective diffusion of long-range electron carriers. The fraction of non-appressed membranes based on the selective solubilisation of thylakoids with digitonin was 26%, lower than the morphometric determination, indicating the presence of non-appressed domains inaccessible to the detergent, most probably because of the high three-dimensional complexity of the thylakoid system in S. martensii. Particularly, strong irregularity of grana stacks is determined by assembling thylakoid layers of variable width that tend to slide apart from each other as the number of stacked layers increases.

Silicon nanoparticles: Comprehensive review on biogenic synthesis and applications in agriculture.

Recent advancements in nanotechnology have opened new advances in agriculture. Among other nanoparticles, silicon nanoparticles (SiNPs), due to their unique physiological characteristics and structural properties, offer a significant advantage as nanofertilizers, nanopesticides, nanozeolite and targeted delivery systems in agriculture. Silicon nanoparticles are well known to improve plant growth under normal and stressful environments. Nanosilicon has been reported to enhance plant stress tolerance against various environmental stress and is considered a non-toxic and proficient alternative to control plant diseases. However, a few studies depicted the phytotoxic effects of SiNPs on specific plants. Therefore, there is a need for comprehensive research, mainly on the interaction mechanism between NPs and host plants to unravel the hidden facts about silicon nanoparticles in agriculture. The present review illustrates the potential role of silicon nanoparticles in improving plant resistance to combat different environmental (abiotic and biotic) stresses and the underlying mechanisms involved. Furthermore, our review focuses on providing the overview of various methods exploited in the biogenic synthesis of silicon nanoparticles. However, certain limitations exist in synthesizing the well-characterized SiNPs on a laboratory scale. To bridge this gap, in the last section of the review, we discussed the possible use of the machine learning approach in future as an effective, less labour-intensive and time-consuming method for silicon nanoparticle synthesis. The existing research gaps from our perspective and future research directions for utilizing SiNPs in sustainable agriculture development have also been highlighted.

Long-Term Alleviation of the Functional Phenotype in Chlorophyll-Deficient Wheat and Impact on Productivity: A Semi-Field Phenotyping Experiment.

Wheat mutants with a reduced chlorophyll synthesis are affected by a defective control of the photosynthetic electron flow, but tend to recover a wild-type phenotype. The sensitivity of some mutants to light fluctuations suggested that cultivation outdoors could significantly impact productivity. Six mutant lines of Triticum durum or Triticum aestivum with their respective wild-type cultivars were cultivated with a regular seasonal cycle (October-May) in a semi-field experiment. Leaf chlorophyll content and fluorescence parameters were analysed at the early (November) and late (May) developmental stages, and checked for correlation with morphometric and grain-production parameters. The alleviation of the phenotype severity concerned primarily the recovery of the photosynthetic-membrane functionality, but not the leaf chlorophyll content. Photosystem II (PSII) was less photoprotected in the mutants, but a moderate PSII photoinhibition could help control the electron flow into the chain. The accumulation of interchain electron carriers was a primary acclimative response towards the naturally fluctuating environment, maximally exploited by the mature durum-wheat mutants. The mutation itself and/or the energy-consuming compensatory mechanisms markedly influenced the plant morphogenesis, leading especially to reduced tillering, which in turn resulted in lower grain production per plant. Consistently with the interrelation between early photosynthetic phenotype and grain-yield per plant, chlorophyll-fluorescence indexes related to the level of photoprotective thermal dissipation (pNPQ), photosystem II antenna size (ABS/RC), and pool of electron carriers (Sm) are proposed as good candidates for the in-field phenotyping of chlorophyll-deficient wheat.

Diversity of responses to nitrogen deficiency in distinct wheat genotypes reveals the role of alternative electron flows in photoprotection.

