Vegetative Stage Research Articles

SCREENING OF RICE GERMPLASM AGAINST DROUGHT STRESS USING MORPHOLOGICAL PARAMETERS

Oryza sativa L. is a staple diet for billions of people in the world. Different rice varieties' drought stress responses and their effects on both qualitative and quantitative variables. Rice is the second main exportable product of Pakistan and the agriculture sector has shown remarkable growth, with the crop sector posting a growth of 6.58% in Fiscal year 2022. Drought have a bad effect on the vegetative and reproductive stages of crops. Drought stress can reduce crop yield production. The RCBD design, two-way ANOVA factorial analysis, Tukey test, Genetic advance and Heritability were used for this experiment. This study specifically focuses on the response of rice genotypes to drought stress and its effect on morphological parameters such as plant height, panicle length, stem diameter, flag leaf length and width, number of panicles per plant, and 1000-grain weight. Drought tolerance genotypes were screened out and used to the standard Index of IRRI to identify morphological processing in Rice Research Institute Kala Shah Kaku, Pakistan. Total 35 rice genotypes were sown under drought stress with checked variety. Six varieties perform better production under drought stress conditions. These varieties like Pokkoli, Vehari, Nonabokra, Kalomonk, PK10683, and Basmati 375 show better perform under drought stress. The findings of this research can contribute to the development of drought-tolerant rice varieties and enhance food security in drought-prone areas. The importance of qualitative parameters, such as panicle curvature and awning, is also explored, with potential implications for the visual appearance and market preferences of rice grains. Overall, this research provides valuable insights into the genetic basis and potential breeding strategies for improving drought tolerance in rice.

Rational reduction of planting density and enhancement of NUE were effective methods to mitigate maize yield loss due to excessive rainfall

The impact of excessive rainfall or waterlogging on maize growth and yield have been widely studied, but the effects of planting density and N management under waterlogging remain unknown. We observed the changes in maize yield caused by excessive rainfall via a short-term experiment (2017 to present) in Changchun (125°14.231′–125°14.914′ E, 43°56.603′–43°57.274′ N), China. The experiment was conducted at four planting densities (45,000, 60,000, 75,000 and 90,000 plants/ha) and three nitrogen (N) rates (120, 180, and 240 kg/ha). The objective was to explore the effect of excessive precipitation on maize yield through changes in maize growing conditions, and the uptake, allocation, and utilization of N under different planting densities and N rates from 2019 to 2022. The precipitation during the whole growth period of maize in 2019 (542.9 mm) and 2020 (560.0 mm) was normal, while it was excessive in 2021 (829.10 mm) and 2022 (953.56 mm), especially during the vegetative stage from V12 to VT (355.60–482.10 mm). Excessive rainfall negatively affected the growth, photosynthetic characteristics (Pn: −20.00 %, SPAD: −50.50 %), absorption (−56.86 %), distribution (−15.83 %), N utilization efficiency (NUE: −29.69 %), and grain yield (−44.67 %) of maize. Our results indicate that yield loss was minimized (−22.88 %) when the planting density was appropriately reduced (from 75,000 to 60,000 plants/ha) and the N rate was increased from 180 to 240 kg/ha. The effect of different waterlogging durations on yield exhibited a significantly negative linear relation (R2 > 0.80). This study revealed the physiological mechanism of the sustained effects of excessive rainfall on maize growth and yield. Waterlogging significantly affected the SPAD of maize (p < 0.01, R2 = 0.04), resulting in insufficient kernel N content (p < 0.001, R2 = 0.16) and decreased NUE (p < 0.001, R2 = 0.48). These factors significantly affected yield and exerted a significant negative correlation with planting density (p < 0.05). Our findings improved understanding of planting density and N management for growth and yield of maize under excessive rainfall conditions in mid-high latitude agriculture areas of the world.

