Individual and combined effects of high-temperature stress at booting and flowering stages on rice grain quality.

BACKGROUND: High temperature stress (HTS) has become a serious threat to rice grain quality and few studies have examined the effects of HTS across multiple stages on rice grain quality. In the present study, we conducted 2 years of HTS treatments under three temperature regimes (32/22 °C, 40/30 °C and 44/34 °C) and HTS durations of 2 days and 4 days at three critical stages: booting, flowering, and a combination of booting and flowering. We employed the heat degree days (HDD) metric, which accounts for both the level and duration of HTS, to quantify the relationships between grain quality traits and HTS. RESULTS: The results revealed the diverse effects of HTS on rice grain quality at different stages, durations and temperature levels. HTS significantly (P < 0.05) reduced grain quality, with the highest sensitivities (reduction per 1 °C day-1 increase in HDD) observed at the flowering stage, followed by the combined and booting stages treatments under mild HTS treatment (40/30 °C). However, under extreme HTS treatments (44/34 °C) for 4 days, rice grains subjected to combined HTS treatment experienced complete mortality. CONCLUSION: Pre-exposed to HTS at the booting stage within a certain intensity can alleviate the adverse effects of post-flowering HTS on grain quality. This provides valuable insights for assessing the potential impact of multiple HTS events on the grain quality under future climate warming. © 2024 Society of Chemical Industry.

Calcium lignosulfonate-induced modification of soil chemical properties improves physiological traits and grain quality of maize (Zea mays) under salinity stress.

Introduction: Salinity negatively affects maize productivity. However, calcium lignosulfonate (CLS) could improve soil properties and maize productivity. Methods: In this study, we evaluated the effects of CLS application on soil chemical properties, plant physiology and grain quality of maize under salinity stress. Thus, this experiment was conducted using three CLS application rates, CLS0, CLS5, and CLS10, corresponding to 0%, 5%, and 10% of soil mass, for three irrigation water salinity (WS) levels WS0.5, WS2.5, and WS5.5 corresponding to 0.5 and 2.5 and 5.5 dS/m, respectively. Results and discussion: Results show that the WS0.5 × CLS10 combination increased potassium (K 0.167 g/kg), and calcium (Ca, 0.39 g/kg) values while reducing the sodium (Na, 0.23 g/kg) content in soil. However, the treatment WS5.5 × CLS0 decreased K (0.120 g/kg), and Ca (0.15 g/kg) values while increasing Na (0.75 g/kg) content in soil. The root activity was larger in WS0.5 × CLS10 than in WS5.5 × CLS0, as the former combination enlarged K and Ca contents in the root while the latter decreased their values. The leaf glutamine synthetase (953.9 µmol/(g.h)) and nitrate reductase (40.39 µg/(g.h)) were higher in WS0.5 × CLS10 than in WS5.5 × CLS0 at 573.4 µmol/(g.h) and 20.76 µg/(g.h), leading to the improvement in cell progression cycle, as revealed by lower malonaldehyde level (6.57 µmol/g). The K and Ca contents in the leaf (881, 278 mg/plant), stem (1314, 731 mg/plant), and grains (1330, 1117 mg/plant) were greater in WS0.5 × CLS10 than in WS5.5 × CLS0 at (146, 21 mg/plant), (201, 159 mg/plant) and (206, 157 mg/plant), respectively. Therefore, the maize was more resistance to salt stress under the CLS10 level, as a 7.34% decline in yield was noticed when salinity surpassed the threshold value (5.96 dS/m). The protein (13.6 %) and starch (89.2 %) contents were greater in WS0.5 × CLS10 than in WS5.5 × CLS0 (6.1 %) and (67.0 %), respectively. This study reveals that CLS addition can alleviate the adverse impacts of salinity on soil quality and maize productivity. Thus, CLS application could be used as an effective soil amendment when irrigating with saline water for sustainable maize production.

