Increased Nitrogen Levels Research Articles

Effects of water salinity and nitrogen fertilization on the growth and yield of ‘BRS Gabriela’ castor beans

The castor bean has attracted the attention of many farmers as an alternative crop for the National Program of Biofuel and its extensive use in the ricinochemical industry. The crop requires large planting areas to meet the demands of the fuel market. The aim of the present study was to evaluate the effects of irrigation water salinity and nitrogen fertilization on the growth and production of castor beans, ‘BRS Gabriela’, in a protected environment. The present study was conducted at the Center of Technology and Natural Resources of the Federal University of Campina Grande. The experimental design was completely randomized in a 5 × 4 factorial with three replications and one plant per plot. The treatments consisted of irrigation water with five electrical conductivity (ECw) levels of 0.7, 1.7, 2.7, 3.7, and 4.7 dS m-1 associated with four nitrogen levels of 60, 80, 100, and 120 mg of N kg-1 of soil. The interaction between water salinity and nitrogen rates did not exert significant effects on the variables studied. Increased salinity of irrigation water affected the growth in height and stem diameter of castor beans in all periods, and leaf area from 90 days after sowing. Increased nitrogen levels had a positive effect on leaf area at 60, 90, 120, and 150 days after sowing. The total mass of seeds, one hundred seed mass, yield, and number of fruits per plant decreased with the increase in water salinity, and the total mass of seeds was the most affected variable.

Effects of nitrogen level on structure and physicochemical properties of rice starch

Nitrogen application is an important agronomic measure affecting rice growth, yield and grain quality. This study investigated physicochemical properties and the structure of two rice varieties under three different nitrogen levels (0, 150 and 300 kg/ha) at one location in one year. The increasing nitrogen level decreased starch granule size. The granule surface at high nitrogen level was more uneven and pitting compared with non and medium nitrogen level. The apparent amylose content decreased with increasing nitrogen level. The starch samples of all nitrogen levels were in conformity with the characteristics of A-type crystallinity. High relative crystallinity was observed at the high nitrogen level. Starch had lower degree of order at short-rang scale with increasing nitrogen level. Starch samples at the high nitrogen level had higher swelling power and solubility, gelatinization enthalpy, lower pasting properties, gelatinization temperature. This study indicated that nitrogen level significantly affected the structure and physicochemical properties of rice starch, and would provide some information for applications of starch in food and non-food industries.

Productivity and Economics of Hybrid Maize ( Zea mays L.) under different Fertilizer Doses in the Inner T erai Region of Nepal

Maize ( Zea mays L.) v arieties differ in their response to nutrient supply . Optimum fertilizer dose is necessary to explore the yield potential of a v ariety . A field experiment w as conducted at Rampur , Chitw an, during winter season of 2012/13 and 2013/14 to study the productivity of hybrid maize RML-32 X RML-17 to different lev el of nitrogen, phosphorus and potash. T reatment factors -1 -1 included tw o lev els of potash (40 and 60 kg K O ha ) and phosphorus (60 and 90 kg P O ha ) and 2 2 5 -1 -2 -1 four lev els of nitrogen (120, 160, 200 and 240 kg N ha ). Number of ears m , kernel rows ear , kernels -1 -1 row , grain and stov er yield ha w ere increased with increased nitrogen lev els. Increased phosphorus doses significantly decreased days to 50% tasselling and silking. Soil analysis results indicated that increased N and P doses had increased av ailable N, P and soil organic matter , but -1 -1 decreased soil pH. The highest mean grain yield of 9.35 t ha w as obtained when 200 kg N ha -1 -1 applied with 60:40 P O :K O kg ha . Application of 200:60:40 kg N: P O K O ha gav e the highest net 2 5 2 2 5 : 2 -1 returns of Rs 1,34,696 ha with the highest benefit cost ratio of 1.9. Farmers of Chitw an are -1 suggested to apply 200:60:40 N:P O :K O kg ha for grain production of hybrid maize RML-32 × RML-17

Effects of Applied Nitrogen Amounts on the Functional Components of Mulberry (Morus alba L.) Leaves.