Identifying the physiological traits associated with DNA marker using genome wide association in wheat under heat stress

Heat stress poses a significant environmental challenge that profoundly impacts wheat productivity. It disrupts vital physiological processes such as photosynthesis, by impeding the functionality of the photosynthetic apparatus and compromising plasma membrane stability, thereby detrimentally affecting grain development in wheat. The scarcity of identified marker trait associations pertinent to thermotolerance presents a formidable obstacle in the development of marker-assisted selection strategies against heat stress. To address this, wheat accessions were systematically exposed to both normal and heat stress conditions and phenotypic data were collected on physiological traits including proline content, canopy temperature depression, cell membrane injury, photosynthetic rate, transpiration rate (at vegetative and reproductive stage and ‘stay-green’. Principal component analysis elucidated the most significant contributors being proline content, transpiration rate, and canopy temperature depression, which exhibited a synergistic relationship with grain yield. Remarkably, cluster analysis delineated the wheat accessions into four discrete groups based on physiological attributes. Moreover, to explore the relationship between physiological traits and DNA markers, 158 wheat accessions were genotyped with 186 SSRs. Allelic frequency and polymorphic information content value were found to be highest on genome A (4.94 and 0.688), chromosome 1A (5.00 and 0.712), and marker Xgwm44 (13.0 and 0.916). Population structure, principal coordinate analysis and cluster analysis also partitioned the wheat accessions into four subpopulations based on genotypic data, highlighting their genetic homogeneity. Population diversity and presence of linkage disequilibrium established the suitability of population for association mapping. Additionally, linkage disequilibrium decay was most pronounced within a 15–20 cM region on chromosome 1A. Association mapping revealed highly significant marker trait associations at Bonferroni correction P < 0.00027. Markers Xwmc418 (located on chromosome 3D) and Xgwm233 (chromosome 7A) demonstrated associations with transpiration rate, while marker Xgwm494 (chromosome 3A) exhibited an association with photosynthetic rates at both vegetative and reproductive stages under heat stress conditions. Additionally, markers Xwmc201 (chromosome 6A) and Xcfa2129 (chromosome 1A) displayed robust associations with canopy temperature depression, while markers Xbarc163 (chromosome 4B) and Xbarc49 (chromosome 5A) were strongly associated with cell membrane injury at both stages. Notably, marker Xbarc49 (chromosome 5A) exhibited a significant association with the 'stay-green' trait under heat stress conditions. These results offers the potential utility in marker-assisted selection, gene pyramiding and genomic selection models to predict performance of wheat accession under heat stress conditions.

Improving Water-Efficient Irrigation in Terrain Durio Zibethinus Farming Using Hybrid Ant Colony Optimization-Based Soil Moisture Prediction Model

The vegetation stage of Durio Zibethinus trees is characterized by active root development, leaf expansion, and the initiation of reproductive structures. During this crucial phase, adequate irrigation is necessary to satisfy the trees' water requirements. A well-irrigated durian plantation encourages effective nutrient absorption, resulting in healthier trees with increased pest and disease resistance. Understanding the water needs of durian trees is essential for irrigation management to optimize water application and prevent water stress and waterlogging. Typically, sensors measure the soil moisture within the root zone. However, installing soil moisture sensors at each tree is laborious and prohibitively expensive. Using climatic data to forecast the value is a viable option in such a scenario. Climate data are used to create soil moisture predictions incorporated into the irrigation model. This research employs Ant Colony Optimization- Support Vector Regression (ACO-SVR) to predict soil moisture levels. The model is compared to other optimization methods, and its accuracy is assessed using statistical methods. Finally, the prediction models' findings determine the irrigation volume and schedule.

