Nitrogen Uptake Efficiency Research Articles

Photo-crosslinkable biodegradable polymer coating to control fertilizer release

A photo-crosslinkable biodegradable polymer based on a poly(ɛ-caprolactone) backbone was herein developed to enhance the efficiency of nitrogen uptake from fertilizers. To this end, ammonium and calcium nitrate fertilizers were coated with photo-crosslinkable acrylate-endcapped urethane-based poly(ɛ-caprolactone) through fluidized bed technology. We hypothesized that the coating would enable to control the release time of nitrogen species from the granules for 1-3 months. Fourier transform infrared spectroscopy was used to monitor the reaction progress while chemical structure verification of the acrylate-endcapped urethane-based poly(ɛ-caprolactone) was executed via 1H-NMR spectroscopy. The physical properties and crosslinking efficiency of the coating material were determined through rheological measurements, gel fraction determination and thermogravimetric analysis before and after crosslinking. The data showed that the optimal fluidized bed processing temperature was 29°C. Scanning electron microscopy allowed to evaluate both the coating application and final coating thickness onto the polymer coated fertilizer granules. Three different coating thicknesses were applied onto each granule type. The polymer coated fertilizers were evaluated for their nitrate and ammonium release properties in sand substrate columns on laboratory scale. Osmocote bloom was used as reference throughout the experiments. The resulting cumulative release curves were fitted to a normalized non-linear regression with variable slope and the release was found to be based on a diffusion mechanism. Nitrogen release dynamics were primarily controlled by the thickness of the coating layer. The longest release times were observed for the ammonium nitrate and calcium nitrate granules with thickest coating layers (105 ± 10 μm and 148 ± 12 μm, respectively); 75 % nitrate was released after 75 - 77 and 74 - 75 days, respectively. The release was shown to be in line with the target release time of a commercial fertilizer included as benchmark throughout the release study. The herein developed polymer can be considered promising to serve as coating material for controlled release fertilizer development because of its benefits as compared to Osmocote (i.e., single coating application possible, biodegradable coating, no additional toxic components or solvents and room temperature processing).

Maize-soybean intercropping at optimal N fertilization increases the N uptake, N yield and N use efficiency of maize crop by regulating the N assimilatory enzymes.

Surplus use of chemical nitrogen (N) fertilizers to increase agricultural Q9 production causes severe problems to the agricultural ecosystem and environment. This is contrary to N use efficiency and sustainable agricultural production. Hence, this study was designed to investigate the effect of maizesoybean intercropping on N uptake, N yield, N utilization use efficiency, and the associated nitrogen assimilatory enzymes of maize crops under different N fertilization for two consecutive years 2021-2022. The findings of the study showed that intercropping at the optimal N rate (N1) (250 kg N ha-1) increased significantly maize grain yield by 30 and 34%, residue yield by 30 and 37%, and 100-grain weight by 33 and 39% in the year 2021 and 2022, respectively. As compared with mono-cropping, at this optimal N rate, the respective increase (of maize's crop N yield indices) for 2021 and 2022 were 53 and 64% for grain N yield, and 53 and 68% for residue N yield. Moreover, intercropping at N1 resulted in higher grain N content by 28 and 31%, residue N content by 18 and 22%, and total N uptake by 65 and 75% in 2021 and 2022, respectively. The values for the land equivalent ratio for nitrogen yield (LERN) were greater than 1 in intercropping, indicating better utilization of N under the intercropping over mono-cropping. Similarly, intercropping increased the N assimilatory enzymes of maize crops such as nitrate reductase (NR) activity by 19 and 25%, nitrite reductase (NiR) activity by 20 and 23%, and glutamate synthase activity (GOGAT) by 23 and 27% in 2021 and 2022, respectively. Consequently, such increases resulted in improved nitrogen use efficiency indices such as N use efficiency (NUE), partial factor nitrogen use efficiency (PFNUE), nitrogen uptake efficiency (NUpE), and nitrogen agronomic efficiency (NAE) under intercropping than mono-cropping. Thus, this suggests that maize-soybean intercropping under optimal N fertilization can improve the nitrogen status and nitrogen use efficiency of maize crops by regulating the nitrogen assimilatory enzymes, thereby enhancing its growth and yield. Therefore, prioritizing intercropping over an intensive mono-cropping system could be a better option for sustainable agricultural production.

