A Study on the Functional Identification of Overexpressing Winter Wheat Expansin Gene TaEXPA7-B in Rice under Salt Stress.

Expansin is a cell wall relaxant protein that is common in plants and directly or indirectly participates in the whole process of plant root growth, development and morphogenesis. A well-developed root system helps plants to better absorb water and nutrients from the soil while effectively assisting them in resisting osmotic stress, such as salt stress. In this study, we observed and quantified the morphology of the roots of Arabidopsis overexpressing the TaEXPAs gene obtained by the research group in the early stage of development. We combined the bioinformatics analysis results relating to EXPA genes in five plants and identified TaEXPA7-B, a member of the EXPA family closely related to root development in winter wheat. Subcellular localization analysis of the TaEXPA7-B protein showed that it is located in the plant cell wall. In this study, the TaEXPA7-B gene was overexpressed in rice. The results showed that plant height, root length and the number of lateral roots of rice overexpressing the TaEXPA7-B gene were significantly higher than those of the wild type, and the expression of the TaEXPA7-B gene significantly promoted the growth of lateral root primordium and cortical cells. The plants were treated with 250 mM NaCl solution to simulate salt stress. The results showed that the accumulation of osmotic regulators, cell wall-related substances and the antioxidant enzyme activities of the overexpressed plants were higher than those of the wild type, and they had better salt tolerance. This paper discusses the effects of winter wheat expansins in plant root development and salt stress tolerance and provides a theoretical basis and relevant reference for screening high-quality expansin regulating root development and salt stress resistance in winter wheat and its application in crop molecular breeding.

Response of soil CO2 emissions and water-carbon use efficiency of winter wheat to different straw returning methods and irrigation scenarios.

BACKGROUND: The shortage of water resources and the increase of greenhouse gas emissions from soil seriously restrict the sustainable development of agriculture. Under the premise of ensuring a stable yield of winter wheat through a reasonable irrigation scenario, identifying a suitable straw returning method will have a positive effect on agricultural carbon sequestration and emission reduction in North China Plain. RESULTS: Straw burying (SR) and straw mulching (SM) were adopted based on traditional tillage under in the winter wheat growing season of 2020-2021 and 2021-2022. Three irrigation scenarios were used for each straw returning method: no irrigation (I0), irrigation 60 mm at jointing stage (I1), and irrigation of 60 mm each at the jointing and heading stages (I2). Soil moisture, soil respiration rate, cumulative soil CO2 emissions, yield, water use efficiency (WUE) and soil CO2 emission efficiency (CEE) were mainly studied. The results showed that, compared to SM, SR improved the utilization of soil water and enhanced soil carbon sequestration. SR reduced soil respiration rate and cumulative soil CO2 emissions in two winter wheat growing seasons, and increased yield by increasing spike numbers. In addition, with an increase in the amount of irrigation, soil CO2 emissions and yield increased. Under SR-I1 treatment, WUE and CEE were the highest. SR-I1 increases crop yields at the same time as reducing soil CO2 emissions. CONCLUSION: The combination of SR and irrigation 60 mm at jointing stage is a suitable straw returning irrigation scenario, which can improve water use and reduce soil CO2 emission in NCP. © 2023 Society of Chemical Industry.

Estimation of winter wheat LAI based on color indices and texture features of RGB images taken by UAV.

BACKGROUND: Leaf area index (LAI) is an important indicator for assessing plant growth and development, and is also closely related to photosynthesis in plants. The realization of rapid accurate estimation of crop LAI plays an important role in guiding farmland production. In study, the UAV-RGB technology was used to estimate LAI based on 65 winter wheat varieties at different fertility periods, the wheat varieties including farm varieties, main cultivars, new lines, core germplasm and foreign varieties. Color indices (CIs) and texture features were extracted from RGB images to determine their quantitative link to LAI. RESULTS: The results revealed that among the extracted image features, LAI exhibited a significant positive correlation with CIs (r = 0.801), whereas there was a significant negative correlation with texture features (r = -0.783). Furthermore, the visible atmospheric resistance index, the green-red vegetation index, the modified green-red vegetation index in the CIs, and the mean in the texture features demonstrated a strong correlation with the LAI with r > 0.8. With reference to the model input variables, the backpropagation neural network (BPNN) model of LAI based on the CIs and texture features (R2 = 0.730, RMSE = 0.691, RPD = 1.927) outperformed other models constructed by individual variables. CONCLUSION: This study offers a theoretical basis and technical reference for precise monitor on winter wheat LAI based on consumer-level UAVs. The BPNN model, incorporating CIs and texture features, proved to be superior in estimating LAI, and offered a reliable method for monitoring the growth of winter wheat. © 2024 Society of Chemical Industry.

