Nitrogen Physiological Efficiency Research Articles

Optimizing Nitrogen Fertilization for Enhanced Rice Straw Degradation and Oilseed Rape Yield in Challenging Winter Conditions: Insights from Southwest China

The crop straw returning to the field is a widely accepted method to utilize and remediate huge agricultural waste in a short period. However, the low temperatures and dry conditions of the winter season in Southwest China can be challenging for the biodegradation of crop straw in the field. With a similar aim, we designed a short-term study where rice straw was applied to the field with different concentrations of nitrogen (N) fertilizer while keeping phosphorus (P) constant; CK, (N0P0); T1, (N0P90); T2, (N60P90); T3, (N120P90); and T4, (N180P90) were added to evaluate its impact on straw degradation during cold weather. We found that high fertilization (T4) significantly improved crop yield, organic matter, and lignocellulose degradation under cold temperatures (21.5–3.2 °C). It also significantly improved soil nitrogen agronomic efficiency, nitrogen use efficiency, and nitrogen physiological efficiency. The yield was highest in T4 (1690 and 1399 kg/ha), while T3 acted positively on soil lignocellulolytic enzyme activity, which in turn resulted in higher degradation of OM and lignocellulosic material. Pearson’s correlation analysis revealed that total nitrogen, total phosphorus, available nitrogen, and available phosphorus were important variables that had a significant impact on soil EC, bulk density, water holding capacity, and soil enzymes. We found that nitrogen application significantly changed the soil bacterial community by increasing the richness and evenness of lignocellulolytic bacteria, which aided the degradation of straw in a short duration. This study’s finding indicates that the decomposition of crop straw in the field under cold weather stress was dependent on nutrient input, and N, in an appropriate amount (N120-180), was suitable to achieve higher yield and higher decomposition of straw in such an environment.

Study of integrated application of biological and organic manures on nitrogen physiological efficiency and some agronomic traits of alfalfa under in Kashan region

Study of integrated application of biological and organic manures on nitrogen physiological efficiency and some agronomic traits of alfalfa under in Kashan region

Management Strategy of Slow-Release Nitrogen Fertilizers for Direct-Sown Cotton after Wheat Harvest

The direct-sown cotton after wheat harvest (DSCWH) cropping system has attracted wide attention due to reduced labor inputs compared to transplanting. However, the management strategy of slow-release nitrogen is unclear in such a system. This study aims to investigate the impact of different timings and dosages of slow-release nitrogen fertilizer on the yield, biomass accumulation and distribution, and nitrogen absorption and nitrogen utilization in the DSCWH cropping system. This study was investigated at the experimental farm of Yangzhou University, China in 2020 and 2021, with the short-season cotton variety “Zhongmian 50” used as experimental material. Three dosages of the slow-release nitrogen fertilizer (45 kg·ha−1, 90 kg·ha−1, and 135 kg·ha−1) were applied at two stages of growth (two-leaf and four-leaf). The results showed that applying a 90 kg·ha−1 dosage at the two-leaf stage achieved the highest yield, which was increased by 12.6% compared to the no-fertilization control. Applying 90 kg·ha−1 of the slow-release nitrogen at the two-leaf stage promoted biomass accumulation, especially in reproductive organs, and this increase in biomass of reproductive organs was attributed to optimum nitrogen accumulation in reproductive organs (80~140 kg·ha−1). In addition, when 90 kg·ha−1 was applied at the two-leaf stage, there was a significant enhancement in nitrogen recovery efficiency (NRE), nitrogen agronomic use efficiency (NAE), and nitrogen physiological efficiency (NPE), with increases of 7.2% to 13.0%, 5.7% to 5.8%, and 5.6% to 6.5%, respectively. These results revealed that applying slow-release nitrogen fertilizer with the optimal dosage at the seedling stage could significantly enhance nitrogen use efficiency, nitrogen accumulation and partitioning, and biomass accumulation and distribution, which ultimately resulted in a higher lint yield in DSCWH. Therefore, to optimize yield and NUE, 90 kg·ha−1 slow-release nitrogen applied at the two-leaf stage would be recommended in the direct-sown cotton after wheat harvest cropping system.

