Abstract

In order to explore the optimum amount of nitrogen application of winter wheat, a field experiment was conducted at Wenxi experimental site of Shanxi Agriculture Wenxi. Nitrogen application significantly increased the Net Photosynthesis Rate (P_N), intercellular carbon dioxide concentration (C_i) and transpiration rate (E) of post-anthesis flag leaves. Compared to other nitrogen application rates, 210 kg ha^–1 was the best compared to other nitrogen application rates, with the nitrogen of 210 kg ha^–1 nitrogen application increased nitrogen accumulation in all growth stages. The content of each protein component increased. With 210 kg ha^–1 of nitrogen application, the albumin, globulin, prolamin, and glutenin was high in content and showed no significant with those of 240 kg ha^–1 application rate. The protein yield at 210 kg ha^–1 were significantly improved compared to other nitrogen application rates. The prolamin and glutenin (storage protein) were the highest at 210 kg ha^–1. Significantly improved the protein yield at 210 kg ha^–1 compared to other nitrogen application rates.

1. Introduction

Wheat (Triticum aestivum L.) is one of the most important food crops in the world, and it is also an important food crop in China, and production plays an important role in China’s national economic production. Improving yield and quality in production has always been an important task for wheat cultivation workers. The yield and quality of wheat was affected by varieties, environmental factors, and cultivation measures ¹. Nitrogen fertilizer has a major input rate in the production of direct seeded nitrogen application the spring using ammonium nitrate ². Compared to increase chlorophyll content and promoted photosynthesis during grain filling, and N can significantly reduce the number of infertile spike, and increased wheat yield ³. The improvement of soil water status, seedling establishment, and crop yield can also be increased mainly through improving water infiltration, and retention ⁴. The efficient recovery of fertilizer nitrogen by crops is desirable both for economic reasons, and to minimize environmental problems. However, various studies in China have shown that nitrogen losses following the use of fertilizer ⁵. Available water and nitrogen are considered the most limiting factors in wheat production in most parts of the world, especially in arid, and semi-arid regions. Therefore, supplemental irrigation, and nitrogen fertilizer application are required to soil water stress, and stabilize yields ⁶. The highest nitrogen uptake in the growth period occurred from reviving stage to anthesis stage. The proportion of nitrogen accumulated in leaf, and stem was high before the anthesis stage and the accumulated nitrogen rate in stem reached peak at the anthesis stage ⁷. Nitrogen deposition has dramatically altered terrestrial ecosystem properties and processes, such as plant nutrient cycling, photosynthetic carbon assimilation, and species diversity ⁸. Under nitrogen, the grain-filling process is sustained mainly by photosynthesis in the upper parts of wheat plants, such as the flag leaves and wheat ears ^{9, 10}. In N-limited ecosystem, N deposition can satisfy plant N demand and stimulate photosynthetic capacity and plant growth ^{11, 12}. The species-specific response to N deposition increase depends largely on their physiological adaptations in natural grassland community ^{13, 14}.

Different functional groups exhibit divergent photosynthetic capacity, and nutrient cycling in response to altered N availability ¹⁶. Nitrogen (N) is an essential mineral nutrient for plant growth, expands soil fertility, and crop productivity ¹⁷. A proper amount of N fertilizer application is considered a key for high crop production ¹⁸. An increase in grain yield is often associated with low protein content ¹⁹. In China, farmers are excessively applying N fertilizers to sustain further increase grain yield, but grain yield does not keep synchronous increase with excessive N application ²⁰. For dryland wheat production, the major task is to use method which could effectively enhance the soil moisture consumption. Nitrogen rate has been used for dryland wheat production and results have shown that compared with nitrogen fertilizer, the increased the growth of wheat at various growth stages and improve the efficiency of water uptake, and increase yield ²¹. High nitrogen use efficiency resulting in increased grain protein content may come from improved capacity of the grain to accrue nitrogen supply to the grains ²². Grain protein content decreased in the year with low precipitation (335.0 mm), while increased in the year with high precipitation (673.1 mm), (534.7 mm) ²³. Nitrogen fertilizer expands soil fertility and crop productivity. Nitrogen is an essential mineral nutrient for plant growth ²⁴. In China, farmers excessively apply nitrogen fertilizers because of their hope to sustain further grain yield increases but grain yield does not keep synchronous increase with excessive nitrogen application ²⁵.