Durum Wheat at Risk in a Climate Change Scenario: The Carotenoid Content is Affected by Short Heat Waves.

Short heat waves (SHW), defined as periods of several consecutive days with high temperatures above the developmental optimum, will become more frequent due to climate change. The impact of SHW on yield and yield-related parameters has received considerable interest, but their effects on grain quality remain poorly understood. We employed a simulation approach to investigate the impact of SHW on durum wheat quality over a 7 day period, starting 1 week after anthesis. During the SHW treatment, carried out using portable polyethylene tents, the temperature in the treated plots increased by 10-15 °C during daily hours. The SHW treatment reduced the number of grains per spike, thousand kernel weight, and total carotenoid content in grains in stressed plants in comparison to control plants. However, no differences in the protein content or percentage of vitreous grains were observed. The behavior of individual carotenoids in response to SHW appears to differ, suggesting a differential change in the balance between ß,ε- and ß,ß-branches of the carotenoid biosynthetic pathway as a consequence of SHW-induced stress. The present study highlights the importance of developing efficient breeding strategies for reduced sensitivities to heat stress. Such strategies should not only prioritize yield but also encompass grain quality.

Comparative Proteomic Analysis Provides New Insights into Improved Grain-filling in Ratoon Season Rice.

Grain-filling of rice spikelets (particularly for the later flowering inferior spikelets) is an important characteristic that affects both quality and yield. Rice ratooning technology is used to cultivate a second crop from dormant buds that sprout from stubble left after the first harvest. This study used two rice varieties, the conventional indica rice 'Jinhui 809' and the hybrid indica-japonica rice 'Yongyou 1540', to assess the impact of rice ratooning on grain-filling. The results indicated that the grain-filling process in inferior spikelets of ratoon season rice (ISR) showed significant improvement compared to inferior spikelets of main crop (late season) rice (ISL). This improvement was evident in the earlier onset of rapid grain-filling, higher seed-setting percentage, and improved grain quality. A label-free quantitative proteomic analysis using mass spectrometry identified 1724 proteins with significant abundance changes, shedding light on the molecular mechanisms behind the improved grain-filling in ISR. The functional analysis of these proteins indicated that ratooning stimulated the metabolic processes of sucrose-starch, trehalose, and hormones in rice inferior spikelets, leading to enhanced enzyme activities related to starch synthesis, elevated concentrations of trehalose-6-phosphate (T6P), indole-3-acetic acid (IAA) and zeatin riboside (ZR) during the active grain-filling phase. This research highlighted the importance of the GF14f protein as a key regulator in the grain-filling process of ISR. It revealed that GF14f transcriptional and protein levels declined more rapidly in ISR compared to ISL during grain-filling. Additionally, the GF14f-RNAi plants specific to the endosperm exhibited improved quality in inferior spikelets. These findings suggest that the enhancement of starch synthesis, increased levels of IAA, ZR, and T6P, along with the rapid decrease in GF14f protein, play a role in enhancing grain-filling in ratoon season rice.

Halotolerant Microorganism-Based Soil Conditioner Application Improved the Soil Properties, Yield, Quality and Starch Characteristics of Hybrid Rice under Higher Saline Conditions.

Soil salinity represents a significant factor affecting agricultural productivity and crop quality. The present study was conducted to investigate the effects of soil conditioner (SC) comprising halotolerant microorganisms on the soil fertility, yield, rice quality, and the physicochemical and structural properties of starch in hybrid rice under saline conditions. The experimental treatments were composed of two high-quality hybrid rice varieties, i.e., 'Y Liangyou 957' (YLY957) and Jing Liangyou 534 (JLY534), and two soil amendment treatments, i.e., the application of SC at control levels and 2250 kg hm-2, or 'CK and SC', respectively. The crop was subjected to a mixture of fresh and sea water (EC 11 dS/m). The results demonstrated that the application of SC significantly enhanced the rice yield under salt stress conditions owing to an increase in the number of grains per panicle. Furthermore, SC was found to be effective in improving the organic matter and soil nutrient content. Furthermore, the application of SC resulted in an improvement in antioxidant defense, higher leaf SPAD values, and greater crop biomass, as well as the translocation of photo-assimilates at the heading stage. The application of SC not only improved the milling and appearance quality but also enhanced the taste value of rice by increasing the amylose and reducing the protein content. Furthermore, the application of SC also decreased the indentations on the surfaces of starch granules and cracks on the edges of the granules. The rice varieties subjected to SC exhibited excellent pasting properties, characterized by reduced proportions of amylopectin short chains and a lower gelatinization temperature and enthalpy of gelatinization. Overall, these findings serve to reinforce the efficacy of soil conditioner as a valuable tool to improve rice productivity and sustainability with improved rice grain quality under saline conditions.

