Potassium (K) is a primary limiting macronutrient for plant growth. Inappropriate K application decisions can lead to reduced yield and potassium use efficiency (KUE). Given the scarcity and non-renewable nature of K resources, developing an indicator for critical K input is essential. The apparent K balance is a simplified method calculated from fertilizer inputs and crop K uptake, enabling straightforward agronomic evaluation. Here, we hypothesize that the apparent K balance serves as a valuable indicator for determining critical K input. A twelveyear field trial with six K treatments (0, 30, 60, 90, 120, and 150 kg K ha-1 per year) was conducted to assess grain yield response to apparent K balance, establish a K input-output framework, and determine critical K input in a winter wheat-summer maize rotation system in North China. The crop yield, K uptake, and K fertilizer recovery efficiency initially increased but then declined with increasing K fertilizer rates, likely due to excessive Kinduced nutrient imbalance and salt stress. The K balance threshold can be determined based on the target yield to be pursued. A K balance of 0 -9.77 kg K ha-1 per year achieved optimal yield and maintained soil fertility. The K input-output framework provided a clear visualization of the K balance and KUE relationships. The critical K input range of 56.6 -62.5 kg K ha-1 achieved high yields with KUE improving to 85 -100 %, while sustaining high levels of soil available K and organic matter. Overall, optimizing K input within appropriate K balance thresholds enhances crop yield, KUE and soil quality simultaneously. This study provides new insights for determining critical K balance and K input, offering guidance for field-scale K management.

IntroductionThe plant genome encodes a plethora of proteins with structural similarity to animal receptor protein kinases, collectively known as receptor-like protein kinases (RLKs), which predominantly localize to the plasma membrane where they activate their kinase domains to convey extracellular signals to the interior of the cell, playing crucial roles in various signaling pathways. Despite the large number of members within the RLK family, to date, only a few have been identified as pattern-recognition receptors (PRRs), leaving many potential RLKs that could play roles in plant immunity undiscovered.MethodsIn this study, a recombinant strategy was initially employed to screen the kinase domains of 133 RLKs in the Arabidopsis genome to determine their involvement in the pathogen-triggered immunity (PTI) pathway. Subsequently, 6 potential immune-related recombinant RLKs (rRLKs) were selected for the creation of transgenic materials and underwent functional characterization analysis. Finally, a sequence analysis was conducted on the kinase domains of these 133 RLKs as well as the known immune RLK receptor kinase domains from other species.ResultsIt was found that 24 rRLKs activated the PTI response in Arabidopsis fls2 mutant protoplasts following flg22 treatment. Consistently, when 6 of these rRLKs were individually expressed in fls2 background, they exhibited diverse PTI signal transduction capabilities via different pathways while all retained membrane localization. Intriguingly, sequence analysis revealed multiple conserved amino acid sites within kinase domains of these experimentally identified immune-related RLKs in Arabidopsis. Importantly, these patterns are also preserved in RLKs involved in PTI in other species.DiscussionThis study, on one hand, identifies common features that theoretically can enhance our understanding of immune-related RLKs and facilitate the discovery of novel immune-related RLKs in the future. On the other hand, it provides experimental evidence for the use of recombinant technique to develop diverse rRLKs for molecular breeding, thereby conferring high resistance to plants without compromising their normal growth and development.

Phosphorus (P) is a nonrenewable resource and a critical element for plant growth that plays an important role in improving crop yield. Excessive P fertilizer application is widespread in agricultural production, which not only wastes phosphate resources but also causes P accumulation and groundwater pollution. Here, we hypothesized that the apparent P balance of a crop system could be used as an indicator for identifying the critical P input in order to obtain a high yield with high phosphorus use efficiency (PUE). A 12-year field experiment with P fertilization rates of 0, 45, 90, 135, 180, and 225 kg P2O5 ha-1 was conducted to determine the crop yield, PUE, and soil Olsen-P value response to P balance, and to optimize the P input. Annual yield stagnation occurred when the P fertilizer application exceeded a certain level, and high yield and PUE levels were achieved with annual P fertilizer application rates of 90-135 kg P2O5 ha-1. A critical P balance range of 2.15-4.45 kg P ha-1 was recommended to achieve optimum yield with minimal environmental risk. The critical P input range estimated from the P balance was 95.7-101 kg P2O5 ha-1, which improved relative yield (>90%) and PUE (90.0-94.9%). In addition, the P input-output balance helps in assessing future changes in Olsen-P values, which increased by 4.07 mg kg-1 of P for every 100 kg of P surplus. Overall, the P balance can be used as a critical indicator for P management in agriculture, providing a robust reference for limiting P excess and developing a more productive, efficient and environmentally friendly P fertilizer management strategy.