The objective of this study was to compare the differences of soil water and nitrogen utilization, yield and grain formation under different nitrogen application rates, the optimal nitrogen application rate was determined to achieve the goal of high yield, high quality and green production of winter wheat

2. Materials and Methods

The experiment was conducted in the wheat experimental base of Shanxi agricultural university in Wenxi, Shanxi Province, China (34°35′N, 110°15′E) from 2016 to 2017, which belonto the temperate continental climate zone. The experimental area was located in the southeastern Loess Plateau. Winter wheat was sowed in late September or early October and harvested in early to late June. The summer fallow is from harvest in the previous growing season (early/mid-June every year) to sowing in the next growing season (late September/early October). Approximately 60% of the annual precipitation occurs between July and September during the summer fallow season and no irrigation system.

This site has a typical, semi-arid, warm temperate climate with 486.8 mm average annual precipitation (the sum of fallow season and growth period precipitation), 12.9°C average daily temperature, and 2242 h of yearly sunshine. The rainfall during the whole year and fallow period were 80.2 mm and 120 mm less than the average long-term precipitation, respectively (Figure 1), while the precipitation during the growth stage was the same. Weather data were collected and recorded by weather station (AWS 800, Campbell Scientific, Inc., USA) about 100-metres distance from the experimental field.

The experiment had a single-factor randomized block design. Winter wheat (Triticum aestivum L.), cultivar ‘Yunhan 20410’ (a locally adopted high-yielding wheat variety) were obtained from the Wenxi Agriculture Bureau, Wenxi, China. N in the form of 46% (wt/wt) urea was applied at the rates of 0, 90, 120, 150, 210 and 240 kg N ha^–1 (N0, N90, N120, N150, N210 and N240, respectively) before sowing, the machine we used was showed in Figure 2.

Before sowing, each treatment was performed with three replicates. Pure P₂O₅ and K₂O were applied at the rate of 38 and 75 kg ha⁻¹ respectively. The seeds were sown on September 26, 2016 and harvested at June 1, 2017. Planted in manual with row spacing of 20 cm and sowing quantity of 225 kg ha⁻¹. Approximately 20–30 cm of the post-harvest stubble was left intact to increase soil organic carbon and reduce evaporation, and the remaining wheat stubble (20–30 cm) was plowed to a 25–30 cm depth using a rotator at the beginning to middle of July by deep plowing, as described by ²⁶. During whole growing season, weed was well controlled by hand and no irrigation was applied in each experimental year. The field was kept free from insects, pests, and diseases using pesticides as needed.

Crop water consumption (Ey, mm) during growing season was evaluated using the following formula:

Where R (mm) is precipitation amount during growing season. ΔSWS (mm) is soil water storage change by the crops (i.e., water storage at harvest minus water storage at sowing in the 0–200 cm soil layer).

At sowing and harvest for every pot, the soil was homogeneously mixed and a soil sample was taken from each pot (approximately 100 g) and divided into two sub-samples. The first sub-sample was extracted with 2M KCl, and the extracts analysed for NH₄⁺-N. NO₃-N ²⁷.

Photosynthetic characteristics i.e. leaf net photosynthetic rate (P_N), transpiration rate (E), intercellular CO₂ concentration (C_i), and stomatal conductance (g_s) of the flag leaf were measured by CI-340 hand-held photosynthesis measurement system from 9:00 to 11:00 h. In order to compare photosynthetic characteristics of leaves with a similar developmental age, gas-exchange measurements of each cultivar were conducted immediately after the flag leaves fully expanded. The measurements of P_N, g_s, C_i, and E, were acquired in a system with a leaf chamber temperature of 25°C and the carbon dioxide concentration in the leaf chamber was kept at 380 µmol (CO₂) mol⁻¹ by using a CO₂ injector with a high-pressure liquid CO₂ cartridge source. The photosynthetic active radiation was set at 1,500 µmol (photon) m⁻² s⁻¹. The external humidity was noted as 40 –50%. The variations of gas-exchange parameters caused by different ambient environmental conditions. To minimize the diurnal variation of photosynthesis, the measurements were suspended when significant midday depression occurred.