Optimization of Nitrogen Fertilizer Management in the Yellow River Irrigation Area Based on the Root Zone Water Quality Model

Strategic management of nitrogen fertilizers can not only mitigate agricultural nitrogen pollution but also significantly enhance crop yield and nitrogen use efficiency. This study was designed to determine the optimal nitrogen fertilizer management strategy for the Yellow River irrigation area. Leveraging two years of field data related to soil water nitrogen and summer maize growth indices, parameters for the Root Zone Water Quality Model 2 (RZWQM2) were calibrated and validated. Subsequently, various scenarios were generated to simulate the impacts of different nitrogen application rates and basal chasing ratios on summer maize yield, nitrogen agronomic efficiency, nitrogen physiological efficiency, and nitrogen apparent recovery rate. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was employed for a comprehensive evaluation. RZWQM2 can effectively simulate the dynamic changes in soil moisture and nitrogen in the Yellow River irrigation area, and the results indicated that the mean relative error (MRE) between the simulated and observed values varied from 5.77% to 14.09%, and 4.36% to 33.01%, while the root mean square error (RMSE) ranged from 0.016 to 0.037 cm3/cm3, and 0.111 to 1.995 mg/kg. The normalized root mean square error (NRMSE) varied between 6.20% to 14.42% and 5.24% to 17.84%, respectively. The results validate the model’s effectiveness in simulating summer maize yields and nitrogen metrics under varying nitrogen fertilizer management practices. A nitrogen application rate of 180–200 kg/hm2 (expressed in terms of pure nitrogen) in the Yellow River irrigation area could adequately meet the requirements for summer maize production. The recommended nitrogen fertilizer management strategy in the Yellow River irrigation area involves applying 200 kg/hm2 of nitrogen in a 1:2:1 ratio during the sowing, trumpeting, and anthesis stages.

Precise delivery of nitrogen at tillering stage enhances grain yield and nitrogen use efficiency in double rice cropping systems of South China

Nitrogen fertilizer management substantially affects the growth, productivity, and nitrogen use efficiency (NUE) of rice production systems. To assess the effects of precise application of nitrogen fertilizer at tillering stage as ‘tillering-fertilizer’ on grain yield and nitrogen use efficiency, field trials were conducted in the late season of 2019 and 2020, in addition to a radioisotope 15 N tracer experiment. The experiment was comprised of four N fertilizer treatments i.e., no fertilizer application as a control (T1), traditional surface broadcast fertilization (90 kg N/ha as basal fertilizer and 60 kg N/ha as tillering fertilizer, T2), deep placement of tillering fertilizer (surface broadcast at 90 kg N/ha as basal fertilizer and 45 kg N/ha as tillering fertilizer at 10 cm depth, T3), deep placement of tillering fertilizer (surface broadcast at 90 kg N/ha as basal fertilizer and 30 kg N/ha as tillering fertilizer at 10 cm depth, T4) and two rice cultivars i.e., Wufengyou 615 and Yuxiangyouzhan . Results showed that grain yield remained 18.8% and 12.4% higher owing to increase in productive panicles and grain filling, 42.2% and 38.9% higher nitrogen agronomic efficiency, 4.6% and 10.4% higher nitrogen recovery efficiency, and 10.2% and 7.8% higher nitrogen physiological efficiency in T3 than T2 for Wufengyou 615 and Yuxiangyouzhan , respectively. Moreover, nitrogen derived from fertilizer in T3 was increased by 8.0% and 4.4% compared to T2 for Wufengyou 615 and Yuxiangyouzhan , respectively whereas the residual rate of T3 was increased by 31.5%. In addition, the T3 treatment substantially enhanced the leaf area index and leaf chlorophyll content that led to improved photosynthesis and the activities of enzymes related to nitrogen metabolism. Overall, 45 kg N/ha as tillering fertilizer at 10 cm depth and surface broadcast at 90 kg N/ha as basal fertilizer can improve grain yield as well as nitrogen use efficiency in late season rice production system of South China. • Precise delivery of nitrogen (PDN) at tillering stage (TS) can enhance grain yield in rice. • PDN at TS can improve nitrogen use efficiency in rice. • PDN at TS can increase nitrogen residual rate in the soil and decrease nitrogen unaccounted rate.