Enhanced fruit yield and quality of tomato by photosynthetic bacteria and CO2 enrichment under reduced irrigation

Reduced irrigation generally induces the tomato fruit yield reduction but enhance the fruit quality. Elevated CO2 (eCO2) injection is a common technique for alleviating water stress while eCO2 could inevitably lead to the element concentration dilution in the plant organs. Inoculated with photosynthetic bacteria (PSB) are confirmed to form a symbiotic relationship with crop roots, thereby promoting root development, and improving crop root nutrient and water uptake capacity. Yet, it remains unknown whether PSB could mitigate the adversely effect of nutrient dilution under eCO2 condition and the yield decline under reduced irrigation. To investigate that, two water treatments, including reduced irrigation (RI, plants were irrigated to 75% field water capacity) and full irrigation (FI, plants were irrigated to 90% field water capacity) of tomato plants, were grown under normal ambient CO2 (aCO2, 400 ppm) and elevated CO2 (eCO2, 800 ppm) conditions, respectively. And photosynthetic bacteria were inoculated in half plants. The results showed that inoculation of PSB improved the effectiveness of CO2 stimulation on biomass and yield in tomato plants grown under reduced irrigation conditions. The stimulation effects have been associated with increased advantages linked to their root system, we have observed that CO2 and PSB inoculation promoted the root development and antioxidant abilities. These consequently increased nitrogen uptake efficiency under eCO2 and reduced irrigation conditions, and increased nitrogen accumulation in various organs. Furthermore, eCO2 and inoculation with PSB individually or in combination ameliorated yield penalties under reduced irrigation conditions. Combined elevated CO2 and inoculation with PSB resulted in the highest fruit quality. Collectively, the responses of tomato fruit yield and quality to water-reduced irrigation regimes are further enhanced by the combination of eCO2 and PSB inoculation, and this would be efficacious in greenhouse tomato cultivation and future agriculture production.

Unraveling Genomic Regions Controlling Root Traits as a Function of Nitrogen Availability in the MAGIC Wheat Population WM-800.

An ever-growing world population demands to be fed in the future and environmental protection and climate change need to be taken into account. An important factor here is nitrogen uptake efficiency (NUpE), which is influenced by the root system (the interface between plant and soil). To understand the natural variation of root system architecture (RSA) as a function of nitrogen (N) availability, a subset of the multiparent advanced generation intercross (MAGIC) winter wheat population WM-800 was phenotyped under two contrasting N treatments in a high-throughput phenotyping system at the seedling stage. Fourteen root and shoot traits were measured. Subsequently, these traits were genetically analyzed using 13,060 polymorphic haplotypes and SNPs in a genome-wide association study (GWAS). In total, 64 quantitative trait loci (QTL) were detected; 60 of them were N treatment specific. Candidate genes for the detected QTL included NRT1.1 and genes involved in stress signaling under N-, whereas candidate genes under N+ were more associated with general growth, such as mei2 and TaWOX11b. This finding may indicate (i) a disparity of the genetic control of root development under low and high N supply and, furthermore, (ii) the need for an N specific selection of genes and genotypes in breeding new wheat cultivars with improved NUpE.

Aerated drip irrigation improves water and nitrogen uptake efficiencies of tomato roots with associated changes in the antioxidant system

• After aerated drip irrigation, soil oxygen content significantly increased. • The duration and sequence of aeration changed the root antioxidant system. • The root antioxidant system correlated root morphology of tomato. • Root antioxidant systems and growth affect water and nitrogen uptake efficiency of tomato. China has the largest area of vegetable cultivation in greenhouse vegetable system in the world. However, the excessive application of irrigation and fertilizers has caused soil degradation and hardening, even leading to injury and yield loss in vegetable. Increasing soil aeration oxygen can improve crop water and nutrient uptake efficiencies. However, its effects on crop antioxidant systems are less known. Due to the sensitivity of the antioxidant system to changes in soil oxygen content, it is expected that aerated drip irrigation (ADI) delivering microbubble water to the crop rhizosphere will alter root antioxidant enzyme activities, malondialdehyde (MDA) content, and osmotic regulators in tomato plants. We conducted pot experiments under eight irrigation regimes: five aerated durations (0%, 25%, 50%, 75%, and 100%) of the subsurface drip irrigation period aerated (CK, A 25% , A 50% , A 75% , and A), with two aerated sequences (L: subsurface drip irrigation follow by aerated drip irrigation, F: aerated drip irrigation follow by subsurface drip irrigation) for the A 25% , A 50% and A 75% treatments. All treatments with ADI had an average of 7.63% higher oxygen concentration (OC) than the CK treatment at 74 d after transplanting. The principal component analysis revealed that MDA of all treatments had the greatest effect on the antioxidant system, while aerated drip irrigation reduced MDA content. Increasing aeration duration from A 25% to A 75% significantly affected antioxidant enzyme activities and root growth parameters, and the L treatment had higher values than the F treatment. The L -A 75% treatment had the highest water use efficiency, nitrogen uptake efficiency, and yield. The structural equation model demonstrated that ADI indirectly promotes tomato water and nitrogen uptake efficiencies by affecting the antioxidant system and root growth.