Profiling and Improvement of Grain Quality Traits for Consumer Preferable Basmati Rice in the United States.

Basmati rice is a premium aromatic rice that consumers choose primarily because of its distinct aroma and excellent grain quality. The grain quality of Basmati rice (GQBR) reflects the perspectives of producers, processors, sellers, and consumers related to the production, processing, marketing, and consumption of Basmati rice. Consumers, an invaluable part of the production demand and value chain of the Basmati rice industry, have the freedom to choose from different types of aromatic rice. Consumers expect their preferred Basmati rice to possess all superior rice grain qualities, including the physical, biochemical, and physiological properties. Gene functional analysis explained that a 10-base pair deletion in the promoter region of the OsSPL16 gene causes the slender grains in Basmati rice, whereas an 8-base-pair deletion in exon 7 of the OsBadh2 gene (located in the fgr region on rice chromosome 8) results in the distinct aroma. Furthermore, a combination of the genetic characteristics of the gw8 and gs3 genes has led to the creation of a long-grain Basmati-type rice cultivar. It has also been demonstrated that agricultural, genetic, and environmental conditions significantly influence GQBR. Hence, research on improving GQBR requires a multidimensional approach and sophisticated elements due to the complexity of its nature and preference diversity. This review covers the basic definitions of grain quality traits, consumer preference criteria, influencing factors, and strategies for producing superior-quality Basmati rice in the United States. This knowledge will be useful in improving the grain quality of Basmati and Basmati-type rice, as well as developing appropriate breeding programs that will meet the preferences of different countries and cultures.

Biological Roles of Lipids in Rice.

Lipids are organic nonpolar molecules with essential biological and economic importance. While the genetic pathways and regulatory networks of lipid biosynthesis and metabolism have been extensively studied and thoroughly reviewed in oil crops such as soybeans, less attention has been paid to the biological roles of lipids in rice, a staple food for the global population and a model species for plant molecular biology research, leaving a considerable knowledge gap in the biological roles of lipids. In this review, we endeavor to furnish a current overview of the advancements in understanding the genetic foundations and physiological functions of lipids, including triacylglycerol, fatty acids, and very-long-chain fatty acids. We aim to summarize the key genes in lipid biosynthesis, metabolism, and transcriptional regulation underpinning rice's developmental and growth processes, biotic stress responses, abiotic stress responses, fertility, seed longevity, and recent efforts in rice oil genetic improvement.

A single amino acid substitution in the AAA-type ATPase LRD6-6 activates immune responses but decreases grain quality in rice.

Plant spotted leaf (spl) mutants are useful to reveal the regulatory mechanisms of immune responses. Thus, in crop plants, their agronomic traits, especially the grain quality are usually ignored. Here, we characterized a rice spl mutant named spl-A (spotted leaf mutant from A814) that shows autoimmunity, broad-spectrum disease resistance and growth deterioration including decreased rice quality. A single nucleotide mutation of C1144T, which leads to change of the 382nd proline to serine, in the gene encoding the ATPases associated with diverse cellular activities (AAA)-type ATPase LRD6-6 is responsible for the phenotype of the spl-A mutant. Mechanistically, this mutation impairs LRD6-6 ATPase activity and disrupts its interaction with endosomal sorting complex required for transport (ESCRT)-III subunits OsSNF7.1/7.2/7.3. And thus, leading to compromise of multivesicular bodies (MVBs)-mediated vesicle trafficking and accumulation of ubiquitinated proteins in both leaves and seeds of spl-A. Therefore, the immune response of spl-A is activated, and the growth and grain quality are deteriorated. Our study identifies a new amino acid residue that important for LRD6-6 and provides new insight into our understanding of how MVBs-mediated vesicle trafficking regulates plant immunity and growth, including grain quality in rice.