Prediction of secondary metabolites in maize under different nitrogen inputs by hyperspectral sensing and machine learning

Flavonoids are compounds resulting from secondary plant metabolism that provide benefits to human health by food. This study aimed to accuracy of predicting flavonoids in maize plants subjected to different nitrogen rates using hyperspectral reflectance and machine learning (ML) algorithms. The experiment was carried out in randomized blocks in a 4 × 5 factorial design (four N inputs: 0; 30; 60 and 120 % of the recommended N input; and five readings of the reflectance spectra in maize leaves from different vegetative stages: V6, V8, V10, V12 and V14, in four replications, totaling 80 treatments. N rates were applied in the V4 and V8 phenological stages, using urea as the N source. For hyperspectral analysis, four leaves from each treatment were collected and analyzed using a spectroradiometer (FieldSpec 4 HRes, Analytical Spectral Devices), capturing the spectrum in the 350 to 2500 nm range. Subsequently, the leaf samples used in the reflectance readings were dried, ground and subjected to isoflavone quantification, analyzed by ultra-performance liquid chromatography in three repetitions, quantifying daidzein 1 (D1), daidzein 2 (D2), genistein 1 (G1), genistein 2 (G2), and total isoflavones. Data obtained was subjected to machine learning analysis, testing two data set input configurations: wavelengths (WL) and calculated spectral bands (B), and D1, D2, G1, G2 and total isoflavones as output variables. The ML algorithms tested were artificial neural networks (ANN), REPTree (DT), M5P decision tree (M5P), ZeroR (R), Random Forest (RF) and support vector machine (SVM), evaluated according to their performance by the correlation coefficient (r) and mean absolute error (MAE). The results show that the SVM algorithm had the highest accuracy in predicting the variables D1, D2, G1, G2 and total isoflavones, outperforming the other algorithms when WL was used as input in dataset.

Effect of Transplanting Dates and Nutrient Management Options on Nutrient Partitioning and Accumulation in Rice

ABSTRACT Rice is the most important crop in India and additionally the hub of food security of the worldwide population. Integrated application of manures and fertilizers played a pivotal role for improvement of soil physico-chemical properties under different cropping systems as well as nutrient accumulation and grain yield in rice. The present investigation was conducted in sandy loam soil at Agronomy Research Farm of Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India during 2018–2019 having sub-humid climate. Field experiment was designed to evaluate the effect of two date of transplanting, which were allotted to main plots and three combinations of nutrient management options allotted for sub plots on rice crop (var. Naveen). Among all the plant parts, leaf showed higher accumulation of nitrogen (3.69, 1.92%), stem showed higher accumulation of both phosphorus (0.43, 0.35%) and potassium (2.59, 2.09%) than other plant parts during vegetative stages, while panicle showed higher accumulation of nitrogen (1.22%), phosphorus (0.28%) during harvesting stages of the rice crop. Significantly higher nitrogen accumulation in different plant parts were optimized under Soil Test Based Fertilizer Recommendation (STBFR) + Green Manure (GM; Sesbania rostrata) (0.99, 0.46, 1.28%) method of nutrient management, while phosphorus (0.10, 0.11, 0.28%) and potassium (1.00, 1.64, 0.33%) accumulation were found to be significantly higher in different plant parts under STBFR + Farm Yard Manure (FYM) method of nutrient management. Thus, early transplanting and application of STBFR + GM/FYM could be recommended for higher nutrient accumulation in rice crop.

Rhizosphere Microbiome Co-Occurrence Network Analysis across a Tomato Domestication Gradient.

When plant-available phosphorus (P) is lost from a soil solution, it often accumulates in the soil as a pool of unavailable legacy P. To acquire legacy P, plants employ recovery strategies, such as forming associations with soil microbes. However, the degree to which plants rely on microbial associations for this purpose varies with crop domestication and subsequent breeding. Here, by generating microbial co-occurrence networks, we sought to explore rhizosphere bacterial interactions in low-P conditions and how they change with tomato domestication and breeding. We grew wild tomato, traditional tomato (developed circa 1900), and modern tomato (developed circa 2020) in high-P and low-P soil throughout their vegetative developmental stage. Co-occurrence network analysis revealed that as the tomatoes progressed along the stages of domestication, the rhizosphere microbiome increased in complexity in a P deficit. However, with the addition of P fertilizer, the wild tomato group became more complex, surpassing the complexity of traditional and modern tomato, suggesting a high degree of responsiveness in the rhizosphere microbiome to P fertilizer by wild tomato relatives. By illustrating these changing patterns of network complexity in the tomato rhizosphere microbiome, we can further understand how plant domestication and breeding have shaped plant-microbe interactions.