This study investigated the effects of applied nitrogen amounts on specific functional components in mulberry (Morus alba L.) leaves. The relationships between mineral elements and the functional components in mulberry leaves were examined using mulberry trees cultivated in different soil conditions in four cultured fields. Then, the relationships between the nitrogen levels and the leaf functional components were studied by culturing mulberry in plastic pots and experimental fields. In the common cultured fields, total nitrogen was negatively correlated with the chlorogenic acid content (R(2) = -0.48) and positively correlated with the 1-deoxynojirimycin content (R(2) = 0.60). Additionally, differences in nitrogen fertilizer application levels affected each functional component in mulberry leaves. For instance, with increased nitrogen levels, the chlorogenic acid and flavonol contents significantly decreased, but the 1-deoxynojirimycin content significantly increased. Selection of the optimal nitrogen application level is necessary to obtain the desired functional components from mulberry leaves.

Aqueous suspensions of carbon black with ethylenediamine and polyacrylamide-modified surfaces: Applications for chemically enhanced oil recovery

Enhanced oil recovery (EOR) technologies mitigate the demand for new reservoirs and are pathways for more efficient uses of non-renewable hydrocarbons. Hydrolyzed polyacrylamide (HPAM) has been used as a thickening agent in aqueous media for EOR. However, HPAM shows low salt and temperature tolerances. Carbon black (CB) is a nanoparticle that exhibits chemical and thermal stability but poor dispersability in polar solvents. In this work, CB surfaces were sequentially modified with ethylenediamine (EDA) and acrylamide (AM) to fabricate CB-EDA-AM particles. These particles had increased nitrogen levels from 0.33% at the CB to 7.19% in the CB-EDA-AM, and the formation of amine and amide groups were identified by XPS analyses. TEM and AFM images suggest the formation of oligomers on the CB-EDA-AM surfaces, which was confirmed by the presence of a glass transition temperature at 114 °C in the DSC curve. For the first time, we report that in harsh salinity and elevated temperature conditions, 5 ppm of surface-modified CB nanoparticles can enhance the rheological stability of HPAM aqueous fluids. A shear stress test performed in brine medium indicated the modified CB particles have showed a maximum gain of 29% in stability at high shear rates compared with neat polymeric solutions.

Change in the bryophyte diversity and species composition of Central European temperate broad-leaved forests since the late nineteenth century

The diversity and species composition of the bryophyte flora colonizing the forest floor, live trees and deadwood in semi-natural broad-leaved forests of northern Germany was compared between a recent survey in 2013 and historical records from around 1900. The survey was based on the comparison of presence/absence data and their interpretation with help of ecological indicator values. Total species richness has declined in bryophytes growing on the forest floor but not in the other guilds, whereas a dramatic species turnover was found for all three guilds. This turnover was apparently primarily driven by the increased atmospheric load of reactive nitrogen from anthropogenic emissions. Sensitive species were replaced by more eutrophication-tolerant bryophytes; liverworts are overrepresented among the sensitive and thus declining species. Promotion of the competitive strength of vascular plants due to increased nitrogen levels is the likely cause of the reduction of bryophyte species richness on the forest floor. Former acidification by high atmospheric sulfur dioxide loads has left an imprint in the bryophyte vegetation by having favored acidophytic species and discriminating against basiphytic species. An increase in the mean indicator value for temperature suggests a beginning effect of climate warming on the bryophyte vegetation. Change in forest structure had an apparently smaller imprint on the bryophyte diversity of the studied semi-natural forests than atmospheric chemistry and climate. In this respect, bryophytes differ from the ecologically similar lichens, where published studies from the same region showed a dramatic decline of species richness and a stronger susceptibility to forest management.