Long noncoding RNAs (lncRNAs) are transcripts with lengths of more than 200 nt and limited protein-coding potential. They were found to play important roles in plant stress responses. In this study, the maize drought-tolerant inbred line AC7643 and drought-sensitive inbred line AC7729/TZSRW, as well as their recombinant inbred lines (RILs) were selected to identify drought-responsive lncRNAs in roots. Compared with non-responsive lncRNAs, drought-responsive lncRNAs had different sequence characteristics in length of genes and number of exons. The ratio of down-regulated lncRNAs induced by drought was significantly higher than that of coding genes; and lncRNAs were more widespread expressed in recombination sites in the RILs. Additionally, by integration of the modifications of DNA 5-methylcytidine (5mC), histones, and RNA N6-methyladenosine (m6A), it was found that the enrichment of histone modifications associated with transcriptional activation in the genes generated lncRNAs was lower that coding genes. The lncRNAs-mRNAs co-expression network, containing 15,340 coding genes and 953 lncRNAs, was constructed to investigate the molecular functions of lncRNAs. There are 13 modules found to be associated with survival rate under drought. We found nine SNPs located in lncRNAs among the modules associated with plant survival under drought. In conclusion, we revealed the characteristics of lncRNAs responding to drought in maize roots based on multiomics studies. These findings enrich our understanding of lncRNAs under drought and shed light on the complex regulatory networks that are orchestrated by the noncoding RNAs in response to drought stress.

IntroductionHumic substances (HSs), components of plant biostimulants, are known to influence plant physiological processes, nutrient uptake and plant growth, thereby increasing crop yield. However, few studies have focused on the impact of HS on overall plant metabolism, and there is still debate over the connection between HS’ structural characteristics and their stimulatory actions.MethodsIn this study, two different HSs (AHA, Aojia humic acid and SHA, Shandong humic acid) screened in a previous experiment were chosen for foliar spraying, and plant samples were collected on the tenth day after spraying (62 days after germination) to investigate the effects of different HSs on photosynthesis, dry matter accumulation, carbon and nitrogen metabolism and overall metabolism in maize leaf.Results and discussionThe results showed different molecular compositions for AHA and SHA and a total of 510 small molecules with significant differences were screened using an ESI-OPLC-MS techno. AHA and SHA exerted different effects on maize growth, with the AHA inducing more effective stimulation than the SHA doing. Untargeted metabolomic analysis revealed that the phospholipid components of maize leaves treated by SHA generally increased significantly than that in the AHA and control treatments. Additionally, both HS-treated maize leaves exhibited different levels of accumulation of trans-zeatin, but SHA treatment significantly decreased the accumulation of zeatin riboside. Compared to CK treatment, AHA treatment resulted in the reorganization of four metabolic pathways: starch and sucrose metabolism, TCA cycle, stilbenes, diarylheptanes, and curcumin biosynthesis, and ABC transport, SHA treatment modified starch and sucrose metabolism and unsaturated fatty acid biosynthesis. These results demonstrate that HSs exert their function through a multifaceted mechanism of action, partially connected to their hormone-like activity but also involving hormoneindependent signaling pathways.

IntroductionMaize has a high demand for nitrogen during the growth period. The study of metabolic changes in maize can provide a theoretical basis for rational nitrogen nutrition regulation.MethodsIn order to investigate the changes of different metabolites and their metabolic pathways in maize leaves under nitrogen stress, we used ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) for metabolomic analysis of maize leaves under different nitrogen treatments at three critical growth stages (V4, V12 and R1) in a pot experiment under natural conditions.Results and discussionThe results showed that nitrogen stress significantly affected sugar metabolism and nitrogen metabolism, and affected carbon and nitrogen balance, and the effects of stress on maize leaves metabolism increased with the growth process. Metabolic pathways such as the TCA cycle and starch and sucrose metabolism were mainly affected at the seeding stage (V4). The stress response to nitrogen deficiency also showed significant upregulation of flavonoids such as luteolin and astragalin during the booting stage (V12) and anthesis-silking stage (R1). During R1 stage, the synthesis of tryptophan and phenylalanine and the degradation of lysine were significantly affected. Compared with nitrogen stress, the metabolic synthesis of key amino acids and jasmonic acid were intensified and the TCA cycle was promoted under nitrogen sufficiency conditions. This study initially revealed that the response mechanism of maize to nitrogen stress at the metabolic level.