Nano-Biochar Suspension Mediated Alterations in Growth, Physio-Biochemical Activities and Nutrient Content in Wheat (Triticum aestivum L.) at the Vegetative Stage.

Nano-biochar is a source of blackish carbonaceous material, a prerequisite for sustainable crop productivity. By using a variety of feedstock materials, nanobiochar synthesis can be employed via pyrolysis. Therefore, a project was initiated to explore the morpho-physio-biochemical alteration at the vegetative stage of wheat crops after the foliar application of nanobiochar suspension (NBS). This investigation was conducted at the Botanical Research Area of the University of Lahore in a randomized complete block design (RCBD) arrangement, with four treatments (0, 1, 3, and 5% NBS) by maintaining three replications for each treatment using the wheat variety "Zincol". Nano biochar suspension in above mentioned concentrations were foliarly applied at the end of tillering/beginning of leaf sheath elongation of wheat seedlings to assess the morphological changes (root length, shoot length, number of leaves, fresh biomass/plant, dry biomass/plant), physio-biochemical alterations (total free amino acids, total sugars, chlorophyll content, protein, phenols, flavonoids), and nutrient uptake (Na, K, Ca, Mg, N, P contents. Our findings indicate that the foliar application of 3% NBS yielded the most favorable results across all measured attributes. Furthermore, Treatment-4 (5% NBS) specifically improved certain traits, including leaf area, total soluble proteins, and leaf calcium content. Finally, all NBS resulted in a decrease in carotenoid and sodium content in wheat seedlings.

Metabolomic profiling of Greyia radlkoferi on water stress, phenological growth stages, and leaf age using 1H NMR

Greyia radlkoferi Szyszyl (Melianthaceae) is a native plant to southern Africa identified as a viable commercial crop. The leaf extract is rich in flavonoid compounds with the ethanolic leaf extract found to treat skin hyper-pigmentation of humans without adverse effects (anti-tyrosinase activity value IC50 17.86 μg/ml). Anti-tyrosinase activity is found to be variable between plants, even when planted at the same site, which raises concerns regarding commercial production, necessitating the need for cultivation interventions that will not compromise the activity of the extract. Interventions to limit the variation were thus explored by imposing targeted water stress (different durations) before harvesting and determining the effect on the different phenological growth stages and activity of different leaf ages. The inhibitory tyrosinase activity was evaluated using mushroom tyrosinase and kojic acid as a control and data was presented as IC50 values. The metabolomics investigation was conducted through the use of nuclear magnetic resonance (1H NMR) analysis coupled with the multivariate statistical data set. Pattern recognition methods such as principal component analysis (PCA) and orthogonal projection on latent structure-discriminant analysis (OPLS-DA) were employed to obtain the metabolic discrimination between the treatments. No clear pattern was observed in the grouping of samples exposed to targeted water stress on both plant age and leaf position, except for younger leaves of one month and four months old which had a strong clustering of high activity samples as compared to older leaves of six months old. However, plant materials harvested during the flowering growth stage had a strong grouping of samples producing high anti-tyrosinase activity as compared to the budding and vegetative growth stages. The study determined the changes in the concentration of various compounds, although quantification of compounds should be determined in the future.

Climate change does not impact the water flow of barley at the vegetative stage, ameliorates at anthesis and worsens after subsequent drought episodes

Climate change will bring the interaction of stresses such as increased temperature and drought under high [CO2] conditions. This is likely to impact on crop growth and productivity. This study aimed to (i) determine the response of barley water relations to vegetative and anthesis drought periods under triple interaction conditions, (ii) test the possibility to prime barley plants for drought, and (iii) analyse the involvement of aquaporins in (i) and (ii). The water status of barley was not affected by drought at the vegetative stage, regardless of the environmental conditions. At the anthesis stage, when the water shortage period was more severe, barley plants growing under combined elevated CO2 and temperature conditions were able to maintain a better water status compared with plants grown under current conditions. Elevated CO2 and temperature conditions reduced the stomatal conductance and slowed down the plant water flow through a root-leaf hydraulic conductivity coordination. Leaf HvPIP2;1 and HvTIP1;1 aquaporins seemed to play a key role regulating barley's water flow, while leaf and root HvPIP2;5 provided basic level of water flow. At anthesis drought and under future combined conditions, plants showed a reduced cell dehydration and decrease in leaf relative water content compared with plants grown under current conditions. Exposure to a previous drought did not prime the water status of barley plants to a subsequent drought, but instead worsened the response under future conditions. This was due to an imbalance between the roots versus shoot development.