Long‐term influence of sod cutting depth on the restoration of degraded wet heaths

AbstractTemperate heaths have an unfavorable conservation status in most European biogeographical regions. Increasing nitrogen levels promote competitive grass species such asMolinia caerulea, which is a main threat to heathland conservation in Europe. This article investigates the long‐term influence of sod cutting and the resulting changes in soil properties on the heath composition, integrity, and structure. In 15 nature reserves across the northern half of Belgium, we used (1) a large number of plots (203); (2) a broad range of sod cut depths (2–40 cm), and (3) a temporal dimension that describes how long the effects of sod cutting persist (census up to 19 years after sod cutting). Multivariate analyses were used in order to explore the influence of sod cut depth and time after sod cutting on the soil and vegetation properties. There was a positive relationship between sod cut depth and soilpHand water level, and a negative relationship with Al3+,NH4+, and total organic matter (TOM). However, only a limited number of typical (target) species appeared after sod cutting, and then only weakly. Most of the time they remained a minor component of the restored vegetation. Moreover,M. caeruleareappeared and its cover significantly increased during the years following sod cutting. Although we were able to show that sod cut depth has a differential effect on soil properties and vegetation recovery, it also appeared that sod cutting does not restore wet heaths in the long term when applied in regions with high nitrogen deposition.

Methane emissions from sheep grazing pearl millet (Penissetum americanum (L.) Leeke) swards fertilized with increasing nitrogen levels

This study aimed at quantifying methane emissions from sheep grazing pearl millet swards (Penissetum americanum (L.) Leeke) as affected by nitrogen (N) fertilization doses (50, 100, 200 and 400kgNha−1). The experimental period was 70days of pasture use, from February to April 2011. The grazing method was continuous stocking with variable stocking rate, so pasture structure was intended to be similar (30cm sward height) among treatments. Thirty six tester animals aging 5 months and initially weighing 20±1.6kg were used for evaluations. Intake (OMI) was estimated by their relationship with N content on faeces. The sulfur hexafluoride (SF6) technique was used for two sampling periods of five consecutive days each to quantify daily methane (CH4) production. Parameters related to sward structure was not affected by N fertilization, but herbage accumulation increased linearly (P<0.05). Greater (P<0.05) stocking rate, weight gain per area and CP content were observed with higher fertilization levels. N doses did not affect (P>0.05) OMI, and methane emissions expressed as a ratio of OMI. Results indicated that increasing nitrogen doses decrease methane emissions per animal. When expressed as grams of methane per kilogram of organic matter ingested or energy converted into methane, no difference was observed. However, emissions per unit area increase as a consequence of higher stocking rates allowed by the increase in forage production. Sheep emitted 16.3g of methane per kg of ingested organic matter and converted 5.1% of ingested gross energy into methane.

Can mussels be used as sentinel organisms for characterization of pollution in urban water systems?

Abstract. Urbanization strongly impacts aquatic ecosystems by decreasing water quality and altering water cycles. Today, much effort is put towards the restoration and conservation of urban waterbodies to enhance ecosystem service provision, leading to liveable and sustainable cities. To enable a sustainable management of waterbodies, the quantification of the temporal and spatial variability of pollution levels and biogeochemical processes is essential. Stable isotopes have widely been used to identify sources of pollution in ecosystems. For example, increased nitrogen levels in waterbodies are often accompanied with a higher nitrogen stable isotope signature (δ15N), which can then be detected in higher trophic levels such as mussels. The main aim of this study was to assess the suitability of nitrogen stable isotopes as measured in mussels (Mytilus edulis), as an indicator able to resolve spatial and temporal variability of nitrogen pollution in an urban, tidally influenced estuary (Swan River estuary in Western Australia). Nitrogen concentrations were generally low and nitrogen stable isotope values of nitrate throughout the estuary were well within natural values of uncontaminated groundwater, organic nitrate from soils, or marine-derived sources, indicating groundwater inflow rather than pollution by human activity was responsible for differences between sites. The δ15N signature in mussels was very stable over time within each site which indicated that mussels can be used as time-integrated sentinel organisms in urban systems. In addition, our study shows that the nature of the relationship between δ15N in the mussels and the nitrate in the water can provide insights into site-specific biogeochemical transformation of nutrients. We suggest that mussels and other sentinel organisms can become a robust tool for the detection and characterization of the dynamics of a number of emerging anthropogenic pollutants of concern in urban water systems.

