为明确不同产量潜力小麦品种干物质积累、转运及根系衰老的差异,本试验选择烟农 1212、济麦 22和良星 99 共 3 个不同产量潜力小麦品种为材料,分析比较 3 个品种干物质积累与分配、叶绿素相对含量、根系衰老特性、产量和水分利用效率的差异.结果表明:①烟农 1212 开花期、成熟期及开花后干物质积累量显著高于其他品种,开花后干物质积累量对籽粒贡献率显著高于良星 99;②不同小麦品种开花期旗叶叶绿素相对含量无显著差异,开花后 7、14、21、28 d和 35d烟农 1212 均显著高于其他品种;③烟农 1212 开花期和开花后 10d和20d的0～20、20～40 cm土层根系超氧化物歧化酶活性均显著高于其他品种,根系丙二醛含量均显著低于其他品种;④烟农 1212 单位面积穗数与其他品种无显著差异,穗粒数、千粒重、籽粒产量和水分利用效率均显著高于其他品种.综上,烟农 1212 灌浆期旗叶叶绿素相对含量高、花后根系衰老缓慢,为本试验条件下高产高效小麦品种.上述结果表明,协同提高开花后干物质同化量及其对籽粒贡献率是提高小麦产量潜力的重要途径.

Clarifying factors that underpinning the variation in wheat yield components between high and middle soil fertility fields is critical to increase grain production and narrow yield gap for smallholder farming systems in the Huang–Huai–Hai Plain (3HP), which characterized by a large variation in soil fertility. Two-year field experiments were conducted to investigate wheat tillering, leaf photosynthesis, and grain filling characteristics in different soil fertility fields: high soil fertility field (HF) and middle soil fertility field (MF). Results showed that the spike formation rate in HF was 12.7%–13.0% higher than that in MF, leading to an 18.0%–19.8% increase in spike number. In addition, HF improved canopy light interception and leaf photosynthesis characteristics after anthesis and delayed leaf senescence, contributing to the increase in both the active grain filling period and grain filling rate. This resulted in a higher 1,000 grain weight in HF, which was 8.2%–8.3% higher than that in MF. Compared to MF, HF obtained higher yields at 9,840 kg ha−1 in 2017/18 and 11,462 kg ha−1 in 2018/19, respectively. In summary, higher spike number and 1,000-grain weight, which were mediated by spike-formation rate, maximization of light interception and improved leaf photosynthesis. These results would have important implications for narrowing yield gap between MF and HF in the 3HP.

Selecting high-yielding wheat varieties for cultivation can effectively increase water use efficiency (WUE) in the Huang–Huai–Hai Plain, where is threatened by increasing water shortages. To further identify the difference in water use and its relationship with root morphology and senescence characteristics, wheat varieties with different yield potentials—Yannong 1212 (YN), Jimai 22 (JM), and Liangxing 99 (LX)—were studied in a high-yielding wheat field. The water consumption percentage (CP) in YN decreased from planting to anthesis; however, crop evapotranspiration and CP increased from anthesis to maturity compared with JM and LX. In YN, a higher soil water consumption from anthesis to maturity in the 0–100 cm soil layer was partly attributed to the greater root weight density in the 20–60 cm soil layer. In topsoil (0–40 cm), root length density, root surface area density, and root diameter at 20 days after anthesis, root superoxide dismutase activity, and root triphenyl tetrazolium chloride reduction activity during mid grain filling stage were higher in YN than in JM and LX. YN had the highest grain yields of 9,840 and 11,462 kg ha–1 and increased grain yield and WUE by 12.0 and 8.4%, respectively, as compared with JM, and by 30.3 and 21.3%, respectively, as compared with LX. Ensuring more soil water extraction post-anthesis by increasing roots in the 20–60 cm soil profile, improving root morphology traits, and alleviating root senescence in the topsoil during mid-grain filling stage will assist in selecting wheat varieties with high yield and WUE.

Evaluating the effects of nitrogen (N) on photosynthesis characteristics and photoassimilate partitioning via vascular bundles (VB) under water-saving irrigation is crucial to maximum grain yield of environment-friendly wheat production in the North China Plain (NCP). Field experiments were conducted with four N application rates 0 (N 0 ), 180 (N 180 ), 240 (N 240 ), and 300 (N 300 ) kg N ha −1 under 70% and 65% relative soil water content (RSWC) at jointing and anthesis, respectively. Results showed that, compared with N 0 , N 180 significantly improved the photosynthetic parameters and chlorophyll fluorescence of flag leaf after anthesis. N application improved the anatomical parameters both in the flag leaf and the stem. Total transverse area of VB in the flag leaf and in the stem internode below the ear under N 180 was 17.95–23.70% and 37.91–43.90% larger than those of N 0 , respectively, due to the increased numbers and transverse area of VB. Furthermore, N 180 had higher dry matter assimilation after anthesis (DMA) and its contribution to the grain. N 180 increased grain yield by 14.23–23.24% compared with N 0 , and N supply exceeding 180 kg N ha −1 did not further increase yield. Moreover positively correlations were showed among photosynthesis characteristics after anthesis, total transverse area of VB in the flag leaf and in the stem internode below the ear, DMA and grain yield. In summary, the recommended N application rate was 180 kg N ha −1 under RSWC-based supplemental irrigation that can produce grain yield over 7500 kg ha −1 for at least 2 years in the NCP.