Above-ground plant at anthesis, and maturity was sampled from 20 randomly selected plants in each plot for the measurement of DM in stem + sheath, glume + spike, grain and total plant dry matter. Samples were initially oven-dried at 105°C for 30 min and weighed after further drying at 70°C until constant weight was attained. The stem + sheath, glume + spike, grain and total plant N concentration of the oven-dried, ground, and acid-digested plant samples was determined using the indophenol-blue colorimetric method ²⁸.

At maturity, 20 plants from each plot were randomly sampled from the inner rows for the determination of yield components such as ear number, seed number per ear and weight of thousand seed. Plot grain yield was determined by harvesting all plants in the area of 20m², shelled using machine and the grain was air-dried for the determination of grain yield.

At maturity, plants were randomly sampled from three 1 m² areas from each plot to determine grain number per spike and 1000 grain weight. All plants from the plots were harvested on 9 June 2017. Grains were air-dried whereas aboveground plant parts were oven dried until constant weight to determine the grain yield (kg ha⁻¹) and dry biomass.

After flowering period listed growth consistent and the same day flowering of wheat spike and peeling grain was placed in the oven dried at 105°C for 20 min and then at 80°C for 12 hours for dry weight. The quality, and speed of weighing samples greatly affect the overall quality of the test. Then the grain was weighed, and phenol method was used to determine the content of sucrose, and ketone color method was used to determine the total soluble total sugar content. H₂SO₄-H₂O₂-Phenol blue color method was used to determine the seed protein, and component content ²⁹.

The data of Photosynthesis Physiological and winter wheat growth yield was processed and statistically analyzed through SPSS-22 and SAS-8.6 (SAS Institute Inc., North Carolina, and USA). A two-way ANOVA was used to study the main influence and interaction of on yield, When there is a significant interaction effect between Photosynthesis, SPAD and yield, the Least Significant Difference (LSD) method was used for variance analysis, and independence T test, and the significance level was set to α=0.05, Differences were considered statistically significant when p ≤ 0.05.

3. Results

Effect of nitrogen fertilizers on water use of wheat influences total water consumption during the growth period with the increase of nitrogen application, the total water consumption in the growth period wheat increased first, and then decreased (Figure 3). The total water consumption in the growth period of the N210 treatment was significantly higher than in other treatments, was the lowest in N0. The differences between N150 and N240, N90, N120, and N0, were not significant to each other. Therefore, we can be seen that N210 increased the total water consumption during growth period of wheat, which was conducive to the growth and development.

Effects of nitrogen fertilizers on the increase of nitrogen application, the proportion of precipitation, and water content of wheat fields decreased first then increased water consumption of soil, storage, and its proportion increased (Table 2). The balance of precipitation water consumption was the lowest in N240, and the highest in N0 and N240 was different from other treatments. The proportion of water consumption was also the lowest in N240 and the highest in N0. The soil water storage, water consumption and proportion were the lowest in N0 the highest in N240, and N240 were significantly higher than other nitrogen applications. The N240 reduced the dependence of wheat on precipitation during growth and enhanced the utilization of wheat to soil water storage.

The soil nitrogen contention different soil layers increased gradually with the increase of nitrogen application N240 in different fertility periods and the N0 content was the lowest without the use of nitrogen treatment (Figure 4). There were no significant differences in soil nitrogen content between the nitrogen treatments in winter, and found no significant between the other soil layers. The nitrate- nitrogen content of 0-20 cm soil layer at N240 in wintering stage was significantly higher than other nitrogen application treatment, and on 20-60 cm soil layer, it’s N210, and N240 reach the highest. At maturity, the nitrate nitrogen content of 0-120 cm soil nitrogen content to N240 was significantly higher than other nitrogen treatments. In 120-160 cm soil layer was also the highest but not significant differences compared with different nitrogen treatment. The difference between treatments found in 160 cm in maturity and excessive nitrogen fertilizer was not conducive to wheat absorption of nitrogen, yield and increase in the number per spike. The yield and three elements were the highest at N240, and N210, respectively. Therefore, they were equipped with N240, and were applied with N210 which increased production.

