Post-anthesis Dry Matter Accumulation Research Articles

Assessing the impact of early and terminal droughts on root growth, grain yield and yield stability in old and modern wheat cultivars on the Loess Plateau

Understanding changes in root traits of high-yielding genotypes that consistently perform during different drought periods is crucial for improving wheat production and yield stability. A 2-year field trial and a pot experiment were conducted to determine the response of root growth and grain yield to early and terminal droughts in old and modern cultivars (FC3: 1960s and CH1: 2010s) under rainfed and irrigated conditions in the field. Rainfed wheat faced terminal drought in 2015–2016 and early drought in 2016–2017. Plants in the pot experiment were exposed to terminal drought, early drought, and well-watered. Both field and pot experiments showed higher grain yield in modern cultivar CH1 compared to FC3. Early and terminal droughts reduced grain yield in both cultivars, with a greater reduction in FC3. CH1 exhibited higher yield stability under drought conditions and experienced less reduction in early drought. Compared to FC3, CH1 produced more root biomass in the early growth stage. At anthesis, CH1 had significantly lower root biomass and root length density in the topsoil layer (00.2 m) and higher in the subsoil layer (0.21.0 m) than FC3, respectively. At maturity, the retention rate of subsoil root biomass in CH1 was higher, especially under early drought (80.2 % in field and 93.9 % in pot experiments). Both cultivars consumed similar seasonal water use, but CH1 reduced pre-anthesis water use and consumed more water after anthesis. This study indicates that modern cultivar had vigorous root growth at early stage. A higher proportion of root biomass preserved in deep soil after anthesis enhanced post-anthesis water use and photosynthetic rate, improved post-anthesis dry matter accumulation, and thus resulted in higher thousand kernel weight. These factors ensure higher yield and yield stability under both early and terminal drought stress.

Optimizing One-Time Nitrogen Fertilization for Rice Production Using Controlled-Release Urea and Urease Inhibitors

One-time fertilization with controlled-release urea (CRU) is a research hotspot for its lower labor cost and stability of nitrogen (N) supply for rice growth. Yet the fertilizer formulation needs to be further improved to better adjust the N supplement to meet the demand of rice plants and obtain a higher grain yield. Therefore, the effects of novel fertilizer formulations composed of CRU, urease inhibitor (UI) and nitrification inhibitor (NI) on the rice growth and photosynthetic characteristics as well as high-yield formation were tested through a two-year field experiment. The result indicated that the combined use of CRU and UI treatment can achieve higher yields than with CRU at the same N application level. Meanwhile, with a 20% reduction of N use, one-time application of CRU + UI can obtain the same high yield as the conventional split application of urea. Compared with conventional fertilization and CRU treatment, the CRU + UI treatment had suitable leaf area and biomass accumulation at the vegetative growth stage and high effective stem tiller rate. More post-anthesis dry matter accumulation, higher net photosynthesis rate and low senescence rate were guaranteed for its high yield and nitrogen agronomic efficiency.

Improving Photosynthesis and Grain Yield in Wheat through Ridge–Furrow Ratio Optimization

The ridge–furrow planting pattern is an effective strategy to improve grain yield, and changes in the ridge and furrow microenvironments affect wheat yield. However, the mechanism by which wheat yields are increased at different ridge–furrow ratios is unclear. In this study, four planting modes, namely the traditional planting mode (M1) and ridge–furrow ratios of 50:50 cm (M2), 75:50 cm (M3), and 100:50 cm (M4), were established for wheat under field conditions from 2021 to 2023; the effects of different treatments on light energy utilization, dry matter accumulation and transport, and grain yield were studied. The findings demonstrated that the M3 treatment exhibited the highest enhancements in parameters such as leaf area index (LAI), canopy photosynthetically effective radiation interception rate, relative chlorophyll content (SPAD) index, and net photosynthetic rate. Moreover, the M3 treatment displayed superior grain filling compared to other treatments. The post-anthesis assimilate accumulation in the M3 treatment was 11.93%, 4.69%, and 13.13% higher than that of M1, M2, and M4 treatments, respectively, and the grain yield in M3 increased by 7.70–9.56%, 3.13–4.91%, and 8.69–10.90% compared with those in M1, M2, and M4 in the two growing seasons, respectively. In summary, under the conditions of this study, the M3 treatment led to higher LAI and SPAD values in flag leaves post-anthesis compared to the other treatments. Moreover, M3 optimized canopy structure, led to the highest canopy interception rate, and increased photosynthetic rates per individual plant. Consequently, there was a significant increase in post-anthesis dry matter accumulation, resulting in the highest grain yield achieved among the treatments.