Nitrate Reductase and Glutamine Synthetase Enzyme Activities and Chlorophyll in Sorghum Leaves (Sorghum bicolor) in Response to Organic Fertilization

Sorghum is a plant that mainly requires chemical nitrogen fertilization. There are organic fertilizers that can provide nutrients to plants with great benefits to the soil, such as chicken manure. To determine the influence of organic fertilization on nitrate reductase (NR), glutamine synthetase (GS), and the amount of chlorophyll, sorghum plants were grown using the following four treatments: soil (T1), soil + chicken manure 100 kg ha−1 of nitrogen (N) (T2), soil + chicken manure 200 kg ha−1 N (T3), and soil + ammonium sulfate 100 kg ha−1 N (T4). Leaves were sampled in the vegetative stage (VS), the reproductive stage (RS), and the maturation stage (MS). The highest NR activity occurred in plants with T2 and T3 in the VS. The highest GS activity was in T3 and T4 in the RS. The amount of chlorophyll a was the same in all phenological stages. However, the amount of chlorophyll b was influenced by the type of fertilization at different phenological stages. Organic fertilizers (OF) produced the highest NR activity. On the other hand, GS activity was higher with chemical fertilization (T4), which was equal to the second dose of organic fertilization (T3). Finally, chlorophyll a and b were influenced by both types of fertilization, and was different from T1.

Enhancing stress resilience in soybeans (Glycine max): assessing the efficacy of priming and cross-priming for mitigating water deficit and waterlogging effects.

Priming enables plants to respond more promptly, minimise damage, and survive subsequent stress events. Here, we aimed to assess the efficacy of priming and cross-priming in mitigating the stress caused by waterlogging and/or dehydration in soybeans (Glycine max ). Soybean plants were cultivated in a greenhouse in plastic pots in which soil moisture was maintained at pot capacity through irrigation. The first stress was applied in plants at the vegetative stage for 5days and involved either dehydration or waterlogging, depending on the treatment. Subsequently, the plants were irrigated or drained and maintained at pot capacity until the second stress. For the second stress, the conditions were repeated in plants at the reproductive stage. We then evaluated the levels of hydrogen peroxide (H2 O2 ), lipid peroxidation, total soluble sugars (TSS), amino acids, proline, and starch, and the activity of antioxidant, fermentative, and aminotransferase enzymes. Under waterlogging and dehydration, priming and cross-priming significantly increased the activity of antioxidant enzymes and the levels of TSS, amino acids, and proline while reducing H2 O2 concentration and lipid peroxidation. Under waterlogging, priming suppressed fermentative activity and increased carbohydrate content. This demonstrates that soybean plants activate their defence systems more promptly when subjected to priming.

Effect of different timing of water deficit combined with foliar application of ascorbic acid on physiological variables of sour passion fruit