The net photosynthesis P_n increased with the nitrogen application day after anthesis, showing a single peak increase trend (Figure 5A). Net photosynthesis P_n remained highest at N240 at 0, 7, 14 d after anthesis and was not significantly different from N90 and N150, but net photosynthesis P_n increased with increasing N application at 21 d and 28 d. Net photosynthesis P_n was highest at N210 at 28 d, but was not significantly different from N120, N150 and N240. Net photosynthesis P_n of flag leaf days after anthesis was significantly increased with increasing N application, but the effect of high N240 kg ha^–1 treatment was weakened at the late filling stage, and N240 could sustain the whole growth stage.

The substomatal CO₂ concentration C_i in the flag leaves of wheat decreased gradually with the growing process and decreased first and then increased with the increase of N at different stages days after anthesis (Figure 5B). The N210 was significantly lower than other treatments on 0, 7, 14d, and 21 days after anthesis. N210 was the lowest at 28d after anthesis, but the difference was not significant compared to N240. The increase of nitrogen fertilizer can significantly reduce the substomatal CO₂ concentration Ci in the leaves of the flags days after anthesis.

The stomatal conductance g_s of flag leaf increased with increasing N at different periods after anthesis (Figure 5C). The N210 was significantly higher than the other treatments at 0, 7, 14 d after anthesis, and N0 was the lowest and N210 was the highest, but the differences were not significant at 21 and 28 days. Increasing N significantly increased flag leaf stomatal conductance g_s, but the effect lasted until mid-growth, and weakened later.

The transpiration rate Tr of flag leaves decreased gradually with the grouting process, and the T_R of flag leaves increased first, and then decreased with the increase of N in different stages days after anthesis (Figure 5D). The N210 and N240 were significantly higher than other treatments on 14 d and 21 d, and N0 was the lowest. N210 was significantly higher than other treatments on 28 d, and N0 was the lowest. The increase of N can significantly enhance the transpiration rate Tr of flag leaves days after anthesis, which could last for the whole growth stage, and the effect of N210 was obtained best.

The correlation between photosynthetic characteristics of flag leaves, and yield after anthesis was analyzed (Table 3). The yield was positively correlated with net photosynthetic rate of flag leaves at 21d and 28d after anthesis (P < 0.01). It was significantly positively correlated with intercellular CO₂ concentration of flag leaves 14d after anthesis, and extremely significantly positively correlated with C_i of flag leaves 21days, and 28d after anthesis. And stomataal conductance g_s of flag leaves were significantly positively correlated from 0 d to 21 d. And Tr of flag leaves in all post-anthesis periods were significantly positively correlated with yield. That enhanced net photosynthesis rate P_n of flag leaves in the late stage of grain filling, reduced intercellular CO₂ concentration of flag leaves in the late stage of grain filling, enhanced stomataal conductance g_s of flag leaves in the early stage of grain filling, and increased transpiration rate Tr of flag leaves in the early stage of grain filling, thus realizing yield increase.

The accumulation of plant nitrogen increased with wheat growth, and it showed a trend of increasing and then decreasing in each growth stage with the increase of N (Figure 6). The nitrogen accumulation of wheat plants in different growth stages was the highest in N210, and showed a significant difference, and it was the lowest in N0. The N210 promotes nitrogen accumulation in plants at all growth stages and provides a nitrogen source for high yield. The nitrogen of N210 could obtain nitrogen accumulation, which increased in all growth stages.

Soluble sugar content, sucrose content, and starch content all first increased, and decreased with the increase of N240, and they all attain the highest at N210. The lowest soluble sugar, sucrose, and starch were counted in N0, but it was not significant between N0, N90 and N120 (Table 4). The nitrogen application significantly affects soluble sugar, sucrose, and starch content when nitrogen application is a certain level.

With the increase of nitrogen application rate, the water use efficiency of N210 increased firstly and then decreased (Figure 7). As a result, the water use efficiency of N210 was the highest, but the difference was not significant compared with N120 and N150. On the other hand, the water use efficiency of N0 was the lowest, and the difference was not significant with that of N90 and N240. Therefore, N150 can improve the water use efficiency of wheat during growth stages.

