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A high-quality canopy architecture is central to obtaining high crop yields. A field experiment was carried out at the Wuqiao Experimental Station from 2015 to 2019 under four irrigation schemes (W0, no irrigation after sowing; W1, 75 mm irrigation at jointing stage; W2, 75 mm irrigation at jointing and anthesis stages, respectively; W3, 75 mm irrigation at tillering, jointing and anthesis stages, respectively) to investigate the canopy structure, canopy apparent photosynthesis (CAP), canopy temperature (CT), yield and water use efficiency (WUE). The results showed that increasing irrigation times improved the leaf area index (LAI), non-leaf area index (NLAI) and light interception (LI) of the spike and total canopy but decreased the canopy temperature (CT) after anthesis. The CAP in the W3 treatment was consistently lower than that in the W1 treatment, suggesting lower effective utilization of light energy under the W3 treatment. Increasing irrigation times improved wheat yield, but the W2 treatment had no significant difference in yield compared to the W3 treatment. In addition, the W1 and W2 treatments had higher WUEs. The CT, organ temperature and LI were closely positively associated with each other, but they were all strongly negatively related to the yield. Overall, the W2 treatment was the best irrigation scheme for constructing a reasonable canopy architecture for winter wheat, obtaining more efficient water use and yield in the North China Plain (NCP). CT and organ temperature can be used as proxy parameters to estimate the canopy structure. [ABSTRACT FROM AUTHOR]

Water stress is a primary trigger for reducing grain number per spike in wheat during the reproductive period. However, under stress conditions, the responses of plant organs and the interactions between them at the molecular and physiological levels remain unclear. In this study, when water stress occurred at the young microspore stage, RNA-seq data indicated that the spike had 970 differentially expressed genes, while the stem, comprising the two internodes below the spike (TIS), had 382. Abscisic acid (ABA) signal transduction genes were down-regulated by water stress in both these tissues, although to a greater extent in the TIS than in the spike. A reduction in sucrose was observed, and was accompanied by increases in cell wall invertase (CWIN) and sucrose:sucrose 1-fructosyl-transferase (1-SST) activities. Hexose and fructan were increased in the TIS but decreased in the spike. ABA was increased in the spike and TIS, and showed significant positive correlation with CWIN and 1-SST activities in the TIS. Overall, our results suggest that water stress induces the conversion of sucrose to hexose by CWIN, and to fructan by 1-SST, due to increased down-regulation of ABA signal transduction related-genes in the TIS; this leads to deficient sucrose supply to the spike and a decrease in grain number. [ABSTRACT FROM AUTHOR]

Selecting more water‐efficient wheat (Triticum aestivum L.) varieties that are suited to no seasonal irrigation is an important way to improve water use efficiency (WUE) in the North China Plain (NCP). The goal of this study was to assess the yield and WUE of wheat, maize (Zea mays L.), and rotation, and to determine the traits of high‐WUE wheat varieties and clarify the mechanism for increasing WUE. Experiments were conducted during the 2012–2016 seasons using 10 common winter wheat varieties under no seasonal irrigation (W0) or two irrigation events (W2, irrigation at jointing and anthesis). No seasonal irrigation treatment decreased wheat and rotation yield, and improved maize yield and WUE of maize and rotation. No seasonal irrigation treatment decreased 150‐mm irrigation amount, reduced soil water content in 0–2‐m soil depth at wheat maturity and 1–2‐m depth after maize harvest, and extended the maize grain filling stage. Compared with the wheat genotype with the lowest WUE ('Nongda 211'), under W0 condition, the genotype with the highest WUE, 'Nongda 5133,' could improve rotation yield and WUE by 10.7 and 10.9%, respectively. The WUE of wheat had a strong positive association with yield across the genotypes. High‐WUE varieties had a higher leaf area index at anthesis and higher late‐season photosynthesis rate and/or delayed canopy senescence under W0. This study indicated that W0 in wheat growing season could improve maize yield, narrow the rotation yield gap with W2 treatment, and improve wheat and rotation WUE by combining with high‐WUE wheat varieties. [ABSTRACT FROM AUTHOR]