Changes in phosphorus-related performance attributes of dryland winter wheat cultivars released between the 1940s and 2010s in Shaanxi Province, China.

BACKGROUND: Water and nutrients are two main determinants of wheat yield, which are vital for maintaining high crop yields. In the present study, the effects of water and phosphate fertilization on wheat yield, photosynthetic parameters, water productivity and phosphate use efficiency were investigated. Five dryland wheat cultivars from the 1940s to the 2010s that are widely cultivated in Shaanxi Province, China, were used. Experiments were conducted from 2019 to 2022 using two irrigation levels (normal rainfall and no precipitation after the reviving stage) and two phosphorus application levels (0 and 100 kg ha-1). RESULTS: Compared with old cultivars ('Mazha'), the grain yield of modern cultivars ('Changhan 58') was 89.24% higher and was closely correlated with chlorophyll index, leaf area index, photosynthetic rate and tillers. With the replacement of cultivars, the phosphorus content, water potential and phosphatase activity of wheat leaves increased. Considering water-phosphorus interactions, the water use efficiency and phosphorus use efficiency of wheat showed a significant positive correlation. CONCLUSION: Our findings indicate that modern wheat cultivars are more responsive to phosphorus. Further analysis revealed that modern varieties have evolved two phosphorus absorption strategies in response to phosphorus deficiency - namely, the formation of a phosphorus supply source, which may result in larger numbers of green organs; and an increase in phosphorus sinks, which tended to activation and transport of plant phosphorus. Our results may thus contribute to water conservation, increased yields and the development of strategies for efficient phosphorus fertilization. © 2024 Society of Chemical Industry.

Effects of climate change and deep fertilization on the growth and yield of winter wheat in the Loess Plateau of China.

BACKGROUND: Global temperature is projected to rise continuously under climate change, negatively impacting the growth and yield of winter wheat. Optimizing traditional agricultural measures is necessary to mitigate potential winter wheat yield losses caused by future climate change. This study aims to explore the variations in winter wheat growth and yield on the Loess Plateau of China under future climate change, identify the key meteorological factors affecting winter wheat growth and yield, and analyze the differences in winter wheat yield and root characteristics under different fertilization depths. RESULTS: Meteorological data from 20 General Circulation Models were applied to drive the Decision Support System for Agrotechnology Transfer model, simulating the future growth characteristics of winter wheat under various fertilization depths. The Random Forest model was used to determine the relative importance of meteorological factors influencing winter wheat yield, root length density and leaf area index. The results showed that temperature and high emission concentration were primary factors influencing crop yield under future climate change. The temperature increase projected from 2021 to 2100 would be anticipated to shorten the phenology period of winter wheat by 2-16 days and reduce grain yield by 2.9-12.7% compared to the period from 1981 to 2020. Conversely, the root length density and root weight of winter wheat would increase by 1.2-10.9% and 0.2-24.1%, respectively, in the future, and excessive allocation of root system resources was identified as a key factor contributing to the reduction in winter wheat yield. Compared with the shallow fertilization treatment (N5), the deep fertilization treatments (N15 and N25) increased the proportion of roots in the deep soil layer (30-60 cm) by 2.7-10.2%. Because of the improvement in root structure, the decline in winter wheat yield under deep fertilization treatments in the future is expected to be reduced by 1.2% to 6.5%, whereas water use efficiency increases by 1.1% to 2.4% compared to the shallow fertilization treatment. CONCLUSION: The deep fertilization treatment can enhance the root structure of winter wheat and increase the proportion of roots in the deep soil layer, thereby effectively mitigating the decline in winter wheat yield under future climate change. Overall, optimizing fertilization depth effectively addresses the reduced winter wheat yield risks and agricultural production challenges under future climate change. © 2024 Society of Chemical Industry.

Long-term annual mapping and spatial-temporal dynamic analysis of winter wheat in Shandong Province based on spatial-temporal data fusion (2000-2022).