Effects of irrigation and nitrogen application on NO3--N distribution in soil, nitrogen absorption, utilization and translocation by winter wheat

Irrigation and nitrogen application can not only increase wheat yield, but also cause nitrogen loss and soil nitrate accumulation. This study aimed to assess the effects of irrigation amount and nitrogen application rate on the soil NO3--N distribution and nitrogen absorption and utilization of winter wheat (Triticum aestivum L.) during the 2015–2020 growth season in the North China Plain. The experiments were designed in split plot arrangement, with irrigation amount (W0, no irrigation; W1, 60 mm irrigation at jointing; and W2, 60 mm irrigation at jointing and anthesis) as the main plots and nitrogen application rate (N0, 0; N120, 120 kg ha−1; and N240, 240 kg ha−1) as the subplots. The plants under W2N120 and W2N240 showed no significant difference in yield throughout the experimental period. With the decrease in soil total nitrogen content, the yield difference between the plants under N0 and those under N120 and N240 gradually increased throughout the experimental period. Compared with that of the plants under W2N240, the mean NO3--N content of the plants under W2N120 in the 0–1 m and 1–2 m soil layers decreased by 17.4% and 19.2%, respectively, in 2018–2020. The NO3--N concentration decreased with increasing soil depth, and the NO3--N concentration in each soil layer increased with increasing nitrogen application rate. Irrigation and nitrogen application increased nitrogen accumulation in vegetative organs at anthesis and nitrogen transport to grains. Compared with those of the plants under W2N240, the mean nitrogen uptake efficiency, nitrogen use efficiency, nitrogen fertilizer productivity, and nitrogen harvest index of the plants under W2N120 increased by 91.3%, 2.6%, 95.5%, and 1.9%, respectively. These results suggest that applying 120 kg ha−1 nitrogen and irrigating 60 mm at jointing and anthesis are the optimal measures for winter wheat in the North China Plain.

Multi-omics analysis reveals the mechanism of bHLH130 responding to low-nitrogen stress of apple rootstock.

Nitrogen is critical for plant growth and development. With the increase of nitrogen fertilizer application, nitrogen use efficiency decreases, resulting in wasted resources. In apple (Malus domestica) rootstocks, the potential molecular mechanism for improving nitrogen uptake efficiency to alleviate low-nitrogen stress remains unclear. We utilized multi-omics approaches to investigate the mechanism of nitrogen uptake in two apple rootstocks with different responses to nitrogen stress, Malus hupehensis and Malus sieversii. Under low-nitrogen stress, Malus sieversii showed higher efficiency in nitrogen uptake. Multi-omics analysis revealed substantial differences in the expression of genes involved in flavonoid and lignin synthesis pathways between the two materials, which were related to the corresponding metabolites. We discovered that basic helix-loop-helix 130 (bHLH130) transcription factor was highly negatively associated with the flavonoid biosynthetic pathway. bHLH130 may directly bind to the chalcone synthase gene (CHS) promoter and inhibit its expression. Overexpressing CHS increased flavonoid accumulation and nitrogen uptake. Inhibiting bHLH130 increased flavonoid biosynthesis while decreasing lignin accumulation, thus improving nitrogen uptake efficiency. These findings revealed the molecular mechanism by which bHLH130 regulates flavonoid and lignin biosyntheses in apple rootstocks under low-nitrogen stress.

Straw incorporation and nitrogen reduction effect on the uptake and use efficiency of nitrogen as well as soil CO2 emission of relay strip intercropped soybean.