Modeling nitrous oxide emission from rivers: a global assessment.

Estimates of global riverine nitrous oxide (N2 O) emissions contain great uncertainty. We conducted a meta-analysis incorporating 169 observations from published literature to estimate global riverine N2 O emission rates and emission factors. Riverine N2 O flux was significantly correlated with NH4 , NO3 and DIN (NH4 +NO3 ) concentrations, loads and yields. The emission factors EF(a) (i.e., the ratio of N2 O emission rate and DIN load) and EF(b) (i.e., the ratio of N2 O and DIN concentrations) values were comparable and showed negative correlations with nitrogen concentration, load and yield and water discharge, but positive correlations with the dissolved organic carbon:DIN ratio. After individually evaluating 82 potential regression models based on EF(a) or EF(b) for global, temperate zone and subtropical zone datasets, a power function of DIN yield multiplied by watershed area was determined to provide the best fit between modeled and observed riverine N2 O emission rates (EF(a): R2 =0.92 for both global and climatic zone models, n=70; EF(b): R2 =0.91 for global model and R2 =0.90 for climatic zone models, n=70). Using recent estimates of DIN loads for 6400 rivers, models estimated global riverine N2 O emission rates of 29.6-35.3 (mean=32.2) Gg N2 O-Nyr-1 and emission factors of 0.16-0.19% (mean=0.17%). Global riverine N2 O emission rates are forecasted to increase by 35%, 25%, 18% and 3% in 2050 compared to the 2000s under the Millennium Ecosystem Assessment's Global Orchestration, Order from Strength, Technogarden, and Adapting Mosaic scenarios, respectively. Previous studies may overestimate global riverine N2 O emission rates (300-2100 Gg N2 O-Nyr-1 ) because they ignore declining emission factor values with increasing nitrogen levels and channel size, as well as neglect differences in emission factors corresponding to different nitrogen forms. Riverine N2 O emission estimates will be further enhanced through refining emission factor estimates, extending measurements longitudinally along entire river networks and improving estimates of global riverine nitrogen loads.

Combining no-tillage, rice straw mulch and nitrogen fertilizer application to increase the soil carbon balance of upland rice field in northern Benin

Agricultural management practices are frequently non conservative and can lead to substantial loss of soil organic carbon and soil fertility, but for many regions in Africa the knowledge is very limited. To study the effect of local agricultural practices on soil organic carbon content and to explore effective ways to increase soil carbon storage, field experiments were conducted on an upland rice soil (Lixisol) in northern Benin in West Africa. The treatments comprised two tillage systems (no-tillage, and manual tillage), two rice straw managements (no rice straw, and rice straw mulch at 3 Mgha⿿1) and three nitrogen fertilizer levels (no nitrogen, 60kgha⿿1, 120kgha⿿1). Phosphorus and potassium fertilizers were applied to be non-limiting at 40kg P2O5ha⿿1 and 40kgK2Oha⿿1 per cropping season. Heterotrophic respiration was higher in manual tillage than no-tillage, and higher in mulched than in non-mulched treatments. Under the current management practices (manual tillage, with no residue and no nitrogen fertilization) in upland rice fields in northern Benin, the carbon added as aboveground biomass and root biomass was not enough to compensate for the loss of carbon from organic matter decomposition, rendering the upland rice fields as net sources of atmospheric CO2. With no-tillage, 3Mgha⿿1 of rice straw mulch and 60kgNha⿿1, the soil carbon balance was approximately zero. With no other changes in management practices, an increase in nitrogen level from 60kgNha⿿1 to 120kgNha⿿1 resulted in a positive soil carbon balance. Considering the high cost of inorganic nitrogen fertilizer and the potential risk of soil and air pollution often associated with intensive fertilizer use, implementation of no-tillage combined with application of 3 Mg ha⿿1 of rice straw mulch and 60kgNha⿿1 could be recommended to the smallholder farmers to compensate for the loss of carbon from organic matter decomposition in upland rice fields in northern Benin.