Timely sown maize hybrids improve the post-anthesis dry matter accumulation, nutrient acquisition and crop productivity

Delayed sowing of maize hybrids could exacerbate the capability of maximizing the yield potential through poor crop stand, root proliferation, nutrient uptake, and dry matter accumulation coupled with the inadequate partitioning of the assimilates. This study appraised the performance of five recent maize hybrids viz., PMH-1, PJHM-1, AH-4158, AH-4271, and AH-8181 under timely and late sown conditions of the irrigated semi-arid ecologies. Timely sowing had the grain and stover yields advantage of 16–19% and 12–25%, respectively over the late sown maize hybrids. The advanced hybrids AH-4271 and AH-4158 had higher grain yields than the others. During the post-anthesis period, a greater dry matter accumulation and contribution to the grain yield to the tune of 16% and 10.2%, respectively, was observed under timely sown conditions. Furthermore, the nutrient acquisition and use efficiencies also improved under the timely sown. The nutrient and dry matter remobilization varied among the hybrids with AH-4271 and PMH-1 registering greater values. The grain yield stability index (0.85) was highest with AH-4158 apart from the least yield reduction (15.2%) and stress susceptibility index (0.81), while the maximum geometric mean productivity was recorded with the AH-4271 (5.46 Mg ha−1). The hybrids AH-4271 and PJHM-1 exhibited improved root morphological traits, such as root length, biomass, root length density, root volume at the V5 stage (20 days after sowing, DAS) and 50% flowering (53 DAS). It is thus evident that the timely sowing and appropriate hybrids based on stress tolerance indices resulted in greater yields and better utilization of resources.

Effects of nitrogen application on seed yield, dry matter and nitrogen accumulation of Siberian wildrye (Elymus sibiricus L.)

Siberian wildrye (Elymus sibiricus L.) is a perennial and self-fertilizing forage grass that support animal husbandry and environmental sustenance in the world. In order to explore influence of nitrogen(N) application in Siberian wildrye seed production, the field experiments were conducted to evaluated the effect of different N treatments (of 0, 30, 60, 90 and 120 kg/hm2) on dry matter, N accumulation, transport and utilization, yield components and seed yield of Siberian wildrye DJ-01, which was generated and stored in our lab. The results showed that the 90 kg/hm2 group significantly improved Fertile tillers m−2, spikelets per fertile tiller, 1000-grain weight and seed yield. Furthermore, the seed yield of 90 kg/hm2 group reached 899.3 kg/hm2 and elevated 45.6% compared with 0(CK) group. Moreover, we found that Siberian wildrye exhibited more advantages in dry matter and N translocation. The increment of grain N depended on pre-anthesis dry matter translocation (Pre-DMT) and pre-anthesis N translocation (Pre-NT), but not post-anthesis dry matter accumulation (Post-DMA) and post-anthesis N uptake (Post-NU) to seed yield. With the increase of N, N partial productivity and N absorption efficiency gradually decreased. All data showed the 90 kg/hm2 had the best effects on seed yield components, seed yield, dry matter accumulation (DMA), N accumulation and N efficiency. These results provide an ideal strategy to expand the plant area of Siberian wildrye.