Winter wheat, as one of the world's key staple crops, plays a crucial role in ensuring food security and shaping international food trade policies. However, there has been a relative scarcity of high-resolution, long time-series winter wheat maps over the past few decades. This study utilized Landsat and Sentinel-2 data to produce maps depicting winter wheat distribution in Google Earth Engine (GEE). We further analyzed the comprehensive spatial-temporal dynamics of winter wheat cultivation in Shandong Province, China. The gap filling and Savitzky-Golay filter method (GF-SG) was applied to address temporal discontinuities in the Landsat NDVI (Normalized Difference Vegetation Index) time series. Six features based on phenological characteristics were used to distinguish winter wheat from other land cover types. The resulting maps spanned from 2000 to 2022, featuring a 30-m resolution from 2000 to 2017 and an improved 10-m resolution from 2018 to 2022. The overall accuracy of these maps ranged from 80.5 to 93.3%, with Kappa coefficients ranging from 71.3 to 909% and F1 scores from 84.2 to 96.9%. Over the analyzed period, the area dedicated to winter wheat cultivation experienced a decline from 2000 to 2011. However, a notable shift occurred with an increase in winter wheat acreage observed from 2014 to 2017 and a subsequent rise from 2018 to 2022. This research highlights the viability of using satellite observation data for the long-term mapping and monitoring of winter wheat. The proposed methodology has long-term implications for extending this mapping and monitoring approach to other similar areas.

Assessment of soil fertility and nutrient management strategies in calcareous soils of Khuzestan province: a case study using the Nutrient Index Value method.

Soil fertility (SF) is a crucial factor that directly impacts the performance and quality of crop production. To investigate the SF status in agricultural lands of winter wheat in Khuzestan province, 811 samples were collected from the soil surface (0-25 cm). Eleven soil properties, i.e., electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (TN), calcium carbonate equivalent (CCE), available phosphorus (Pav), exchangeable potassium (Kex), iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), and soil pH, were measured in the samples. The Nutrient Index Value (NIV) was calculated based on wheat nutritional requirements. The results indicated that 100%, 93%, and 74% of the study areas for CCE, pH, and EC fell into the low, moderate, and moderate to high NIV classes, respectively. Also, 25% of the area is classified as low fertility (NIV < 1.67), 75% falls under medium fertility (1.67 < NIV value < 2.33), and none in high fertility (NIV value > 2.33). Assessment of the mean wheat yield (AWY) and its comparison with NIV showed that the highest yield was in the Ramhormoz region (5200 kg.ha-1), while the lowest yield was in the Hendijan region (3000 kg.ha-1) with the lowest EC rate in the study area. Elevated levels of salinity and CCE in soils had the most negative impact on irrigated WY, while Pav, TN, and Mn availability showed significant effects on crop production. Therefore, implementing SF management practices is essential for both quantitative and qualitative improvement in irrigated wheat production in Khuzestan province.

Selenium uptake, translocation, subcellular distribution and speciation in winter wheat in response to phosphorus application combined with three types of selenium fertilizer.

BACKGROUND: Selenium (Se) deficiency causes a series of health disorders in humans, and Se concentrations in the edible parts of crops can be improved by altering exogenous Se species. However, the uptake, transport, subcellular distribution and metabolism of selenite, selenate and SeMet (selenomethionine) under the influence of phosphorus (P) has not been well characterized. RESULTS: The results showed that increasing the P application rate enhanced photosynthesis and then increased the dry matter weight of shoots with selenite and SeMet treatment, and an appropriate amount of P combined with selenite treatment increased the dry matter weight of roots by enhancing root growth. With selenite treatment, increasing the P application rate significantly decreased the concentration and accumulation of Se in roots and shoots. P1 decreased the Se migration coefficient, which could be attributed to the inhibited distribution of Se in the root cell wall, but increased distribution of Se in the root soluble fraction, as well as the promoted proportion of SeMet and MeSeCys (Se-methyl-selenocysteine) in roots. With selenate treatment, P0.1 and P1 significantly increased the Se concentration and distribution in shoots and the Se migration coefficient, which could be attributed to the enhanced proportion of Se (IV) in roots but decreased proportion of SeMet in roots. With SeMet treatment, increasing the P application rate significantly decreased the Se concentration in shoots and roots but increased the proportion of SeCys2 (selenocystine) in roots. CONCLUSION: Compared with selenate or SeMet treatment, treatment with an appropriate amount of P combined with selenite could promote plant growth, reduce Se uptake, alter Se subcellular distribution and speciation, and affect Se bioavailability in wheat.