Intercropping can increase crop N uptake and reduce carbon emissions. However, the effects of straw incorporation and N reduction on N use and carbon emissions in intercropping are still unclear. We explored the mechanism of N uptake, N use efficiency, and CO2 emissions in the wheat-maize-soybean relay strip intercropping system. A two-year field experiment was conducted with two straw managements, i.e., wheat straw incorporation (SI) and straw removal (SR), and four N application levels of soybean, i.e., 60 (N60), 30 (N30), 15 (N15), and 0 kg N ha-1 (N0). We assessed soil properties, CO2 emissions, and characteristics of roots, nodules, and aboveground N uptake of intercropped soybean. Results showed that geometry mean diameter of aggregate, soil porosity, soil total N, and soil urease activity were notably greater in SI than in SR. N input reduced from N60 to N30 did not significantly affect the soil total N content and urease activity in SI. The root length, root surface area, root volume, root biomass, root bleeding intensity, and inorganic N content of bleeding sap were greater in SI than in SR. In the SI, although the root length and surface area peaked at N60, the root biomass and inorganic N content of bleeding sap were insignificant between N60 and N30. The nodule number, nodule dry weight, nodule nitrogenase activity, and nodule nitrogen fixation potential in SI were notably increased compared with SR. The nodule nitrogen fixation potential in SI notably increased with the decrease of N input at the R3 stage, but it peaked in N30 at the R5 stage. On average, the aboveground N uptake and nitrogen recovery efficiency (RE) was notably higher by 43.7% and 76.8% in SI than in SR. SI+N30 achieved the greatest aboveground N uptake and RE. The CO2 emission and accumulated CO2 emission were notably greater in SI than in SR, and the accumulated CO2 emission of SI was the lowest with N30 input. In conclusion, SI+N30 promoted N uptake and utilization efficiency with reduced CO2 emissions during the soybean cropping season. It provides a potential strategy for sustainable agricultural development in intercropping systems.

Improving Nitrogen Availability and Ananas comosus L. Merr var. Moris Productivity in a Tropical Peat Soil Using Clinoptilolite Zeolite

Pineapple cultivation in nitrogen deficient and acidic peat soils leads to poor growth, yield, and fruit quality of pineapples. A study was conducted to determine whether clinoptilolite zeolite (CZ) could improve soil nitrogen availability, growth, yield, and fruit quality of pineapples grown in drained peat soils. Laboratory leaching experiments were conducted to determine the effectiveness of CZ in controlling nitrogen loss from peat soils, whereas an ion-exchange resin method was used to determine nitrogen availability in pineapple cultivation. Treatments evaluated were: (i) different amounts of CZ (25, 50, 70, and 100%) + NPK fertilizer, (ii) NPK fertilizer, and (iii) peat soil only. The peat soils with CZ reduced ammonium and nitrate losses because of the sorption of ammonium within the lattices of the CZ via ion exchange. Co-application of CZ (25%) and NPK fertilizers was more effective in increasing soil ammonium availability, whereas the use of CZ (25% to 100%) improved nitrogen uptake and use efficiency, growth, yield, and fruit quality of pineapple because CZ could regulate the availability of nitrogen ions for pineapple uptake. The buffering capacity of CZ increased soil pH and facilitated organic nitrogen mineralization. The co-application of CZ and NPK fertilizers can be used to improve nitrogen availability and pineapple productivity in tropical peat soils.

Interactive effects of solar radiation and inorganic nutrients on biofiltration, biomass production, photosynthetic activity and the accumulation of bioactive compounds in Gracilaria cornea (Rhodophyta)

Interactive effects of solar radiation and inorganic nitrogen and phosphate on biofiltration capacity, biomass production, photosynthetic activity and the accumulation of bio-active compounds were studied in the red alga Gracilaria cornea grown in tanks with a seawater open-flow system during 35 days. Two light conditions were utilized: outdoor (O), full solar natural radiation, and indoor, inside of a greenhouse (G) where UV-B radiation was cut-off and part of the UV-A radiation was filtered. Two inorganic nitrogen and phosphate concentrations were used: High nutrients (HN; 100–200μM of NH4+ and 20μM of KHPO4) and Low nutrients (LN; 10–20μM of NH4+ and 1μM of KHPO4). Growth and biomass productivity were related to the daily integrated electron transport rate determined in situ, as an estimator of daily photosynthetic activity. Nitrogen uptake efficiency (NUE) was close to 100 % under LN, whereas under HN it ranged from 50 to 70 % in the first week of culture, decreasing to 10–15 % in the rest of the experimental period. Nitrogen uptake rate (NUR) ranged from 20 to 45 mmol N m−2 h−1 under HN, and 5 to 18 mmol N m−2 h−1 in LN treatments. Morphological and pigmentation changes were evident through the culture period. The thalli under HN were more reddish under the indoor treatments, than that in LN. The internal compounds increased throughout the experimental period. Mycosporine-like amino acids (MAAs) were accumulated under HN. N plays a photoprotective role due to both the increased photosynthesis and the MAA content. Maximal MAA productivity reached 113–253 mg MAAs m−2 d−1 under the O-HN treatment, the highest level reported until now in the bibliography. G. cornea could be used for bioremediation of high N content waters. In addition, under full solar radiation and high N availability produce high levels of bioactive compounds as MAAs, polyphenols and biliproteins for cosmeceutical applications.

