Levels Of Nitrogen Application Research Articles

Effects of Water and Nitrogen Coupling on Yield, Quality, Water and Nitrogen Use Efficiencies of Greenhouse Muskmelon

The proficient supply of water and nitrogen is a key factor in facility agriculture. In order to pursue high yields, most farmers blindly irrigate and fertilize, leading to yield reduction, quality decline, soil salinization, and fertility destruction. A successive two-year greenhouse experiment was carried out on fruit quality, yield, irrigation water use efficiency (IWUE), and nitrogen use efficiency (NUE) of greenhouse muskmelon (Cucumis melo L.) under drip fertigation, which can provide a scientific basis for local muskmelon intensive production in Southeast China. The experiments were conducted in 2020 and 2021, with three irrigation levels 80% (W1), 100% (W2), and 120% (W3) of ETc and three N levels 60 (N1), 95 (N2), and 130 (N3) kg N ha−1. The amount of drip irrigation water was determined every 5 days based on crop evapotranspiration (ETc). The seasonal irrigation amount ranged from 209.77 mm to 298.86 mm in 2020 and from 201.22 mm to 286.04 mm in 2021. The highest muskmelon yield was obtained in the treatment of W3N3 with an average of 27.38 t ha−1 in 2020 and 27.10 t ha−1 in 2021. Although the yield was improved by increasing nitrogen supply, there was no significant difference between N2 and N3 treatment in two years under the irrigation level of W2 and W3. The highest irrigation water use efficiency was observed in the W1N3 treatment in 2020 and 2021. The NUE increased with decreasing N rates at the same irrigation level. Under the same nitrogen application level, TSS and Vc under low water (W1) were higher than that under medium water (W2) and high water (W3) treatment. The highest content of nitrate in low water and high nitrogen (W1N3) treatment was 55.41 µg/g in 2020 and 52.50 µg/g in 2021, respectively. The yield and quality of muskmelon are often incompatible, for instance, W2N2 treatment can obtain a higher yield, but W1N2 treatment maximizes Vc, TSS of muskmelon quality. Our findings suggest that the irrigation level of 1.0 ETc, nitrogen level of 95 N ha−1, and 3500 kg·ha−1 of decomposed organic fertilizer was recommended as the best combination, which can improve the yield, quality, IWUE, NUE of muskmelon under drip fertigation with soil mulching in the experimental site.

Effect of nitrogen application levels on photosynthetic nitrogen distribution and use efficiency in soybean seedling leaves

BackgroundNitrogen nutrition is strongly associated with crop growth and development. Nitrogen application level affects leaf size as well as nitrogen content and distribution, and thus affects photosynthetic nitrogen-use efficiency (PNUE) and yield. In this study, soybean varieties “Jinyuan 55” and “Keshan 1” were treated with nitrogen as urea at: N0, 0 kg hm−2; N0.5, 60 kg hm−2; N1, 120 kg hm−2; and N1.5, 180 kg hm−2. We compared the effect of nitrogen level on plant morphology, biomass, photosynthetic physiology, nitrogen distribution, PNUE, and other soybean seedling leaf characteristics. ResultsMaximum carboxylation and electron transfer, net photosynthetic rates, and PNUE of both soybean varieties showed initial significant increases with increasing nitrogen application rate and subsequent stabilization. PNUE, carboxylation system components, electron transport components, and non-photosynthetic system distribution ratios in the photosynthetic system increased and subsequently decreased with increased nitrogen application rate. The nitrogen ratio between carboxylation and electron transport systems was positively correlated with PNUE in both soybean varieties. The nitrogen ratio in light-harvesting and non-photosynthetic systems showed a linear negative correlation with PNUE. ConclusionsOverall, an appropriate nitrogen level maintained a high photosynthetic nitrogen ratio, whereas low- or high-nitrogen conditions increased or decreased the nitrogen ratio in non-photosynthetic and photosynthetic systems, respectively, thus decreasing the PNUE and photosynthetic capacity. Moreover, increased nitrogen application rate led to a decreased nitrogen ratio in the light-harvesting system and an increased nitrogen ratio of electron transport and carboxylation systems. Our results provide a theoretical basis for optimizing leaf nitrogen distribution, determining optimum nitrogen levels, and promoting soybean seedling growth.