The proportion of water consumption at sowing jointing, and jointing Anthesis stage increased first, and then decreased with the increase of nitrogen application rate. The proportion of water consumption at jointing Anthesis stage increased with the nitrogen application rate. The proportion of water consumption at Anthesis to maturity stage decreased first, and then increased (Table 5). At the of sowing, jointing, and jointing Anthesis , the water consumption of N210 treatment was significantly higher than that of other treatments the proportion of water consumption at jointing, Anthesis stage was the highest in N210 treatment, but the difference was not significant compared to that of N120, and N150. However, the water consumption proportion at flowering stage in N210 treatment was significantly lower than that of other treatments. In conclusion, combined to N210 increased the water consumption at sowing jointing, and Anthesis stages, but decreased the water consumption at late growth stage while increasing the water consumption ratio at early growth stage.

The dry matter quality of various organs in N210 at maturity showed the order of grain > stem + leaf sheath, glume + spike, leaf (Table 6). With the increase of nitrogen application rate, the dry matter of all organs increased, and then decreased at maturity. The dry matter weight of all organs was significantly higher in N210 than in other treatments, and the lowest in N0, N90. The dry matter quality of each organ of winter wheat at maturity stage was significantly improved N210 was the best.

The dry matter weight and its proportion in each growth stage was the highest at jointing-flowering stage (Table 7). Plant dry matter weight increased first, and then decreased with the increase of nitrogen application rate at jointing-flowering and flower stages. The dry matter quality of N210 treatment was higher than that of other treatments in each growth stage, and the difference between sowing-jointing, and jointing - flowering stage was significant. The dry matter quality of N240 treatment was the lowest in each growth stage. N210 increased plant dry matter quality in the whole growth process, especially in the middle and late growth, laying a foundation for high yield.

With the increase of nitrogen application rate, the nitrogen translocation before flowering and nitrogen accumulation after anthesis increased firstly and then decreased. The contribution of nitrogen translocation after anthesis to grains increased first and then reduced, but the contribution of nitrogen accumulation after flowering to grains first decreased, and then increased (Table 8). N210 had the highest nitrogen translocation after anthesis, and had a significant difference from other N treatments. N210 had the highest contribution rate to grains, but had no significant difference with N210, and N240. N210 had the highest nitrogen accumulation after flowering, and considerably differed from other nitrogen application rates. N0 had the lowest contribution rate to grains, but had no significant difference with N0, N90, N210 and N240. Combined to N210 can increase pre-anthesis nitrogen transport, and post-anthesis nitrogen accumulation, increase the contribution rate of pre-anthesis nitrogen transport to grains and promote nitrogen transport to grains.

The N absorption efficiency, N use efficiency, and N production efficiency were the highest in N210 and the lowest in N240. The N absorption efficiency and N production efficiency of N90 were significantly different from those of other N treatments, and the N use efficiency was significantly different from that of N120, N150, and N240. It can be seen that (Table 9). Nitrogen efficiency was low with the increase of nitrogen application rate, appropriate nitrogen use reduction, and improvement of nitrogen efficiency are essential goals in wheat production.

The response of wheat processing quality to nitrogen fertilizer was different (Table 10). In general, with the increase of nitrogen application rate, the processing quality falling value, formation time, stability time, wet gluten, and gluten index all showed a trend of gradual increase, and N210 was the highest, On the other hand, there was no significant difference in settling value between N120, N150 and N240 treatments. In addition, there was no significant difference in falling value, stabilizing time, wet gluten, and gluten index between N120, N150 and N240 treatments, while water absorption was relatively stable, and N210 was the highest.

The spike number, grain number per spike, and the weight of thousands of grains yield with the increasing nitrogen application showed the first increase trend and then decreased (Table 11). The yield and components were the highest in N150, and its spike number, and yield were significantly different from other nitrogen treatments. It can optimize the output of yield components and achieve a high yield in N150.With the increasing nitrogen rate, yield components increased first and then decreased. The yield and its components are the highest at N150.

The effect of nitrogen fertilizers on grain protein and its components were significantly different (Table 12). The contents of albumin and globulin soluble protein increased first and then decreased with the nitrogen application. The highest albumin valuewas in N240 and the difference between N240, and 210 were not significant. The highest value of globulin soluble protein was N240, and the difference between N120, N150, N210, and N240 were not significant. The contents of glutenin storage protein increased with the increase of nitrogen application with the highest content of N210, but the difference in glutenin content was not significant compared with N240, and the content of Gliadin in N240 was significantly higher than that of other nitrogen application treatments. Glu/Gli were the highest at N210, but the difference was not significant between N210 with N0, N90 and N120. The protein contents, and yield were significantly higher at N210 than in other nitrogen applications. The nitrogen fertilizer has apparent regulation of protein storage, and it was more conducive to quality improvement.