Response of Growth and Production of Red and Green Okra Plants to Effect of Organic Fertilization

The effect of nitrogen on growth, and development of plants, metabolism, dry matter production has been well investigated. Extensive research has been conducted on organic fertilizers especially, i.e. the compost. This study investigated the effect of compost on okra pods yield, nitrogen agronomic use efficiency, supplied of nitrogen recovery efficiency and supplied nitrogen physiological efficiency in okra (Abelmoschus esculentus L. Moench). A completely randomized experimental design of 2x4 factorial patterns with three replications was used in this study. Factor (I) was the okra species (Green okra - Red okra) and factor (II) was the doses of compost (0, 50, 100 and 150 kg N ha−1). Kind of okra has different effects on the parameters observed. Results showed that green okra and red okra showed increased yield due to the increase in the nitrogen dose through compost. Agronomic use efficiency of green okra and red okra increased with increasing doses of compost. The nitrogen recovery efficiency of green okra and red okra also, increased with increasing doses of compost. Nitrogen physiological efficiency of green okra and red okra increased with increasing compost doses. An increase in compost doses resulted in increased nitrogen uptake, pods yield, Agronomic efficiency, nitrogen recovery efficiency and nitrogen physiological efficiency of both green and red okra. Increased compost doses resulted in decreased nitrogen use efficiency in green okra. Green okra is more efficient in using organic nitrogen from compost.

Effects of increasing panicle-stage N on yield and N use efficiency of indica rice and its relationship with soil fertility

Because of the higher nitrogen (N) recovery efficiency (NRE) of panicle-stage fertilization compared with basal and tillering fertilization, increasing the proportion of N topdressing at the booting stage (panicle-N) is recommended and commonly practiced in parts of China. To investigate the effects of increasing panicle-N on grain yield and N use efficiency (NUE) and the relationships of the increase and the rice cultivar and soil fertility status, we increased the percentage of panicle-N from 20% to 40% by correspondingly reducing the N amount applied only at the tillering stage in both high- and low-fertility blue clayey paddy fields in 2018 and 2019. Four indica cultivars with diverse panicle types were used, and their grain yield, dry matter accumulation, and NUE were compared. In high-fertility soil, increasing topdressing panicle-N from 20% to 40% reduced tillering ability and reduced the effective panicle numbers of the multi- and medium-panicle cultivars Huanghuazhan (HHZ), C Liangyouhuazhan (CHZ), and Tianyouhuazhan (THZ). These cultivars gave the greatest yield when 30% of N was supplied as panicle fertilizer, whereas the yield, NRE, N agronomic efficiency (NAE), and nitrogen physiological efficiency (NPE) of the heavy-panicle inbred cultivar Yangdao 6 (YD6) continued to increase, resulting in improved dry matter accumulation and grain filling in the late growth stage. The yield, NAE, NRE, and NPE of YD6 peaked when the panicle-N constituted 40%. While in low-fertility soil, the multipanicle cultivar HHZ showed the greatest yield when 30% of fertilizer-N was applied once at the panicle initiation (PI) stage, while the medium-panicle cultivar CHZ showed the greatest yield when the panicle-N percentage was 40%. Our results suggest that the percentage of panicle-N fertilizer should not exceed 30% for multipanicle cultivars, while can be appropriately increased to 40% for heavy-panicle indica cultivars. The effect of increasing topdressing panicle-N on the yield of medium-panicle cultivars was related to soil fertility. The optimum panicle-N percentage was 30% in the high-fertility soil and 40% in the low-fertility soil.

Effects of soil preparation and mulching practices together with different urea applications on the water and nitrogen use of winter wheat in semi-humid and drought-prone areas