Nitrogen fertilization and precipitation affected Wheat (Triticum aestivum L.) in dryland the Loess Plateau of South Shanxi, China

Wheat (Triticum aestivum L.) is a staple crop worldwide, and its yield has improved since the green revolution, which was attributed to chemical nitrogen (N) fertilizer application. An experiment was conducted to set seven nitrogen application levels of N0, N90, N120, N150, N180, N210 and N240 kg ha−1 before sowing. The results showed that grain yield under the nitrogen rate of N210 kg ha−1 was significantly increase the water intake during jointing to anthesis, Soil water storage of dryland wheat in fallow period was higher than water consumption in jointing stage and the leaf area index at anthesis, the tiller percentage rate, the jointing-anthesis, and nitrogen accumulation were closely related to yield and its components. Nitrogen fertiliser rate N150 kg ha−1 significantly increased dry matter buildup from jointing to flowering in dryland wheat compared to N fertiliser rate N210 kg ha−1. The rise of nitrogen application rate, there were no significant variance in nitrogen accumulation of Stem + leaf sheath and cob + glume at maturity, respectively. N fertiliser rate N210 kg ha−1 compared to N180 kg ha−1 significantly reduced grain gliadin content in dryland wheat, respectively. Wheat crops under N210 kg ha−1 could achieve both high NUE and grain yield simultaneously with only moderate N fertilizer in South Shanxi, China.

Effects of Nitrogen Fertilizer on Photosynthetic Characteristics and Yield

This study aims to understand the influence of chlorophyll fluorescence parameters on the yield of winter wheat in some areas of China. Nitrogen (N) application is believed to improve photosynthesis in flag leaves, ultimately increasing the final yield. The results from different parameters of research showed that the grain number per spike improved by 12.2% and the 1000-grain weight by 7.3%, respectively. At 20–30 days after anthesis, the activities of superoxide dismutase (SOD), peroxidase (POD), and soluble protein in flag leaves of N150 were found to be the most effective. The grain yield under N manure partial substitution for N fertilizer treatment increased by 23 and 15%, respectively. The important implications of photosynthetic characteristics of variable fluorescence yield of the light-adapted state are that the contents of clear, ball, alcohol soluble, gluten, protein, and flour quality showed an increasing trend, while the contents of amylose, amylopectin, total starch, and direct/branch ratio were decreased of wheat. The net photosynthetic rate, transpiration rate, and relative chlorophyll content of wheat. The outcome of the present investigation suggests that chlorophyll fluorescence parameters could be a valuable insight into understanding yield stability under stress conditions. Moreover, the investigated parameters could be useful criteria for the selection of photosynthetic energy under varying nitrogen application levels.

Effects of sugarcane variety and nitrogen application level on the quality and aerobic stability of sugarcane tops silage.

To better understand the effects of sugarcane variety and nitrogen application level on silage, we analyzed the fermentation quality, microbial community dynamics, and aerobic exposure of sugarcane tops silage from three sugarcane varieties (B9, C22, and T11) treated with three levels of nitrogen (0, 150, and 300 kg/ha urea). After 132 days of silage, the sugarcane tops silage produced from variety B9, with strong nitrogen fixation ability, treated with nitrogen had the highest crude protein (CP) contents, pH, and yeast counts (P < 0.05), as well as the lowest Clostridium counts (P < 0.05), and the CP increased with increasing N application level (P < 0.05). In contrast, the sugarcane tops silage produced from variety C22, with poor nitrogen fixation ability, treated with 150 kg/ha nitrogen had the highest lactic acid bacteria (LAB) counts, dry matter (DM), organic matter (OM) and lactic acid (LA) contents (P < 0.05), as well as the lowest acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents (P < 0.05). However, these results were not present in the sugarcane tops silage produced from variety T11, with no nitrogen fixation ability, whether it was treated with nitrogen or not; although the silage was treated with 300 kg/ha nitrogen, the ammonia-N (AN) content was the lowest (P < 0.05). After 14 days of aerobic exposure, Bacillus abundance increased in the sugarcane tops silage produced from variety C22 treated with 150 kg/ha nitrogen and from varieties C22 and B9 treated with 300 kg/ha nitrogen, while Monascus abundance increased in the sugarcane tops silage produced from varieties B9 and C22 treated with 300 kg/ha nitrogen and from variety B9 treated with 150 kg/ha nitrogen. However, correlation analysis showed that Monascus was positively correlated with Bacillus irrespective of nitrogen level and sugarcane variety. Our results indicated that sugarcane variety C22, with poor nitrogen fixation ability, treated with 150 kg/ha nitrogen produced the highest sugarcane tops silage quality and inhibited the proliferation of harmful microorganisms during spoilage.

