Split nitrogen fertilizer application improved grain yield in winter wheat (Triticum aestivum L.) via modulating antioxidant capacity and 13C photosynthate mobilization under water-saving irrigation conditions
Ecological Processes volume 10, Article number: 21 (2021)
A water-saving cultivation technique of supplementary irrigation based on soil moisture levels has been adopted for winter wheat production in the Huang-Huai-Hai Plain of China, due to the enhanced water-use efficiency. However, appropriate split nitrogen management may further improve crop growth and grain yield. Here, we conducted a 2-year field experiment to determine if split nitrogen management might improve wheat productivity by enhancing 13C photosynthate mobilization and the antioxidant defense system under water-saving conditions. Split nitrogen management involved a constant total nitrogen rate (240 kg ha−1) split in four different proportions between sowing and jointing stage, i.e., 10:0 (N1), 7:3 (N2), 5:5 (N3), and 3:7 (N4). The N3 treatment significantly enhanced “soil-plant analysis development” values, superoxide dismutase antioxidant activity, soluble protein content, sucrose content, and sucrose phosphate synthetase activity, although it reduced the accumulation of malondialdehyde (MDA). The N3 treatment ultimately increased the amount of dry matter assimilation after anthesis significantly. In addition, the 13C isotope tracer experiment revealed that the N3 treatment promoted the assimilation of carbohydrates after anthesis and their partitioning to the developing grains. Compared to the unequal ratio treatments (N1, N2, and N4), the equal ratio treatment (N3) increased grain yield by 5.70–16.72% via increasing 1000-grain weight and number of grains per spike in both growing seasons. Therefore, we recommend the use of a 5:5 basal-topdressing split nitrogen fertilizer application under water-saving irrigation conditions to promote antioxidant enzyme activity and the remobilization of photosynthate after anthesis for improving wheat grain yield.
Winter wheat is a widely cultivated crop in the Huang-Huai-Hai Plain of China (HPC), a very important area of wheat production in China (He et al. 2017). The identification of methods to increase wheat grain yield in HPC is increasingly crucial for grain productivity and food security in China (Liu et al. 2020a). Water is an important factor for wheat development and grain yield. However, recurrent water shortages in the region of the HPC, mainly due to climate change and increased water demand, threatens the sustainability of winter wheat production. Therefore, reasonable irrigation management recommendations are urgently needed.
Traditionally, farmers in the region of the HPC irrigate winter wheat by flooding four to six times during the growth season, for a total irrigation water use of 300–400 mm. However, serious water consumption affects the sustainable development of this irrigation method in the HPC (Dar et al. 2017; Mostafa et al. 2018; Jha et al. 2019). Methods that reduce irrigation water consumption require urgent attention. Our research group previously reported a water-saving cultivation technique of supplementary irrigation based on measuring soil moisture at critical stages. Compared to traditional flood irrigation, this reported technique maintained high grain yield and water use efficiency and decrease water consumption (Man et al. 2014). Our previous research also showed that this irrigation method can promote wheat root growth to a greater soil depth and, consequently, improve the absorption and utilization of soil moisture (Guo et al. 2015). Compared with flood irrigation, the total irrigation water amount was reduced by 200–300 mm under this water-saving irrigation technique (Zhang et al. 2019).
As nitrogen is an essential macronutrient for wheat growth and yield, fertilizer management is generally the most effective way to increase grain yield in winter wheat production (Azam et al. 2020). However, unreasonable nitrogen fertilizer application has led to serious environmental problems, higher fertilizer loss, and lower returns for farmers (Singh et al. 2014; Tan et al. 2017). Therefore, appropriate nitrogen fertilizer management is essential for a sustainable strategy to improve crop yield while reducing environmental risk (Trost et al. 2016). An appropriate basal-topdressing ratio of nitrogen application is the most important component of nitrogen fertilizer management (Zhang et al. 2018). In many areas of the world, farmers commonly tend to apply nitrogen fertilizer at pre-planting due to the convenience of such an application and its priming effect on wheat seedling growth (Santis et al. 2020). However, the nitrogen requirements of wheat have been shown to vary among growth stages (Santis et al. 2020). In addition, nitrogen fertilizer availability can be affected by wheat processes (Lollato et al. 2019). Therefore, wheat nitrogen requirements may not be satisfied if the total amount of nitrogen fertilizer is applied at once, at pre-planting. Alternatively, split nitrogen management at the jointing may contribute towards satisfying the plant nitrogen demand via soil supply, thereby, enhancing nitrogen use efficiency, and ultimately improving grain yield. In addition, the response of wheat to nitrogen fertilization is dependent on the soil-water condition. Li et al. (2012) reported that an appropriate soil moisture level led to improved nitrogen availability and the simultaneous utilization of water and that supplemental irrigation is the main factor that affects the soil water condition. Previous studies reported the effects of the nitrogen application rate, fertilization ratio, and fertilization period on wheat yield under the sufficient irrigation condition (Zhao et al. 2020). However, the effect of split nitrogen fertilization on wheat yield under water-saving irrigation condition requires further investigation. The appropriate nitrogen application under water-saving irrigation may contribute significantly to the sustainable production of winter wheat in the region of the HPC.