Soil preparation and mulching practices in combination with slow-release urea application are important measures for agricultural yield enhancement. However, slow-release urea may cause a yield reduction due to insufficient fertility in early crop growth. We considered whether the ridge-furrow plastic-mulching (RFP) system using different mulch colors could offset this disadvantage. An experiment was conducted using a randomized split-plot design with three soil preparation and mulching practices as the main-plot treatments in combination with three different urea applications as sub-plot treatments. The three soil preparation and mulching practices were flat cropping without mulch (F), the RFP system with white plastic mulch over the ridge (W), and the RFP system with black plastic mulch over the ridge (B); the three urea applications were no urea (N0), slow-release urea (NS), and ordinary urea (NU). The results showed that compared to F, the RFP system (especially B) could increase the use of precipitation and reduce soil water depletion, which ultimately increased the water productivity (WP) of winter wheat. In addition, the nitrogen use efficiency of NS was further improved under the RFP system, while there was essentially no difference between the two different urea types under F. In summary, B could take full advantage of NS to coordinate the relationship between effective spikes per unit area, grains per spike, and 1000-grain weight, maximizing the WP, nitrogen use efficiency, and grain yield. Between 2016 and 2019, the WP and grain yield of B-NS increased by 79.2–107.0% and 75.7–87.0%, respectively, compared to the lowest value (F-N0). The nitrogen agronomic efficiency (NAE), nitrogen physiological efficiency (NPE), nitrogen recovery efficiency (NRE), and nitrogen partial factor productivity (NPFP) of B-NS increased by 116.1–123.3%, 28.5–34.8%, 66.1–71.9%, and 44.1–53.2%, respectively, compared with the lowest value (F-NU).

Protein Hydrolysates and Mo-Biofortification Interactively Modulate Plant Performance and Quality of ‘Canasta’ Lettuce Grown in a Protected Environment

Since the use of protein hydrolysates (PHs) enhances overall plant performance and quality of vegetables, they might be considered as a toll to face a number of concerns essentially associated to the growing request of premium quality foodstuff realized in agreement with eco-friendly agriculture practices. Molybdenum (Mo) is considered a fundamental trace element for human body. Thus, its shortage determines several disorders mainly related to neurological lesion and esophageal cancer. Biofortification of fruiting and leafy vegetables is a promising tool to prevent Mo deficiency in the human diet. The current study was carried out to assess the interactive effect of plant-derived PHs and Mo dosage (0.0, 0.5, 3.0, and 6.0 µmol L−1) on yield, morphology, nutritional and functional features, and nitrogen indices of ‘Canasta’ lettuce. Head fresh weight (HFW), head height (HH), ascorbic acid, K, Mg, total chlorophyll, as well as nitrogen use efficiency (NUE) index were positively correlated to PHs application. Furthermore, ascorbic acid and total chlorophyll were also improved by Mo supply. A great improvement in terms of soluble solid content (SSC), total sugars, total phenolic, carotenoids, Mo and N concentrations, nitrogen uptake efficiency (UE), and nitrogen physiological efficiency (PUE) indices was recorded when PHs application was combined with the highest Mo dosage (6.0 µmol L−1). Consequently, our results suggest that Mo-biofortification and PHs application can positively modulate ‘Canasta’ lettuce plant performance and quality.

Effects of controlled release fertilizer ratio on yield formation and nitrogen absorption and utilization of late-maturing medium <italic>japonica</italic> rice under different mechanized cultivation methods

<p id="C3">Rice cultivars of Nanjing 9108 with good taste quality was adopted as material under the pure nitrogen condition of 270 kg hm^-2in this study. Rice was cultivated with two methods including mechanical transplanting with pothole seedlings (MT) and mechanical transplanting with carpet seedlings (MC). Controlled-release fertilizer and quick-acting nitrogen fertilizer were mixed at a ratio of 5:5. Controlled-release fertilizer was mixed from four different release periods (40, 80, 100, and 120 days) at a ratio of 1:4 to form three mixing modes (40+80, 40+100, and 40+120). Conventional urea split fertilization (CK) was used as a control, and the effects of different controlled-release fertilizer ratios on yield formation and nitrogen accumulation of high-quality <italic>japonica</italic> rice were studied. Under the same fertilizer treatment, compared with mechanical transplanting with carpet seedlings (MC), the two-year yield of mechanical transplanting with pothole seedlings (MT) was significantly increased by 3.9% and 4.9%, respectively. The reason was that the transplanting of pothole seedling machine could improve the accumulation of photosynthetic substances in the middle and late stages and obtain larger panicle type with higher grain number per panicle, seed setting rate, and 1000-grain weight. Under the cultivation mode of pothole seedling transplanting and carpet seedling transplanting, compared with CK, the two-year yield of 40+80 and 40+100 controlled-release fertilizer treatments were higher than CK, and the two-year yield of 40+100 controlled-release fertilizer treatments was the highest, which was significantly increased by 7.3% and 9.2%, respectively. The reason was that 40+100 controlled-release fertilizer treatment had higher effective panicle number and population glume amount. Compared with 40+80 and 40+120 controlled-release fertilizer treatments, the nutrient absorption law of 40+100 controlled-release fertilizer treatment was more consistent with Nanjing 9108, which not only ensured the occurrence of early tillering, but also ensured the stable production of photosynthetic substances at later stage, thus obtaining stable panicle number, grains per panicle, and 1000-grain weight. Compared with CK, the nitrogen recovery efficiency, nitrogen agronomic efficiency, nitrogen physiological efficiency, and nitrogen partial productivity of 40+100 controlled-release fertilizer treatments were significantly increased by 10.0%-12.5%, 24.6%-30.5%, 11.4%-18.6%, and 7.3%-9.1%, respectively. In conclusion, the mechanical transplanting with pothole seedlings (MT) had obvious advantages over mechanical transplanting with carpet seedlings (MC), which was a cultivation method that was conducive to high-quality <italic>japonica</italic> rice. At the same time, the 40+100 controlled-release fertilizer ratio could better meet the nutrient requirements of good-quality <italic>japonica</italic> rice at various stages, and could obtain high yield, which could be used as a simplified fertilization scheme for high-quality <italic>japonica</italic> rice.