Kinetic parameters related to nitrogen uptake in 'Okinawa' peach rootstocks are altered by 'Chimarrita' scion Nitrogen uptake in 'Okinawa' peach rootstock.

The kinetic parameters of peach rootstock are a major factor contributing to its nitrogen (N) uptake efficiency, which directly affects the yield and quality parameters. However, the impact of grafting on N kinetic parameters is not sufficiently known as rootstocks are grafted with other scion cultivars before being transplanted to the field. The objective of this study was therefore to evaluate whether the grafting of 'Okinawa' rootstock with the scion cultivar 'Chimarrita' can alter the kinetic parameters related to N uptake. The plants were acclimatized in Hoagland solution for 21 days and, sequentially, were tested to assess the depletion of the internal reserves at 15 and 30 days in CaSO4 solution. Morphological and physiological parameters were evaluated, and kinetic parameters were calculated. The depletion period for to reach the minimum concentration (Cmin ) of NO3 - and NH4 + in the plant was 62 h and 56 h, respectively. The optimal time for internal reserve depletion for 'Okinawa' rootstock with and without the 'Chimarrita' scion was 30 days. 'Okinawa' rootstock grafted with 'Chimarrita' scion cultivar was more efficient in NO3 - and NH4 + uptake. © 2022 Society of Chemical Industry.

Comparative Evaluation of Mineral and Organo-Mineral Nitrogen Fertilization and the Role of Amino Acids as Plant Growth Promoters in Maize Cultivation

The challenge to increase nitrogen uptake efficiency in intensively cultivated soils without runoffs and atmospheric release has been difficult to handle and usually leads to the excess application of mineral fertilizers. In the present study, four combinations of two different N fertilizers and a control were used in maize cultivation to evaluate the use of different types of N fertilization in the case of agronomic and plant physiology characteristics, as well as the quantity and quality characteristics of maize’s yield. The results show that, when the full rate of mineral fertilization with the addition of half rate of organo-mineral fertilizer with amino acids (MF+OMAA/2) was used, maize presented a 16% yield increase in comparison with the control, followed by mineral fertilization (MF) with a 10% increase. Protein content was increased in all treatments by 3–6% compared to the control, with the conventional fertilization and the alternates with lower rates of mineral fertilization not differing significantly. The nitrogen content in the leaves of maize increased in both measurements (11–23% and 19–40% at 70 and 107 days after sowing, respectively) of the different fertilizer treatments compared to the control. The results of this study confirm that the organo-mineral fertilizer containing amino acids can be used as an alternative or additive N fertilization that can decrease the use of conventional mineral fertilizers or can result in improved seed productivity and protein content in maize farms.

Yield Productivity and Nitrogen Uptake of Wheat Crop Are Highly Dependent on Irrigation Water Availability and Quality under Water-Limited Conditions

ABSTRACT The water scarcity can limit yield productivity of wheat, and this issue can be controlled using various management practices. The main objectives of this study were: 1) to investigate how N application rates and water quality affect the yield productivity, and plant growth characterization and nitrogen uptake of wheat crop under water-limited conditions; 2) to describe the relationships between nitrogen application rates and yields of wheat plants at low-quality water application times; 3) to predict the efficiencies of applied N fertilizers at different rates and water use efficiency. Field experiments on wheat crop were conducted for two consecutive growing seasons (2016–2017) at a private farm at Abis-Alexandria. The experimental design was split-plot design with three replicates. The main plot was nitrogen application rates (0, 75, 150, and 225 kg N ha−1) in the form of urea fertilizer (46% N). The sub-main plot was low-quality water application (LQW) (0%, 25%, 50%, and 75% from applied water requirements of wheat crop) co-applied with high-quality water (HQW). The obtained results indicated that the application of nitrogen fertilization with different rates significantly increased the economical and biological yields, grain/biological-nitrogen use efficiency, agronomic efficiency, nitrogen uptake, and water use efficiency for both grain and biological yields in the two seasons of cultivations. Moreover, the yield attributes such as spike length, number of plants and tillers were also significantly affected by N fertilization. Application of LQW at 25% and 50% co-applied with 75% and 50% HQW did not significantly decrease the yield and yield attributes of wheat in both seasons of cultivations. In contrast, the application of LQW at 75% co-applied with 25% HQW was significantly decreased the studied parameters. In conclusion, the best application ratio of LQW and HQW was 1:1 at 50% of LQW co-applied with 50% HQW at which the yield and its attributes of wheat did not significantly reduced.