Leaf senescence is a developmental process that involves the degradation of macromolecules, such as nucleic acids and proteins, the accumulation of reactive oxygen species, and the transition from nutrient assimilation to nutrient remobilization (Nehe et al. 2020). The commencement of grain growth from anthesis onwards coincides with leaf senescence (Kitonyo et al. 2018a, 2018b). The plant leaves are the major sites for photosynthesis, which, together with the pre-anthesis reserves, supply the assimilates for grain-filling (Kitonyo et al. 2018a, 2018b). Premature leaf senescence can lead to a reduction in wheat canopy size (Yang et al. 2017), loss of light use efficiency, and decreased crop yield (Thapa et al. 2018). A delayed onset of senescence with longer functional photosynthesis (stay green) may produce more assimilates for developing grains and, thus, has the potential to maximize grain yield (Wu et al. 2019; Li et al. 2019). Nitrogen is a key factor in regulating the leaf senescence of crops (Roche et al. 2017). Previous studies have demonstrated that nutrient stress due to nitrogen deficiency induces the premature senescence of flag leaves (Jiang et al. 2020). In contrast, high nitrogen levels delay the initiation of flag leaf senescence and prolong the leaf functional period (Luo et al. 2018). However, previous nitrogen management studies have focused predominantly on the agronomic and physiological bases of yield potential under sufficient irrigation conditions. More research is needed to develop an optimal water and nitrogen management system to support the use of water-saving irrigation, especially involving fertigation techniques, for winter wheat production in the HPC. Therefore, in this study, the working hypothesis is that split nitrogen management techniques would significantly affect the grain yield by impacting the antioxidant capacity and 13C photosynthate mobilization under water-saving irrigation condition. The objectives of the present study were to (1) examine and compare the antioxidant capacity of flag leaves between different nitrogen treatments after anthesis; (2) investigate differences in 13C photosynthate assimilation, distribution, and redistribution between different nitrogen treatments under water-saving irrigation; and (3) determine the optimal nitrogen management technique under water-saving irrigation.
Materials and methods
Field experiments were conducted during the winter wheat growing seasons in 2016–2017 and 2017–2018 at the experimental station in Shijiawangzi Village, Xiaomeng Town, Yanzhou, Jining City, Shandong Province, China (35° 40′ N, 116° 41′ E) (Fig. 1). This region is a typical plain region of the HPC, which has a warm temperature continental climate. The soil in the region is classified as clay loam. The top 0–20 cm soil layer contained 14.20 g kg−1 organic matter concentration, 1.13 g kg−1 total nitrogen, 122.60 mg kg−1 available nitrogen, 129.44 mg kg−1 available potassium, and 38.11 mg kg−1 available phosphorus. The crop previously grown at the study was corn, and all residual straw was incorporated into the soil after harvest.
Experimental design and crop management
Winter wheat variety “Jimai 22”, a cultivar widely used in the HPC, was selected for the field experiments. The experiment included four treatments at a nitrogen application rate of 240 kg ha−1, with fertilizer ratios of base to topdressing of fertilizer, namely, 10:0 (N1), 7:3 (N2), 5:5 (N3), and 3:7 (N4). A randomized complete block design was used in a split-plot arrangement with three replications. All plots were 20 m2 in size. The distance between two adjacent plots receiving different application treatments was 2 m to avoid the interference of nitrogen and irrigation factors. Soil moisture management in the experimental plot was based on the water-saving cultivation technique of supplementary irrigation by measuring soil moisture. Briefly, the relative water content in the 0–40 cm soil layer was supplemented to 70% at the jointing and anthesis stages of wheat.
The irrigation amount was calculated using the formula: M=10 × r × H × (βi−βj), where M represents the amount of irrigation and r represents the bulk density of the quasi-moist soil depth, H represents the pseudo-moist soil depth, βi represents the design water content, and βj represents the water content of the soil before irrigation. Irrigation was conducted with a hose and measured using a meter (Man et al. 2014).
Urea (N 46%), calcium superphosphate (P2O5 12%), and potassium chloride (K2O 60%) were used as the nitrogen, phosphate, and potassium fertilizers, respectively. The basal nitrogen fertilizer and the phosphate (150 kg ha−1) and potassium (112.5 kg ha−1) fertilizers were spread on the soil surface prior to sowing. Immediately after application, the fertilizers were mixed into the top 0–20 cm layer of soil using a rotary cultivator. At the joining stage of the cultivated wheat, nitrogen fertilizer was applied in furrows, which were immediately covered with soil. After fertilizer application, wheat seeds were sown at a depth of 4 cm on October 12, 2016, and October 24, 2017, and the three-leaf basic determining was 1.8 million ha−1. Plants were harvested on June 8, 2017, and June 7, 2018. All other agronomic management protocols were maintained consistent in all treatments following the recommendations of local farmers for high yield.
Sample collection, analyses, and calculations
SPAD value determination
The soil-plant analysis development (SPAD) value of the flag leaves was measured in 10 randomly selected plants per treatment, at 7-day intervals from anthesis to maturity (measuring 5 times altogether, every year from 2016 to 2018), using an SPAD-502 chlorophyll meter model (SPAD-502, Soil-plant Analysis Development Section, Minolta Camera Co., Osaka, Japan) (Ren et al. 2020).