Neglecting acclimation of photosynthesis under drought can cause significant errors in predicting leaf photosynthesis in wheat.

Extreme climatic events, such as heat waves, cold snaps and drought spells, related to global climate change, have become more frequent and intense in recent years. Acclimation of plant physiological processes to changes in environmental conditions is a key component of plant adaptation to climate change. We assessed the temperature response of leaf photosynthetic parameters in wheat grown under contrasting water regimes and growth temperatures (Tgrowth ). Two independent experiments were conducted under controlled conditions. In Experiment 1, two wheat genotypes were subjected to well-watered or drought-stressed treatments; in Experiment 2, the two water regimes combined with high, medium and low Tgrowth were imposed on one genotype. Parameters of a biochemical C3 -photosynthesis model were estimated at six leaf temperatures for each factor combination. Photosynthesis acclimated more to drought than to Tgrowth . Drought affected photosynthesis by lowering its optimum temperature (Topt ) and the values at Topt of light-saturated net photosynthesis, stomatal conductance, mesophyll conductance, the maximum rate of electron transport (Jmax ) and the maximum rate of carboxylation by Rubisco (Vcmax ). Topt for Vcmax was up to 40°C under well-watered conditions but 24-34°C under drought. The decrease in photosynthesis under drought varied among Tgrowth but was similar between genotypes. The temperature response of photosynthetic quantum yield under drought was partly attributed to photorespiration but more to alternative electron transport. All these changes in biochemical parameters could not be fully explained by the changed leaf nitrogen content. Further model analysis showed that both diffusional and biochemical parameters of photosynthesis and their thermal sensitivity acclimate little to Tgrowth , but acclimate considerably to drought and the combination of drought and Tgrowth . The commonly used modelling approaches, which typically consider the response of diffusional parameters, but ignore acclimation responses of biochemical parameters to drought and Tgrowth , strongly overestimate leaf photosynthesis under variable temperature and drought.

First record of cyst nematode (Heterodera filipjevi) on winter wheat from Shanxi Province in North China.

Heterodera avenae, H. filipjevi, and H. laptipons are considered to be the major cyst nematode pathogens affecting most cereals and causing severe crop losses (Smiley and Yan 2015). In China, H. filipjevi was first recorded in Xuchang, Henan Province (Peng et al. 2010). Recently, H. filipjevi has been found in Anhui, Hebei, Shandong and Xinjiang provinces of China (Cui et al. 2021). To further understand the latest occurrence and distribution of H. filipjevi in China, a survey of cyst nematodes was conducted in the wheat planting area of Shanxi Province of North China from June 2018 to November 2020. White female cysts (5.8 ± 2.99 cysts per plant) were found on wheat roots in the sandy soil, and wheat was displaying symptoms of dwarfing, yellowing, and had few tillers in Licheng of Changzhi (N36°32´010´´, E113°27´039´´; N36°29´050´´, E113°23´023´´; N36°29´035´´, E113°22´020´´) and Zezhou of Jincheng (N35°33´057´´, E112°56´020´´) in Shanxi Province, and second-stage juveniles (J2s) were obtained from 13 soil samples using the sieving-decanting method. Four of the 13 samples were identified as H. filipjevi on the basis of morphological and molecular studies of female cysts and J2s. Morphologically, the cysts were lemon shaped and featured a pronounced vulval cone. The color ranged from light to dark brown. The white female shell was covered with a white crystalline layer. The vulval cone was bifenestrate with horseshoe-shaped bullae numerous and distinct, and a strongly developed underbridge. The main measurements (mean ± SD, range) of cysts (n = 13) were as follows: body length including neck 780.5 ± 53.9 µm (692 to 843 µm); body width 527.3 ± 55.5 µm (435 to 620 µm); length/width ratio 1.50 ± 0.21 (1.20 to 1.93); fenestra length 55.5 ± 4.1 µm (49 to 61 µm); fenestra width 24.8 ± 2.2 µm (21.1 to 28.8 µm); vulval slit length 9.0 ± 0.7 µm (7.8 to 9.6 µm); and underbridge length 66.8 ± 5.0 µm (61 to 77 µm). The measurements of J2s (n = 13) were as follows: body length 554.4 ± 23.4 µm (520to 587 µm); stylet length 22.7 ± 0.7 µm (21.5 to 23.8 µm); tail length 61.0 ± 5.5 µm (51.2 to 68.9 µm); and hyaline tail terminus length 37.3 ± 2.7 µm (33.4 to 42.3 µm). These morphological measurements are within the range characteristic of H. filipjevi (Peng et al. 2010). Genomic DNA was extracted from individual cyst (n = 6) and the rDNA internal transcribed spacer (ITS) sequence was amplified using the universal primers TW81 and AB28 (Joyce et al. 1994). The PCR test for each sample was repeated five times. The obtained ITS sequences (GenBank accession No. OQ421499 to OQ421502, 1054 bp) showed more than 99.5% similarity to those of H. filipjevi from the United States (GU079654 and KP878490), Turkey (KR704304 and KR704292), and China (MW789611, KY448473 and KT314234). The results were confirmed again by the species-specific primers HfF1 and HfR1of H. filipjevi and the target PCR fragments of 646 bp were obtained (Peng et al. 2013). The pathogenicity of H. filipjevi was verified by infesting winter wheat (Triticum aestivum 'Wenmai 19') and studying nematode developmentand reproduction with growth chamber (Cui et al. 2015). Eggs were hatched at 14-16°C, and freshly hatched J2s were used to inoculate wheat plants when the roots were approximately 1-centimeter long. Fifteen wheat plants were inoculated with 200 J2s, and three wheat plants without J2s were set as controls (Cui et al. 2021). Parasitic J2s and third- and fourth-stage juveniles were found in roots stained with acid fuchsin at 5, 15, and 25 days after inoculation (DAI), adult females were detected at 50 DAI, and a mean of 23.7 cysts per pot were extracted at 70 DAI (Cui et al. 2015). The morphological and molecular characteristics of the new cysts were identical to those of the H. filipjevi cysts from the original field samples, and no cysts formed in the control groups. Wheat is the main food and economic crop in Shanxi, and H. filipjevi, a potential threat to cereal crop production in Shanxi, should arouse sufficient attention. H. filipjevi is major cyst nematode pathogens of wheat and shows high prevalence in China. The loss of wheat production due to H. filipjevi is as high as 32.3% when the initial density ≥ 64 eggs/mL in soil (Li 2018). To the best of our knowledge, this is the first report of H. filipjevi in Shanxi Province of North China.