Spectral technology is theoretically effective in diagnosing N stress in maize (Zea mays L.), but its application is affected by varietal differences. In this study, the responses to N stress, leaf N spectral diagnostic models and the differences between two maize varieties were analysed. The variety “Jiyu 5817” exhibited a greater response to different N stresses at the 12-leaf stage (V12), while “Zhengdan 958” displayed a greater response in the silking stage (R1). Correlation analysis showed that the spectral bands more sensitive to leaf N content were 548–556 nm and 706–721 nm at the V12 stage in “Jiyu 5817” and 760–1142 nm at the R1 stage in “Zhengdan 958”. An N spectral diagnostic model that considers the varietal effect improves the model fit and root mean square error (RMSE) with respect to the model without it by 10.6% and 29.2%, respectively. It was concluded that the V12 stage for “Jiyu 5817” and the R1 stage for “Zhengdan 958” were the best diagnostic stages and were more sensitive to N stress, which can further guide fertilization decision-making in precision fertilization.

Nitrogen (N) fertilizer application has revolutionized agricultural productivity, but excessive N fertilizer application has resulted in low N use efficiency (NUE) and high N accumulation, increasing the risk of N losses. Here, we hypothesize that the apparent N balance can be used as an indicator to identify the N input for obtaining high yield with a high NUE. Thus, a 12-year field experiment involving seven N treatments (0, 120, 240, 360, 480, 600, and 720 kg N ha-1 per year) in a typical winter wheat-summer maize rotation system in North China was conducted to investigate the response of crop yield and NUE to the N balance under different N application rates and to identify the N input-output framework. The annual yield increased in a linear-platform and NUE decreased with increasing N fertilizer application. The N balance and yield are strongly correlated to predict changes in yield, and a critical N balance of 44.4-64.9 kg N ha-1 per year was recommended for optimal yield with minimal risk of N loss. The N balance and NUE can be presented in the framework of N input-output, and the critical N input estimated from the N balance of 217-252 kg N ha-1 could obtain high productivity with high NUE (74.3-79.6 %). Overall, the apparent N balance could be used as a key indicator for optimizing N input, providing a strong reference for limiting N excess in intensive production areas and evaluating agronomic and environmental performance in N management. Data Availability: The datasets generated during and analyzed during the current study are available from the corresponding author on reasonable request.

Bamboo has great potential for manufacturing heterotypic engineered components, owing to its excellent flexibility and toughness. To better understand how bamboo sliver fractures behave under bending stress and to learn what biophysical properties of bamboo contribute to their flexural toughness, bamboo slivers with different fiber cell (FC) contents and moisture contents (MCs) were placed under bending stress and real-time cracking behaviors were observed using in situ microscopy. Results showed that high FC content or MC reduced the formation of fractures and their rate of progression in bamboo slivers. When flexural deformation increased by 1 μm, the fractures increased by 0.48 μm and 0.08 μm in low-FC-content (18%) and high-FC-content (54%) bamboo slivers, respectively. The fractures increased by 0.25 μm, 0.16 μm, and 0.06 μm when MC was 2%, 7%, and 17%, respectively. The tensile properties of the pure FC and parenchyma cells showed that both fiber and moisture content contributed to toughening by deflecting fractures. This study provides critical experimental evidence on the effects of the fibrous structure and water content on the flexural fracture behaviors of bamboo slivers. Furthermore, it provides a theoretical foundation for the selection of raw materials for bamboo-winding and bamboo-woven composites.