Superoxide dismutase, malondialdehyde content, soluble protein content, sucrose content, and sucrose phosphate synthetase activity determination
One hundred single stems that flowered on the same day in each plot were tagged and sampled from anthesis to maturity within a 7-day interval, while 20 flag leaves were sampled at each sampling stage (sampling 5 times altogether, every year from 2016 to 2018). Sampled flag leaves were frozen in liquid nitrogen for 1 min and then stored at −80 °C. One half of the sampled flag leaves was used to measure superoxide dismutase (SOD), malondialdehyde (MDA) content, and soluble protein content, while the other half was used to measure the sucrose content and sucrose phosphate synthetase (SPS) activity.
For SOD enzyme extraction, 500 mg of the fresh leaves was ground in 5 mL extraction buffer consisting of 100 mmol L−1 potassium phosphate buffer (pH 7.0), 1 mmol L−1 ethylenediaminetetraacetic acid (EDTA), and 1% polyvinylpolypyrrolidone (PVPP). The extract was centrifuged at 20,000 rpm for 20 min at 4 °C. The supernatant was collected and used to determine SOD activity, MDA content, and soluble protein content, following the methods described by Lv et al. (2017). SOD activity was evaluated based on its ability to inhibit the photoreduction of nitroblue tetrazolium (NBT). In turn, MDA content was calculated using the thiobarbituric acid reaction. Soluble protein content was calculated by Coomassie Brilliant Blue staining.
For SPS enzyme extraction, 500 mg of fresh leaves was ground in 7 mL extraction buffer consisting of 50 mmol L−1 HEPES buffer (pH 7.5), 5 mmol L−1 ethylenediaminetetraacetic acid (EDTA), 1 mmol L−1 DL-Dithiothreitol (DTT), 2 mmol L−1 potassium chloride (KCl), and 1% polyvinylpolypyrrolidone (PVPP). The extract was centrifuged at 10,000 rpm for 10 min at 4 °C. The supernatant was collected and used to determine SPS activity and sucrose content, following Feng et al.’s method (Feng et al. 2019).
Dry matter accumulation and translation
Overall, 20 single stems were randomly sampled from each plot by cutting at ground level at anthesis and maturity stages, and separated into vegetative organs and grains (only at maturity). All plant samples were oven-dried to a constant weight at 70 °C to determine dry mater biomass. Dry matter accumulation and translocation indices were calculated using the following equations (Latifmanesh et al. 2018):
where DMT is the dry matter translocation amount (kg ha−1), DMA is the dry matter accumulation amount at anthesis, DMM is the dry matter of vegetative plant parts at maturity, CDMT is the contribution of pre-anthesis assimilates to grain (%), GY is the grain yield, DMAA is the dry matter accumulation amount after anthesis, and CDMAA is the contribution of dry matter accumulation amount after anthesis to grains.
Carbon isotope analysis
We conducted a leaf isotope-tagging experiment using 13CO2 in both growing seasons. Ten representative single stems in each experimental plot were selected at anthesis. We encased the flag leaf of each selected single stem in a 0.1-mm-thick Mylar plastic bag, which permitted sunlight to pass at levels up to 95% of the natural intensity. The bags were sealed at the base with adhesive tape and subsequently injected with 3.5 mL of 13CO2. After allowing photosynthesis to proceed for 30 min, 13CO2 in each bag was extracted through a KOH washer to absorb the remaining 13CO2, and the bag was removed. This experiment was conducted from 09:00 to 11:00 a.m. on sunny days. At 72 h after processing from anthesis and maturity stages, the wheat plants were randomly sampled from each plot by cutting at the ground level. All plants were separated into stems and sheaths, leaves, glumes (spike axis and kernel husks), and grains (only at maturity), and oven-dried to a constant weight at 70 °C to determine the aboveground biomass. All samples were milled to a fine powder using a ball mill, for use in the carbon isotope analysis. The carbon isotope content of milled samples (5 mg) was determined using an online system composed of an elemental analyzer, a TripleTrap, and a mass spectrometer (Carlo Erba 2100, Milan, Italy). The distribution of 13C photosynthates among different organs was determined (Gao et al. 2017).
Grain yield and yield component determination
Grain yield and yield components were evaluated at the harvest of winter wheat stage (Gaju et al. 2014).
Correlations between the photosynthesis performance parameters and grain filling after anthesis were analyzed using the SPSS 13.0 software (α = 0.05). An analysis of variance was used to assess the effects of irrigation and nitrogen fertilizer treatments on wheat photosynthetic performance and grain-filling parameters using GLM in SPSS 13.0. A logistic equation of grain filling was modeled using SPSS 13.0. All graphics were produced using Excel and SigmaPlot 12.5.
The chlorophyll content (SPAD value)
Changes in SPAD value of flag leaves after anthesis are shown in Fig. 2. Split nitrogen treatment had significant effects on the SPAD value in both growth seasons (Additional file 1: Table 1). In 2016–2017, the mean SPAD value of the N3 treatment was significantly higher than that of the N1 and N2 treatments, and no significant differences were detected between the N3 and N4 treatment. Similar results were obtained in both growth seasons. These results indicated that plants under the N3 treatment maintained a longer effective duration of photosynthesis, compared with the other treatments.