Evaluation of Seed Transmission Rates of Wheat Streak Mosaic Virus in Mechanically Inoculated Winter and Spring Wheat Cultivars in Montana.

Wheat streak mosaic disease is caused by wheat streak mosaic virus (WSMV) and two other viruses and persistently limits wheat yields in the Great Plains region of the United States. Seed transmission of viruses is an important consideration in international movement and is important epidemiologically. Seed transmission of WSMV in wheat was first reported from Australia in 2005, but there is little data from United States cultivars on the rate of seed transmission. In 2018, mechanically inoculated winter and spring wheat cultivars were evaluated in Montana. We found differences in WSMV seed transmission rates between winter and spring wheat, with average transmission rates in spring wheat (3.1%) being five times higher compared to winter wheat (0.6%). Seed transmission rates in spring wheat were twice as high as the highest previously reported transmission rate for individual genotypes, 1.5%. The results from this study provide a strong argument for increasing the current testing of seed for breeding purposes prior to international movement when WSMV has been observed and caution against using grain from WSMV-infected fields as seed source because it can heighten the risk of wheat streak mosaic outbreaks.

OXPHOS Organization and Activity in Mitochondria of Plants with Different Life Strategies.

The study of the supramolecular organization of the mitochondrial oxidative phosphorylation system (OXPHOS) in various eukaryotes has led to the accumulation of a considerable amount of data on the composition, stoichiometry, and architecture of its constituent superstructures. However, the link between the features of system arrangement and the biological characteristics of the studied organisms has been poorly explored. Here, we report a comparative investigation into supramolecular and functional OXPHOS organization in the mitochondria of etiolated shoots of winter wheat (Triticum aestivum L.), maize (Zea mays L.), and pea (Pisum sativum L.). Investigations based on BN-PAGE, in-gel activity assays, and densitometric analysis revealed both similarities and specific OXPHOS features apparently related to the life strategies of each species. Frost-resistant winter wheat was distinguished by highly stable basic I1III2IVa/b respirasomes and V2 dimers, highly active complex I, and labile complex IV, which were probably essential for effective OXPHOS adaptation during hypothermia. Maize, a C4 plant, had the highly stable dimers IV2 and V2, less active complex I, and active alternative NAD(P)H dehydrogenases. The latter fact could contribute to successful chloroplast-mitochondrial cooperation, which is essential for highly efficient photosynthesis in this species. The pea OXPHOS contained detergent-resistant high-molecular respirasomes I1-2III2IVn, highly active complexes IV and V, and stable succinate dehydrogenase, suggesting an active energy metabolism in organelles of this plant. The results and conclusions are in good agreement with the literature data on the respiratory activity of mitochondria from these species and are summarized in a proposed scheme of organization of OXPHOS fragments.