Self-Regulation of Soil Enzyme Activity and Stoichiometry under Nitrogen Addition and Plastic Film Mulching in the Loess Plateau Area, Northwest China

Soil extracellular enzyme activity (EA) and its eco-enzyme stoichiometric ratio (ES) are extremely sensitive to environmental change. This study aimed to clarify the change law of EA and ES in soil with different nitrogen addition levels under plastic film mulching, and to optimize the application amount of nitrogen fertilizer that was used. Based on the location experiment of plastic film mulching fertilization that has been ongoing since 2015, soil samples were collected from different depths (0–10 cm, 10–20 cm and 20–30 cm) during the harvest period of spring maize in October 2021. Four soil extracellular enzyme activities (β-1,4 glucosidase (βG), β-1, 4-N-acetylglucosidase (NAG), leucine aminopeptidase (LAP) and alkaline phosphatase (AP)) involved in soil carbon (C), nitrogen (N) and phosphorus (P) cycling at different nitrogen application levels (0, 90, 150, 225 and 300 kg·hm−2) were studied under two planting patterns of no plastic film mulching (LD) and plastic film mulching (PM). The latest discovery of this study is that the activities of soil EA involved in the cycling of soil carbon C, N and P are similar in different soil depths (0–10 cm, 10–20 cm and 20–30 cm). Both EC:P and EC:P in the soil in this area are less than 1:1, indicating that the soil is limited by N and P. Comprehensive analysis showed that a nitrogen application level of 225 kg·hm−2 was beneficial to the balance of soil nutrients and the improvement of soil EA at harvest. At the same time, PM can effectively improve the soil EA and is more conducive to the balance of soil nutrients. Redundancy analysis (RDA) showed that EA and ES were strongly correlated with pH, soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP). Most importantly, this study revealed that the activity of extracellular enzymes in arid and semi-arid areas was constantly self-regulated with the addition of nitrogen, which provided theoretical and technical support for the efficient use of nitrogen under the condition of plastic film mulching.

Nutrients Availability in Quality Protein Maize (QPM) Cobs at Various Levels of Nitrogen Application

Nutrients Availability in Quality Protein Maize (QPM) Cobs at Various Levels of Nitrogen Application

On correlation between canopy vegetation and growth indexes of maize varieties with different nitrogen efficiencies.

Studying the canopy spectral reflection characteristics of different N-efficient maize varieties and analyzing the relationship between their growth indicators and spectral vegetation indices can help the breeding and application of N-efficient maize varieties. To achieve the optimal management of N fertilizer resources, developing N-efficient maize varieties is necessary. In this research, maize varieties, i.e., the low-N-efficient (Zhengdan 958, ZD958), the high-N efficient (Xianyu 335, XY335), the double-high varieties (Qiule 368, QL368), and the double inefficient-type varieties (Yudan 606 YD606), were used as materials. Results indicate that nitrogen fertilization significantly increased the vegetation indices NDVI, GNDVI, GOSAVI, and RVI of maize varieties with different nitrogen efficiencies. These findings were consistent with the performance of yield, dry matter mass, and leaf nitrogen content and were also found highest under both medium and high nitrogen conditions in the double-high variety QL368. The correlations of dry matter quality, leaf nitrogen content, yield, and vegetation indices (NDVI, GNDVI, RVI, and GOSAVI) at the filling stage of different N-efficient maize varieties were all highly significant and positive. In this relationship, the best effect was found at the filling stages, with correlation coefficients reaching 0.772-0.942, 0.774-0.970, 0754-0.960, and 0.800-0.960. The results showed that the yield, dry matter weight, and leaf nitrogen content of maize varieties with different nitrogen efficiencies increased first and then stabilized with the increase in the nitrogen application level in different periods, and the highest nitrogen application level of maize yield should be between 270 and 360 kg/hm2. At the filling stage, canopy vegetation index of maize varieties with different nitrogen efficiencies was positively correlated with yield, dry matter weight, and leaf nitrogen content, especially GNDVI and GOSAVI on the leaf nitrogen content. It can be used as a means to predict its growth index.

Appropriate Water-Nitrogen Regulation Mode to Improve Productivity of Mixed-Sowing Grassland of Bromus inermis and Alfalfa