Antioxidation indexes of flag leaves
Changes in MDA content, SOD activity, and soluble protein content in the flag leaves after anthesis are shown in Fig. 3. Split nitrogen treatments had no significant effects on MDA content, SOD activity, and soluble protein content at 0 DAA after anthesis (Additional file 1: Table 2). However, significant differences were detected among the different treatments at 7, 14, 21, and 28 DAA. Compared with the N1 and N2 treatments, the N3 treatment showed significant increases in SOD activity and soluble protein content at 7, 14, 21, and 28 DAA after anthesis and a significant decrease in MDA content. No significant differences were detected between N3 and N4 treatments. These results indicated that the N3 treatment extended the duration of high SOD activity and soluble protein content, which was conducive to delaying the senescence and apoptosis of leaf cells.
Sucrose content and SPS activity of flag leaves
Changes in the sucrose content and SPS activity levels in the flag leaves after anthesis are shown in Fig. 4. The sucrose content and SPS activity first increased and then decreased as senescence progressed from 0 to 28 DAA. Sucrose content and SPS activity were highest at 14 DAA. Split nitrogen treatments had significant effects on sucrose content and SPS activity (Additional file 1: Table 3). Significantly higher levels were detected in the N3 treatment compared to the N1 treatment, whereas no significant differences were detected between N3 and N2 treatments or the N3 and N4 treatments at 0 DAA. At 7 DAA, the sucrose content in the N3 treatment was significantly higher than that in the N1 and N2 treatments, while no significant differences were detected between N3 and N4 treatments. From 14 to 28 DAA, sucrose content was highest in the N3 treatment, followed by the N2 and N4 treatments, while the lowest content was detected in the N1 treatment. SPS activity was similar across treatments. Overall, sucrose content and SPS activity in the flag leaves were improved by the N3 treatment.
Translocation after anthesis in vegetative organ
In 2016–2017, total dry matter biomass at anthesis and maturity and the DMT did not differ significantly among treatments (Table 1). The CDMT did not differ significantly among the N2, N3, and N4 treatments, but the CDMT from the N1 treatment was always higher than that of the other nitrogen treatments. The DMAA was the highest in the N3 treatment, followed by N2 and N4 treatments, and lowest in the N1 treatment. The CDMAA was significantly higher in the N3 treatment compared to the N1 treatment but did not differ significantly with respect to the N2, or the N4 treatments. The results obtained in 2017–2018 showed almost the same trends as those obtained in 2016–2017. Altogether, our data indicated that the dry matter assimilation after anthesis was higher under the N3 treatment and that the dry matter redistribution from the vegetative organs to the developing grain remained at a higher level after anthesis.
13C photosynthate distribution in different organs of wheat
The changes in distribution of 13C photosynthate among different organs at 72 h after labeling and at maturity are shown in Table 2. In 2016–2017, stems, sheaths, spike axes, and husks under the N3 treatment had higher 13C photosynthate contents by averages of 15.80% and 10.52% and 11.99% and 8.17% compared to those under the N1 and N2 treatments, respectively. However, no significant differences were detected between the N3 and N4 treatments. Additionally, the leaf 13C photosynthate content did not differ significantly among treatments at 72 h after labeling. At maturity, the 13C photosynthate contents in the leaves, stems, and sheaths were significantly lower in the N3 treatment than in the other split nitrogen treatments. The spike axis and husk 13C photosynthate content were significantly higher in the N3 treatment than in the N1 and N2 treatments; however, no significant differences were detected between the N3 and N4 treatments. The grain 13C photosynthate content was higher under the N3 treatment by averages of 24.43%, 11.83%, and 6.44% compared to the N1, N2, and N4 treatments, respectively. Similar responses to treatments were observed in both growth seasons. Overall, the N3 treatment significantly increased carbohydrate assimilation after anthesis and their distribution from vegetative organs to the grains, which likely accounts for the higher grain yield observed for plants in the N3 treatment.
13C photosynthate translocation after anthesis
In both growth seasons, split nitrogen treatments had no effect on the translocation amount of the spike axis and husk 13C photosynthates but did significantly affect the translocation amounts of leaf and stem 13C photosynthates (Fig. 5). In 2016–2017, the translocation amounts of leaf and stem 13C photosynthates under the N3 treatment were higher by averages of 16.03%, 12.63%, and 11.51%, and 27.97%, 17.00%, and 8.52% compared to the N1, N2, and N4 treatments, respectively. The second growth season showed similar results. Collectively, these results indicated that the N3 treatment substantially promoted the translocation of photosynthates to the grain, especially from the leaves and stems.
Grain yield and yield components
The effects of split nitrogen fertilizer treatments on grain yield and its components in both growth seasons are shown in Table 3. Split nitrogen fertilizer treatments significantly affected grain yield in both the 2016 and 2017 seasons. Compared with N1, N2, and N4 treatments, the N3 treatment increased grain yield by 16.27%, 7.09%, and 5.70% in 2016–2017 and 16.72%, 8.88%, and 5.89% in 2017–2018, respectively. The 1000-grain weight and the number of grains per spike were significantly higher in the N3 treatment, compared with any other split nitrogen treatments. Spike number did not differ significantly among the treatments in both growth seasons. These results indicated that the N3 treatment led to a significant increase in grain yield that was mainly attributed to the increase in 1000-grain weight and the number of grains per spike.