Overexpression of TaMYB4 Confers Freezing Tolerance in Arabidopsis thaliana.

Freezing stress is one of the main factors limiting the growth and yield of wheat. In this study, we found that TaMYB4 expression was significantly upregulated in the tillering nodes of the strong cold-resistant winter wheat variety Dongnongdongmai1 (Dn1) under freezing stress. Weighted gene co-expression network analysis, qRT-PCR and protein-DNA interaction experiments demonstrated that monodehydroascorbate reductase (TaMDHAR) is a direct target of TaMYB4. The results showed that overexpression of TaMYB4 enhanced the freezing tolerance of transgenic Arabidopsis. In TaMYB4 overexpression lines (OE-TaMYB4), AtMDHAR2 expression was upregulated and ascorbate-glutathione (AsA-GSH) cycle operation was enhanced. In addition, the expression of cold stress marker genes such as AtCBF1, AtCBF2, AtCBF3, AtCOR15A, AtCOR47, AtKIN1 and AtRD29A in OE-TaMYB4 lines was significantly upregulated. Therefore, TaMYB4 may increase freezing tolerance as a transcription factor (TF) in Arabidopsis through the AsA-GSH cycle and DREB/CBF signaling pathway. This study provides a potential gene for molecular breeding against freezing stress.

Effects of supplemental irrigation on grain yield and water and nitrogen efficiencies of winter wheat in the North China Plain.

BACKGROUND: Aiming at unbalanced coordination of irrigation and fertilization of winter wheat in the eastern North China Plain, this study investigated the effect of fertigation on wheat grain yield, grain quality, and water use efficiency (WUE) and nitrogen use efficiency (NUE) in seven irrigation and nitrogen (N) fertilization treatments. Under the field conditions, the traditional irrigation and fertilization method (total N amount of 240 kg ha-1 , application of 90 kg ha-1 at sowing irrigation at jointing and anthesis, with topdressing N of 150 kg ha-1 at jointing) was used as the control (CK). There were six fertigation treatments to compare with CK. For the fertigation treatments, the total amount of N application was set to 180 kg ha-1 and 90 kg ha-1 was applied at sowing and the remaining N fertilizer was applied through fertigation. The fertigation treatments included the combination of three fertigation frequencies (S2: at jointing and anthesis; S3: at jointing, anthesis, and filling; S4: at jointing, booting, anthesis, and filling) and two soil water replenishment depths (M1: 0-10 cm; M2: 0-20 cm). The six treatments were S4M2, S4M1, S3M2, S3M1, S2M2, and S2M1. RESULT: Compared with CK, three and four irrigations (S3 and S4) maintained higher soil and plant analyzer development value and photosynthetic rate after anthesis. These treatments increased soil water extraction while reducing crop water consumption during the whole growing season, promoted the assimilation and translocation of dry matter into the grain after anthesis, and increased the 1000-grain weight. These fertigation treatments also significantly increased WUE and NUE. At the same time, the high grain protein content and grain protein yield were maintained. Compared with the CK, high wheat yield was maintained by S3M1 (drip irrigation fertilizer at the jointing, anthesis, and filling, and the depth of the moisture replenishment is 10 cm). This fertigation treatment significantly increased yield by 7.6%, WUE by 30%, NUE by 41.4%, and partial factor productivity from applied N by 25.8%; grain yield, grain protein content, and grain protein yield also performed well. CONCLUSION: Consequently, S3M1 treatment was suggested to be a good practice for reducing irrigation water and N input in the eastern North China Plain. © 2023 Society of Chemical Industry.

Genetic variation in nitrogen-use efficiency and its associated traits in dryland winter wheat (Triticum aestivum L.) cultivars released from the 1940s to the 2010s in Shaanxi Province, China.