Effect of Reducing Nitrogen and Applying Organic Fertilizer on Nitrogen Use Efficiency and Rice Yield in Red Soil Regions of the Southern China

To explore the amount of reducing N fertilizer, a 2-year field experiment was conducted to investigate the effects of reducing N fertilizer and applying organic fertilizer on nitrogen use efficiency (NUE) and rice yield in red soil regions of the Southern China. On the basis of applying 4500 kg/ha organic fertilizer and local custom fertilization with 204 kg/ha urea application, five treatments including no nitrogen fertilization (CK), local customary nitrogen application (N100), and nitrogen reduction of 10% (N90), 20% (N80), and 30% (N70) were conducted. The results showed that nitrogen agronomic efficiency (NAE), nitrogen recovery efficiency (NRE), nitrogen physiological efficiency (NPE) and nitrogen partial factor productivity (NPFP) of N90 treatment were significantly higher than those of other treatments, and the yield was as high as 9.33 t/ha, which showed a significant differences compared with CK and N100. The output value, benefit, and benefit-cost ratio of N90 were significantly higher than those of N100, which increased by 6.38%, 6.42%, 8.35%, and 8.20%, respectively. In addition, while applying the same amount of organic fertilizer, the rate of nitrogen reduction has little effect on the soil organic matter content, meaning that N90 can achieve high NUE and high yield in rice. It is good to provide the theory basis for fertilizer decision-making in practice.

Optimizing nitrogen application for drip-irrigated winter wheat using the DSSAT-CERES-Wheat model

Improper application of nitrogen fertilizer for winter wheat production in the North China Plain (NCP) limits N use efficiency and increases the risk of non-point pollution. Crop simulation models may help with the assessment of N fertilizer management, to improve nitrogen use efficiency and to mitigate environmental pollution. In this study, the DSSAT-CERES-Wheat model was calibrated and validated with two-year field experiment, which coupled with five N rates (0, 120, 180, 240, and 300 kg ha−1) and three irrigation levels (40, 30, and 20 mm per irrigation) under drip irrigation. The calibrated DSSAT-CERES-Wheat model performed well in simulating the anthesis date (nRMSE=1.47%, d=0.89), maturity date (nRMSE=0.97%, d=0.92), shoot biomass (nRMSE=10.97%, d=0.92), grain yield (nRMSE=6.19%, d=0.96), and actual evapotranspiration (nRMSE=9.96%, d=0.76) of drip-irrigated winter wheat in two years. The calibrated model was subsequently used to evaluate drip-irrigated winter wheat production in response to six N rates (0, 120, 180, 240, 300, and 360 kg ha−1) under 40 meteorological scenarios, and the results showed that grain yields, water use efficiency, irrigation water use efficiency, and net margins increased with increasing N application rates until it reached 180 kg ha−1. Above 180 kg ha−1, negligible changes were measured in these values as the N rate increased. The nitrogen physiological efficiency and nitrogen partial factor productivity were greatly improved at a N rate of 180 kg ha−1, compared with those at a N rate of 240, 300, and 360 kg ha−1. Consequently, N rate of 180 kg ha−1 was the optimal nitrogen application rate for drip-irrigated winter wheat production. These results may provide a scientific basis for nitrogen management of drip-irrigated winter wheat in the NCP.