Nitrogen (N) deficiency represents an important limiting factor affecting photosynthetic productivity and the yields of crop plants. Significant reported differences in N use efficiency between the crop species and genotypes provide a good background for the studies of diversity of photosynthetic and photoprotective responses associated with nitrogen deficiency. Using distinct wheat (Triticum aestivum L.) genotypes with previously observed contrasting responses to nitrogen nutrition (cv. Enola and cv. Slomer), we performed advanced analyses of CO2 assimilation, PSII, and PSI photochemistry, also focusing on the heterogeneity of the stress responses in the different leaf levels. Our results confirmed the loss of photosynthetic capacity and enhanced more in lower positions. Non-stomatal limitation of photosynthesis was well reflected by the changes in PSII and PSI photochemistry, including the parameters derived from the fast-fluorescence kinetics. Low photosynthesis in N-deprived leaves, especially in lower positions, was associated with a significant decrease in the activity of alternative electron flows. The exception was the cyclic electron flow around PSI that was enhanced in most of the samples with a low photosynthetic rate. We observed significant genotype-specific responses. An old genotype Slomer with a lower CO2 assimilation rate demonstrated enhanced alternative electron flow and photorespiration capacity. In contrast, a modern, highly productive genotype Enola responded to decreased photosynthesis by a significant increase in nonphotochemical dissipation and cyclic electron flow. Our results illustrate the importance of alternative electron flows for eliminating the excitation pressure at the PSII acceptor side. The decrease in capacity of electron acceptors was balanced by the structural and functional changes of the components of the electron transport chain, leading to a decline of linear electron transport to prevent the overreduction of the PSI acceptor side and related photooxidative damage of photosynthetic structures in leaves exposed to nitrogen deficiency.

Fast chlorophyll a fluorescence induction (OJIP) phenotyping of chlorophyll-deficient wheat suggests that an enlarged acceptor pool size of Photosystem I helps compensate for a deregulated photosynthetic electron flow.

The wheat lines affected by a decrease in the leaf chlorophyll content typically experience a biomass loss. A known major problem of the chlorophyll-deficient wheat mutants is their limited prevention of Photosystem I (PSI) over-reduction brought about by an insufficient cyclic electron flow, potentially exposing them to a higher sensitivity to light fluctuations. However, the resistance of some mutant lines against fluctuating light suggests the occurrence of regulatory processes compensating for the defect in cyclic electron flow. In this study, a phenotyping approach based on fast chlorophyll a fluorescence induction (OJIP transient), corroborated by P700 redox kinetics, was applied to a collection of chlorophyll-deficient wheat lines, grown under continuous or fluctuating light. Quantitative parameters calculated from the OJIP transient are considered informative about Photosystem II (PSII) functional antenna size and photochemistry, as well as the functioning of the entire photosynthetic electron transport chain. The mutants tended to recover a wild-type-like chlorophyll content, and mature plants could hardly be distinguished based on their effective PSII antenna size. Nevertheless, specific OJIP-derived parameters were strongly correlated with the phenotype severity, in particular the amplitude of the I-P phase and the I-P/J-P amplitude ratio, which are indicative of a more capacitive pool of PSI final electron acceptors (ferredoxin and ferredoxin-NADP+ oxidoreductase, FNR). We propose that the enlargement of such pool of electron carriers is a compensatory response operating at the acceptor side of PSI to alleviate potentially harmful over-reduced states of PSI. Our results also suggest that, in chlorophyll-deficient mutants, higher FV /FM cannot prove a superior PSII photochemistry and wider I-P phase is not indicative of a higher relative content of PSI.

Classification of high-throughput phenotyping data for differentiation among nutrient deficiency in common bean.

The development of automated, image-based, high-throughput plant phenotyping enabled the simultaneous measurement of many plant traits. Big and complex phenotypic datasets require advanced statistical methods which enable the extraction of the most valuable traits when combined with other measurements, interpretation, and understanding of their (eco)physiological background. Nutrient deficiency in plants causes specific symptoms that can be easily detected by multispectral imaging, 3D scanning, and chlorophyll fluorescence measurements. Screening of numerous image-based phenotypic traits of common bean plants grown in nutrient-deficient solutions was conducted to optimize phenotyping and select the most valuable phenotypic traits related to the specific nutrient deficit. Discriminant analysis was used to compare the efficiency of groups of traits obtained by high-throughput phenotyping techniques (chlorophyll fluorescence, multispectral traits, and morphological traits) in discrimination between nutrients [nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and iron (Fe)] at early and prolonged deficiency. Furthermore, a recursive partitioning analysis was used to select variables within each group of traits that show the highest accuracy for assigning plants to the respective nutrient deficit treatment. Using the entire set of measured traits, the highest classification success by discriminant function was achieved using multispectral traits. In the subsequent measurements, chlorophyll fluorescence and multispectral traits achieved comparably high classification success. Recursive partitioning analysis was able to intrinsically identify variables within each group of traits and their threshold values that best separate the observations from different nutrient deficiency groups. Again, the highest success in assigning plants into their respective groups was achieved based on selected multispectral traits. Selected chlorophyll fluorescence traits also showed high accuracy for assigning plants into control, Fe, Mg, and P deficit but could not correctly assign K and N deficit plants. This study has shown the usefulness of combining high-throughput phenotyping techniques with advanced data analysis to determine and differentiate nutrient deficiency stress.