Long-term organic and N fertilization influence the quality and productivity of pearl millet under pearl millet-wheat sequence in north India.

The present investigation reported that FYM application in different seasons influenced root, shoot, and seedling length, straw K, vigour index-I, nutrient uptake, grain, and stover yield of pearl millet significantly (P < 0.05) and followed the order: both seasons > kharif > rabi. Applying FYM in both seasons resulted in higher N, P, and K content in pearl millet grain (1.99%, 0.17%, and 0.37%, respectively) followed by kharif season application (1.93, 0.16, and 0.35%, respectively). Applying 15 t FYM ha-1 significantly increased the grain N (13.19%), P (63.16%), K (22.29%), protein (13.56%), stover N (32.76%), P (46.66%) and root length (29.83%) over FYM0. After 50 cropping cycles, continuous application of FYM15, FYM10, and FYM5 significantly improved vigour index-I by 52.85, 39.26, and 23.63% over no FYM, respectively. Applying 120 kg N ha-1 significantly increased N (6.38%), P (15.89%), and protein (6.03%) content, germination (5.91%), and vigour indexes (24.52 to 30.91%) of pearl millet grain over no fertilizer N. The treatment FYM15 × N120 increased the seedling length of pearl millet by 30.54 over N120 and 11.08% over FYM15 alone, respectively. Adding FYM either during both seasons or in the kharif season along with fertilizer N proved superior in improving the quality and yield of pearl millet.

Straw return enhances grain yield and quality of three main crops: evidence from a meta-analysis.

Straw return is regarded as a widely used field management strategy for improving soil health, but its comprehensive effect on crop grain yield and quality remains elusive. Herein, a meta-analysis containing 1822 pairs of observations from 78 studies was conducted to quantify the effect of straw return on grain yield and quality of three main crops (maize, rice, and wheat). On average, compared with no straw return, straw return significantly (p< 0.05) increased grain yield (+4.3%), protein content (+2.5%), total amino acids concentration (+1.2%), and grain phosphorus content (+3.6%), respectively. Meanwhile, straw return significantly (p< 0.05) decreased rice chalky grain rate (-14.4%), overall grain hardness (-1.9%), and water absorption of maize and wheat (-0.5%), respectively. Moreover, straw return effects on grain yield and quality traits were infected by cultivated crop types, straw return amounts, straw return methods, and straw return duration. Our findings illustrated that direct straw return increased three main crop grain yields and improved various quality traits among different agricultural production areas. Although improper straw return may increase plant disease risk and affect seed germination, our results suggest that full straw return with covered or plough mode is a more suitable way to enhance grain yield and quality. Our study also highlights that compared with direct straw return, straw burning or composting before application may also be beneficial to farmland productivity and sustainability, but comparative studies in this area are still lacking.

Enhancing Maize Yield and Quality with Metal-Based Nanoparticles without Translocation Risks: A Brief Field Study.