Scientific selection of appropriate herbage planting management mode is an important guarantee to promote artificial grassland development and grassland productivity. In this study, three-year-old alfalfa (Medicago sativa L.) and bromus inermis were applied to analyze the effects of planting patterns (bromus inermis and alfalfa mixed-sowing D1, bromus inermis mono-sowing D2), nitrogen application (pure nitrogen) level (N1: 60 kg·ha−1, N2: 120 kg·ha−1), and water regulation (upper and lower limits of irrigation are calculated as a percentage of field capacity θf, W1: slight water deficit 65~85% θf, W2: moderate water deficit 55~85% θf, W3: serious water deficit 45~85% θf) on herbage growth and water-nitrogen use efficiency. This research applied the principal component analysis, the TOPSIS model, and the combination evaluation to evaluate each treatment. Results demonstrated that (1) the plant height, leaf area index, and yield of mixed-sowing herbage were 81.63%, 119.52%, and 111.51%, higher than the mono-sowing herbage. Increasing the amount of irrigation and nitrogen application could enhance herbage yield. The herbage yield with the W1N2 treatment was the highest. In this treatment, the mixed-sowing herbage yield was 26,050.73 kg·ha−1, and the mono-sowing herbage yield was 12,186.10 kg·ha−1. (2) The crude protein content of mixed-sowing herbage increased by 41.44%, higher than mono-sowing herbage, and the relative feeding value decreased by 16.34%. Increasing irrigation and nitrogen application could improve the quality of herbage. Meanwhile, the quality of herbage treated with W1N2 was the best. (3) The water use efficiency (WUE), irrigation water use efficiency (IWUE), partial factor productivity of nitrogen (PFPN), and crude protein water use efficiency (CPWUE) of mixed-sowing herbage were significantly higher than mono-sowing herbage. The PFPN and the CPWUE of herbage improved with increasing irrigation amount. Meanwhile, the WUE, the IWUE, and the CPWUE of herbage also improved with increasing nitrogen application amount. The results showed that mixed-sowing of alfalfa and bromus inermis with slight water deficit (upper and lower limit of irrigation was 65~85% θf) and nitrogen application (120 kg·ha−1) could have the best comprehensive production effect. At the same time, it was a planting and management mode of high yield, high quality, and high efficiency of artificial herbage in the oasis-desert interlacing area of Hexi, Gansu Province, China, and areas with similar climates.

Changes in canopy microclimate of faba bean under intercropping at controlled nitrogen levels and their correlation with crop yield.

The relationship between the microclimate of the intercropping faba bean canopy and yield, and its response to nitrogen application, was studied in the crop canopy to clarify that intercropping and nitrogen application changed the microclimate of the faba bean canopy and affected the yield. In field experiments in Eshan and Xundian, the growth index, light transmittance, interception rate of photosynthetic effective radiation, temperature, relative humidity, and yield of the faba bean were determined using three planting methods (wheat monoculture, faba bean monoculture, and wheat-faba bean intercropping) and four nitrogen application levels, N0 (0 kg/hm2 ), N1 (45 kg/hm2 ), N2 (90 kg/hm2 ), and N3 (180 kg/hm2 ). The results showed that the application of nitrogen improved the growth index of monoculture and intercropping broad beans significantly, reduced the canopy light transmittance and temperature significantly, and increased the interception rate and relative humidity of photosynthetic effective radiation significantly. Compared with N0, the yield of broad bean in both places was the highest in N1, which increased by 14% (Eshan) and 15% (Xundian). Multiple linear stepwise regression and path analysis showed that the decrease in canopy light transmittance during the faba bean pod-setting stage and the interception rate of photosynthetic effective radiation during pod-bulging stage, caused by excessive nitrogen application, were the main climatic and ecological factors limiting the increase in the intercropping faba bean yield in Eshan and Xundian respectively. The optimum nitrogen application rate recommended in production is 45kg/hm2 , to reduce the nitrogen application rate and maximize the productivity of the wheat and faba bean system. © 2023 Society of Chemical Industry.

Response of Water-Nitrogen Distribution and Use to Water Deficit under Different Applied Nitrogen Fertilizer Rates in Bromus inermis Grassland