Optimized Potential of Utilization Efficiency and Productivity in Wheat by Integrated Chemical Nitrogen Fertilization and Stimulative Compounds

Abstract Foliar sprays application is an important crop management strategy, which could help to maximize yield and other beneficial substances. Therefore, a field experiment was conducted at Kafrelsheikh University research farm, Egypt, to study the effect of stimulating compounds (control, salicylic acid and ascobien) and nitrogen levels (0, 57.5, 115, 172.5 and 230 kg N ha-1) on yield and nitrogen utilization efficiency of wheat. Results indicated that spraying of ascobien and increasing nitrogen level had significant effect on yield traits. Interaction between stimulating compounds and nitrogen were achieved progressive increases in all yield traits, furthermore, the magnitude of increments was much more pronounced in response to salicylic acid and control treatments in both seasons. It was observed no statistically significant difference between 172.5 and 230 kg N ha-1 in both seasons. A significant interactive effect were observed on grain N uptake, whole plant N uptake, nitrogen harvest index (NHI), nitrogen utilization efficiency (NUtE) and nitrogen use efficiency (NUE) by using foliar spraying combined with N fertilizer. Grain N uptake and whole plant N uptake were closely correlated with nitrogen under stimulating compounds, whereas ascobien with 172.5 kg N ha-1 was more effective than salicylic acid in both seasons. Interestingly, foliar spraying of ascobien and N level of 172.5 kg ha-1 was the optimal and could be a useful to improve the efficiency of N-fertilizer and it can be saved 57.5 kg N ha-1. Consequently, could be the key to reduce the need for chemical fertilizers and decrease the cost of production.

Response of red pepper to deficit irrigation and nitrogen fertigation

ABSTRACTThe main objective of this investigation was to evaluate the response of red pepper grown in a subhumid climate to different irrigation and nitrogen levels. Open-field trials were conducted in the Marmara Region, Turkey. Plants were subjected to three water levels [full irrigation (FI) = 100% crop evapotranspiration (ETc) and two deficit irrigations (DIs)= 66 and 33% ETc restoration] and four levels of N (0, 80, 160, and 240 kg N ha−1) during the 2012, 2013, and 2014 growing seasons. A split-plot experimental design was used. The highest values of biomass and marketable yield (MY) were observed under FI. DI significantly increased the fruit soluble solids content. The biomass yield, MY, and fruit weight significantly improved with increasing nitrogen levels. The 240 kg N ha−1 treatment under FI provided the maximum net income. Increasing N supply under DI conditions enhanced the water-use efficiency based on both biomass yield and MY. These results indicate that with respect to the yield, the net income, and the water productivity of red pepper, the FI with a nitrogen supply of 160–240 kg ha−1 is recommended for drip irrigated and N-fertigated red pepper under subhumid climate conditions.

Impact of nitrogen nutrition on productivity and nutrient use efficiency of potato (Solanum tuberosum L.) In an inceptisol of west Bengal, India

The experiment was carried out at the District Seed Farm, Adisaptagram, Hooghly (West Bengal), India during two consecutive winter seasons of 2011-12 and 2012-13 to find out optimum N dose of potato cultivars for getting higher yield as well as to identity efficient potato cultivars regarding N use. Average yield of potato cultivars increased significantly with increase in N supply up to 225 kg N ha-1, then tended to decrease slightly as nitrogen levels increased further. Tuber yield of cultivars Kufri Shailja and Kufri Jyoti was increased significantly with increase in nitrogen level up to 225 kg N ha-1 and further addition of N decreased yield. Yield of Kufri Himalini was increased with increase in N level up to 300 kg N ha-1 but the yield increment from 225 kg N ha-1 to 300 kg N ha-1 was not significant. Application of less N decreased average potato tuber yield by 5.3, 18.7 and 65.1% with 150, 75 and 0 kg N ha-1 respectively, compared to 225 kg N ha-1. Nitrogen use efficiency (NUE) decreased towards higher N levels for all cultivars. NUE of Kufri Himalini was higher at all N levels. The results revealed that irrespective of cultivar 225 kg N ha-1 was the optimum for getting higher tuber yield of potato and cultivar Kufri Himalini was the most efficient in case of N use.SAARC J. Agri., 13(2): 141-150 (2015)