Fusarium ear rot (FER) is a common fungal disease in maize (Zea mays L.) caused by Fusarium verticillioides. Resistant germplasm resources for FER are rare in cultivated maize; however, teosintes (Z. mays ssp. parviglumis and Z. mays ssp. diploperennis), which are wild-type species of maize, have the potential to offer a novel source of resistance alleles to enhance pathogen resistance in modern maize. Therefore, the aim of this study was to identify favorable alleles that confer significant levels of resistance toward FER. Three populations of BC2F8 recombinant inbred lines (RILs) were developed by crossing two different teosintes, Z. diploperennis and Z. parviglumis, with maize inbred lines B73 and Zheng58, and were screened for FER resistance. We found that Z. diploperennis and Z. parviglumis had higher resistance toward F. verticillioides in the leaves than B73 and Zheng58. However, the resistance toward F. verticillioides in the leaf and ear was unrelated among RILs. FER resistance was positively correlated with grain yield in the B73 × diploperennis (BD) and Zheng58 × parviglumis (ZP) populations, partly because the quantitative trait loci (QTLs) of FER resistance and yield traits were located close together. Four coincident QTLs (qFERbd5.177, qFERbd10.140, qFERzp4.066, and qFERzp5.116) and two highly reliable resistance-yield synergistic QTLs (qFERbd10.140 and qFERzp4.066) were identified in the BD and ZP populations, opening up the possibility of breeding for FER resistance without reducing yield.

基于叶绿素计测定的SPAD值与植物叶片叶绿素和氮浓度的关系,详细综述了用叶绿素计在玉米、小麦、水稻以及其他作物上进行氮素营养诊断的研究进展.第一,"相对SPAD值"、"氮饱和指数"或"归一化SPAD"等指标能够消除或减小品种、生育期及区域年际间的误差;第二,不同生育期应选择理想指示叶作为诊断目标;第三,不同叶位间的SPAD差值与氮素营养的关系较为稳定可靠.总结了基于SPAD的作物营养诊断和推荐施肥技术规范、不同作物种类SPAD值及其衍生参数的筛选、模型的稳定性和普适性,除氮素外其他营养元素与SPAD的响应关系等方面存在的问题和不足.在此基础上提出了利用叶绿素计开展植物氮素营养诊断与施肥需要进一步研究的方向:一是建立基于SPAD的不同作物氮素营养诊断的技术规范;二是确定基于叶片SPAD值的作物氮营养丰缺指标;三是建立基于叶片SPAD值的作物施肥模型;四是开发基于SPAD的施肥决策支持系统;五是开展钾、镁、铁、锰等与叶绿素合成有关的其他营养元素与SPAD值的关系研究.

Lateral organ boundaries domain (LBD) proteins are plant-specific transcription factors. Class-I LBD genes have been widely demonstrated to play pivotal roles in organ development; however, knowledge on class-II genes remains limited. Here, we report that ZmLBD5, a class-II LBD gene, is involved in the regulation of maize (Zea mays) growth and the drought response by affecting gibberellin (GA) and abscisic acid (ABA) synthesis. ZmLBD5 is mainly involved in regulation of the TPS-KS-GA2ox gene module, which is comprised of key enzyme-encoding genes involved in GA and ABA biosynthesis. ABA insufficiency increases stomatal density and aperture in overexpression plants and causes a drought-sensitive phenotype by promoting water transpiration. Increased GA(1) levels promotes seedling growth in overexpression plants. Accordingly, CRISPR/Cas9 knockout lbd5 seedlings are dwarf but drought-tolerant. Moreover, lbd5 has a higher grain yield under drought stress conditions and shows no penalty in well-watered conditions compared to the wild type. On the whole, ZmLBD5 is a negative regulator of maize drought tolerance, and it is a potentially useful target for drought resistance breeding.