Differences and mechanisms of post-anthesis dry matter accumulation in rice varieties with different yield levels

Post-anthesis dry matter accumulation (PDMA) plays an important role in yield, but the differences and mechanisms of PDMA among rice varieties with different yield levels are still unclear. Field experiments were conducted using six rice varieties with medium, high, and super high yield levels selected to not only analyze the relationship between PDMA and yield but also compare the physiological indexes among different varieties. The effects of grain fertilizer on PDMA and yield were also observed. PDMA and apparent transferred mass of non-structural carbohydrate (NSC) in stems from heading to maturity were significantly positively correlated with yield. The physiological indexes (root oxidation activity, zeatin ​+ ​zeatin riboside contents in roots and leaves, and leaf photosynthetic rate) at 0–20 days after anthesis (DAA) of super high-yielding varieties were significantly higher than those of medium-yielding and high-yielding varieties. In addition, the α-amylase activity in stems at 30–50 DAA of super high-yielding varieties was significantly higher than other varieties. Compared with no grain fertilizer application rate (GFAR), the GFAR for maximum yield and yield increase of super high-yielding varieties were higher than other varieties. The above physiological indexes at 10–20 DAA were increased under GFAR at 54 ​kg ​ha−1. The α-amylase activity at 30–50 DAA was inhibited under GFAR at 81 ​kg ​ha−1 that hindered NSC translocation, resulting in decreased yield. Our results indicated that higher PDMA and NSC translocation were the crucial characteristics that benefited the yield formation of super high-yielding rice varieties.

Effects of Controlled Release Urea Formula and Conventional Urea Ratio on Grain Yield and Nitrogen Use Efficiency of Direct-Seeded Rice

A one-off application of bulk blend urea (BBU), which includes a controlled release urea formula and conventional urea, has been recommended to simplify fertilisation management for direct-seeded rice. However, the effects of different basal application ratios of controlled-release urea formula and conventional urea on yield and nitrogen (N) use efficiency remain unknown in direct-seeded rice. This study set up three BBU treatments in which the controlled-release urea formula provided 50% (BBU1), 60% (BBU2), and 70% (BBU3) of the total N. This study measured their effects on grain yield and N use efficiency of direct-seeded rice. Split fertilisation with conventional urea was used as the control (CK). The study concluded four key points: (i) the grain yield of direct-seeded rice decreased as the proportion of controlled-release urea formula increased, (ii) BBU1 increased grain yields by 8.1–8.6% and 10.2–10.6% compared to BBU2 and BBU3, respectively, as well as a greater number of panicles and spikelets per m2, and post-anthesis dry matter accumulation, (iii) the N recovery efficiency and N agronomic efficiency of BBU1 were significantly higher than those of BBU2 and BBU3 treatments, and the nitrogen accumulation was also found to be more, and (iv) compared with the CK, BBU1 achieved considerable grain yield and nitrogen use efficiency while reducing the amount of fertilisation. In conclusion, the appropriate reduction of the basal application ratio of the controlled-release urea formula for direct-seeded rice increased grain yield and nitrogen use efficiency.

Intercropping modulates the accumulation and translocation of dry matter and nitrogen in maize and peanut

Intercropping increases resource capture due to species complementarities, but it is not clear to which extent intercropping also affects the redistribution of carbohydrates and nitrogen (N) within the plant. Here, we examined in two years field experimentation the accumulation and translocation of dry matter and N in maize and peanut in pure stands and intercrops at five N input levels. Post-anthesis dry matter accumulation in the cob was on average 117 g plant −1 in sole maize and 159 g plant −1 in intercropped maize, of which post-anthesis dry matter translocation contributed 9 and 19 g plant −1 , respectively. Intercropping increased post-anthesis N accumulation of maize from 0.77 to 1.29 g N plant −1 and N translocation to cobs from 0.94 to 1.16 g N plant −1 , but it decreased the contribution of post-anthesis N translocation to grain from 54.0% in sole maize to 46.9% in intercropped maize. The kernel number was 486 per cob in sole maize and 609 per cob in intercropped maize, and the thousand-kernel weight was 320 g and 336 g, respectively. In peanut, intercropping decreased post-anthesis dry matter accumulation from 14.8 to 9.4 g plant −1 , post-anthesis N accumulation from 0.37 to 0.24 g N plant −1 and N translocation to the pods from 0.25 to 0.14 g N plant −1 . The pod number per plant in peanut decreased from 10.6 in the sole crop to 8.6 in intercropping. Nitrogen fertilization increased dry matter accumulation and translocation in intercropped maize, but had little impact in sole maize or in sole or intercropped peanut. In both species, dry matter translocation to the reproductive organs contributed slightly to the yield, while the post-anthesis contribution of N translocation was of the same order of magnitude as that of N uptake. • Retranslocation of dry matter made a small contribution to yield. • Retranslocation of nitrogen made a large contribution to nitrogen yield. • Intercropped maize increased nitrogen and dry matter accumulation and translocation. • Intercropped peanut decreased dry matter accumulation and translocation. • Nitrogen fertilizer effects were minor, except in sole maize.