Our previous studies have shown physiological and yield intensification of selected crops with the application of nanoparticles (NPs). However, the impact on the quantitative, qualitative, and yield parameters of maize (Zea mays L.) in field conditions remains highly debated. This study aimed to evaluate the effects of zinc oxide (ZnO-NPs), gold NPs anchored to meso-biosilica (Au-NP-bioSi), and titanium dioxide (TiO2-NPs) as biological stimulants under field conditions during the vegetation season of 2021 in the Central European region. The study assessed the effects on the number of plants, yield, yield components, and nutritional quality, including mineral nutrients, starch, and crude protein levels. The potential translocation of these chemically-physically stable NPs, which could pose a hazard, was also investigated. The results indicate that Au-NP-bioSi and ZnO-NPs-treatments were the most beneficial for yield and yield components at a statistically significant level. Mineral nutrient outcomes were varied, with the NP-free variant performing the best for phosphorus-levels, while Au-NP-bioSi and ZnO-NPs were optimal for crude protein. Starch content was comparable across the TiO2-NPs, Au-NP-bioSi, and control variants. Importantly, we observed no hazardous translocation of NPs or negative impacts on maize grain quality. This supports the hypothesis that NPs can serve as an effective tool for precise and sustainable agriculture.

Response of rice yield, grain quality to chilling at grain filling stages.

BACKGROUND: This study aims to quantify the impacts of chilling at the grain filling stage on rice yield and grain quality. A factorial experiment with four levels of temperature and duration of chilling treatments at the early and late grain filling stages was conducted in 2017, 2018 and 2019. RESULTS: Per 10 °C·day increase in the accumulated cooling degree day at the early and late grain filling stages, the rice emergence-maturity duration was delayed by 0.8% (0.6%) and rice yield decreased by 2.2% (1.7%). Chilling at the early grain filling stage decreased the rice heading rate, while chilling at the late grain filling stage increased rice amylose but decreased protein content. For chilling treatment at the early grain filling stage, rice yield and grain quality were mainly correlated with seed-setting rate, whereas for chilling treatment at the late grain filling stage the rice yield and grain quality were mainly correlated with 1000-grain weight. CONCLUSION: This study improved the understanding of how chilling at the grain filling stages affects rice phenology, yield and grain quality, providing a theoretical basis for maintaining rice yield while ensuring grain quality. The results could be used to guide the rice-growing community in combating chilling at grain filling stages. © 2024 Society of Chemical Industry.

Effects of Nitrogen Accumulation, Transportation, and Grain Nutritional Quality and Advances in Fungal Endophyte Research in Quinoa (Chenopodium quinoa Willd.) Plants.

This study aims to understand the influence of nitrogen accumulation, fungal endophyte, yield, nitrogen use efficiency, and grain nutritional quality parameters on the yield of quinoa in some areas of China. The endophytic microbial community in plants plays a crucial role in plant growth, development, and health, especially in quinoa plants under different nitrogen fertilizer levels. The results from the present study indicated that appropriate nitrogen application significantly enhanced the nitrogen accumulation and yield of quinoa grains during maturity, increasing by 34.54-42.18% and 14.59-30.71%, respectively. Concurrently, protein content, amylose, total starch, ash, and fat content also increased, with respective growth rates of 1.15-18.18%, 30.74-42.53%, 6.40-12.40%, 1.94-21.94%, and 5.32-22.22%. Our constructed interaction network of bacterial and fungal communities revealed that bacteria outnumbered fungi significantly, and most of them exhibited synergistic interactions. The moderate increase in N150 was beneficial for increasing quinoa yield, achieving nitrogen use efficiency (NUE) of over 20%. The N210 was increased, and both the yield and NUE significantly decreased. This study provides novel insights into the impact of nitrogen fertilizer on quinoa growth and microbial communities, which are crucial for achieving agricultural sustainable development.

OsG6PGH1 affects various grain quality traits and participates in the salt stress response of rice.