Favorable crop population architecture is the foundation for obtaining high crop yields and water productivity (WP) under limited irrigation. A field experiment was conducted at Wuqiao Experimental Station from 2015 to 2018 using the 'Nongda399′ wheat variety under the four seeding density and three irrigation schemes to explore the population architecture, canopy apparent photosynthesis (CAP), organ contribution, yield, and WP of winter wheat (Triticum aestivum L.). Compared with conventional high-yield cultivation (SD1W3), the water-saving cultivation (SD3W1) obtained a comparable yield meanwhile improved the WP in the range of 14.2–39.2%. The non-significant change in the yield under SD3W1 was primarily due to the increasing seeding density under W1 irrigation treatment, which improved the spike number and grains per unit area, especially the main stem spike, and had no significant effect on the thousand kernel weight (TKW). Increases in grain yield was generally caused by increases in CAP by constructing a reasonable canopy architecture with higher leaf area index (LAI) and non-leaf area index (NLAI) of the total canopy and upper strata, especially the spike area index (SAI) of the upper strata. Therefore, more light was intercepted by spikes, which improved the contribution of spike photosynthesis to yield. Increasing the seeding density also improved the assimilate remobilization contribution (RC) of pre-anthesis and decreased the post-anthesis leaf photosynthesis contribution to yield. Increasing the seeding density under limited irrigation improved the root length density (RLD), especially in 120–200 cm soil layer, which increased the absorption and use of deep soil moisture and improved WP. Overall, when sowing time from October 10–20, the appropriate seeding density of approximately 525–600 plants m−2 with 75 mm of irrigation at the jointing stage was the best cultivation practice for saving water and obtaining a comparable yield and a high water productivity of winter wheat in the North China Plain (NCP). • Increasing the seeding density improved the spike area index of the upper strata. • Higher seeding density improved the contribution of spike photosynthesis to yield. • Higher seeding density improved the contribution of remobilization before anthesis. • Increasing the seeding density improved the root length density in the deeper soil layers. • Increasing the seeding density under limited irrigation improved the yield and water productivity. [ABSTRACT FROM AUTHOR]

• Contribution of spikes photosynthesis to grain yield of wheat was 20%. • No current models explicitly consider contribution of spike photosynthesis to grain. • Simulation results of excluding & including spike contributions are investigated. • APSIM overestimated leaf contribution to compensate neglection of spike contribution. • Most current models may simulate wheat yield correctly partly for the wrong reasons. Process-based crop models are increasingly used to simulate Genotype by Environment by Management interactions (GxExM), and to evaluate importance of physiological traits to assist in breeding selections. This requires the model to correctly simulate the key physiological processes that determine grain yield. Although spike photosynthesis contributes to grain yield of wheat, it has not been explicitly simulated in most crop models. Here we present experimental data from China and Mexico, derived from estimates of spike contributions to grain yield of wheat, and compared them with previous results. We then used the APSIM model to investigate the consequences of excluding and including spike contributions on simulation results, against the data from China consisting of 4 irrigation and plant density treatments. Our results show that the contribution of spikes photosynthesis to grain yield ranged from 9.8% to 39.0% with an average of 20.1%, consistent with results from previous studies. However, despite the omission of the contribution from spike photosynthesis to grain yield, APSIM captured the dynamics of LAI and biomass and grain yield with acceptable accuracy. Across the treatments, the APSIM (version 7.9) explained >78% of the variation in yield (RMSE = 737 kg ha-1) and biomass (RMSE = 1438 kg ha-1) compared with the experimental data. This highlight the fact that APSIM performed well in simulating yield partly for the wrong reasons. Adding spike contribution to APSIM improved the simulations of biomass and yield, particularly under high yield level. More detailed analysis revealed that APSIM overestimated leaf contribution to compensate neglection of spike contribution, explained by the overestimation of leave biomass and underestimation of stem biomass. While APSIM captured the trend of changes in pre-anthesis remobilization contribution to grain yield, it also underestimated this contribution across treatments. Future improvements should include the inclusion of spike photosynthesis contribution with correct spike light interception and RUE, and improved modelling of biomass partitioning to different organs and the remobilization of biomass to grain from pre-anthesis growth. [ABSTRACT FROM AUTHOR]