Excessive nitrogen (N) input and irrigation exacerbate N leaching in winter wheat production in the North China Plain (NCP). To explore the optimal N for better N remobilization and higher N utilization of wheat under water-saving irrigation will be conductive to less environmental contamination. A field experiment was conducted at 300 (N 300 ), 240 (N 240 ), 180 (N 180 ), and 0 (N 0 ) kg N ha −1 of N application under supplemental irrigation (SI) that brought the relative soil water content (RSWC) to 70% at jointing and 65% at anthesis. Compared with N 0 , N 180 improved the free amino acid content in the flag leaf and grain after anthesis, dry matter and plant N accumulation at maturity, N translocation amount of vegetable organs and its contribution to grain from anthesis to maturity. Compared to N 240 and N 300 , N 180 increased the N translocation efficiency of vegetable organs, and reduced the soil NO 3 -N residue in the 60–180 cm soil layer, which contributing to no significant reduction in grain yield and grain protein yield, but higher grain N recovery efficiency ( G RE N ), N recovery efficiency (RE N ), and N partial factor productivity (PFP N ). Positive relationships were found between leaf N translocation efficiency and grain yield, grain protein yield, PFP N , G RE N , and RE N . Therefore, N 180 is appropriate to obtain a steady grain yield over 7.5 t ha −1 for at least 2 years under SI based on RSWC in the NCP.

With the large-spike wheat cultivar Shannong 23 as test material,a field experiment was conducted by increasing the relative soil moisture content to 70% and 65% at jointing and anthesis stages. Four nitrogen levels,0 (N0), 180 (N1), 240 (N2) and 300 kg·hm-2(N3), were designed to examine the effects of nitrogen application rates on the interception of photosynthetic active radiation (PAR) and dry matter distribution of wheat at different canopy layers. The results showed that the total stem number of wheat population at anthesis stage, the leaf area index at 10, 20 and 30 days after anthesis, PAR capture ratio at upper and middle layers and total PAR capture ratio in wheat canopy on day 20 after anthesis of treatment N2 were significantly higher than those in the treatments of both N0 and N1. Those indexes showed no significant increase when the application rate increased to 300 kg·hm-2(N3). The vegetative organ dry matter accumulation of all layers at maturity stage of treatment N2 were significantly higher than N0 and N1. Compared with treatment N0 and N1, N2 increased the grain and total dry matter accumulation by 36.7% and 35.4%, 9.5% and 10.2%, respectively, but had no significant difference with treatment N3. The vegetative organ dry matter accumulation at all layers, grain and total dry matter accumulation were significantly and positively correlated with PAR capture ratio at upper and middle layers, and had no significant correlation with that at lower layer. The vegetative organ dry matter accumulation at all layers was significantly and positively correlated with grain dry matter accumulation. The application rate at 240 kg·hm-2(N2) would be the optimum treatment under the present experimental condition.

To clarify the appropriate nitrogen application rate for high-yielding and water-saving of winter wheat production in Huang-Huai winter wheat region,field experiment was conducted under the condition of the relative soil moisture content at jointing and anthesis stages being 70％ and 65％.Wheat cultivar Shannong 23 was supplied with nitrogen fertilizer at 0 (N0),180 (N1),240 (N2),and 300 (N3) kg N · hm-2.We explored the water consumption characteristics and water and nitrogen use efficiencies in response to different nitrogen application rate.The results showed that the consumption amount of soil water in 20-160 cm soil layers for treatment N2 was significantly higher than that of treatment N0 and N1,but no significant difference was found when compared with N3.Compared to treatment N0 and N1,N2 decreased the irrigation water amount by 7.35％ and 9.51％,respectively,and significantly increased the soil water consumption,water consumption and water consumption percentage from jointing to anthesis.When the N application rate reached to 300 kg · hm-2,irrigation water amount was increased by 9.59％,and no significant difference was found under N2 treatment in soil water consumption,water consumption and water consumption percentage from jointing to anthesis.Compared to N1 treatment,N2 increased the grain yield,water use efficiency of precipitation and irrigation water productivity by 9.53％,9.54％ and 21.04％ respectively.While N application rate reached to 300 kg · hm-2,there was no significant difference under N2 treatment in grain yield.Irrigation water use efficiency and nitrogen partial productivity were decreased by 7,55％ and 18.94％,respectively.Therefore,the optimal N application rate was 240 kg · hm-2 (N2) under the present experimental conditions.