Cytoplasmic 6-phosphogluconate dehydrogenase (G6PGH) is a key enzyme in the pentose phosphate pathway that is involved in regulating various biological processes such as material metabolism, and growth and development in plants. However, it was unclear if OsG6PGH1 affected rice grain quality traits. We perform yeast one-hybrid experiments and reveal that OsG6PGH1 may interact with OsAAP6. Subsequently, yeast in vivo point-to-point experiments and local surface plasmon resonance experiments verified that OsG6PGH1 can bind to OsAAP6. OsG6PGH1 in rice is a constitutive expressed gene that may be localized in the cytoplasm. OsAAP6 and protein-synthesis metabolism-related genes are significantly upregulated in OsG6PGH1 overexpressing transgenic positive endosperm, corresponding to a significant increase in the number of protein bodies II, promoting accumulation of related storage proteins, a significant increase in grain protein content (GPC), and improved rice nutritional quality. OsG6PGH1 positively regulates amylose content, negatively regulates chalkiness rate and taste value, significantly affects grain quality traits such as appearance, cooking, and eating qualities of rice, and is involved in regulating the expression of salt stress related genes, thereby enhancing the salt-stress tolerance of rice. Therefore, OsG6PGH1 represents an important genetic resource to assist in the design of high-quality and multi-resistant rice varieties.

Comparative transcriptome analysis of vegetable soybean grain discloses genes essential for grain quality.

BACKGROUND: Vegetable soybean is an important vegetable crop in world. Seed size and soluble sugar content are considered crucial indicators of quality in vegetable soybean, and there is a lack of clarity on the molecular basis of grain quality in vegetable soybean. RESULTS: In this context, we performed a comprehensive comparative transcriptome analysis of seeds between a high-sucrose content and large-grain variety (Zhenong 6, ZN6) and a low-sucrose content and small-grain variety (Williams 82, W82) at three developmental stages, i.e. stage R5 (Beginning Seed), stage R6 (Full Seed), and stage R7 (Beginning Maturity). The transcriptome analysis showed that 17,107 and 13,571 differentially expressed genes (DEGs) were identified in ZN6 at R6 (vs. R5) and R7 (vs. R6), respectively, whereas 16,203 and 16,032 were detected in W82. Gene expression pattern and DEGs functional enrichment proposed genotype-specific biological processes during seed development. The genes participating in soluble sugar biosynthesis such as FKGP were overexpressed in ZN6, whereas those responsible for lipid and protein metabolism such as ALDH3 were more enhanced in W82, exhibiting different dry material accumulation between two genotypes. Furthermore, hormone-associated transcriptional factors involved in seed size regulation such as BEH4 were overrepresented in ZN6, exhibiting different seed size regulation processes between two genotypes. CONCLUSIONS: Herein, we not only discovered the differential expression of genes encoding metabolic enzymes involved in seed composition, but also identified a type of hormone-associated transcriptional factors overexpressed in ZN6, which may regulate seed size and soluble content. This study provides new insights into the underlying causes of differences in the soybean metabolites and appearance, and suggests that genetic data can be used to improve its appearance and textural quality.

Zinc and nitrogen mediate the regulation of growth, leading to the upregulation of antioxidant aptitude, physio-biochemical traits, and yield in wheat plants.

An ample amount of water and soil nutrients is required for economic wheat production to meet the current food demands. Nitrogen (N) and zinc (Zn) fertigation in soils can produce a substantial wheat yield for a rapidly increasing population and bring a limelight to researchers. The present study was designed to ascertain N and Zn's synergistic role in wheat growth, yield, and physio-biochemical traits. A pot experiment was laid out under a complete randomized design with four N levels (N1-0, N2-60, N3- 120, and N4-180 kg ha-1), Zn (T1-0, T2-5, T3-10, and T4-15 kg ha-1) with four replications. After the emergence of the plants, N and Zn fertigation was applied in the soil. The growth traits were considerably increased by combined applications as compared to the sole applications of the N and Zn. The photosynthetic pigments were found maximum due to combined applications of N and Zn, which were positively associated with biomass, growth, yield, and wheat grain quality. The combined application also substantially enhances the antioxidant enzyme activities to scavenge the ROS as H2O2 and reduce lipid peroxidation to protect the permeability of the biologic membranes. The combined higher applications of N and Zn were more responsive to ionic balance in a shoot by maintaining the Na+ for osmotic adjustments, accumulating more Ca2+ for cellular signaling; but, combined applications resulted in K+ reduction. Our present results suggest that appropriate sole or combined applications of N and Zn improve wheat's growth, yield, and antioxidant mechanisms. Previous studies lack sufficient information on N and Zn combined fertigation. We intend to investigate both the sole and combined roles of N and Zn to exploit their potential synergistic effects on wheat.