Mitigation of Salinity-Induced Oxidative Damage, Growth, and Yield Reduction in Fine Rice by Sugarcane Press Mud Application.

Salinity stress is one of the major global problems that negatively affect crop growth and productivity. Therefore, ecofriendly and sustainable strategies for mitigating salinity stress in agricultural production and global food security are highly demandable. Sugarcane press mud (PM) is an excellent source of the organic amendment, and the role of PM in mitigating salinity stress is not well understood. Therefore, this study was aimed to investigate how the PM mitigates salinity stress through the regulation of rice growth, yield, physiological properties, and antioxidant enzyme activities in fine rice grown under different salinity stress conditions. In this study, different levels of salinity (6 and 12 dS m-1) with or without different levels of 3, 6, and 9% of SPM, respectively were tested. Salinity stress significantly increased malondialdehyde (MDA, 38%), hydrogen peroxide (H2O2, 74.39%), Na+ (61.5%), electrolyte leakage (40.32%), decreased chlorophyll content (32.64%), leaf water content (107.77%), total soluble protein (TSP, 72.28%), and free amino acids (FAA, 75.27%). However, these negative effects of salinity stress were reversed mainly in rice plants after PM application. PM application (9%) remained the most effective and significantly increased growth, yield, TSP, FAA, accumulation of soluble sugars, proline, K+, and activity of antioxidant enzymes, namely, ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD). Thus, these findings suggest a PM-mediated eco-friendly strategy for salinity alleviation in agricultural soil could be useful for plant growth and productivity in saline soils.

Alterations of Oxidative Stress Indicators, Antioxidant Enzymes, Soluble Sugars, and Amino Acids in Mustard [Brassica juncea (L.) Czern and Coss.] in Response to Varying Sowing Time, and Field Temperature.

The impact of elevated temperature at the reproductive stage of a crop is one of the critical limitations that influence crop growth and productivity globally. This study was aimed to reveal how sowing time and changing field temperature influence on the regulation of oxidative stress indicators, antioxidant enzymes activity, soluble sugars (SS), and amino acids (AA) in Indian Mustard. The current study was carried out during the rabi 2017-2018 and 2018-2019 where, five varieties of mustard viz. Pusa Mustard 25 (PM-25) (V1), PM-26 (V2), BPR-541-4 (V3), RH-406 (V4), and Urvashi (V5) were grown under the field conditions on October 30 (normal sowing; S1), November 18 (late sowing; S2) and November 30 (very late sowing; S3) situations. The S1 and S3 plants, at mid-flowering stage, showed a significant variation in accumulation of SS (8.5 and 17.3%), free AA (235.4 and 224.6%), and proline content (118.1 and 133%), respectively, and played a crucial role in the osmotic adjustment under stress. The results showed that S3 sowing, exhibited a significant induction of the hydrogen peroxide (H2O2) (110.2 and 86.6%) and malondialdehyde (23.5 and 47.5%) concentrations, respectively, which indicated the sign of oxidative stress in plants. Interestingly, the polyphenol oxidase, peroxidase, superoxide dismutase, and catalase enzyme activities were also significantly increased in S3 plants compared to S1 plants, indicating their significant roles in ameliorating the oxidative stress. Furthermore, the concentration of fatty acid levels such as palmitic, stearic, oleic, and linoleic acids level also significantly increased in S3 plants, which influenced the seed and oil quality. The study suggests that the late sowing significantly impaired the biochemical mechanisms in Indian mustard. Further, the mustard variety V4 (RH-406) was found to be effective for cultivation as well as environmental stress adoption in Indian soils, and it could be highly useful in breeding for developing heat-tolerant genotypes for ensuring the food security.

The impact of newly synthesized sulfonamides on soil microbial population and respiration in rhizospheric soil of wheat (Triticum aestivum L.).