[目的]研究冬小麦–夏玉米轮作体系下砂质潮土长期施磷的作物产量效应、磷肥利用效率、土壤有效磷农学阈值及有效磷对土壤磷素盈亏的响应关系,为农田磷素养分管理提供依据.[方法]磷肥长期定位试验自2008年起在河北廊坊进行,种植制度为冬小麦–夏玉米轮作,供试土壤为砂质潮土,设置6个施磷(P2O5)水平(0、45、90、135、180、225?kg/hm2),依次表示为P0、P45、P90、P135、P180、P225.在2020年(试验的第12年)测定作物产量、作物吸磷量、土壤有效磷含量,分析了周年产量和土壤有效磷演变特征、作物有效磷农学阈值、土壤有效磷与累积磷盈亏的关系.[结果]施磷显著提高了冬小麦–夏玉米周年产量和作物吸磷量,产量与吸磷量随施磷水平提高先升高后降低.达到最高周年产量(14627?kg/hm2)的施磷量为152?kg/hm2.以该最高产量的90％为实际生产目标,适宜施磷量为90?kg/hm2.磷肥利用率随轮作周期延长而提高,12年平均磷素表观利用率和累积利用率变幅分别为36.98％～98.10％和26.26％～71.85％.周年施磷量超过90?kg/hm2时,施磷对作物吸磷量影响不显著,且磷肥表观利用率、累积利用率显著降低.P0～P225处理表观磷盈余12年平均值分别为–11.30、–7.38、0.94、20.05、37.21、57.68?kg/hm2;至2020年累积磷盈亏分别为–144.92、–88.57、11.33、240.56、446.48、692.15?kg/hm2.砂质潮土有效磷含量随累积磷盈余量的变化呈现两段线性关系,拐点出现在土壤累积磷盈余量P?218.81?kg/hm2.低于此值时,土壤每盈余P?100?kg/hm2,有效磷含量上升0.48?mg/kg;当土壤累积磷盈余高于此值时,土壤每盈余P?100?kg/hm2,有效磷含量上升3.37?mg/kg.冬小麦、夏玉米有效磷农学阈值分别为10.20、5.93?mg/kg,施磷量为90?kg/hm2时,冬小麦、夏玉米季土壤有效磷含量最接近农学阈值.[结论]在作物秸秆还田条件下,砂质潮土冬小麦–夏玉米轮作体系周年施磷量为90?kg/hm2,可以兼顾冬小麦–夏玉米轮作周年对磷素的需求,维持土壤磷素的表观平衡,在保证产量的前提下实现磷素平衡和磷肥高效施用.砂质潮土磷的储存阈值为218.81?kg/hm2,当土壤磷累积量低于该阈值时,施磷提高土壤有效磷含量的效果较低;而当磷累积量高于该阈值时,施磷可显著提升土壤磷的有效性.

本研究以两个不同玉米品种(冀玉5817和郑单958)为研究对象,同步获取其关键功能叶片(玉米生育前期为最上部完全展开叶、吐丝后为穗位叶)氮含量和光谱反射率,分析不同施氮水平下两个品种关键功能叶片氮含量的响应特征和产量反应.研究表明,不同品种在整个生育期的叶片氮含量的变化整体趋势一致,两个玉米品种最优氮处理均为180 kg/hm2,冀玉5817氮含量在成熟期之前普遍高于郑单958,两个品种对不同氮处理响应有所差异.本研究建立基于优化处理的氮素丰缺诊断指标,即氮胁迫指数(NSI)和氮胁迫光谱指数(NSSI).基于光谱参数NVI(570,670)构建的NSSI对缺氮响应比较敏感,并且对两个品种均适用.该方法及其构建的参数通过与同条件下优化处理进行比较,避免了氮素营养的光谱诊断受品种和生育期的影响,并且光谱参数可实时、快速和无损地获取,为玉米生育期内氮肥的优化调控提供了依据.

The delta-1-pyrroline-5-carboxylate synthetase (P5CS) gene exercises a protective function in stressed plants. However, the relationship between proline accumulation caused by P5CS and abiotic stress tolerance in plants is not always clear, as P5CS overexpression has been reported to repress plant growth under normal conditions in several reports. We re-evaluated the role of P5CS in drought-tolerant rice breeding by expressing the AtP5CS1 and feedback-inhibition-removed AtP5CS1 (AtP5CS1F128A) genes under the regulation of an ABA-inducible promoter to avoid the potential side effects of P5CS overexpression under normal conditions. ABA-inducible AtP5CS1 and AtP5CS1F128A increased seedling growth in a nutrient solution (under osmotic stress) and grain yield in pot plants. However, the evidently deleterious effects of AtP5CS1 on grain quality, tiller number, and grain yield in the field indicated the unsuitability of P5CS for drought-tolerance breeding.