Soil warming and straw return impacts on winter wheat phenology, photosynthesis, root growth, and grain yield in the North China Plain

Soil temperature rise caused by global warming is one of the most serious threats to crop physiology and production. Straw return is considered as a potential strategy to improve soil health and agricultural productivity. However, little is known about their interactive effects on wheat growth and production, which limits the development of strategies and technological innovations for future food security. Therefore, in the two wheat seasons from 2018 to 2020, with or without straw return, the heating cable was laid at a depth of 20 cm to increase the soil temperature by 3.8 ℃, and the phenology, photosynthesis, root growth, and grain yield of winter wheat were studied. Soil warming advanced the anthesis date by one week and promoted pre-anthesis wheat growth and dry matter transportation. However, soil warming decreased post-anthesis duration, leaf area index, SPAD, net photosynthesis, and spectral vegetation indexes. Therefore, post-anthesis dry matter accumulation and grain filling were inhibited, lowering the 1000-grain weight and harvest index. Furthermore, the post-anthesis root weight, length, surface area densities and root to shoot ratio were also decreased under soil warming. Finally, soil warming reduced the grain yield by 35.2% in the dry 2018–2019 year. However, the wheat growth characteristics were considerably higher and no difference in grain yield was detected among treatments in the wet 2019–2020 season, indicating that increased precipitation may offset the adverse effect of soil warming on wheat yield. Straw return increased aboveground biomass, but had no effect on wheat yield, probably because the positive effects were limited in the short experimental duration. The findings suggested that soil warming would promote pre-anthesis wheat growth but accelerate post-anthesis wheat senescence, affect dry matter transportation and accumulation, eventually reducing wheat yield in the NCP, especially under dry condition.

Optimization of drip irrigation and fertilization regimes to enhance winter wheat grain yield by improving post-anthesis dry matter accumulation and translocation in northwest China

The excessive irrigation and fertilization are common in wheat (Triticum aestivum L.) production in northwest China, which not only results in resources waste and environmental pollution, but also not necessarily guarantee high wheat yield due to the plant overgrowth. It is thus crucial to explore a suitable irrigation and fertilization strategy that benefits high-yield wheat cultivation by regulating post-anthesis dry matter accumulation and translocation. A consecutive four-season field experiment (2014–2018) was undertaken on drip-fertigated winter wheat with three irrigation levels based on the soil moisture content of moistening layers (W1: normal irrigation, W2: mild deficit irrigation, W3: severe deficit irrigation) and three fertilization (N-P2O5-K2O) rates (F1: 175–117–150 kg ha−1, F2: 125–84–108 kg ha−1, F3: 75–50–65 kg ha−1). The results showed that the logistic growth equation could well describe the accumulation process of aboveground dry matter with R2 ranging 0.989 − 0.999 (P < 0.01). Water stress advanced the thermal time required from sowing to the maximum aboveground dry matter rate, while the maximum aboveground dry matter rate and average accumulated rate of aboveground dry matter increased with the increase of irrigation and fertilization regimes. Dry matter translocation showed a negative relationship with fertilization rate. However, both the post-anthesis dry matter accumulation and its contribution to total dry matter at maturity (CDMA) increased with the increasing fertilization rate. With the increase of water and fertilizer supply, dry matter translocation efficiency decreased, but CDMA showed the opposite trend. The post-anthesis dry matter accumulation was positively related to winter wheat grain yield. When the grain yield reached above 7.5 Mg ha−1 in northwest China, the post-anthesis accumulated dry matter should be more than 4.7 Mg ha−1. It was concluded that the mild deficit irrigation along with N-P2O5-K2O fertilization of 125–84–108 kg ha−1 enhanced the productivity of winter wheat by increasing the post-anthesis dry matter translocation and accumulation.