This study was about the water-nitrogen regulation model and its soil nutrient environment effect for increasing the yield and efficiency of Bromus inermis in the Hexi Corridor, Gansu Province, China. Bromus inermis was used as the research object in this study and four irrigation management types and four nitrogen application levels were set. The four irrigation management types (controlled by the percentage of field capacity (θf) at the jointing stage) were 75–85% (W0), 65–85% (W1), 55–85% (W2) and 45–85% (W3). The four nitrogen application levels were pure nitrogen 0 kg·ha−1 (N0), 60 kg·ha−1 (N1), 120 kg·ha−1 (N2) and 180 kg·ha−1 (N3). The effects of water-nitrogen regulation on the spatial and temporal distribution of soil moisture and nitrate nitrogen (NO3−–N), plant height, chlorophyll content, yield and water-nitrogen use efficiency of Bromus inermis were studied. Results demonstrated that (1) soil water content (SWC) was mainly affected by irrigation and W1 treatment helped maintain shallow soil (0–40 cm) water’s stability and avoided water redundancy or deficit in the 60–80 cm soil layer. The distribution of soil NO3−–N was mainly affected by nitrogen application. The N2 treatment could effectively increase the NO3−–N content in shallow soil (0–40 cm) and prevent nitrate-nitrogen leaching in the 60–100 cm soil layer. (2) Irrigation and nitrogen application could significantly increase the plant height and chlorophyll content of each cut of Bromus inermis. The average plant height and chlorophyll content of the N2W1 treatment were 66.99% and 30.30% higher than N0W3. (3) At the same time, irrigation and nitrogen application could significantly increase the yield of each cut of Bromus inermis, and the interaction between the two had a significant effect on the total yield. The total yield of the N2W1 treatment was the highest (12,259.54 kg·ha−1), 157.95% higher than N0W3. Irrigation and nitrogen application could significantly improve the water-nitrogen use efficiency of Bromus inermis, and their interaction only significantly impacted the partial-factor productivity of the applied nitrogen (PFPN). Meanwhile, the N2W2 treatment had the highest water use efficiency (WUE) (23.12 kg·m−3), and the N1W1 treatment had the highest PFPN (170.87 kg·kg−1). In summary, the moderate nitrogen application rate (120 kg·ha−1) combined with mild water deficit (65–85% θf at the jointing stage) could not only promote the high yield of Bromus inermis, but also avoid the leaching of water and nitrogen in deep soil. It is a suitable water and nitrogen management mode for Bromus inermis in the Hexi Corridor of Gansu Province, China.

Nitrogen nutrition diagnosis and estimation of seed cotton yield based on critical nitrogen concentration for drip irrigation cotton in Southern Xinjiang, China.

The stability and adaptability of the critical nitrogen concentration in drip-irrigated cotton fields in Southern Xinjiang were investigated by measuring the nitrogen uptake (Nuptake), nitrogen nutrition index (NNI), and accumulated nitrogen deficit (Nand). A two-year field study was conducted using five nitrogen levels (0, 75, 150, 300, and 450 kg·hm-2), with cotton cultivars 'Xinluzhong55' and 'Xinluzhong78' as the test materials. We analyzed the effects of nitrogen addition on plant dry matter (PDM) and critical nitrogen concentration dilution curves (PNCc). The Nuptake, NNI, and Nand models as well as a model of the relationships between NNI, Nand, and the relative seed cotton yield (RY) were established based on the PNCc for both cultivars. The results showed that the PNCc, maximum nitrogen concentration (PNCmax), and minimum nitrogen concentration (PNCmin) dilution models in drip-irrigated cotton showed power function relationships with plant dry matter (PDM), with determination coefficients (R2) of 0.905 and 0.960, 0.919 and 0.950, 0.934 and 0.969 for Xinluzhong55 and Xinluzhong78, respectively. Model validation with independent experimental data showed that the critical nitrogen concentrations in cotton grown under drip-irrigated conditions were simulated satisfactorily. The Xinluzhong55 and Xinluzhong78 1:1 line R2, root mean square error (RMSE) and relative estimation error (RE) of the simulated and observed critical nitrogen concentrations were 0.987, 0.051 g·kg-1, 1.95% and 0.984, 0.044 g·kg-1, 1.91%, respectively, showing good stability and adaptability between the two years. According to the Nuptake, NNI, and Nand model, we concluded that 300 kg·hm-2 was the optimum level of nitrogen application in drip-irrigated cotton in Southern Xinjiang. Based on the fitting results of nitrogen level and seed cotton yield, the theoretical appropriate nitrogen applications for Xinluzhong55 and Xinluzhong78 were 322.7 and 336.4 kg·hm-2, respectively. The R2 of NNI, Nand and RY in different growth stages were greater than 0.900, the NNI, Nand and RY estimation model of seed cotton yield based on 1:1 lines of R2, RMSE, and RE were 0.899-0.989, 0.05-0.13, and 4.1%-9.9% and 0.902-0.981, 0.04-0.12, and 5.1%-9.5%, all of which were highly significant. These results could provide new directions for the evaluation and diagnosis of optimum nitrogen application levels and nitrogen status, as well as the estimation of seed cotton yield in drip-irrigated cotton in Southern Xinjiang.