Growth and Production of Crambe Submitted to Doses of Nitrogen and Potassium

The dependence on non-renewable fuels of countries around the world increased the interest for the gradual replacement of fossil fuels with renewable ones. Thus, several development programs for the use of renewable sources for power generation have been created and, in this perspective, biofuels have been highlighted. Crambe is an alternative crop for the production of biodiesel due to its rusticity, precocity, high oil content and adaptability to different climates. Optimum management practices of fertilizer use in crambe cultivation are little known and there are no specific recommendations for its fertilization. Therefore, the objective of this research was to study the effects of mineral fertilizers concerning the nitrogen and potassium elements in the growth and production of crambe. The experiment was installed in a greenhouse, with a completely randomized design. Nitrogen doses used were 30, 60, 90 and 120 kg·ha-1and 50, 75, 100 to 125 kg·ha-1 for potassium. The increase in production was directly proportional to the increase in nitrogen levels. The potassium doses did not cause significant effect on the growth of crambe.

Effect of different spacing and fertilizer levels on growth and yield of different varieties of desi cotton

A field experiment was carried out at Bathinda during kharif, 2013 to evaluate two varieties of cotton planted at 3 different spacing and given 3 different level of fertilizer doses. The maximum plant height, monopodial and sympodial branches/plant of desi cotton were recorded with LD-949, alongwith maximum bolls/plant, boll weight and seed cotton yield. The planting of desi-cotton crop at 67.5× 60 cm resulted in significantly more number of sympodial branches/plant as compared to 67.5 × 30 cm and 67.5 × 45 cm. The maximum bolls/plant of desi cotton were recorded with spacing of 67.5 × 60 cm which was significantly more than 67.5 × 30 cm and at par with 67.5× 45 cm. Planting desi cotton crop at 67.5× 60 cm resulted in more boll weight and seed cotton yield which was at par to 67.5× 30 cm and 67.5× 45 cm. All growth parameters increased with increase in nitrogen level from 75 to 125% of recommended dose of fertilizer (RDF). LD-949 is a superior variety than FDK 124 when planted at 67.5 x 60 cm spacing and with 25% higher fertilizer doses than the RDF levels of NP and K fertilizers.

Emission estimation of nitrous oxide (N2O) from a wheat cropping system under varying tillage practices and different levels of nitrogen fertiliser

Nitrous oxide is a greenhouse gas with high global warming potential emitted from agricultural sources. The effects of tillage practices and different levels of N fertiliser on seasonal fluxes of N2O were investigated in a field planted with the wheat variety Sonalika. The experiment was conducted during 2012–13 and 2013–14 under conventional tillage (CT) and reduced tillage (RT) farming systems in combination with four different levels of nitrogen fertiliser (i.e. zero nitrogen (F1), 60kgNha–1 (F2), 80kgNha–1 (F3) and 100kgNha–1 (F4)). Both tillage practices and fertiliser significantly (P&lt;0.01) affected seasonal cumulative N2O emissions and wheat yield. However, there was no significant difference in N2O emissions between RTF1 and CTF1 (zero nitrogen). Compared with RT, N2O emission decreased under the CT practice by 2.49%, 10.11%, 7.9% and 27.46% in CTF1, CTF2, CTF3 and CTF4 respectively. Highest and lowest seasonal cumulative fluxes were recorded in RTF4 (N 100kgha–1) and CTF1 (N 0kgha–1) respectively. During the wheat-growing period, nitrogen use efficiency decreased with increasing nitrogen levels and treatment with 60 kg-Nha–1 in the CT practice (CTF2) was found to be effective in increasing nitrogen use efficiency and decreasing yield-scaled N2O emissions.