Source–sink relations and responses to sink–source manipulations during grain filling in wheat

The source–sink ratio during grain filling is a critical factor that affects crop yield in wheat, and the main objective of this study was to determine the source–sink relations at both the canopy scale and the individual culm level under two nitrogen (N) levels at the post-jointing stage. Nine widely-used cultivars were chosen for analyzing source–sink relations in southwestern China; and three typical cultivars of different plant types were subjected to artificial manipulation of the grain-filling source–sink ratio to supplement crop growth measurements. A field experiment was conducted over two consecutive seasons under two N rates (N+, 150 kg ha−1; N–, 60 kg ha−1), and three manipulations were imposed after anthesis: control (Ct), removal of flag and penultimate leaves (Lr) and removal of spikelets on one side of each spike (Sr). The results showed that the single grain weights in the three cultivars were significantly decreased by Lr and increased by Sr, which demonstrated that wheat grain yield potential seems more source-limited than sink-limited during grain filling, but the source–sink balance was obviously changed by climatic variations and N deficient environments. Grain yield was highly associated with sink capacity (SICA), grain number, biomass, SPAD values, and leaf area index during grain filling, indicating a higher degree of source limitation with an increase in sink capacity. Therefore, source limitation should be taken into account by breeders when SICA is increased, especially under non-limiting conditions. Chuanmai 104, a half-compact type with a mid-sized spike and a long narrow upper leaf, showed relatively better performance in source–sink relations. Since this cultivar showed the characteristics of a lower reduction in grain weight after Lr, a larger increase after Sr, and a lower reduction in post-anthesis dry matter accumulation, then the greater current photosynthesis during grain filling contributed to the grain after source and sink manipulation.

The Optimal Cultivar × Sowing Date × Plant Density for Grain Yield and Resource Use Efficiency of Summer Maize in the Northern Huang–Huai–Hai Plain of China

In order to explore the optimal cultivar × sowing date × plant density for summer maize (Zea mays L.) in the Northern Huang–Huai–Hai (HHH) Plain of China, field experiments were conducted over two consecutive years (2018–2019) on a loam soil in the Northern HHH Plain. A split–split plot design was employed in this study, and the main plots included three cultivars (HM1: early-maturing cultivar; ZD958: medium-maturing cultivar; DH605: late-maturing cultivar); subplots consisted of three sowing dates (SD1: June 10; SD2: June 17; SD3: June 24); sub-sub plots include two plant densities (PD1: 6.75 × 104 plants ha−1; PD2: 8.25 × 104 plants ha−1). The results showed that the effects of cultivar and plant density on grain yield of summer maize were not significant, and the sowing date was the major factor affecting the grain yield. Delayed sowing significantly decreased the grain yield of summer maize, this was due mainly to the reduced kernel weight, which is associated with the lower post-anthesis dry matter accumulation. Moreover, radiation use efficiency (RUE), temperature use efficiency (TUE), and water use efficiency (WUE) were significantly affected by cultivar, sowing date, and plant density. Selecting early- and medium-maturing cultivars was beneficial to the improvements in RUE and TUE, and plants grown at earlier sowing with higher plant density increased the RUE and TUE. The interactive analysis of cultivar × sowing date × plant density showed that the optimum grain yields of all tested cultivars were observed at SD1-PD2, and the optimum RUE and TUE for HM1, ZD958, and DH605 were observed at SD1-PD2, SD2-PD2, and SD2-PD2, respectively. The differences in the optimum grain yield, RUE, and TUE among the tested cultivars were not significant. These results suggested that plants grown at earlier sowing with reasonable dense planting had benefits of grain yield and resource use efficiency. In order to adapt to mechanized grain harvesting, early-maturing cultivar with lower grain moisture at harvest would be the better choice. Therefore, adopting early-maturing cultivars grown with earlier sowing with reasonably higher plant density would be the optimal planting pattern for summer maize production in the Northern HHH Plain of China in future.