Determining Irrigation Volumes for Enhancing Profit and N Uptake Efficiency of Potato Using WASH_2D Model

Soaring food prices and the intensified scarcity of water resources put a new emphasis on efficient use of water in irrigation. Numerical models for water flow and crop growth can be used to predict crop water stress and make decisions on irrigation management. To this end, a new irrigation scheme was presented to determine the optimum irrigation depths using WASH_2D, a numerical model of water flow and solute transport in soils and crop growth. By using freely available quantitative weather forecasts and volumetric water price as input data to predict soil water flow and give the recommendation of irrigation depths which maximizes net income during each irrigation interval. Field experiments using potato were conducted for two-seasons in a sandy soil in Japan under three irrigation methods, i.e., using the simulation model named treatment “S” (to distinguish, named S1 in first season and S2 in second season), automatic irrigation method using soil moisture sensors named treatment “A”, and refilling irrigation management supplying 100% consumed water named treatment “R”. To compare S with other two treatments, S1 and A was conducted in the first season, then S2 and R was conducted in the second season. Results showed that S1 improved potato yield by 19%, and reduced water by 28%, resulting in an increased net income by 19% compared with A in the first season. There was no significant difference when compared with R in the second season, which was mainly due to the frequent rainfall during second growing season. In addition, S improved the nitrogen uptake efficiency (NUPE) by 39% and 11% compared with A and R, respectively. The simulated values of water content were in fair agreement with those measured in the root zone. In short, simulated irrigation method was effective in improving yield, saving water and increasing NUPE of potato compared with automatic and refilling irrigation methods in sandy field.

Contribution of arbuscular mycorrhizal fungi to nitrogen and phosphorus uptake efficiency and productivity of faba bean crop on contrasting cropping systems

The present study was focused on evaluating the effect of AMF (Arbuscular Mycorrhizal Fungi) inoculation on nitrogen and phosphorus uptake efficiency and productivity of faba bean (Vicia faba L.) crop, under different fertilization levels on organic or conventional cropping systems. The 2-year field experiment was conducted in central Greece and laid out in a split-plot design, with three replications, two main plots (AMF inoculation treatments) and five sub-plots (fertilization treatments). The results demonstrated that plants of AMF inoculated plots exhibited greater plant height, leaf area index (LAI), leading to higher biomass, and consequently higher final seed yields. Regarding the quality parameters, including nutrients (nitrogen and phosphorus) uptake and their utilization indices, similar results to those of the productivity results were found with the AMF inoculated plants presented the higher values. Finally, all the parameters of the root system, including AMF root colonization and weighted mycorrhizal dependency (WMD), were negatively affected by fertilization level, particularly in an inorganic form. As a conclusion, the current study confirmed that replacement of inorganic inputs by organic in combination with AMF inoculation, should be seriously considered as a sustainable practice of faba bean crop cultivation under Mediterranean conditions.

Critical nitrogen dilution curve and dry matter production parameters for several Mediterranean vegetables