Phenology, growth and productivity of rice (Oryza sativa l.) under reduced sunlight intensity and foliar nitrogen application

The field experiments related to the study were conducted at Punjab Agricultural University, Ludhiana and Krishi Vigyan Kendra, Bahowal. There were 20 treatment combinations comprising of four levels of sunlight intensity [control (full sunlight), 50% reduction in sunlight light intensity during 15-45(R15-45), 46-75(R46-75) and 76-105(R76-105) DAT] and five levels of foliar nitrogen application [control (only recommended nitrogen, no foliar spray), spray of 3% urea before (NB), midway(NM), afterwards(NA) and midway-afterwards(NMA) the reduction in sunlight intensity in addition to the recommended nitrogen application]. Radiation level of R15-45 significantly preponed (2-5 days) the occurrence of phenological stages from maximum tillering to physiological maturity. Similarly, R46-75 significantly preponed (3-9 days) the occurrences of flag leaf initiation to physiological maturity. The nitrogen level of NB, significantly delayed the occurrence of flag leaf initiation to physiological maturity stages (2-5 days), NM delayed flag leaf initiation to physiological maturity (2-4 days), NA delayed anthesis to physiological maturity (1-4 days) and NMA delayed panicle emergence to physiological maturity (2-5 days). Plant height of rice was significantly increased due to R15-45 (5.21-5.26%) and R46-75 (6.95-7.61%) and also with foliar nitrogen application levels of NB, NM, NA and NMA by 9.95-9.89, 9.65-10.06, 8.06-7.57 and 9.65-9.29 per cent, respectively. Number of tillers m-2 was significantly reduced (4.71-15.99%) under low light conditions and was increased (5.59-23.34%) with foliar nitrogen application. Yield attributes were affected by the reduced sunlight intensity and foliar nitrogen application. Grain yield was significantly reduced as a result of R15-45 (9.19-11.41%), R46-75 (14.29-16.35%) and R76-105 (8.15-10.67%) and foliar nitrogen application levels of NB, NM and NMA resulted in significant increase the grain yield by 9.32-10.19, 5.74-6.38 and 4.59-5.74 per cent respectively, as compared to control.

Effects of nitrogen application level on the physiological characteristics, yield and fruit quality of blackberry

To study the optimal amount of nitrogen application for blackberry plants, different amounts of ammonium sulfate were applied to three-year-old healthy ‘Shuofeng’ blackberry plants at three key growth stages (early bud burst, the flowering stage and the fruit veraison stage) to explore the effects of nitrogen fertilizer application level on the physiological characteristics of leaves, yield and fruit quality of blackberry. Overall, the leaves turned yellow, and cellular metabolism was disrupted in the CK group (no nitrogen fertilization). Among the nitrogen treatments, the leaf chlorophyll content, photosynthesis efficiency and antioxidant enzyme activity were significantly higher under the T2 (40 g plant−1) and T3 (60 g plant−1) treatments than under the T1 (20 g plant−1) and T4 (80 g plant−1) treatments, while the contents of ascorbic acid, glutathione, hydrogen peroxide and malondialdehyde showed the opposite trends. The yield, single-fruit weight, solids–acids ratio and anthocyanin contents of blackberry fruits increased first and then decreased with increasing nitrogen application. The contents of polyphenols and ellagic acid in fruits decreased with increasing nitrogen application. Correlation and principal component analysis showed that yield and its components were closely related to leaf photosynthesis characteristics and the antioxidant system (P<0.05). Application of 20 g ammonium sulfate per plant at early bud burst, the flowering stage and the fruit veraison stage was profitable, which resulted in more vigorously growth, increased yield and fruit quality, while the production cost was the most economical because of the low fertilizer consumption.

Linear dependency of winter wheat yield and nitrogen use efficiency on the pre-anthesis temperature in the lower reach of the Yangtze River

Global warming is expected to enhance the nitrogen (N) absorption capability of crops, which causes a change in nitrogen fertilizer input. However, the impacts of warming and nitrogen application on crop growth, yield and nitrogen use efficiency (NUE) are still unclear. Here, we conducted a 4-year field experiment of nighttime warming before winter wheat anthesis to explore the response of winter wheat yield to warming and the variation in nitrogen use efficiency under different nitrogen application levels (N150: 150 kg·ha−1, N225: 225 kg·ha−1, and N375: 375 kg·ha−1). The results showed that warming shortened the winter wheat vegetative growth period (VGP) by 8.3 days, while it prolonged the reproductive growth period (RGP) by 6.7 days. However, there was no significant difference in the growth period of winter wheat between nitrogen treatments. Meanwhile, warming increased winter wheat yield by increasing the number of effective spikes and grains per spike. Every 1 °C increase in pre-anthesis temperature increased winter wheat yield by 45.48, 55.78 and 60.88 g·m−2 for the N150, N225 and N375 treatments, respectively. There was no significant difference in yield between the N225 and N375 treatments, but the nitrogen partial factor productivity (PFPN) and the nitrogen utilization efficiency (NUtE) of N225 were significantly higher than those of N375. PFPN and NUtE were positively correlated with pre-anthesis air temperature under different nitrogen treatments. Multiple linear regression showed that a 1.0 °C increase enhanced NUtE by 11.62%, 9.75% and 7.85% for the N150, N225 and N375 treatments, respectively, and enhanced the PFPN by 7.77%, 8.94% and 9.81% respectively. Therefore, we suggest that 225 kg·ha−1 is an appropriate amount of nitrogen application in the lower reach of the Yangtze River under future climate warming.