Micro-sprinkling irrigation simultaneously improves grain yield and protein concentration of winter wheat in the North China Plain

Increased grain yield (GY) and grain protein concentration (GPC) are the two main targets of efforts to improve wheat (Triticum aestivum L.) production in the North China Plain (NCP). We conducted a three-year field experiment in the 2014–2017 winter wheat growing seasons to compare the effects of conventional irrigation practice (CI) and micro-sprinkling irrigation combined with nitrogen (N) fertilizer (MSI) on GY, GPC, and protein yield (PY). Across the three years, GY, GPC, and PY increased by 10.5%–16.7%, 5.4%–8.0%, and 18.8%–24.6%, respectively, under MSI relative to CI. The higher GY under MSI was due primarily to increased thousand-kernel weight (TKW). The chlorophyll content of leaves was higher under MSI during the mid–late grain filling period, increasing the contribution of post-anthesis dry matter accumulation to GY, with consequent increases in total dry matter accumulation and harvest index compared to CI. During the mid–late grain filling period, the canopy temperature was markedly lower and the relative humidity was higher under MSI than under CI. The duration and rate of filling during the mid–late grain filling period were also higher under MSI than CI, resulting in higher TKW. MSI increased the contribution of post-anthesis N accumulation to grain N but reduced the pre-anthesis remobilization of N in leaves, the primary site of photosynthetic activity, possibly helping maintain photosynthate production in leaves during grain filling. Total N at maturity was higher under MSI than CI, although there was little difference in N harvest index. The higher GPC under MSI than under CI was due to a larger increase in grain N accumulation than in GY. Overall, MSI simultaneously increased both GY and GPC in winter wheat grown in the NCP.

Effects of tillage practices on grain yield formation of wheat and the physiological mechanism in rainfed areas

Although the effect of tillage practices on crops has been well studied, the systematic effect of these practices on the yield formation process of wheat in rainfed regions is often poorly reported. Here, four tillage practices, namely, strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R) and rotary tillage after subsoiling (RS), were performed during 3 wheat–growing seasons to study the effect of tillage practices on the yield formation process and the physiological mechanism in rainfed wheat. SRS and SR reduced the tiller numbers but increased the percentage of earring tillers. SRS and SR produced the spike numbers similar to those produced by RS and R but increased the grain numbers per spike by increasing the number of grains per spikelet. SRS reduced the evapotranspiration (ET) during the early–filling stage and increased the ET and water consumption ratio during the mid– and late–filling stages. Because of increased water consumption, the flag leaf water potential by SRS was improved during the late–filling stage; photosynthetic rate and superoxide dismutase activity also improved. Accompanied by the improvement in physiological characteristics, the post–anthesis dry matter accumulation by SRS increased significantly. The average grain yield by SRS in the three growing seasons was 6.0 %, 13.4 % and 7.0 % higher than those by SR, R and RS, respectively. The yield–increasing effect of subsoiling once could last for 3 years but the growth rate on the third year decreased from 8.6 % to 3.2 % in SRS, and decreased from 6.0 %–4.2 % in RS.

Dry matter and nitrogen accumulation, partitioning, and translocation in synthetic-derived wheat cultivars under nitrogen deficiency at the post-jointing stage

Synthetic hexaploid wheat-derived cultivars (SDCs) show substantially improved yield potential compared with that of nonsynthetic-derived cultivars (NSCs) developed by conventional breeding. However, the relationship between the high-yielding traits of SDCs and nitrogen (N) use efficiency, especially their performance under N deficiency, is unclear. A field experiment was conducted in two successive seasons examining the responses of six genotypes (three SDCs and three NSCs) under two N treatments: N+ (N sufficiency, N nutrition index ≥ 1) and N− (N deficiency, N nutrition index < 1). N deficiency had a significantly negative effect on grain yield (GY) and yield-related traits. Compared with that of NSCs, SDCs showed 14% (N+) and 16% (N−) higher GY. This yield gain was mainly attributable to the higher total dry matter (DM) and post-anthesis DM accumulation of SDCs under both N treatments. On average, SDCs showed higher chlorophyll content than NSCs in the three upper leaves from 0 to 32 days post-anthesis, which was highly positively correlated with GY under both N treatments. Total and fertilizer N accumulation were significantly decreased under N deficiency. Compared with that of NSCs, SDCs showed lower grain protein concentrations under both N treatments, which was negatively correlated with GY. In addition, SDCs showed significantly higher N use efficiency and N utilization efficiency (NUtE) than NSCs, and a positive correlation was detected between NUtE and GY. The results indicated that SDCs show advantages over NSCs in GY, DM accumulation, and NUtE under N deficiency, and thus cultivation of SDCs shows potential to reduce N waste and environmental contamination.