Effects of split nitrogen fertilization on flag leaf antioxidant capacity
Chlorophyll is essential for leaf photosynthesis, and its content in wheat leaves reflects their photosynthetic capacity (Hlavacova et al. 2018). Nitrogen affects and participates in chlorophyll synthesis (Christopher et al. 2014; Gaju et al. 2014). Moderate split nitrogen fertilizer application has been shown to increase leaf chlorophyll content, which promotes the growth of aboveground parts, such as leaves, and thus leads to an increase in biomass (Xie et al. 2016; Yang et al. 2017; Tian et al. 2020). In our study, moderate split nitrogen ratios readjusted the flag leaf antioxidant capacity, such that plants under the N3 treatment showed the highest SOD activity and soluble protein content after anthesis, compared with the other split nitrogen treatments. In contrast, in the unequal ratio treatments (N1, N2, N4), the increase in antioxidant enzyme activity was not sufficient for detoxification of reactive oxygen species, which caused damage to photosystems and contributed to chlorophyll degradation (Zhang et al. 2018). The results of this study showed that flag leaf SPAD values decreased significantly under excessive basal or topdressing nitrogen fertilizer treatments. However, SPAD values significantly improved, and MDA content was significantly reduced under the N3 treatment, which indicated that the N3 treatment was the most appropriate split nitrogen treatment for the protection of chlorophyll integrity and functionality. These responses and the low level of chlorophyll degradation under the N3 treatment may be associated with plants maintaining a higher water status as a result of an improved root system under this treatment (Kitonyo et al. 2018a, 2018b). Overall, these findings indicated that the equal ratio treatment resulted in the flag leaves having a longer duration of photosynthetic capacity than those in any of the unequal ratio treatments (Kitonyo et al. 2017), which favored higher levels of photosynthetic assimilation.
Effects of split nitrogen fertilization on dry matter accumulation amount, 13C-photosynthate translocation, and distribution
One objective of the experiment was to determine how split nitrogen fertilizer treatment affects photosynthate assimilation, distribution, and redistribution. Our experiment allowed to observe positive effects of the split nitrogen treatments on assimilation in vegetative organs, photosynthesis capacity, and grain yield. SPS enzyme transforms photosynthesis assimilates into sucrose and contributes to grain yield (Liu et al. 2020b). The results of our study showed that sucrose content of flag leaves was higher in the N3 treatment than in the other split nitrogen treatments from 14 DAA to 28 DAA, which coincided with the N3 treatment having the highest SPS activity. The final grain yield of winter wheat is determined by the ability of dry matter assimilation in the grain-filling stage (Kamiji et al. 2014). Our results showed that the dry matter assimilation after anthesis was significantly reduced under excessive basal or topdressing nitrogen fertilizer regimens, which was in accordance with previous observations (Liang et al. 2017).
Our assessment of the amount of 13CO2 fixed by wheat plants and translocated to each organ showed that the leaves provided an efficient model to appraise the contribution of each vegetative organ to the grain under different split nitrogen treatments. Our 13C-isotope tracer experiment revealed that the equal ratio treatment (N3) significantly increased the 13C photosynthate accumulation post-anthesis and its contribution to grain compared to the unequal ratio treatments (N1, N2, and N4). This is likely the result of an improved source-sink relationship because dry matter partitioning was biased towards the reproductive organs. The equal ratio treatment resulted in a higher accumulation of dry matter compared to the unequal ratio treatments, especially during anthesis. This higher accumulation of dry matter seemingly occurred because a higher abundance of assimilates at anthesis enabled plants grown under the equal ratio treatment to produce more leaves with enhanced longevity, as needed to increase the source capacity and thus, optimize leaf cover for light interception and use (Lv et al. 2017; Si et al. 2020). Photosynthates are produced by photosynthesis, and nutrient deficiencies at grain-filling stage can accelerate leaf senescence by increasing ROS production (Okamura et al. 2018), while the supply of nitrogen fertilizer during grain-filling can delay leaf senescence and increase wheat yield (Zhang et al. 2019).
In addition, our findings demonstrated that split nitrogen application altered the dry matter allocation among plant organs in wheat plants. Total 13C assimilates translocated to the grain, the stems, and sheaths made the highest contribution, followed by the spike axes and husks, while leaves made the lowest contributions. In this study, as basal or topdressing nitrogen fertilizer increased, wheat plants showed an increase in vegetative dry matter accumulation and a decrease in dry matter allocation to spikes. These effects negatively affected dry matter accumulation in the grain at grain-filling stage, which led to a reduced dry matter accumulation in the grain at maturity (Finnan et al. 2019). However, it is noteworthy that the N3 treatment not only increased the amount of photosynthesis assimilates produced in the post-anthesis period, but also promoted the post-anthesis translocation of carbohydrates from the vegetative organs to the grains as well, thus, further supporting the notion that equal ratio treatments (such as that of N3) can increase grain yield under conditions of water-saving irrigation.