Precision Nitrogen Fertilizer and Irrigation Management for Apple Cultivation Based on a Multilevel Comprehensive Evaluation Method of Yield, Quality, and Profit Indices

Precise and efficient fertilizer and irrigation management is critical for apple production in the Loess Plateau, China. In this study, we established three levels of nitrogen application and irrigation in nine treatments in an apple orchard based on a completely randomized block design. Then, we analyzed different apple indicator responses to nitrogen and irrigation and their related interactions. More importantly, we used the multilevel comprehensive fuzzy evaluation value (MFCE) method to combine the weights of all indicators to obtain the comprehensive growth indicators for apples. Finally, we analyzed the effect of nitrogen and irrigation coupling on the comprehensive growth of apples and then determined the optimal interval for nitrogen application and irrigation. The results indicated that an increase in the amount of irrigation was beneficial for apple yield, but excessive nitrogen fertilizer application significantly reduced apple yield. The apple indicators were not sensitive to irrigation and nitrogen application and their related interactions; they were mainly controlled by the apple cultivar. On the other hand, an increase in the amount of nitrogen fertilizer or a reduction in the amount of irrigation could improve apple quality. The results of the comprehensive evaluation showed that the T5 treatment was most beneficial for the comprehensive growth of apples. To obtain the optimal interval for nitrogen application and irrigation more precisely, we used multiple linear regression based on the MFCE values of apples, nitrogen, and irrigation in R language. Nitrogen and irrigation showed a positive effect on the comprehensive growth of apples when the irrigation amount was low. However, nitrogen application and irrigation had a negative effect on the comprehensive growth of apples when the irrigation level was high. After optimization, the optimal nitrogen application and irrigation amounts were 170.5–189.5 kg·hm−2 and 38.4–42.7 mm, respectively. We recommend using this irrigation and fertilizer management scheme for apple orchards in China’s Loess Plateau.

Performance of Three Boro Rice Varieties Under Different Levels of Nitrogen Application

A field exper iment was carr ied out to study the effect of levels of nitrogen on the performance of three Boro rice varieties e.g. cv. BRRI dhan28, cv BRRI dhan29 and cv. Surjomoni. The experiment comprised four levels of nitrogen viz. 0 kg N ha-1, 60 kg N ha-1, 120 kg N ha-1 and 180 kg N ha- 1 . The experiment was laid out in a randomized complete block design with three replications. The highest grain yield (4.23 t ha-1) was obtained from cv. BRRI dhan29 because of production of the highest number of both total tillers m-2 and effective tillers m-2. BRRI dhan28 produced higher grain yield (3.39 t ha-1) compared to that of Surjomoni (3.07 t ha-1). Application of 120 kg N ha-1 produced the highest grain yield (4.23 t ha-1) because of the production of the highest number of both total tillers m- ' and effective tillers m-2 in the t reatment . Appl icat ion of 180 kg N ha-1 produced the second-highest grain yield (3.70 t ha-1) and 0 kg N ha-1 produced the lowest grain yield (2.76 t ha-1). Interaction between variety and levels of nitrogen significantly influenced all parameters studied except plant height, total tillers hill -1, effective tillers hill-1, non-effective tillers hill-1, length of panicle, number of sterile spikelets panicle-1 and 1000-grain weight. The highest grain yield (4.60 t ha-1) was obtained from BRRI dhan29 with the application of 120 kg N ha-1 and the lowest grain yield (2.40 t ha- 1 ) was obtained f rom the treatment combination of Surjomoni and 0 kg N ha-1. Rice variety BRRI dhan29 can be provided with 120 kg N ha-1 to get the highest and economic production of the crop.&#x0D; Vol. 9, No. 3, December 2022: 267-278