BACKGROUND: Improving the nitrogen-use efficiency (NUE) of wheat can help mitigate the problems of poor soil fertility under dryland conditions. We conducted field experiments using three nitrogen (N) fertilization levels (0, 120, and 180 kg ha-1 ) applied to eight dryland wheat cultivars to assess NUE and its associated traits. RESULTS: The grain yield significantly increased with the improvement in variety, mainly as a result of a substantial increase in 1000-grain weight and harvest index. Modern wheat varieties have stabilized at an optimal plant height and exhibited improved performance in terms of NUE, partial N productivity, N harvest index, and grain protein content compared to older varieties. The NUE of wheat gradually increased with variety replacement. The net photosynthesis rate of the flag leaves in the filling stage improved with the year of cultivar release; Increasing soil-plant analysis development (SPAD) values of flag leaves in the flowering and filling stages were observed over time, with the flag leaves of modern varieties showing a high chlorophyll content in the filling stage. Additionally, the principal component analysis showed that the SPAD value, grain number per unit area, transpiration rate, leaf area, and grain protein content positively contributed to the clustering of the N180 and modern cultivars (from the 2000s to 2010s). CONCLUSION: Overall, high levels of N application did not significantly improve the NUE of wheat. However, modern wheat varieties can optimize N distribution, increase flag leaf photosynthetic capacity, and improve photosynthesis ability, thus enhancing NUE to achieve high yields under a suitable level of N supply. © 2022 Society of Chemical Industry.

Delayed irrigation at the jointing stage increased the post-flowering dry matter accumulation and water productivity of winter wheat under wide-precision planting pattern.

BACKGROUND: The North China Plain (NCP) faces a severe water shortage, and the amount of rainfall cannot guarantee the growth and development of winter wheat. Therefore, it is important to explore a suitable irrigation and planting pattern to solve the problem of water shortage in this region. RESULTS: A 4-year experiment was carried out in the NCP during 2015-2019. The main plots included two planting patterns: a wide-precision planting pattern (W) and a conventional planting pattern. Two irrigation regimes were established for each planting pattern: 60-mm irrigation at the jointing stage (I1) and 60-mm irrigation delayed 10 days at the jointing stage (I2). The soil water consumption, dry matter translocation, grain yield and crop water productivity were investigated. The results showed that WI2 treatment obtained the highest grain yield and crop water productivity. The wide-precision planting pattern could significantly decrease soil water consumption; however, delayed irrigation effectively reduced soil water consumption only in normal rainfall years. The coupling of delayed irrigation at the jointing stage and a wide-precision planting pattern significantly enhanced dry matter accumulation after flowering and the contribution of dry matter accumulation after flowering to grain yield during the growing seasons. WI2 could decrease the evapotranspiration and improve the grain yield, thus increasing crop water productivity. CONCLUSION: The combination of a wide-precision planting pattern and delayed irrigation at the jointing stage was the appropriate agronomic practice for efficient grain yield and crop water productivity in the North China Plain. © 2022 Society of Chemical Industry.

Genetic architecture of end-use quality traits in soft white winter wheat.

BACKGROUND: Genetic improvement of end-use quality is an important objective in wheat breeding programs to meet the requirements of grain markets, millers, and bakers. However, end-use quality phenotyping is expensive and laborious thus, testing is often delayed until advanced generations. To better understand the underlying genetic architecture of end-use quality traits, we investigated the phenotypic and genotypic structure of 14 end-use quality traits in 672 advanced soft white winter wheat breeding lines and cultivars adapted to the Pacific Northwest region of the United States. RESULTS: This collection of germplasm had continuous distributions for the 14 end-use quality traits with industrially significant differences for all traits. The breeding lines and cultivars were genotyped using genotyping-by-sequencing and 40,518 SNP markers were used for association mapping (GWAS). The GWAS identified 178 marker-trait associations (MTAs) distributed across all wheat chromosomes. A total of 40 MTAs were positioned within genomic regions of previously discovered end-use quality genes/QTL. Among the identified MTAs, 12 markers had large effects and thus could be considered in the larger scheme of selecting and fixing favorable alleles in breeding for end-use quality in soft white wheat germplasm. We also identified 15 loci (two of them with large effects) that can be used for simultaneous breeding of more than a single end-use quality trait. The results highlight the complex nature of the genetic architecture of end-use quality, and the challenges of simultaneously selecting favorable genotypes for a large number of traits. This study also illustrates that some end-use quality traits were mainly controlled by a larger number of small-effect loci and may be more amenable to alternate selection strategies such as genomic selection. CONCLUSIONS: In conclusion, a breeder may be faced with the dilemma of balancing genotypic selection in early generation(s) versus costly phenotyping later on.