Application of controlled release urea improved grain yield and nitrogen use efficiency: A meta-analysis.

The application of controlled release urea (CRU) has been proposed as a crucial method to reduce the adverse environmental effects induced by conventional urea (CU). Yet, a systematic and quantitative analysis on how CRU affects staple crop production including wheat (Triticum aestivum L.), maize (Zea mays L.), and rice (Oryza sativa L.) is lacking. Here, a meta-analysis was conducted to determine how CRU influences soil chemical properties, total nitrogen (TN) uptake, grain yield, and nitrogen use efficiency (NUE) of staple crop in China. The results indicated that CRU application significantly increased soil organic carbon (SOC), TN, and available nitrogen (AN) by 5.93%, 3.89% and 13.98% respectively overall, while soil pH showed no significant changes. Compared to the application of CU, applying CRU significantly increased grain yield by 7.23%, which was mainly owing to the higher TN uptake (9.13%) across all the studies. In addition, the application of CRU significantly increased NUE, nitrogen agronomy efficiency (NAE), utilization rate of nitrogen fertilizer (NUR), and nitrogen physiological efficiency (NPE) by an average of 23.4%, 34.65%, 25.83% and 15.8% respectively which could be attributed to the slow nitrogen (N) release characteristics of CRU. The positive effect of CRU on grain yield and NUE of staple crop was greatest when the content of SOC and TN were extremely low, indicating that it was most effective to improve grain production of infertile soil by applying CRU. The finding of this study indicated that the application of CRU should be promoted for grain production, especially for infertile soil.

Nitrogen efficiency indexes for evaluating nitrogen uptake and use in ornamental bromeliad’s root system and tank

Abstract: The objective of this work was to evaluate if nitrogen use efficiency (NUE) indexes can elucidate functional differences in nutrient uptake between the root system and tank of epiphytic bromeliads. The bromeliads Guzmania lingulata and Vriesea 'Harmony' received fertilizers in their tanks or through their roots using modified Hoagland &amp; Arnon solution, with 0.00, 2.62, or 5.34 mmol L-1 nitrogen, as urea. After 90 days, nitrogen contents in leaves and plant biomass were evaluated, and NUE indexes were calculated. Guzmania lingulata and V. 'Harmony' fertilized in their tanks with 5.34 mmol L-1 had the highest averages of nitrogen uptake efficiency and recovery efficiency; those fertilized with 2.62 mmol L-1 through their roots showed the highest averages of NUE, nitrogen utilization efficiency, nitrogen physiological efficiency, and biomass conversion efficiency. The NUE indexes, besides being an effective tool to assess the nutritional status of ornamental bromeliads, reveal that the root system of epiphytic bromeliads is functional for nitrogen uptake and use.

Effect of Nitrogen Rates on Dry Matter Cumulation and Nitrogen Partition of Wheat Plants Under Different Planting Methods

T WO FIELD trials were conducted at the Agricultural Experiment Station, Faculty of Agriculture Ain Shams University, Kalubia, Egypt during 2013/2014 and 2014/2015 growing seasons to investigate the response of wheat to nitrogen fertilizer rates under different planting methods. Each experiment contained twelve treatments which were the combination of four planting methods (Broadcasting (conventional tilled flat method), rows (20 cm apart), ridge (ridge width 60 cm) and bed (bed width 120 cm)) and three nitrogen fertilizer rates (60, 80 and 100 kg Nitrogen/fad (faddan = 4200 m2). Design of experiments was split plot design with three replications, where planting methods in the main plot and nitrogen rates in the sub plots. Data revealed that planting methods and nitrogen rats were significant affected on dry weight of wheat plant organs. Leaves; tillers and spikes dry weight (g/m2) were markedly increased with increasing nitrogen rates (60, 80 and 100 kg N/fad). Weight of leaves was markedly decreased by progressing plants towards maturity. On the other hand, N use efficiency (NUE) and nitrogen physiological efficiency (NPE) exhibiting maximum values, they were 42.68 kg grains/kg applied nitrogen and 43.45 kg grains/kg of N absorbed, respectively when plants were fertilized with 60 kg N/fad followed by adding 80 and 100 kg N/fad. Planting wheat on bed exhibited statistically maximum leaves, tillers and spikes dry weight (g/m2) in comparable to the other plant methods during phenological stages of wheat growth. Planting wheat on bed exhibiting maximum nitrogen use efficiency (42.50 kg grains/kg N applied) and nitrogen physiological efficiency (43.28 kg grains/kg N absorbed). Grain nitrogen yield (GNY), straw nitrogen yield (SNY) and total nitrogen yield (TNY), were increased by increasing nitrogen rates up to 100 kg N/fad under sowing methods treatment. Meanwhile 60 or 80 kg N/fad exhibited maximum values of NUE and N recovery efficiency (NRE) under sowing on ridge or on bed.