Effects of Nitrogen Application Level on Growth and Yield Of Winter Wheat

In order to achieve higher crop yield and improve the utilization efficiency of nitrogen fertilizer resources. Effect of nitrogen on the tillering ability, the aboveground dry matter mass and yield of winter wheat (WW) during the growing period were analyzed in a field experimental plot of Qinling Field Monitoring Center Station in Baoji City, Shaanxi Province from 2020 to 2021. Results demonstrated that nitrogen use significantly improved the tillering ability of WW during the overwintering and turning green stage; however, the use of nitrogen &gt; 120 kg/hm2 did not have a significant impact on the tillering ability of WW. The growth stages were directly proportional to the extent of aboveground dry matter accumulation (DMA) of WW and were found to be maximum at maturity. Greater usage of nitrogen significantly enhanced aboveground DMA before the jointing stage, but nitrogen application as high as 270 kg/hm2 was not conducive to the aboveground DMA after the jointing stage. For WW, at first, the yield increased and then decreased with the increased concentration of nitrogen. When the nitrogen application level was 120 kg/hm2, the highest yield of WW was 7506 kg/ha. However, there was an insignificant increase in yield at nitrogen levels &gt; 120 kg/hm2. In the study area, at nitrogen &gt; 195 kg/hm2, a decrease in yield was observed. Therefore, the recommended nitrogen application level in this area was 120kg/hm2. Bangladesh J. Bot. 51(4): 937-941, 2022 (December) Special

Effect of Post-Drought Rehydration on Winter Wheat Fluorescence and Photosynthetic Indices under Different Levels of Nitrogen Application

Studying the response of winter wheat to post-drought rehydration is conducive to understanding the efficient utilization of water-saving technology, such as regulating deficit irrigation and increasing water use efficiency. The controlled condition experiment in the rain shelter was conducted in 2020. The two water stress treatments, including post-drought rehydration at the jointing and heading stages, were combined with high nitrogen (N) (250 kg/hm2), low N (125 kg/hm2), and no N (0 kg/hm2, control). The effects of post-drought rehydration on the relative chlorophyll content (SPAD), major fluorescence parameters, and photosynthetic indexes of winter wheat were determined. The results showed that post-drought rehydration increased the SPAD value, the efficiency of light energy conversion, maximum potential photo-electron transport, and the photosynthetic indices and decreased the photochemical quenching coefficient. Among them, the compensatory effect of rehydration at the heading stage on SPAD, fluorescence parameters, and photosynthetic indexes was more significant (p &lt; 0.05), and the winter wheat needed a recovery process after rehydration. Increased application of N fertilizer can alleviate the effects of water stress on the fluorescence parameters and photosynthetic properties of flag leaf and promote the degree of the response of fluorescence parameters and photosynthetic properties to rehydration. The specific effects were as follows: high N &gt; low N &gt; no N application. As a result, winter wheat had a certain compensatory effect of rehydration after timely drought stress; the compensatory effect of rehydration could be enhanced under the condition of increasing N application.

Estimation of Relative Chlorophyll Content in Spring Wheat Based on Multi-Temporal UAV Remote Sensing

Relative chlorophyll content (SPAD) is an important index for characterizing the nitrogen nutrient status of plants. Continuous, rapid, nondestructive, and accurate estimation of SPAD values in wheat after heading stage can positively impact subsequent nitrogen fertilization management strategies, which regulate grain filling and yield quality formation. In this study, the estimation of SPAD of leaf relative chlorophyll content in spring wheat was conducted at the experimental base in Wuyuan County, Inner Mongolia in 2021. Multispectral images of different nitrogen application levels at 7, 14, 21, and 28 days after the wheat heading stage were acquired by DJI P4M UAV. A total of 26 multispectral vegetation indices were constructed, and the measured SPAD values of wheat on the ground were obtained simultaneously using a handheld chlorophyll meter. Four machine learning algorithms, including deep neural networks (DNN), partial least squares (PLS), random forest (RF), and Adaptive Boosting (Ada) were used to construct SPAD value estimation models at different time from heading growth stages. The model’s progress was evaluated by the coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAPE). The results showed that the optimal SPAD value estimation models for different periods of independent reproductive growth stages of wheat were different, with PLS as the optimal estimation model at 7 and 14 days after heading, RF as the optimal estimation model at 21 days after heading, and Ada as the optimal estimation model at 28 d after heading. The highest accuracy was achieved using the PLS model for estimating SPAD values at 14 d after heading (training set R2 = 0.767, RMSE = 3.205, MAPE = 0.060, and R2 = 0.878, RMSE = 2.405, MAPE = 0.045 for the test set). The combined analysis concluded that selecting multiple vegetation indices as input variables of the model at 14 d after heading stage and using the PLS model can significantly improve the accuracy of SPAD value estimation, provides a new technical support for rapid and accurate monitoring of SPAD values in spring wheat.