Antibiotics released into agricultural fields through the manure of grazing animals could exert harmful impacts on soil microbes and plants. Antibiotics exert high impacts on environment than other pharmaceuticals due to their higher biological activity. However, little is known about their impacts on plants, despite indications that antibiotics exert negative effects on soil microorganisms, which ultimately harm the plants. It has been demonstrated that beneficial microorganisms promote plant growth and development under various stresses. This study evaluated the toxicity of four newly derived sulfonamides (SAs), i.e., 2-(phenylsulfonyl) hydrazine carbothioamide (TSBS-1), N, 2-bis phenyl hydrazine carbothioamide (TSBS-2), aminocarbonyl benzene sulfonamide (UBS-1), and N, N'-carbonyl dibenzene sulfonamide (UBS-2) on bacterial growth and soil microbial respiration. Each SA was tested at four different concentrations (i.e., 2.25, 2.5, 3, 4 mg/ml) against five rhizospheric bacterial strains, including AC (Actinobacteria sp.), RS-3a (Bacillus sp.), RS-7a (Bacillus subtilis), RS-4a (Enterobacter sp.), and RS-5a (Enterobacter sp.). Antimicrobial activity was checked by disc diffusion method, which showed that inhibition zone increased with increasing concentration of SAs. The UBS-1 resulted in the highest inhibition zone (11.47 ± 0.90 mm) against RS-4a with the highest concentration (4 mg/ml). Except TSBS-1, all sulfonamide derivatives reduced CO2 respiration rates in soil. Soil respiration values significantly increased till 6th day; however, exposure of sulfonamide derivatives suppressed microbial respiration after 6th day. On the 20th day, poor respiration activity was noted at 0.23, 0.2, and 0.4 (CO2 mg/g dry soil) for TSBS-1, UBS-1, and UBS-2, respectively. Our results demonstrate that sulfonamides, even in small concentrations, significantly affect soil microbial population and respiration. Soil microbial respiration changes mediated by sulfonamides were dependent on length of exposure and concentration. It is recommended that antibiotics should be carefully watched and their impact on plant growth should be tested in the future studies.

Pre-Acclimation to Elevated Temperature Stabilizes the Activity of Photosystem I in Wheat Plants Exposed to an Episode of Severe Heat Stress.

The importance of high temperature as an environmental factor is growing in proportion to deepening global climate change. The study aims to evaluate the effects of long-term acclimation of plants to elevated temperature on the tolerance of their photosynthetic apparatus to heat stress. Three wheat (Triticum sp. L.) genotypes differing in leaf and photosynthetic traits were analyzed: Thesee, Roter Samtiger Kolbenweizen, and ANK 32A. The pot experiment was established in natural conditions outdoors (non-acclimated variant), from which a part of the plants was placed in foil tunnel with elevated temperature for 14 days (high temperature-acclimated variant). A severe heat stress screening experiment was induced by an exposition of the plans in a growth chamber with artificial light and air temperature up to 45 °C for ~12 h before the measurements. The measurements of leaf photosynthetic CO2 assimilation, stomatal conductance, and rapid kinetics of chlorophyll a fluorescence was performed. The results confirmed that a high temperature drastically reduced the photosynthetic assimilation rate caused by the non-stomatal (biochemical) limitation of photosynthetic processes. On the other hand, the chlorophyll fluorescence indicated only a moderate level of decrease of quantum efficiency of photosystem (PS) II (Fv/Fm parameter), indicating mostly reversible heat stress effects. The heat stress led to a decrease in the number of active PS II reaction centers (RC/ABS) and overall activity o PSII (PIabs) in all genotypes, whereas the PS I (parameter ψREo) was negatively influenced by heat stress in the non-acclimated variant only. Our results showed that the genotypes differ in acclimation capacity to heat stress, and rapid noninvasive techniques may help screen the stress effects and identify more tolerant crop genotypes. The acclimation was demonstrated more at the PS I level, which may be associated with the upregulation of alternative photosynthetic electron transport pathways with clearly protective functions.

The impact of PEG-induced drought stress on seed germination and seedling growth of different bread wheat (Triticum aestivum L.) genotypes.