The objective of this study was to evaluate the effects of deficit irrigation treatments during different phenological stages and foliar application of ascorbic acid on gas exchange, photosynthetic pigments, chlorophyll fluorescence, electrolyte leakage, relative water content and yield of ‘BRS GA1’ sour passion fruit. Treatments were distributed in randomized blocks, in a split-plot scheme, with plots consisting of six deficit irrigation treatments, based on crop evapotranspiration – ETc (irrigation with 100% ETc - FULL; irrigation with 50% ETc in the vegetative stage - VEG; flowering stage - FLO; fruiting stage - FRU; successively in the vegetative/flowering stages - VEG + FLO and vegetative/fruiting stages - VEG + FRU) and subplots represented by three concentrations of ascorbic acid - AsA (0, 0.5 and 1.0 mM). Water deficit induces changes in photosynthetic activity across all developmental stages of sour passion fruit, resulting in reduced yield in the period of 160 and 200 days after transplanting. Notably, flowering exhibits the greatest physiological acclimatization to water deficit conditions, albeit with more pronounced losses in the yield. When water deficit occurs during the vegetative and fruiting stages and is coupled with foliar application of ascorbic acid at 0.5 mM, there is an enhancement in the synthesis of photosynthetic pigments in ‘BRS GA1’ sour passion fruit. Overall, foliar application of ascorbic acid at concentrations of 0.5 and 1.0 mM emerges as a viable strategy to mitigate the adverse effects of water deficit on the physiology and yield of sour passion fruit at 200 days after transplanting.

OsHAK4 functions in retrieving sodium from the phloem at the reproductive stage of rice.

Soil salinity significantly limits rice productivity, but it is poorly understood how excess sodium (Na+) is delivered to the grains at the reproductive stage. Here, we functionally characterized OsHAK4, a member of the clade IV HAK/KUP/KT transporter subfamily in rice. OsHAK4 was localized to the plasma membrane and exhibited influx transport activity for Na+, but not for K+. Analysis of organ- and growth stage-dependent expression patterns showed that very low expression levels of OsHAK4 were detected at the vegetative growth stage, but its high expression in uppermost node I, peduncle, and rachis was found at the reproductive stage. Immunostaining indicated OsHAK4 localization in the phloem region of node I, peduncle, and rachis. Knockout of OsHAK4 did not affect the growth and Na+ accumulation at the vegetative stage. However, at the reproductive stage, the hak4 mutants accumulated higher Na+ in the peduncle, rachis, husk, and brown rice compared to the wild-type rice. Element imaging revealed higher Na+ accumulation at the phloem region of the peduncle in the mutants. These results indicate that OsHAK4 plays a crucial role in retrieving Na+ from the phloem in the upper nodes, peduncle, and rachis, thereby preventing Na+ distribution to the grains at the reproductive stage of rice.

Electropenetrography Study of Euschistus heros (F.) (Heteroptera: Pentatomidae) Nymphs Feeding on Vegetative Soybean Structures.

The study aimed to understand the feeding behavior of Neotropical brown stink bug nymphs Euschistus heros (F.) on soybean plants during vegetative stage through electropenetrography (EPG) technique. Three distinct phases were identified: non-feeding, pathway, and ingestion. Waveforms representing these phases were consistent across nymphal instars and plant structures, and named Np, Eh1, and Eh2, respectively. Biological interpretations of the waveforms were proposed by integrating visual observations, comparisons with adult waveforms, and histological studies. The waveforms Np, Eh1, and Eh2 were associated with resting/walking, initial stylet-plant contact, and xylem sap ingestion, respectively. Notably, nymphs showed a higher number of Eh1 events and longer durations when feeding on petioles compared to leaves, particularly in younger instars. However, differences between instars diminished in older nymphs. Fifth instars consistently exhibited the highest Eh1 values, and displayed longer xylem ingestion durations compared to other instars. Second instars demonstrated increased xylem ingestion events on petioles compared to leaves. Across plant structures, on petioles, nymphs generally showed longer xylem ingestion durations than on leaf surfaces. Fifth instar consistently had the longest ingestion durations overall. Additionally, statistical differences in xylem ingestion duration were observed between instars within each plant structure, with fifth instars displaying the longest durations. These findings offer valuable insights into the feeding behavior of E. heros nymphs, which could inform the development of more effective pest management strategies for soybean crops.