• Twelve typical Mediterranean vegetables were studied. • The average and critical nitrogen dilution curve coefficients were obtained. • The dry/fresh matter ratios and harvest indexes were also obtained. • There were no differences between the average and critical dilution curves. • Differences of dry matter yield did not affect any of the parameters. Inadequate nitrogen fertilizing practices lead to low nitrogen uptake efficiency (NUE), which increases water NO 3 − pollution, as well as N 2 O emissions to the atmosphere. In order to increase the NUE and decrease the N losses as NO 3 − and N 2 O from the soil-plant system, accurate data about optimum crop N concentrations and dry matter production throughout the growing season are still needed for many vegetables typically grown under Mediterranean climate. For this reason, several N fertilization trials were set up for globe artichoke, carrot, cauliflower, chard, chinese cabbage, early potato, leek, lettuce, onion, red cabbage, romanesco, and spinach, under the semiarid Mediterranean conditions of the Valencian Community (Eastern Spain) during several years. The fresh and dry matter weight ( W ), as well as the nitrogen concentration in the dry matter (% N ) in both the marketable and non-marketable crop parts, was measured between 3 and 7 times throughout their respective growing seasons. The a and b coefficients of the average N dilution curve (% N = a W − b ), for which all % N and W data were used, and the critical N dilution curve (% N c = a W c − b ), for which only the minimun % N for maximum W data were used if available, in addition to the dry/fresh yield matter ratio ( DM ) and the harvest index ( HI ), were calculated for all these crops. No significant differences were observed between the average and critical N dilution curve coefficients in this work. Interestingly, the coefficients of both N dilution curves differed from the ones found in the literature with the exception of those obtained for similar cultivars, e.g., early potatoes, and under similar climatic conditions, i.e., Mediterranean. Besides, there were neither differences of DM and HI among the several N fertilization treatments. Therefore, due to the absence of changes in the N dilution curve and dry matter production coefficients for the different N supplies, all these parameters were estimated on the basis of the whole dataset, i.e., regardless of the N input. The use of the critical nitrogen dilution curve coefficients and dry matter production parameters presented in this work should contribute to better fit the N fertilizer additions to N demands of these vegetables under Mediterranean conditions, mainly, by their use through simulation models. Therefore, the NUE in horticulture should increase and the N losses as NO 3 − to inland and sea waters in these environments, and as N 2 O to the atmosphere should decrease.

Effects of Trichoderma on nitrogen absorption and use efficiency in Lycium chinense roots under saline stress

To clarify the mechanisms underlying the improvement of Trichoderma on Chinese wolfberry (Lycium chinense) growth under saline stress, we analyzed the effects of application of organic fertilizer, Trichoderma agent and fertilizer on nitrogen uptake, assimilation, accumulation and use efficiency in Chinese wolfberry, based on a pot experiment with coastal saline soil. The organic fertilizer was the sterilization substance of Trichoderma fertilizer without viable Trichoderma, without any difference in the content of nutrients (such as nitrogen, phosphorus and potassium) between them. The results showed that the application of organic fertilizer, Trichoderma agent and ferti-lizer significantly increased NO3- and NH4+ influx rate in meristematic zone and NO3- influx rate in maturation zone of roots. The magnitude of such enhancement was greater in the application with Trichoderma fertilizer than organic fertilizer. Compared with the control, the application of Trichoderma agent and fertilizer significantly increased root, stem and leaf biomass and nitrogen content as well as plant nitrogen accumulation, strengthened root and leaf nitrate reductase, nitrite reductase and glutamine synthetase activities, and elevated nitrogen uptake efficiency, photosynthetic rate, stable carbon isotope abundance and photosynthetic nitrogen use efficiency. For all those variables, the beneficial effect was obviously stronger in the application with Trichoderma fertilizer than organic fertilizer. Therefore, Trichoderma facilitated nitrogen uptake, assimilation and accumulation in Chinese wolfberry under saline stress, improved photosynthetic carbon fixation ability and nitrogen use efficiency, and ultimately promoted plant growth.

Residual Effect of Finely-Ground Biochar Inoculated with Bio-Fertilization Impact on Productivity in a Lentil–Maize Cropping System

Biochar fertilization improves soil fertility and carbon sequestration, implying agricultural and environmental advantages. The effect of different sized previously applied biochar and biofertilizer agents on succeeding crops remains poorly known for legume–cereal cropping cycles. This study compared different particle-sized biochar and biofertilizer strains applied to lentils for their residual impact on subsequent maize growth, nutrition, and soil fertility without further polluting the environment. Three particle sizes (<2, 2–5, 5–10 mm) of Babul tree (Acacia arabica) wood biochar was obtained through grinding and sieving and applied prior to the lentil (first) crop at a rate of 500 g m−2. The commercial Rhizobium leguminosarum products Biozote-N and Rhizogold were inoculated to lentil seeds before sowing. The effect of biochar and biofertilizer agents on the succeeding maize (second) crops was evaluated for soil and crop performance. Findings revealed that particle sizes of <2 mm biochar and Biozote-N inoculation enhanced plant height, leaf area and leaf area index, biological yield, and thousand grain weight of the subsequent maize crop. Maize grain yield was enhanced by 2.5%, tissue N uptake by 15%, nitrogen uptake efficiency by 17%, grain protein content by 15%, extractable P by 17%, and soil bulk density by 3% with a residual biochar particle size of <2 mm and Biozote-N inoculation. It was concluded that the finely grounded (<2 mm) biochar particle combined with inoculation of Biozote-N was superior to larger particle sizes for enhancing crop growth and improving soil fertility status at the residual level, benefiting the subsequent crop in a legume–cereal rotation system.