Wheat is an important crop, used as staple food in numerous countries around the world. However, wheat productivity is low in the developing world due to several biotic and abiotic stresses, particularly drought stress. Non-availability of drought-tolerant wheat genotypes at different growth stages is the major constraint in improving wheat productivity in the developing world. Therefore, screening/developing drought-tolerant genotypes at different growth stages could improve the productivity of wheat. This study assessed seed germination and seedling growth of eight wheat genotypes under polyethylene glycol (PEG)-induced stress. Two PEG-induced osmotic potentials (i.e., -0.6 and -1.2 MPa) were included in the study along with control (0 MPa). Wheat genotypes included in the study were 'KLR-16', 'B6', 'J10', '716', 'A12', 'Seher', 'KTDH-16', and 'J4'. Data relating to seed germination percentage, root and shoot length, fresh and dry weight of roots and shoot, root/shoot length ratio and chlorophyll content were recorded. The studied parameters were significantly altered by individual and interactive effects of genotypes and PEG-induced osmotic potentials. Seed germination and growth parameters were reduced by osmotic potentials; however, huge differences were noted among genotypes. A reduction of 32.83 to 53.50% was recorded in seed germination, 24.611 to 47.75% in root length, 37.83 to 53.72% in shoot length, and 53.35 to 65.16% in root fresh weight. The genotypes, 'J4', 'KLR-16' and 'KTDH-16', particularly 'J4' better tolerated increasing osmotic potentials compared to the rest of the genotypes included in the study. Principal component analysis segregated these genotypes from the rest of the genotypes included in the study indicated that these can be used in the future studies to improve the drought tolerance of wheat crop. The genotype 'J4' can be used as a breeding material to develop drought resistant wheat genotypes.

Optimizing nitrogen supply promotes biomass, physiological characteristics and yield components of soybean (Glycine max L. Merr.).

Avoidable or inappropriate nitrogen (N) fertilizer rates harmfully affect the yield production and ecological value. Therefore, the aims of this study were to optimize the rate and timings of N fertilizer to maximize yield components and photosynthetic parameter of soybean. This field experiment consists of five fertilizer N rates: 0, 75, 150, 225 and 300 kg N ha-1 arranged in main plots and four N fertilization timings: V5 (trifoliate leaf), R2 (full flowering stage) and R4 (full poding stage), and R6 (full seeding stage) growth stages organized as subplots. Results revealed that 225 kg N ha-1 significantly enhanced grain yield components, total chlorophyll (Chl), photosynthetic rate (P N), and total dry biomass and N accumulation by 20%, 16%, 28%, 7% and 12% at R4 stage of soybean. However, stomatal conductance (g s ), leaf area index (LAI), intercellular CO2 concentration (Ci) and transpiration rate (E) were increased by 12%, 88%, 10%, 18% at R6 stage under 225 kg N ha-1. Grain yield was significantly associated with photosynthetic characteristics of soybean. In conclusion, the amount of nitrogen 225 kg ha-1 at R4 and R6 stages effectively promoted the yield components and photosynthetic characteristics of soybean.

Quantitative response of wheat to sowing dates and irrigation regimes using CERES-Wheat model.

An experiment was conducted at Punjab Agricultural University, Ludhiana during 2014-15 and 2015-16, keeping four sowing dates {25th Oct (D1), 10th Nov (D2), 25th Nov (D3) and 10th Dec (D4)} in main plots and five irrigation schedules {irrigation at 15 (FC15), 25 (FC25), 35 (FC35) and 45 (FC45) % depletion of soil moisture from field capacity (FC) and a conventional practice} in sub plots. The objective of the study was to evaluate the performance of CERES-Wheat model for simulating yield and water use under varying planting and soil moisture regimes. The simulated and observed grain yield was higher in D1, with irrigation applied at FC15 as compared to all other sowing date and irrigation regime combinations. Simulated grain yield decreased by 19% with delay in sowing from 25th October to 10th December because of 8% reduction in simulated crop evapotranspiration. Simulated evapotranspiration decreased by 16%, wheat grain yield by 23% and water productivity by 15% in drip irrigation at 45% depletion from field capacity as compared to drip irrigation at 15% of field capacity. It was further revealed that the model performed well in simulating the phenology, water use and yield of wheat.

Morpho-physiological and biochemical attributes of Chili (Capsicum annum L.) genotypes grown under varying salinity levels.