The purpose of this study were to explore an accurate model of nitrogen accumulation factoring in temperature and light meteorological conditions from 2018 to 2019, as well as the pattern of nutrient absorption and utilization in transplanted Yongyou No. 15 rice under different conditions of nutrient application, i.e., different ratios of nitrogen, phosphorus and potassium.Using Yongyou No. 15 rice as the experimental material, five groups of samples that received different fertilization treatments and one group of samples that was not treated with fertilizer (N0P0K0) were established under field conditions for two sequential years to study the dynamic changes in rice yield and nitrogen accumulation, as well as the influence of efficiency of fertilizer used under different ratios of nitrogen, phosphorus and potassium. The principal results is that the dynamic change in nitrogen accumulation under optimal fertilization conditions could be expressed by the Gompertz model: y = 178.60 *exp(-exp[2.05-0.0884x]) (R2 =0.985, x represents the number of days after rice transplanting, and y represents nitrogen accumulation). The OPT demonstrated superiority in nitrogen accumulation in Yongyou No. 15 rice, and the days of gradual growth stage (21.78 d) and rapid growth stage (21.75 d) were all higher than those of other treatments. The Gompertz model is suitable for simulating the dynamics of nitrogen accumulation in rice under different nutrient distribution ratios In addition, the analytical method of the accurate model was used to quantitatively describe the dynamic variation of total nitrogen accumulation (TNA) in Yongyou No. 15 rice and explain the mechanism of optimal treatment (OPT) for high yields. The Gompertz model can simulate all the dynamic characteristics of the variation of nitrogen accumulation in rice plants after transplanting. The parameters i.e., N accumulation amount and the precise time to reach it, determined by the models provide a basis to accurately nitrogen regulation in the period of gradual increase and rapid increase in nutrient absorption, which is especially beneficial for the nutrient management in digital agriculture.

【Objective】This paper explored the dynamic prediction model and characteristic parameters of dry matter and nitrogen accumulation in summer maize with different nitrogen supply levels based on effective accumulated temperature, in order to provide a theoretical basis for using effective accumulated temperature to predict summer maize dry matter and nitrogen accumulation.【Method】This study was based on a two-year field experiment in Langfang, Hebei Province (2019-2020), using Zhengdan 958 as the test material, and using the normalization method to fit the dry matter and nitrogen accumulation of summer maize with different nitrogen supply levels through model screening. Based on the normalized Gompertz model of effective accumulated temperature after sowing, and using the growth rate curve and its characteristic parameters, the dry matter and nitrogen accumulation characteristics of summer maize were quantitatively analyzed.【Result】(1) Under the experimental conditions, when the amount of phosphorus and potassium fertilizer was appropriate, the maximum dry matter and nitrogen accumulation of summer maize continued to increase with the increase of nitrogen application rate. (2) The normalized Gompertz model of summer maize dry matter and nitrogen accumulation established with effective accumulated temperature as the independent variable had the good biological significance. The coefficients of determination of the equation were 0.9962-0.9988 and 0.9887-0.9922, respectively. Using the second-year data for model verification, the correlation coefficients of the simulated and measured values were 0.9933-0.9959 and 0.9830-0.9923, and the standardized root mean square errors were 6.64%-16.86% and 7.31%-12.68%, respectively. The prediction effect was good. (3) The growth rate of dry matter and nitrogen accumulation of summer maize at different nitrogen supply levels all showed a “single peak curve”, and its change was closely related to the nitrogen supply level. The performance between treatments was: under the condition of moderate fertilization, the growth rate curve had the characteristics of fast rising and falling, and the growth rate curve of weight loss treatment had the characteristics of slow rising and falling. (4) The effective accumulated temperature ranges of dry matter and nitrogen accumulation during the rapid increase period of summer maize after sowing were 709.35-1 722.54 and 482.50-1 507.61 ℃·d, respectively, and the effective accumulated temperature required for the maximum rate showed that nitrogen accumulation (995.05 ℃·d) was less than dry matter accumulation (1 215.94 ℃·d). Nitrogen supply level obviously affected the accumulation of dry matter and nitrogen in summer maize to enter the accumulation temperature required for the rapid increase period, the accumulated temperature required for the slow increase period, the accumulated temperature required for the maximum increase rate, the maximum increase rate, and the average increase rate during the rapid increase period. Compared with nitrogen fertilizer treatment, the effective accumulated temperature required for summer maize to enter each critical period was significantly reduced, and the growth rate during the critical period increased significantly.【Conclusion】The normalized Gompertz model could not only simulate and predict the dynamic changes of summer maize dry matter and nitrogen accumulation with effective accumulated temperature with different nitrogen supply levels, but also clarify the quantitative relationship between effective accumulated temperature and dry matter and nitrogen accumulation. The Gompertz model based on effective accumulated temperature could be used to predict crop growth and optimal fertilization period, and had strong application value..