Effects of micro-sprinkling with different irrigation amount on grain yield and water use efficiency of winter wheat in the North China Plain

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.

Broadcasting Winter Wheat Can Increase Grain Yield without Reducing the Kernels per Spike and the Kernel Weight

In North China, row spacing is the most common planting pattern used for winter wheat. Currently, there are three sowing and tillage methods for row spacing: rotary tillage sowing with straw return (RTS), subsoil tillage sowing with straw return (DTS), and no-tillage sowing with straw return (NTS). Recently, Hao proposed a new sowing pattern called uniform broadcast sowing with straw return (BSS) which could increase winter wheat yield. In this research, a field experiment was conducted during the growing seasons in 2011–2012 and 2012–2013. The winter wheat (Triticum aestivum L.) variety Jimai 22 was sowed with the four seeding and tillage methods—RTS, DTS, NTS, and BSS—at the China Agriculture University Wuqiao experimental station in the North China Plain. After tillage sowing and determining the sowing efficiency, the effective cover ratio of the seeds was measured, and the emergence ratio was calculated after emergence. In the two growing seasons, the growth and development stages were recorded. The dry matter accumulation (DMA), the yield, and the yield components (spikes per hectare, kernels per spike, and kernel weight) were also determined. We also measured the canopy structure leaf area index (LAI) and the stand uniformity. The results showed that BSS had the lowest emergence rate and lowest plant stands when compared with the other treatments. However, BSS had the highest grain yield at 7599.0 kg·ha−1 and 9763.3 kg·ha−1, which was 11.55, 16.17, 20.16% and 13.01, 15.68, 21.88% higher than DTS, RTS, and NTS in the 2011/2012 and 2012/2013 growing seasons, respectively. The improved grain yield of BSS was due to the increased productive tillers per hectometer-squared, which was attributed to the higher stand uniformity. More importantly, the increased tillers per hectare and grain yield were not accompanied by a reduction in grain number per spike or grain weight. The stand uniformity could facilitate canopy construction and population architecture and result in more even sunlight distribution, increased leaf area index (LAI) and sunlight interception, and enhanced photosynthetic activity. The stand uniformity also could increase both the pre-anthesis and post-anthesis DMA and promote the harvest index (HI). This study indicates that BSS is the most suitable sowing method for winter wheat production in North China.

Effects of Post-Anthesis Nitrogen Uptake and Translocation on Photosynthetic Production and Rice Yield

Post-anthesis nitrogen uptake and translocation play critical roles in photosynthetic assimilation and grain filling. However, their effects on leaf stay-green characteristics, dry matter accumulation, and translocation after anthesis remain unclear. In this study, post-anthesis N uptake and translocation between two different rice genotypes (Yongyou12 and Zhongzheyou1) were compared through soil nitrogen leaching treatments at the meiosis stage (MST) and anthesis stage(AST) respectively, and their effects on leaf stay-green duration, photosynthesis, dry matter accumulation and translocation during ripening and yield formation were estimated. The results showed that the soil nitrate-N and ammonium-N contents in Yongyou12 pots decreased significantly, and post-anthesis N uptake was 2.0–3.4 fold higher in Yongyou12 than in Zhongzheyou1. The activities of N-metabolism enzymes and antioxidant enzymes were higher, and flag-leaf photosynthesis and dry matter accumulation during ripening were greater, in Yongyou12 than in Zhongzheyou1. However, insufficient available soil N led to significant decreases in the activities of N- metabolism enzymes, decreased flag-leaf photosynthesis, increased translocation of dry matter and N pre-anthesis, accelerated leaf senescence, shorter duration of the leaf stay-green period, and decreased dry matter accumulation and grain plumpness. In addition, the effect of N uptake after anthesis on yield is greater for rice genotypes that depend on post-anthesis dry matter accumulation and an expanded sink capacity.