Effects of split nitrogen fertilization on grain yield and yield components
Previous studies have shown that wheat yield was highly correlated with the number of grains per spike and spike number under the sufficient irrigation condition (Rivera-Amado et al. 2019). Current approaches to increase grain yield are mainly focused on increasing the number of grains per spike or 1000-grain weight, but it has proven difficult to further increase the capacity of the grain sink (Agami et al. 2018). Therefore, 1000-grain weight is the most important restrictive factor affecting grain yield. The results of our experiment under conditions of water-saving irrigation further demonstrated that the N3 treatment significantly improved grain yield, which was attributed to a higher number of grains per spike concomitantly with a higher 1000-grain weight.
The unequal ratio treatments (N1, N2, and N4) showed significantly lower yield potential than the equal ratio treatment (N3). This decrease in grain yield can be explained by two factors, mainly: (1) excessive basal nitrogen fertilizer application might have led to an insufficient supply of dry matter for grain filling at the grain-filling stage because the initiation of grain filling requires a large supply of photoassimilate, and (2) excessive topdressing nitrogen fertilizer application delayed plant maturity, as it favored continued vegetative growth. Zhang et al. (2018) reported that nitrogen fertilizer application significantly improved yield by increasing spike number. Interestingly, split nitrogen fertilizer treatments in the present study had no significant effect on spike number (Yang et al. 2017). This discrepancy may be attributed to different climatic conditions and the effects of soil fertility on spike number between the two studies (Li et al. 2020). Nonetheless, our study provides substantial evidence that split nitrogen management can help towards a significant improvement of wheat production. However, the evaluation of the effects of fertilizer management practice on wheat soil environment and wheat yield warrants further research.
Here, we investigated the effects of split nitrogen fertilizer management on 13C photosynthate mobilization and antioxidant enzyme activity in winter wheat under water-saving irrigation conditions. Altogether, our findings confirmed that the 240 kg ha−1 of total nitrogen fertilizer treatment applied in a 5:5 basal-topdressing ratio significantly increased the SPAD values, antioxidant enzymes activities, sucrose content, and SPS activity but reduced the accumulations of MDA in wheat plants. Furthermore, the treatment significantly increased the assimilation of carbohydrates after anthesis and promoted their distribution from vegetative organs to the developing grains. The 5:5 top-dressing N fertilizer treatment effectively increased grain yield by increasing 1000-grain weight and the number of grains per spike. Therefore, combined water-saving irrigation and split nitrogen management are recommended for grain yield improvement of winter wheat in the region of the HPC.
Availability of data and materials
Huang-Huai-Hai Plain of China
Soil-plant analysis development
Sucrose phosphate synthetase
Dry matter translocation amount
Dry matter accumulation amount at anthesis
Dry matter of vegetative plant parts at maturity
Contribution of pre-anthesis assimilates to grain
Dry matter accumulation amount after anthesis
Contribution of dry matter accumulation amount after anthesis to grain
Agami RA, Alamri SAM, Abd El-Mageed TA, Abousekken MSM (2018) Role of exogenous nitrogen supply in alleviating the deficit irrigation stress in wheat plants. Agric Water Manag 210:261–270
Azam B, Mir AMS, Ali E (2020) Effects of salt and nitrogen on physiological indices and carbon isotope discrimination of wheat cultivars in the northeast of Iran. J Integr Agric 19(3):656–667
Christopher JT, Veyradier M, Borrell AK, Harvey G, Fletcher S, Chenu K (2014) Phenotyping novel stay-green traits to capture genetic variation in senescence dynamics. Funct Plant Biol 41:1035–1048
Dar EA, Brar AS, Mishra SK, Singh KB (2017) Simulating response of wheat to timing and depth of irrigation water in drip irrigation system using CERES-wheat model. Field Crop Res 214:149–163
Feng LY, Raza MA, Li ZC, Chen YK, Khalid MH, Du JB, Liu WG, Wu XL, Song C, Yu L, Zhang ZW, Yuan S, Yang WY, Yang F (2019) The influence of light intensity and leaf movement on photosynthesis characteristics and carbon balance of soybean. Front Plant Sci 9:1952
Finnan J, Burke B, Spink J (2019) The effect of nitrogen timing and rate on radiation interception, grain yield and grain quality in autumn sown oats. Field Crop Res 231:130–140
Gaju O, Allard V, Martre P, Le Gouls J, Moreau D, Bogard M, Hubbart S, Foulkes MJ (2014) Nitrogen partitioning and remobilization in relation to leaf senescence, grain yield and grain nitrogen concentration in wheat cultivars. Field Crop Res 155:213–223