4. Discussion

Currently, promoted water saving agriculture is faced with such problems as improving soil water utilization efficiency, reducing ineffective water consumption, and strengthening wheat’s utilization of water in deep soil. In addition to enhancing varieties adjusting crop layout and cultivation mode are low cost efficient and fast. The ability of wheat to adapt to changing conditions in growing depends not only on the genetic characteristics of the variety itself but also on the farmland environment due to changing planting patterns. The planting mode is a factor that can control agricultural production, water and nitrogen utilization efficiency is determined by multiple factors and all factors that can affect grain yield water consumption and nitrogen will directly or indirectly affect water utilization efficiency ³⁰.

Nitrogen application had a regulatory effect on water consumption indexes in different growth stages. Water consumption in the early stage of nitrogen application, and water consumption model coefficient in the late stage of growth promoted soil water and nitrogen use by roots the development of vegetative organs. The appropriate application can improve the utilization ability of wheat to soil water storage, reduce the dependence on natural precipitation, and compensate for the impact of insufficient irrigation on grain yield ³¹. Research showed that nitrogen fertilizer had a more significant effect on water consumption in the different growth stage, and increased nitrogen fertilizer application could increase water consumption in the stage of flowering, Proportion, so that the peak of water consumption moved forward. The results of this study showed that with the increase of nitrogen application, the water consumption in the early and middle stages of growth and their proportion, as well as the water consumption in the jointing flowering stage first increased and then decreased. The water consumption in the later stages first decreased and then increased. The N₂₄₀ kg ha^–1 improved the planting jointing stage, jointing stage, flowering two stage water consumption, and proportion reduced, according to ³². The results show that with the increase of nitrogen fertilizer, the sedimentation value, landing value and formation time, stabilization time, wet gluten and gluten index were increased still, the water absorption rate was relatively stable.

Photosynthetic rate, stomatal conductance, transpiration rate and chlorophyll content are essential components of the photosynthetic physiological characteristics of crops. Nitrogen is the main element of protein synthesis an integral component of grain closely related to the life activities of crops, and an indispensable nutrient limiting factor in agricultural production. As a result, nitrogen has been applied extensively in agricultural production to increase wheat yields over the past few decades. However, some studies have shown that the photosynthetic rate of leaves decreased under the condition of high nitrogen application. The application of a large amount of nitrogen fertilizer in agricultural production directly caused the loss of fertilizerc. ^{33, 34}. The results of this study showed that drill sowing with 240 kg ha^–1 improved the photosynthetic characteristics of flag leaves, significantly increased the net photosynthetic rate, stomatal conductance, and transpiration rate of flag leaves after flowering were significantly reduced the intercellular carbon dioxide concentration.

This may be because the wide-space sowing expanded the width and row spacing and optimized the light conditions for the population in the field. Therefore, the nutrient conditions were good. As a result, the individual plants developed well. The green leaf area index was extensive, function time was long and delayed aging time of the whole plant in the later stage of wheat, to avoid the early aging of the leaves ^{35, 36}. Different studies showed that leaf photosynthesis was closely related to crop yield, and leaf photosynthetic rate was important essential for high crop yield. At the same time, nitrogen fertilizer could enhance plants’ ability to synthesize chlorophyll and was one of the most effective factors to regulate plant leaf photosynthetic capacity ^{37, 38}. Their research experience defines that when the soil water content was the same. The P_n of wheat generally increased first, and then became stable with the nitrogen application. The intercellular carbon dioxide concentration transpiration rate and net photosynthetic rate generally increased first and then decreased, indicating that appropriate nitrogen application improves the photosynthetic capacity of wheat flag leaves during the filling period. Proper nitrogen application is also expected to improve the photosynthetic capacity of winter wheat over ground parts increase the accumulation and transfer of dry matter, and increase wheat yield. The results of this study showed that the photosynthetic indexes in the flag leaves of the broad drill with 240 kg ha^–1 fertilizer all reached the optimal level due to the appropriate nitrogen fertilizer amount promoting the synthesis of chlorophyll. In addition, however, some studies have shown that increased nitrogen fertilizer is beneficial to increase the population leaf area of wheat and optimize the wheat environment. However, excessive nitrogen fertilizer will reduce leaf inclination, and excessive leaf area will lead to an unreasonable wheat structure resulting in wheat yield loss ³⁹.