Germplasm screening is essential to effectively understand the mechanisms underlying aluminum (Al) toxicity, hence guide breeding strategies for alleviating the decline in crop productivity. This study screened a large population of 481 maize acessions by measuring eight net root traits, two biomass traits, and three Al concentration traits of seedlings in hydroponic cultures under Al stress. Aluminum stress significantly restrained the plant biomass and root growth. Meanwhile, genetic correlation analysis indicated that biomass traits were significantly correlated with net root traits in the presence or absence of Al treatment. The relative traits exhibited similar results; Al tolerance coefficient (ATC) of biomass traits and ATC of net root traits. Using principal component analysis (PCA), all maize acessions were classified as tolerant, meso-tolerant, or sensitive to Al stress according to Al tolerance index (ATI). The acessions were further categorized under high-performance, low-performance, or moderate-performance groups according to Al tolerance performance index (API). Subsequently, ATI and API defined seven Al-tolerant acessions with high performance and four Al-sensitive acessions with low performance. This large-scale evaluation of Al tolerance identified high-quality Al-tolerance maize acessions, hence providing vital information for further genetic analyses and breeding of maize for Al tolerance.

Root architecture remodelling is critical for forage moisture in water-limited soil. DEEPER ROOTING 1 (DRO1) in Oryza, Arabidopsis, and Prunus has been reported to improve drought avoidance by promoting roots to grow downward and acquire water from deeper soil. In the present study, we found that ZmDRO1 responded more strongly to abscisic acid (ABA)/drought induction in Zea mays ssp. mexicana, an ancestral species of cultivated maize, than in B73. It was proposed that this is one of the reasons why Zea mays ssp. mexicana has a more noticeable change in the downward direction angle of the root and fewer biomass penalties under water-deficient conditions. Thus, a robust, synthetic ABA/drought-inducible promoter was used to control the expression of ZmDRO1B73 in Arabidopsis and cultivated maize for drought-resistant breeding. Interestingly, ABA-inducible ZmDRO1 promoted a larger downward root angle and improved grain yield by more than 40% under water-limited conditions. Collectively, these results revealed that different responses to ABA/drought induction of ZmDRO1 confer different drought avoidance abilities, and we demonstrated the application of ZmDRO1 via an ABA-inducible strategy to alter the root architecture of modern maize to improve drought adaptation in the field.

The BRI1-EMS suppressor 1 (BES1)/brassinazole-resistant 1(BZR1) transcription factors play crucial roles in plant growth, development, and stress response. However, little is known about the function of maize’s BES1/BZR1s. In this study, the ZmBES1/BZR1-3 and ZmBES1/BZR1-9 genes were cloned from maize’s inbred line, B73, and they were functionally evaluated by analyzing their expression pattern, subcellular localization, transcriptional activation activity, as well as their heterologous expression in Arabidopsis, respectively. The results of the qRT-PCR showed that the ZmBES1/BZR1-3 and ZmBES1/BZR1-9 genes were predominantly expressed in the root, and their expression was significantly down-regulated by drought stress. The ZmBES1/BZR1-3 and ZmBES1/BZR1-9 proteins localized in the nucleus but showed no transcriptional activation activity as a monomer. Subsequently, it was found that the heterologous expression of the ZmBES1/BZR1-3 and ZmBES1/BZR1-9 genes in Arabidopsis decreased drought tolerance, respectively. The transgenic lines showed a more serious wilting phenotype, shorter root length, lower fresh weight, and higher relative electrolyte leakage (REL) and malondialdehyde (MDA) content compared to the control under drought stress. The RNA-sequencing data showed that the 70.67% and 93.27% differentially expressed genes (DEGs) were significantly down-regulated in ZmBES1/BZR1-3 and ZmBES1/BZR1-9 transgenic Arabidopsis, respectively. The DEGs of ZmBES1/BZR1-3 gene’s expressing lines were mainly associated with oxidative stress response and amino acid metabolic process and enriched in phenylpropanoid biosynthesis and protein processing in the endoplasmic reticulum. But the DEGs of the ZmBES1/BZR1-9 gene’s expressing lines were predominantly annotated with water deprivation, extracellular stimuli, and jasmonic acid and enriched in phenylpropanoid biosynthesis and plant hormone signal transduction. Moreover, ZmBES1/BZR1-9 increased stomatal aperture in transgenic Arabidopsis under drought stress. This study indicates that ZmBES1/BZR1-3 and ZmBES1/BZR1-9 negatively regulate drought tolerance via different pathways in transgenic Arabidopsis, and it provides insights into the underlying the function of BES1/BZR1s in crops.