Differences in Early Root Endophytic Bacterial Communities between Japanese Sake Rice Cultivars and Table Rice Cultivars

Sake, which is produced mainly from japonica rice (Oryza sativa subsp. japonica), is one of the most important alcohol products in Japan. In this study, we aimed to investigate a hypothesis that the early root endophytic bacterial communities in Japanese sake rice cultivars would be distinct from those in table rice cultivars, comparing four sake rice cultivars and two table rice cultivars. Rice roots in the vegetative stage were collected 0, 3, and 6 weeks after transplanting, and 16S rRNA gene amplicon sequencing revealed significant differences in bacterial community composition diversity between the sake and table rice cultivars. The root endophytic bacterial communities at the transplanting differed significantly between the rice cultivars, indicating differences in each seed-derived endophytic community. After an overall dominance of Pantoea and Methylobacterium-Methylorubrum at the transplanting, the endophytic community was gradually replaced by soil-derived bacteria that varied by the rice cultivars. Notably, PERMANOVA results showed that the rice endophytic bacterial community composition differed significantly between the sake and table rice cultivars (p &lt; 0.001). These results highlight the distinct root endophytic bacterial composition in the sake rice cultivars compared to those in the table rice cultivars, supporting our hypothesis.

Temporal and spatial patterns of extreme heat on wheat in China under climate change scenarios

Revealing the spatial-temporal pattern of extreme heat on staple crops is crucial for proposing adaptation strategies to mitigate climate change-related agricultural risks. Studies in this field generally focus on the reproductive stage and rely on a single-staged threshold temperature to construct extreme heat indicators, which particularly neglect the vegetative stage of wheat. Therefore, to measure the extreme heat risks more scientifically across the entire life cycle of wheat, our study defines a new comprehensive extreme heat index (CEHI) that considers specific thresholds in both the reproductive and vegetative stages. In general, under three climate scenarios (RCP2.6, RCP4.5, and RCP8.5), approximately 20 % of the wheat-planting regions in China, especially in winter wheat regions such as the North China Plain, the Sichuan Basin, and the Xinjiang Tarim Basin, are projected to face high levels of extreme heat. Meanwhile, from 2010 to 2099, the average growth rates of extreme heat in China under RCP2.6, RCP4.5, and RCP8.5 scenarios are approximately 0.08, 0.06, and 0.1, respectively. By the century's end, the proportion of wheat-planting regions experiencing high and very high levels (CEHI≥0.4) of extreme heat is projected to increase from 18.0 %, 17.9 %, and 18.4 % to 21.4 %, 25.1 %, and 28.9 % under RCP2.6, RCP4.5, and RCP8.5 scenarios. Among them, RCP8.5 has the highest extreme heat severity on wheat in China, followed by RCP4.5, while RCP2.6 has minimal severity. Under the RCP8.5 scenario, the proportions of very high, high, moderate, low, and very low levels of extreme heat are 3.4 %, 18.5 %, 16.7 %, 14.9 %, and 46.5 %, respectively. Meanwhile, our study also emphasizes that although higher-latitude spring wheat regions will experience a significantly increasing trend in extreme heat, this may not spell long-term damage to wheat. Therefore, with consideration of varied temperature sensitivities across wheat growth stages, our study indicates that CEHI serves as an effective method to comprehensively and scientifically assess extreme heat on wheat. Furthermore, based on the regional and varietal differences in extreme heat under climate change, our study highlights the importance of developing region- and variety-specific policies to ensure the sustainability of wheat.

Synthesis and Biological Evaluation of Cyanoacrylamides and 5-Iminopyrrol-2-Ones Against Naegleria fowleri.

Primary amoebic meningoencephalitis is caused by the free-living amoeba Naegleria fowleri. The lack of standardized treatment has significantly contributed to the high fatality rates observed in reported cases. Therefore, this study aims to explore the anti-Naegleria activity of eight synthesized cyanoacrylamides and 5-iminopyrrol-2-ones. Notably, QOET-109, QOET-111, QOET-112, and QOET-114 exhibited a higher selectivity index against Naegleria compared to those of the rest of the compounds. Subsequently, these chemicals were assessed against the resistant stage of N. fowleri, demonstrating activity similar to that observed in the vegetative stage. Moreover, characteristic events of programmed cell death were evidenced, including chromatin condensation, increased plasma membrane permeability, mitochondrial damage, and heightened oxidative stress, among others. Finally, this research demonstrated the in vitro activity of the cyanoacrylamide and 5-iminopyrrol-2-one molecules, as well as the induction of metabolic event characteristics of regulated cell death in Naegleria fowleri.