Crop Yield and Nutrient Efficiency under Organic Manure Substitution Fertilizer in a Double Cropping System: A 6-Year Field Experiment on an Anthrosol

The combination of organic manure and inorganic fertilizer plays a role in increasing crop yield and nutrient efficiency, but such effectiveness varies with crop, soil, management, and climate. Here, a 6-year field experiment was conducted to evaluate the effects of substituting organic manure with inorganic fertilizer on crop yield, grain protein content, and nitrogen and phosphorus efficiency under a winter wheat-summer maize cropping system on Anthrosol. Five treatments were included: recommended nitrogen (N), phosphorus (P) and potassium (K) fertilizers (NPK), 75% NPK + 25% organic manure (M), 50% NPK + 50% M, 25% NPK + 75% M, and 100% M, respectively. Wheat, maize, and annual yield were 1643–8438 kg ha−1, 4847–11,104 kg ha−1, and 10,007–17,496 kg ha−1. Organic manure treatments produced the same crop yield as NPK treatment except for 100% M. Grain protein content of wheat and maize was 7.9–15.1% and 5.6–12.6%. Organic manure treatments yielded significantly lower wheat grain protein content but had no significant effect on maize grain protein content relative to NPK treatment. Nitrogen uptake efficiency and nitrogen use efficiency at the cropping system level were 0.67–1.16 and 35.7–60.5 kg kg−1. Phosphorus uptake efficiency and phosphorus use efficiency were 0.28–0.75 and 167–531 kg kg−1. Compared with NPK treatment, 50% M, 75% M, and 100% M improved nitrogen use efficiency but decreased nitrogen uptake efficiency and phosphorus efficiencies. Annual N and P budgets were −1.3–79.1 kg ha−1 a−1 and 25.6–100.1 kg ha−1a−1, and both increased with the increase in organic manure input. Based on crop yield, grain protein content, nitrogen, and phosphorus efficiency and their budget, substitution of 25% inorganic fertilizer with organic manure is the rational combination under the winter wheat–summer maize system on an Anthrosol.

EFECTOS DE LAS FUENTES NITROGENADAS EN LA MORFOFISIOLOGÍA, PRODUCCIÓN Y CALIDAD DE CACAO (Theobroma cacao L.) CCN-51 EN EL SUR DE LA AMAZONIA ECUATORIANA

<p><strong>Background</strong>. In the new global economy, cocoa is an important crop. However, far too little attention has been paid to the nutritional aspects. On the other hand, nitrogen is the most important nutrient in crop production, and mineral nitrogen fertilizers are the most widely used by farmers. Improving the efficiency of nitrogen uptake and utilization could potentially increase crop yields and quality, as well as reduce nitrogen fertilization and environmental pollution. <strong>Objective.</strong> Therefore, the objective of this study was to evaluate the effect of three nitrogen sources on morphological characteristics, yield and quality of CCN-51 cocoa, and soil chemical characteristics in the Ecuadorian Amazon. <strong>Methodology.</strong> A randomized design was established with 4 treatments with the same N dose, but varying the source (amide: urea, calcium nitrate, NC, and ammonium sulfate, SA), plus a control without N application. The investigated variables are soil chemical characteristics, shoot growth, fruit morphology, seed chemical characteristics, production and yield estimates, and agronomic efficiency of the sources. <strong>Results.</strong> NC maintained soil pH at 5.29 points compared to SA and urea, which acidified at a higher rate (4.32 and 3.96), leading to an increase of N and a decrease Ca in the soil. SA increased the fat content in the cocoa seed (54.1 %), with a higher number of fruits per plant (16.7) and, therefore, a better yield (0.799 t/ha). <strong>Implications.</strong> These results provide basic information on the nitrogen source effects and cocoa nutrition to be considered for future research. <strong>Conclusion.</strong> The findings suggested that NC conserves soil pH better than the other sources. SA increases production and fat content, so it can be considered the most efficient. </p>