Gao J, Zhao B, Dong ST, Liu P, Ren BZ, Zhang JW (2017) Response of summer maize photosynthate accumulation and distribution to shading stress assessed by using 13CO2 stable isotope tracer in the field. Front Plant Sci 8:1821
Guo ZJ, Shi Y, Yu ZW, Zhang YL (2015) Supplemental irrigation affected flag leaves senescence post-anthesis and grain yield of winter wheat in the Huang-Huai-Hai Plain of China. Field Crop Res 180:100–109
He G, Cui ZL, Ying H, Zheng HF, Wang ZH, Zhang FS (2017) Managing the trade-offs among yield increase, water resources inputs and greenhouse gas emissions in irrigated wheat production systems. J Clean Prod 164:567–574
Hlavacova M, Klem K, Rapantova B, Novotna K, Urban O, Hlavinka P, Smutna P, Horakova V, Skarpa P, Pohankova E, Wimmerova M, Orsag M, Jurecka F, Trnka M (2018) Interactive effects of high temperature and drought stress during stem elongation, anthesis and early grain filling on the yield formation and photosynthesis of winter wheat. Field Crop Res 221:182–195
Jha SK, Ramatshaba TS, Wang G, Liang Y, Liu H, Gao Y, Duan A (2019) Response of growth, yield and water use efficiency of winter wheat to different irrigation methods and scheduling in North China Plain. Agric Water Manag 217:292–302
Jiang HB, Li HX, Zhao MX, Mei XL, Kang YL, Dong CX, Xu YC (2020) Strategies for timing nitrogen fertilization of pear trees based on the distribution, storage, and remobilization of 15N from seasonal application of (15NH4)2SO4. J Integr Agric 19(5):1340–1353
Kamiji Y, Pang JY, Milroy SP, Palta JA (2014) Shoot biomass in wheat is the driver for nitrogen uptake under low nitrogen supply, but not under high nitrogen supply. Field Crop Res 165:92–98
Kitonyo OM, Sadras OV, Zhou Y, Denton MD (2018b) Nitrogen supply and sink demand modulate the patterns of leaf senescence in maize. Field Crop Res 225:92–103
Kitonyo OM, Sadras VO, Zhou Y, Denton MD (2017) Evaluation of historic Australian wheat varieties reveals increased grain yield and change in senescence patterns but limited adaptation to tillage system. Field Crop Res 206:65–73
Kitonyo OM, Sadras VO, Zhou Y, Denton MD (2018a) Nitrogen supply and sink demand modulate the patterns of leaf senescence in maize. Field Crop Res 225:92–103
Latifmanesh H, Deng AX, Nawaz MM, Li L, Chen ZJ, Zheng YT, Wang P, Song ZW, Zhang CY, Zhang WJ (2018) Integrative impacts of rotational tillage on wheat yield and dry matter accumulation under corn-wheat cropping system. Soil Tillage Res 184:100–108
Li QQ, Zhao XB, Chen YH, Yu SL (2012) Water consumption characteristics of winter wheat grown using different planting patterns and deficit irrigation regime. Agric Water Manag 105:8–12
Li XN, Ulfat A, Shokat S, Liu SQ, Zhu XC, Liu FL (2019) Responses of carbohydrate metabolism enzymes in leaf and spike to CO2 elevation and nitrogen fertilization and their relations to grain yield in wheat. Environ Exp Bot 164:149–156
Li YJ, Ma LS, Wu P, Zhao XN, Chen XL, Gao XD (2020) Yield, yield attributes and photosynthetic physiological characteristics of dryland wheat (Triticum aestivum L.)/maize (Zea mays L.) strip intercropping. Field Crop Res 248:107656
Liang WX, Zhang ZC, Wen XX, Liao YC, Liu Y (2017) Effect of non-structural carbohydrate accumulation in the stem pre-anthesis on grain filling of wheat inferior grain. Field Crop Res 211:66–76
Liu M, Wu XL, Li CS, Li M, Xiong T (2020b) Dry matter and nitrogen accumulation, partitioning, and translocation in synthetic-derived wheat cultivars under nitrogen deficiency at the post-jointing stage. Field Crop Res 248:107720
Liu Y, Zhang XL, Xi LY, Liao YC, Han J (2020a) Ridge-furrow planting promotes wheat grain yield and water productivity in the irrigated sub-humid region of China. Agric Water Manag 231:105935
Lollato RP, Figueiredo BM, Dhillon JS, Arnall DB, Raun WR (2019) Wheat grain yield and grain-nitrogen relationships as affected by N, P, and K fertilization: a synthesis of long-term experiments. Field Crop Res 236:42–57
Luo YL, Tang YH, Zhang X, Li WQ, Chang YL, Pang DW, Xu X, Li Y, Wang ZL (2018) Interactions between cytokinin and nitrogen contribute to grain mass in wheat cultivars by regulating the flag leaf senescence process. Crop J 6:538–551
Lv XK, Han J, Liao YC, Liu Y (2017) Effect of phosphorus and potassium foliage application post-anthesis on grain filling and hormonal changes of wheat. Field Crop Res 214:83–93
Man JG, Wang D, White PJ, Yu ZW (2014) The length of micro-sprinkling hoses delivering supplemental irrigation affects photosynthesis and dry matter production of winter wheat. Field Crop Res 168:65–74
Mostafa H, El-Nady R, Awad M, El-Ansary M (2018) Drip irrigation management for wheat under clay soil in arid conditions. Ecol Eng 121:35–43
Nehe AS, Misra S, Murchie EH, Chinnathambi K, Tyagi BS, Foulkes MJ (2020) Nitrogen partitioning and remobilization in relation to leaf senescence, grain yield and protein concentration in Indian wheat cultivars. Field Crop Res 251:107778