Plant phenology modulates and undersown cover crops mitigate N2O emissions

Mitigation of N2O emissions, a potent greenhouse gas, remain challenging due to knowledge gaps in plant-mediated nitrogen (N) transformation pathways, which limits ability to identify optimal approaches for efficient N utilization. We set up mesocosms with barley, Italian ryegrass, and barley in combination with Italian ryegrass to assess role of cover crop in N2O emission mitigation. Soil emitted N2O was collected simultaneously from the pots with plants at three growth stages: namely, vegetative, canopy expansion, and grain filling. The gas sample N2O contents, N in microbial biomass (MBN), mineral N content, and phospholipid fatty acid (PLFA) analysis in soils were determined at the three growth stages. Cumulatively, highest N2O was emitted from soil under Italian ryegrass (0.056 mg N g−1 soil) followed by barley (0.0051 mg N g−1 soil) and the least under barley and Italian ryegrass combination (0.0014 mg N g−1 soil). The high emissions under Italian ryegrass occurred at vegetative stage due to high reactive N availability. Strong emissions were observed at canopy expansion stage under barley and were linked to access to the large mineral N proportion redistributed to the lower depth as depicted by highest MBN (0.025 mg N g−1 soil) and decreased extractable N (0.0068 mg N g−1 soil). The high emissions under barley correlated with high fungal/bacterial ratio, pointing towards a fungal role in the emissions. The least soil N2O emissions under barley and Italian ryegrass combination were accompanied by elimination of variations induced by the plant growth stages. Absence of 18:2ω6,9 fungal PLFA biomarker under barley and Italian ryegrass combination indicates a potential inhibition and corresponds with reduced N2O emissions. Together, these results broaden our understanding on how plant-soil interactions drives N2O emissions processes and improves our ability to identify optimal plant-based emission mitigation approaches.

Vegetative stage and soil horizon respectively determine direction and magnitude of rhizosphere priming effects in contrasting tree line soils

Abstract Tree lines in high latitudes and high altitudes are considered sentinels of global change. This manifests in accelerated encroachment of trees and shrubs and enhanced plant productivity, with currently unknown implications for the carbon balance of these biomes. Given the large soil organic carbon stocks in many tree line soils, we here wondered whether introducing highly productive plants would accelerate carbon cycling through rhizosphere priming effects and if certain soils would be more vulnerable to carbon loss from positive priming than others. To test this, organic and mineral soils were sampled above and below tree lines in the Swedish sub‐arctic and the Peruvian Andes. A greenhouse experiment was then performed to quantify plant‐induced changes in soil mineralisation rates (rhizosphere priming effect) and new C formation using natural abundance labelling and the C4‐species Cynodon dactylon. Several environmental, plant, soil and microbial parameter were monitored during the experiment to complement the observations on soil C cycling. Priming was predominantly positive at the beginning of the experiment, then systematically decreased in all soils during the plant growth season to be mostly negative at the end of the experiment at plant senescence. Independent of direction of priming, the magnitude of priming was always greater in organic than in corresponding mineral soils, which was best explained by the higher C contents of these soils. Integrated over the entire study period, the overall impact of priming (positive and negative) on the soil C balance was mostly negligible. Though net soil C loss was observed in organic soils from the sub‐arctic tundra in Sweden. Most notably, positive and negative priming effects were not mutually exclusive, rather omnipresent across ecosystems, depending on sampling time. The direction of priming seems to be fluctuating with plant productivity, rhizosphere carbon inputs and nutrient uptake. This highlights the need for integrative long‐term studies if we aim to understand priming effects at ecosystem scale and greenhouse and laboratory studies must be validated in situ to enable reliable ecological upscaling. Read the free Plain Language Summary for this article on the Journal blog.