Climate change is causing soil salinization, resulting in huge crop losses throughout the world. Multiple physiological and biochemical pathways determine the ability of plants to tolerate salt stress. Chili (Capsicum annum L.) is a salt-susceptible crop; therefore, its growth and yield is negatively impacted by salinity. Irreversible damage at cell level and photo inhibition due to high production of reactive oxygen species (ROS) and less CO2 availability caused by water stress is directly linked with salinity. A pot experiment was conducted to determine the impact of five NaCl salinity levels, i.e., 0,1.5, 3.0, 5.0 and 7.0 dS m-1 on growth, biochemical attributes and yield of two chili genotypes ('Plahi' and 'A-120'). Salinity stress significantly reduced fresh and dry weight, relative water contents, water use efficiency, leaf osmotic potential, glycine betaine (GB) contents, photosynthetic rate (A), transpiration rate (E), stomatal conductance (Ci), and chlorophyll contents of tested genotypes. Salinity stress significantly enhanced malondialdehyde (MDA) contents and activities of the enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). In addition, increasing salinity levels significantly reduced the tissue phosphorus and potassium concentrations, while enhanced the tissue sodium and chloride concentrations. Genotype 'Plahi' had better growth and biochemical attributes compared to 'A-120'. Therefore, 'Plahi' is recommended for saline areas to improve chili production.

Grain yield and correlated traits of bread wheat lines: Implications for yield improvement.

Global wheat yields are suffering due to differences in regional climatic conditions and soil fertility. Plant breeders are continuously working to improve the yield per unit area of wheat crop through selecting superior lines as parents. The screening and field evaluation of available lines allow the selection of superior ones and subsequently improved varieties. Therefore, heritable distinctions among 33 bread wheat lines for yield and related attributes were assessed under field conditions. The experiment included thirty lines and three check varieties. Data relating to different plant characteristics was collected at maturity. Significant differences were recorded for yield and related traits of tested wheat lines and check varieties. Wheat lines V6, V12 and V20 proved better with reduced number of days to reach anthesis and other desirable traits compared to check varieties. Days to start heading had strong correlation with spike length and number of spikelets spike-1. Flag leaf area had positive relationship with peduncle length and yield related traits. The 1000-garin weight and grain yield were also correlated with each other. It is concluded that V6, V10 and V20 proved better for all studied traits than the rest of the lines. Therefore, these lines could be used in wheat breeding program as parents to improve yield.

Progressive Genomic Approaches to Explore Drought- and Salt-Induced Oxidative Stress Responses in Plants under Changing Climate.

Drought and salinity are the major environmental abiotic stresses that negatively impact crop development and yield. To improve yields under abiotic stress conditions, drought- and salinity-tolerant crops are key to support world crop production and mitigate the demand of the growing world population. Nevertheless, plant responses to abiotic stresses are highly complex and controlled by networks of genetic and ecological factors that are the main targets of crop breeding programs. Several genomics strategies are employed to improve crop productivity under abiotic stress conditions, but traditional techniques are not sufficient to prevent stress-related losses in productivity. Within the last decade, modern genomics studies have advanced our capabilities of improving crop genetics, especially those traits relevant to abiotic stress management. This review provided updated and comprehensive knowledge concerning all possible combinations of advanced genomics tools and the gene regulatory network of reactive oxygen species homeostasis for the appropriate planning of future breeding programs, which will assist sustainable crop production under salinity and drought conditions.

Photosynthesis research under climate change.

Increasing global population and climate change uncertainties have compelled increased photosynthetic efficiency and yields to ensure food security over the coming decades. Potentially, genetic manipulation and minimization of carbon or energy losses can be ideal to boost photosynthetic efficiency or crop productivity. Despite significant efforts, limited success has been achieved. There is a need for thorough improvement in key photosynthetic limiting factors, such as stomatal conductance, mesophyll conductance, biochemical capacity combined with Rubisco, the Calvin-Benson cycle, thylakoid membrane electron transport, nonphotochemical quenching, and carbon metabolism or fixation pathways. In addition, the mechanistic basis for the enhancement in photosynthetic adaptation to environmental variables such as light intensity, temperature and elevated CO2 requires further investigation. This review sheds light on strategies to improve plant photosynthesis by targeting these intrinsic photosynthetic limitations and external environmental factors.