Nitrogen use efficiency in spring wheat: genotypic variation and grain yield response under sandy soil conditions

SUMMARYAgricultural practices are likely to lower nitrogen (N) fertilization inputs for economic and ecological limitation reasons. The objective of the current study was to assess genotypic variation in nitrogen use efficiency (NUE) and related parameters of spring wheat (Triticum aestivumL.) as well as the relative grain yield performance under sandy soil conditions. A sub-set of 16 spring wheat genotypes was studied over 2 years at five N levels (0, 70, 140, 210 and 280 kg N/ha). Results indicated significant differences among genotypes and N levels for grain yield and yield components as well as NUE. Genotypes with high NUE exhibited higher plant biomass, grain and straw N concentration and grain yield than those with medium and low NUE. Utilization efficiency (grain-NUtE) was more important than uptake efficiency (total NUpE) in association with grain yield. Nitrogen supply was found to have a substantial effect on genotype; Line 6052 as well as Shandawel 1, Gemmiza 10, Gemmiza 12, Line 6078 and Line 6083 showed higher net assimilation rate, more productive tillers, increased number of spikes per unit area and grains per spike, extensive N concentration in grain and straw, heavier grains, higher biological yield and consequently maximized grain yield. The relative importance of NUE-associated parameters such as nitrogen agronomic efficiency, nitrogen physiological efficiency and apparent nitrogen recovery as potential targets in breeding programmes for increased NUE genotypes is also mentioned.

Effects of grafting and nitrogen fertilization on melon yield and nitrogen uptake and utilization

A split-field design experiment was carried out using two main methods of cultivation (grafting and self-rooted cultivation) and subplots with different nitrogen application levels (0, 120, 240, and 360 kg N·hm-2) to investigate the effects of cultivation method and nitrogen application levels on the yield and quality of melons, nitrogen transfer, nitrogen distribution, and nitrogen utilization rate. The results showed that melons produced by grafting cultivation had a 7.3% increase in yield and a 0.16%-3.28% decrease in soluble solid content, compared to those produced by self-rooted cultivation. The amount of nitrogen accumulated in melons grafted in the early growth phase was lower than that in self-rooted melons, and higher after fruiting. During harvest, nitrogen accumulation amount in grafted melon plants was 5.2% higher than that in self-rooted plants and nitrogen accumulation amount in fruits was 10.3% higher. Grafting cultivation increased the amount of nitrogen transfer from plants to fruits by 20.9% compared to self-rooted cultivation. Nitrogen distribution in fruits was >80% in grafted melons, whereas that in self-rooted melons was <80%. Under the same level of nitrogen fertilization, melons cultivated by grafting showed 1.3%-4.2% increase in nitrogen absorption and utilization rate, 2.73-5.56 kg·kg-1 increase in nitrogen agronomic efficiency, and 7.39-16.18 kg·kg-1 increase in nitrogen physiological efficiency, compared to self-rooted cultivation. On the basis of the combined perspective of commercial melon yield, and nitrogen absorption and utilization rate, an applied nitrogen amount of 240 kg·hm-2 is most suitable for graf-ting cultivation in this region.