Okamura M, Arai-Sanoh Y, Yoshida H, Mukouyama T, Adachi S, Yabe S, Nakagawa H, Tsutsumi K, Taniguchi Y, Kobayashi N, Kondo M (2018) Characterization of high-yielding rice cultivars with different grain-filling properties to clarity limiting factors for improving grain yield. Field Crop Res 219:139–147
Ren BZ, Hu J, Zhang JW, Dong ST, Liu P, Zhao B (2020) Effects of urea mixed with nitrapyrin on leaf photosynthetic and senescence characteristics of summer maize (Zea mays L.) waterlogged in the field. J Integr Agric 19(6):1586–1595
Rivera-Amado C, Trujillo-Negrellos E, Molera G, Reynolds MP, Sylvester-Bradley R, Foulkes MJ (2019) Optimizing dry-matter partitioning for increased spike growth, grain number and harvest index in spring wheat. Field Crop Res 240:154–167
Roche J, Turnbull MH, Guo QQ, Novak O, Spath J, Gieseg SP, Jameson PE, Love J (2017) Coordinated nitrogen and carbon remobilization for nitrate assimilation in leaf, sheath and root and associated cytokinin signals during early regrowth of Lolium perenne. Ann Bot 119:1353–1364
Santis MAD, Giuliani MM, Flagella Z, Reyneri A, Blandino M (2020) Impact of nitrogen fertilisation strategies on the protein content, gluten composition and rheological properties of wheat for biscuit production. Field Crop Res 254:107829
Si ZY, Zain M, Mehmood F, Wang GS, Gao Y (2020) Effects of nitrogen application rate and irrigation regime on growth, yield and water-nitrogen use efficiency of drip-irrigated winter wheat in the North China Plain. Agric Water Manag 231:106002
Singh H, Verma A, Ansari MW, Shukla A (2014) Physiological response of rice (Oryza sativa L.) genotypes to elevated nitrogen applied under field conditions. Plant Signal Behav 9:7
Tan Y, Xu C, Liu D, Wu W, Lai R, Meng F (2017) Effects of optimized N fertilization on greenhouse gas emission and crop production in the North China Plain. Field Crop Res 205:135–146
Thapa S, Jessup KE, Pradhan GP, Rudd JC, Liu SY, Mahan JR, Devkota RN, Baker JA, Xue QW (2018) Canopy temperature depression at grain filling correlates to winter wheat yield in the U.S. Southern High Plains. Field Crop Res 217:11–19
Tian D Zhang YY, Mu YJ, Liu JF, He KB (2020) Effect of N fertilizer types on N2O and NO emissions under drip fertigation from an agricultural field in the North China Plain. Sci Total Environ 715:136903
Trost B, Prochnow A, Meyer-Aurich A, Drastig K, Baumecker M, Ellmer F (2016) Effects of irrigation and nitrogen fertilization on the greenhouse gas emissions of a cropping system on a sandy soil in Northeast Germany. Eur J Agron 81:117–128
Wu YW, Li Q, Jin R, Chen W, Liu XL, Kong FL, Ke YP, Shi HC, Yuan JC (2019) Effect of low-nitrogen stress on photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with different low-nitrogen tolerances. J Integr Agric 18(6):1246–1256
Xie Q, Mayes S, Sparkes DL (2016) Early anthesis and delayed but fast leaf senescence contribution to individual grain dry matter and water accumulation in wheat. Field Crop Res 187:24–34
Yang J, Udvardi M (2017) Senescence and nitrogen use efficiency in perennial grasses for forage and biofuel production. J Exp Bot 69:855–865
Yang XL, Lu YL, Ding Y, Yin XF, Raza S, Tong YA (2017) Optimising nitrogen fertilisation: a key to improving nitrogen-use efficiency and minimising nitrate leaching losses in an intensive wheat/maize rotation (2008–2014). Field Crop Res 206:1–10
Zhang HB, Han K, Gu SB, Wang D (2019) Effects of supplemental irrigation on the accumulation, distribution and transportation of 13C-photosynthate, yield and water use efficiency of winter wheat. Agric Water Manag 214:1–8
Zhang L, Liu HH, Sun JQ, Li JC, Song YH (2018) Seeding characteristics and grain yield of maize grown under straw retention affected by sowing irrigation and splitting nitrogen use. Field Crop Res 225:22–31
Zhao HX, Zhang P, Wang YY, Ning TY, Xu CL, Wang P (2020) Canopy morphological changes and water use efficiency in winter wheat under different irrigation treatments. J Integr Agric 19:1105–1116
This work was financially supported by the National Natural Science Foundation of China (31771715, 31771717); Project of Technology System in Modern Wheat Industry, Ministry of Agriculture, China (CARS-3-1-19); and Field Station Union Project of Chinese Academy of Sciences (KFJ-SW-YW035).
The National Natural Science Foundation of China (31771715, 31771717); Project of Technology System in Modern Wheat Industry, Ministry of Agriculture, China (CARS-3-1-19); and Field Station Union Project of Chinese Academy of Sciences (KFJ-SW-YW035).
Ethics approval and consent to participate
Consent for publication
All authors agreed and approved the manuscript for publication in Ecological Processes.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Zhang, Z., Yu, Z., Zhang, Y. et al. Split nitrogen fertilizer application improved grain yield in winter wheat (Triticum aestivum L.) via modulating antioxidant capacity and 13C photosynthate mobilization under water-saving irrigation conditions. Ecol Process 10, 21 (2021). https://doi.org/10.1186/s13717-021-00290-9