Drought exerts a greater influence than growth temperature on the temperature response of leaf day respiration in wheat (Triticum aestivum).

We assessed how the temperature response of leaf day respiration (Rd ) in wheat responded to contrasting water regimes and growth temperatures. In Experiment 1, well-watered and drought-stressed conditions were imposed on two genotypes; in Experiment 2, the two water regimes combined with high (HT), medium (MT) and low (LT) growth temperatures were imposed on one of the genotypes. Rd was estimated from simultaneous gas exchange and chlorophyll fluorescence measurements at six leaf temperatures (Tleaf ) for each treatment, using the Yin method for nonphotorespiratory conditions and the nonrectangular hyperbolic fitting method for photorespiratory conditions. The two genotypes responded similarly to growth and measurement conditions. Estimates of Rd for nonphotorespiratory conditions were generally higher than those for photorespiratory conditions, but their responses to Tleaf were similar. Under well-watered conditions, Rd and its sensitivity to Tleaf slightly acclimated to LT, but did not acclimate to HT. Temperature sensitivities of Rd were considerably suppressed by drought, and the suppression varied among growth temperatures. Thus, it is necessary to quantify interactions between drought and growth temperature for reliably modelling Rd under climate change. Our study also demonstrated that the Kok method, one of the currently popular methods for estimating Rd , underestimated Rd significantly.

Chlorophyll fluorescence and grain filling characteristic of wheat (Triticum aestivum L.) in response to nitrogen application level.

BACKGROUND: This study aims to understand the influence of chlorophyll fluorescence parameters on yield of winter wheat in some areas of China. Nitrogen (N) application is believed to improve photosynthesis in flag leaf ultimately increase final yield. METHODS AND RESULTS: To understand the response of chlorophyll fluorescence parameters of wheat, flag leaf and the effect of N fertilization was carried out at booting stage under greenhouse during year 2018-2019 using winter wheat cultivar "Yunhan-20410' 'Yunhan-618". The results showed that the maximum chlorophyll content of flag leaves occurred at booting stage. Under, Yunhan-20410 condition, maximum photochemical quantum efficiency (FV/Fm), potential activity (ΦPSII), potential activity of PSII (FV/FO), and photochemical quenching coefficient (qp) showed "high-low" variation, and the maximum values were observed between May 4 and May 12. However, Yunhan-20410 showed FV/Fm, FV/FO, and qp showed "low-high-low" curve at booting stage. Compared to Yunhan-618, Yunhan-20410 at booting stage significantly decreased FV/Fm, FV/FO, qp, and ΦPSII (P<0.05), and non-photochemical quenching (NPQ) significantly increased (P<0.05). CONCLUSION: The outcome of present investigation suggest that chlorophyll fluorescence parameters could be valuable insight to understand yield stability under stress condition. Moreover, the investigated parameters could be useful criteria for selection of genotypes under varying nitrogen application levels.

Spatial and interdecadal differences in climatic suitability for winter wheat in China from 1985 to 2014.

The evident climate jump after 2000 in China may have greatly influenced the production of winter wheat, which is one of the nation's major grain crops. To evaluate the impacts of climate change on winter wheat production and identify the climatic factors primarily responsible, we used daily meteorological data from 2244 stations and integrated indicators to examine the decadal changes in the potential plantable zone (PPZ), growth periods, and climatic suitability for winter wheat in China from 1985 to 1999 and from 2000 to 2014. The results showed the following: (1) The PPZ has decreased by approximately 9%, and the main reason may be the increased frequency of extreme cold events in northern China from 2000 to 2014. (2) In most of the PPZ, the suitable sowing date has been delayed, the potential maturity date has advanced, and total days during the potential growing season have significantly decreased because of the increasing temperature. (3) The suitable area and optimal area of winter wheat have significantly decreased by 9% and 13%, respectively. The changes in climatic suitability are affected by both temperature and radiation in the north, whereas the impact is more from precipitation in the south. The climate may be changing in a direction unsuitable for winter wheat. As global warming and climate extremes intensify in the future, winter wheat production may become more challenging, and adequate measures should be adopted to guarantee reliable and high yields.