The amount of fertilization is significantly positively correlated with crop yields, Hence, farmers pursue high yields by applying a large amount of fertilizer resulting in excessive nitrogen being dispersed in the air, water and soil causing a series of environmental, and human health problems ⁴⁰. The supply of nutrients in farmland is determined by the input of soil base fertility and fertilizers, and the soil nutrient supply capacity and characteristics are different under different soil fertility, resulting in different characteristics of crop nutrients absorption and utilization which directly affects the utilization of nutrients ^{41, 42}. The average output of nitrogen rates treatment is 240 kg ha^–1 compared to the nitrogen rates. Relatively coordinated to promote the production composition of the three factors of growth, To achieve a higher production than traditional strip production ^{43, 44}.

The number of spikes significantly increased but the grain weight also increased and spike but did not reach the difference level, and finally achieved increased production. According to ⁴⁵, from the wheat growth situation under different sowing methods the difference in the number of primary seedlings winter and spring equinox between the treatments was not significant indicating that the different sowing methods had a negligible impact on wheat sowing, Seeding and the ability of wheat was similar to that of ordinary strips. ⁴⁶, due to the variety difference, the effect of nitrogen fertilizer on tiller number in each growth stage of the wheat population is different. The growth development characteristics of different varieties appropriate amount of nitrogen fertilizer application and sowing time are selected to achieve reasonable control of tiller number in each growth stage of wheat nitrogen fertilizer amount, especially the 1000 grain weight, and grain number per spike reached significant levels.

However, when nitrogen fertilizerexceeded 90 kg ha^–1, grain number per spike could not reach a significant level when nitrogen fertilizer increased to 120 kg ha^–1 or even 210 kg ha^–1, 1000 grain weight could not reach a significant level. According to ⁴⁷, an increase of nitrogen application, the output, and yield composition of the three factors will not show spike number increase trend, but show the first increase and then decrease the nitrogen application of 120 kg ha^–1 the number grain weight spike reached the maximum at 240 kg ha^–1. Maximized the spike number, and yield the differences were significant. This experiment showed that the yield increases first with the increase of nitrogen application, the number of, spike grains, and thousands grain weight, Then it decreased, the spike number, and yield difference was significant but the difference between the number of spike and thousands grains was not effective N150 kg ha^–1. The number of spike, and yield increased significantly.There was no significant difference between the number of spikes, and the weight of thousands which showed that, a more robustnitrogen fertilizer utilization capacity was more consistent with the previous studies based on the seeding rate affecting the yield.

5. Conclusions

The nitrogen application of 210 kg ha^–1 reduced precipitation, and irrigation increased the water consumption.The proportion of soil water storage increased the water consumption in the sowing extraction and extraction flowering stages and ultimately increased the total water consumption during fertility and improved the efficiency of water utilization at the same time, reduced the high yield of each organ, increased the dry quality of each organ, increased the dry quality of the plant in the extraction-flowering and flowering maturity stage, and its proportion increased the grain weight of each time after flowering, the number of spikes and yield increased significantly. In addition, 210 kg ha^–1 to increase the accumulation of nitrogen in plants during the main fertility period significantly increased the accumulation of N in each stage of fertility the proportion of nitrogen accumulation increased in the pre fertility stage, the amount of N before flowering, and nitrogen accumulation after flowering significantly increased, while ensuring the yield. Therefore, it was beneficial improvingof sugar and protein content and the wheat quality.

Acknowledgements

The authors are thankful to ‘Modern Agriculture Industry Technology System Construction’ (No. CARS-3124), The National Key Research and Development Program of China (No. 2018YFD020040105), The Sanjin Scholar Support Special Funds Projects, National Natural Science Foundation of China (No. 31771727), The ‘1331’ Engineering Key Innovation Cultivation Team Organic Dry Cultivation and Cultiva-tion Physiology Innovation Team (No. SXYBKY201733) for financial support of this study.

References