Response of Potato ( Solanum tuberosum L.) Yield and Yield Components to Nitrogen Fertilizer and Planting Density at Haramaya, Eastern Ethiopia

To investigate the effect of nitrogen fertilizer and planting density on yield and yield components of potato crop (Bubu variety), a field experiment was carried out in Haramaya, Eastern Ethiopia during the rainy season of 2012. The experiment was a 4 x 5 factorial combination and a randomized complete block design with 3 replicates. Treatments included quantity of nitrogen fertilizer (0, 110, 165 and 220 kg N/ha) and planting density (4.17 plant m-2 (80 cm x 30 cm), 4.44 plant m-2 (75 cm x 30 cm), 5.56 plant m-2 (60 cm x 30 cm), 6.67 plant m-2 (60 cm x 25 cm) and 8 plant m-2 (50 cm x 25 cm)). Increasing nitrogen level up to110 kg N/ha lead to more tuber yield, highest stem number, plant height, total dry biomass, total tuber number, large-sized tuber yield (59.01%) and marketable tuber yield. The highest foliar N concentration was recorded at 165 kg N/ha. Increasing planting density resulted in higher tuber yield; total tuber number, total dry biomass yield (%), marketable tuber yield and small-sized tuber yield (16.92%). Highest foliar N concentration was found at the lower planting densities of 4.17 and 4.44 plant m-2. Yield of tuber per hectare was significantly and positively correlated with leaf area index, total tuber number, days to physiological maturity and total dry biomass yield. In conclusion, results of the experiment revealed that 110 kg N/ha and planting density of 6.67 plant m-2 resulted in optimum total (35.50 and 35.66 t/ha, respectively) and marketable tuber yields of the Bubu variety in Haramaya, Eastern Ethiopia during the rainy season.

Effects of different nitrogen sources and levels on tomato fruit quality

The use of nitrogen fertilizers contributes significantly to the proper growth and development of tomato plants, with significant gains in the production of fruit. However, incorrect use of nitrogen can change tomato fruit quality, making it undesirable for consumers. The aim of this work was to study the effect of different sources and levels of nitrogen on tomato quality to improve N management. The field experiment was conducted at the State University of Southwest Bahia - Vitoria da Conquista, Bahia, Brazil. The experimental design was a randomized block with 4 replicates, with three nitrogen sources (calcium nitrate, ammonium sulfate and urea) and four levels of nitrogen (0, 140, 280 and 420 kg ha-1) in a 3×4 factorial. Fruit from the experimental treatments were evaluated for the following characteristics: firmness, pulp pH, titrate able acidity of the juice, ascorbic acid, soluble solids and the ratio of these. Increased levels of nitrogen negatively influenced the levels of ascorbic acid and titrate able acidity. The values of soluble solids and pH did not change with increasing nitrogen level, showing different effects in the sources used only. Due to effects several of different nitrogen sources on fruit quality characteristics, fertilization practices using nitrate and ammonium are recommended in order to improve quality.

Effect of Drought Stress and Nitrogen Fertilizer on Yield and Its Components of Two Wheat Cultivars (Triticum aestivum L.)

Two field experiments were carried out at the Agricultural Experimental Farm of Faculty of Agriculture;Suez Canal University; Ismailia Governorate, Egypt during the two winter seasons (2012/13 and 2013/14). To studyeffect of three irrigation regimes (full irrigation; skipping irrigation at tillering stage or heading stage), three rates ofnitrogen fertilization (50, 75 and 100 kg N/fed) and two wheat cultivars (Sakha 94 and Sids12) and their interactions onyield and yield attributes. The experimental farm is located at Longitude 30o58 and Latitude at 32o23 at height of 13meters above sea level. The texture of experimental site was sandy soil. Split–split plot design with three replicationswas followed. The results showed that skipping irrigation at tillering or heading stage significantly reduction for studiedtraits: plant height, no. of grains/spike, grain weight/plant, 1000 grain weight, grain yield, straw yield, and biologicalyield during seasons with comparison to full irrigation regime. Crude protein content in wheat grains was significantlyincreased by skipping irrigation than of full irrigation treatment. Increasing nitrogen level up to 100 kg significantlyincreased all parameters except harvest index. Sakha 94 cultivar surpassed significantly Sids 12 cultivar in all studiedparameters. Calculations of water stress susceptibility index (S) shown that both wheat cultivars are sensitive to droughtstress conditions.