Drip Fertigation Enhances the Responses of Grain Yield and Quality to Nitrogen Topdressing Rate in Irrigated Winter Wheat in North China.

Conventional water and nitrogen (N) management practice in north China, comprising flood irrigation and N fertilizer broadcast (FB), limits sustainable wheat production. Drip fertigation (DF) has been widely adopted in wheat production in recent years and has effectively improved yields. However, the responses of the yield and quality to the N topdressing rate (NTR) under DF are still unclear. This study determined the responses of the wheat yield and quality to NTR under DF, as well as assessing whether DF could synergistically increase the yield and quality. A field experiment was conducted in north China for two seasons (2021-2023) using a split-plot design with three replicates. The main plot used the management practice (FB and DF) and the sub-plot had N treatment (no N applied, and NTRs of 0, 40, 80, 120, and 160 kg ha-1 with 150 kg N ha-1 as basal fertilizer, denoted as N0, T0, T40, T80, T120, and T160, respectively). Our results showed that high and saturated wheat yields (12.08 and 11.46 t ha-1) were obtained under DF at T80, and the highest yields were produced at T160 (11.71 and 11.30 t ha-1) under FB. Compared with FB, the greatest yield increase of 10.4-12.6% was achieved at T80 under DF. A higher spike number due to the increased effective stem percentage and a greater grain weight because of enhanced post-anthesis biomass production (BPpost) explained the improved yield under DF. The enhanced post-anthesis radiation use efficiency (RUE) led to the greater BPpost under DF. The enhanced specific leaf N, antioxidant capacity, and stomatal conductance under DF explained the higher light-saturated photosynthesis rate of flag leaves, which partly led to the increased post-anthesis RUE. NTR higher than 80 kg ha-1 did not enhance the yield, but it significantly improved the gliadin and glutelin contents, thereby leading to a higher total protein content, better gluten characteristics, and superior processing quality. Therefore, drip fertigation is a practical strategy for increasing both yield and quality with reduced water input and appropriate N input in irrigated winter wheat in north China. Applying 80 kg ha-1 of NTR under drip irrigation produces a high yield, but further gain in grain quality needs a higher NTR.

Effects and molecular mechanisms of polyethylene microplastic oxidation on wheat grain quality.

Polyethylene microplastics (PE MPs) are the main MPs in agricultural soils and undergo oxidation upon environmental exposure. However, the influence of MP oxidation on phytotoxicity (especially for crop fruit) is still limited. This study aimed to explore the effect of PE MP oxidation on crop toxicity. Herein, a combination of plant phenotyping, metabolomic, and transcriptomic approaches was used to evaluate the effects of low-oxidation PE (LOPE) and high-oxidation PE (HOPE) on wheat growth, grain quality, and related molecular mechanisms using pot experiments. The results showed that HOPE induced a stronger inhibition of wheat growth and reduction in protein content and mineral elements than LOPE. This was accompanied by root ultrastructural damage and downregulation of carbohydrate metabolism, translation, nutrient reservoir activity, and metal ion binding gene expression. Compared with HOPE, LOPE activated a stronger plant defense response by reducing the starch content by 22.87 %, increasing soluble sugar content by 44.93 %, and upregulating antioxidant enzyme genes and crucial metabolic pathways (e.g., starch and sucrose, linoleic acid, and phenylalanine metabolism). The presence of PE MPs in the environment exacerbates crop growth inhibition and fruit quality deterioration, highlighting the need to consider the environmental and food safety implications of MPs in agricultural soils.