Winter and spring night-warming improve root extension and soil nitrogen supply to increase nitrogen uptake and utilization of winter wheat ( Triticum aestivum L.)

Abstract Elucidating the effects of asymmetric warming during winter and spring will help develop a feasible crop management strategy for climate change. Field experiments were conducted using the Yangmai-13 (vernal type) and Yannong-19 (semi-winter type) winter wheat cultivars to investigate the effects of night-warming during winter (warming by 1.47–1.53 °C from tillering to jointing), spring (warming by 1.68–1.77 °C from jointing to booting), and winter + spring (warming by 1.53–1.60 °C from tillering to booting) on plant growth and N utilization in 2014–2016. The results showed that the grain yield, N agronomic efficiency (NAE), and N recovery efficiency (NRE) of both cultivars were highly increased in response to night-warming, which were associated with enhanced dry matter and N accumulation, and winter + spring night-warming resulted in greater increases than winter night-warming and spring night-warming. Furthermore, the increase in pre-anthesis N accumulation was much higher than after anthesis, resulting in a greater increase in post-anthesis dry matter accumulation due to more leaf N distribution at anthesis to support photosynthetic production. Root growth characteristics (i.e., root length, surface area and volume, and root bleeding intensity) were significantly promoted, which favored plant N uptake. Soil urease and protease activity as well as the net N mineralization rate, which are involved in soil N supply capacity, were increased, whereas soil inorganic N content and apparent N surplus were clearly decreased, which indicated that plant N uptake capacity was highly improved in response to night-warming conditions. In conclusion, winter and spring night-warming improve pre-anthesis root growth and N uptake ability to promote plant growth, resulting in increased N utilization efficiency with reduced N fertilizer loss, and winter + spring night-warming has more advantages for N uptake and utilization of winter wheat.

Root vertical distribution is important to improve water use efficiency and grain yield of wheat

The winter wheat (Triticum aestivum L.) production of the North China Plain is threatened by increasing water shortages. Therefore, the invention of effective irrigation techniques is crucial to maintain high yields of winter wheat through improved water use efficiency (WUE). In this study, field experiments were carried out in the North China Plain region in 2012–2013 and 2013–2014. Based on the soil moisture regulation at sowing to ensure the normal emergence of the winter wheat, four supplemental irrigation (SI) regimes were set up: no-irrigation after emergence (T1), SI at jointing and anthesis (T2), SI at sowing, jointing and anthesis (T3), and SI at pre-wintering, jointing and anthesis (T4). The results showed that the root length density (RLD), root surface area density (RAD), and root weight density (RWD) in the 0–0.2m soil layer from T2 increased rapidly after jointing and were significantly higher than those from T3 and T4 at anthesis. Those of T2 in the 0.6–0.8m and 0.8–1.0m soil layers were also significantly higher at anthesis. T2 was significantly higher than T1 in the photosynthetic rate (Pn) and instantaneous water use efficiency (WUEleaf) of flag leaves, post-anthesis dry matter accumulation (DMA), contribution of DMA to grain (CDMA), grain yield and WUE, but lower than T1 in the pre-anthesis dry matter remobilization efficiency (DMRE) and contribution of DMR to grain (CDMR). T2 had significantly lower plant populations and dry matter at jointing, Pn and WUEleaf at 28days after anthesis, DMA and CDMA, but higher dry matter increase rate after jointing, tiller survival rate, DMR, DMRE, CDMR and WUE. The combined effect of these differences enabled T2 to have yield that was not significantly different to T4. In summary, SI at joining and anthesis that was based on suitable soil water content at sowing increased the absorbing area of roots in both deep and surface soil layers; accelerated the dry matter accumulation after jointing; increased the Pn and WUEleaf of flag leaves, DMA and DMR; and finally achieved a high grain yield and higher WUE. However, excessive irrigation reduced the WUE by inhibiting the redistribution of dry matter, although the WUEleaf of flag leaves was still increased.