• Predicting micronutrients in wheat kernel and flour using hyperspectral imaging. • The prediction of micronutrients was superior based on the kernel spectra compared to the use of flour spectra. • The Ca, Mg, Mo and Zn nutrients in wheat kernel/flour were predicted with a high credibility. Micronutrients are the key factors to evaluate the nutritional quality of wheat. However, measuring micronutrients is time-consuming and expensive. In this study, the potential of hyperspectral imaging for predicting wheat micronutrient content was investigated. The spectral reflectance of wheat kernels and flour was acquired in the visible and near-infrared range (VIS-NIR, 375–1050 nm). Afterwards, wheat micronutrient contents were measured and their associations with the spectra were modeled. Results showed that the models based on the spectral reflectance of wheat kernel achieved good predictions for Ca, Mg, Mo and Zn (r2 > 0.70). The models based on the spectra reflectance of wheat flour showed good predictive capabilities for Mg, Mo and Zn (r2 > 0.60). The prediction accuracy was higher for wheat kernels than for the flour. This study showed the feasibility of hyperspectral imaging as a non-invasive, non-destructive tool to predict micronutrients of wheat. [ABSTRACT FROM AUTHOR]

• The maximum number of floret primordia was hardly affected by treatments. • Florets that have started abortion can not become fertile florets. • Anthers development determines the number of fertile florets. • Nitrogen application accelerated the rates of floret development and hence increased the number of fertile florets. The dynamics of floret initiation/abortion has been explored widely; however, the mechanisms of increasing floret fertility at anthesis in wheat production remain unclear. In this study, morphological and physiological responses of florets per spikelet and per spike to nitrogen and irrigation treatments in the field were investigated. Each spikelet produced the maximum number of living floret primordia (MFP) and showed no difference between treatments at the W7.5 stage; this ability was hardly affected by treatments. We firstly found that gradually abortive florets during W8.5-W10 stages were delayed due to improving assimilates availability in the spike instead of the 4th-5th inthernode; in fact, these florets would be aborted completely and never become fertile florets. Notably, we found that those florets in which the anther turned green (value ≥ 97) at W7.5 always became fertile, and their number showed a significant positive relationship with number of fertile florets (NFF) at W10. Collectively, more available assimilates in spike accelerated anther turning green during period of early floret development, maintained their development normally and becoming fertile florets, but did not make florets that initiate abortion become fertile florets and increase the MFP. [ABSTRACT FROM AUTHOR]

• Compared to TI120, MI120 and MI150 significantly increased grain yield and WUE. • MI90 ensured grain yield by significantly improving thousand grain weight. • Except for MI60, MI treatments significantly delayed the senescence of flag leaf during grain filling. • MI treatments ensured the water supply in the mainly root distribution zone of wheat. • MI with reducing irrigation promoted water consumption of the deep soil profile. It's very important to guarantee the wheat production and improve water productivity in the North China Plain (NCP). In order to reduce irrigation and ensure the crop production in the NCP, a two-year field experiment of winter wheat was conducted in 2016–2018 using micro-sprinkling irrigation including different irrigation amount treatments (60 mm, MI60; 90 mm, MI90; 120 mm, MI120; and 150 mm, MI150), and the local traditional water-saving and productive flooding irrigation method (TI120) was as a control. The grain yield (GY), dry matter accumulation (DM), root system distribution and water utilization were investigated. The results showed that, the GY of MI60 decreased by 5.1–13.4% compared with TI120; GY of MI90 was comparable with TI120, while that of MI120 and MI150 increased significantly. The higher GY in micro-sprinkling treatments was mainly due to the significant increase of 1,000-grain weight (TGW), which was the result of the significant delay of the senescence in flag leaves during grain filling and then the increase in the post-anthesis DM. In addition, the roots mainly distributed in the 0−60 cm soil profile, and micro-sprinkling ensured the soil water supply in this areas at the critical growth stages; what's more, micro-sprinkling with reducing irrigation treatments significantly promoted the growth of root system to the deep soil layer, which improved the absorption and utilization of moisture stored in soil. Compared with TI120, the same irrigation amount treatment under micro-sprinkling (MI120) significantly increased water use efficiency (WUE) due to higher GY and lower seasonal evapotranspiration (ET); the 125% irrigation amount treatment (MI150) increased WUE due to higher GY and comparable ET; the 75% irrigation amount treatment (MI90) obtained the similar WUE to TI120; the 50% irrigation amount treatment (MI60) got similar or lower WUE to TI120. Overall, suitable reduction of irrigation amount under micro-sprinkling (MI90) can ensure the grain yield of winter wheat and efficient utilization of irrigation water in the NCP. [ABSTRACT FROM AUTHOR]