Optimizing nitrogen management strategy under wheat straw incorporation for higher rice production and nitrogen use efficiency

ABSTRACTNitrogen (N) application plays an important role in rice production. Limited attention has already been paid to optimizing N fertilizer management strategy for higher grain yield and nitrogen use efficiency (NUE) of rice with crop residue incorporation. Field experiments were conducted with the objective to determine the response of several N application methods to rice production and to evaluate their NUE. Three N fertilizer application methods, i.e., local farmers' N fertilizer practice (FNP), modified farmers' N fertilizer practice (MNP), and increased the amount of N fertilizer practice (INP), were adopted with zero N application as control (CK). The results showed that, compared with that under FNP, grain yield was significantly higher under MFP, owing to signficantly enhanced total spikelets as a result of more panicles per unit area. Relative to FNP, MNP markedly increased nitrogen agronomic efficiency (AEN), nitrogen recovery efficiency (REN), nitrogen physiological efficiency (PEN) and nitrogen partial factor productivity (PFPN), but AEN, PEN and PFPN of INP were significantly lower. Further analysis showed that the number of tiller, leaf area index, aboveground biomass, SPAD value, plant N content and N uptake at the early vegetative stage were improved significantly under MNP compared to those under FNP, contributing to higher total aboveground biomass and total N uptake.

Effects of modified fertilization technology on the grain yield and nitrogen use efficiency of midseason rice

Local popular midseason varieties of rice were used to study the effects of modified fertilization technology on the grain yield and nitrogen (N) use efficiency of midseason rice in central China. Field trials with five N treatments and four replications were conducted in Jingmen County (2008–2009), Honghu County (2009–2011), and Chibi County (2008–2011) in Hubei Province. The results showed that, relative to most farmers’ fertilizer practices (FFP), the grain yield of modified farmers’ fertilizer practices (MFP) in eight out of nine experiments showed an increase in ratio ranging from 0.3% to 16.6% and grain yield of super-high-yield fertilizer practice (SHY) in six of nine experiments showed an increase in ratio ranging from 2.4% to 20.9%. Relative to SHY, the grain yield of modified super-high-yield fertilizer practice (MSP) treatments in seven out of nine experiments showed an increase in ratio ranging from 0.2% to 20.4%. Relative to FFP, the nitrogen agronomic efficiency (NAE) and nitrogen physiological efficiency (NPE) values of MFP treatment in eight out of nine experiments showed an increase in ratio ranging from 26.0% to 110.3% and from 1.3% to 46.1%, respectively. Relative to SHY, the NAE and NPE values of MSP treatment in eight out of nine experiments showed an increase in ratio ranging from 5.2% to 151.7% and from 7.4% to 82.6%, respectively. Further analysis showed that the number of panicles in MFP, SHY, and MSP were greater than in FFP. This was attributable to the ability of the modified fertilizer technology to delay functional leaf senescence, maintain optimum leaf area index (LAI), an optimize shoot biomass, to a reasonable tiller number and to a healthy population structure with a high relative amount of productive tiller. This study may provide technical and theoretical support for simultaneously increasing rice grain yield and nutrient use efficiency, for optimization of the use of fertilizer by local farmers, and for facilitating sustainable increases in grain yield.

STUDIES ON DIFFERENCES OF NITROGEN EFFICIENCY AND ROOT CHARACTERISTICS OF OILSEED RAPE (BRASSICA NAPUS L.) CULTIVARS IN RELATION TO NITROGEN FERTILIZATION

Differences of nitrogen efficiency of oilseed rape (Brassica napus L.) cultivars and their physiological properties were studied in a pot experiment, and the ratio of seed yield with no nitrogen supplied to that with normal nitrogen supply was adopted as a nitrogen efficiency coefficient. Results showed that the nitrogen efficiency coefficient determined for eight oilseed rape cultivars varied from 0.37 to 0.69, the ratio of nitrogen uptake amounts per plant, nitrogen transfer velocity from stems and leaves to seeds, and nitrogen physiological efficiency of oilseed rape cultivars under nitrogen stressed condition differed from with normal nitrogen supply. The higher the nitrogen efficiency of a cultivar, the higher the ratio of N uptake in no nitrogen to with N supplied. Under low nitrogen-supplying conditions, high nitrogen efficiency cultivars had longer roots, more lateral roots, higher amounts of reuse of nitrate from stem and leaves, and higher nitrate reductase activities in leaves.