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Search Results: 1 - 10 of 6428 matches for " nitrogen uptake "
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Processes Governing the Retention of Phosphorus and Nitrogen in Nyashishi Wetland  [PDF]
Baraka C. Sekadende, John F. Machiwa, Fredrick F. Mwanuzi
Open Journal of Ecology (OJE) , 2014, DOI: 10.4236/oje.2014.43014
Abstract:

One of the important functions of the wetland is the retention of catchment nutrients and improving lacustrine water quality. This study analyzed how much nutrients were retained in the Nyashishi wetland, southern part of Lake Victoria, and went further to analyze the processes which were responsible in the reduction of nutrients. Three major processes were analysed in this study, namely nutrients uptake by three macrophyte species (Eichhornia crassipes, Cyperus papyrus and Typha domingensis) dominating the Nyashishi wetland, nitrification and denitrification processes. The study demonstrated high nutrients retention especially phosphorus nutrients of which up to 98% were retained. In some occasions, particularly for nitrogen nutrients, there was 0% retention especially during wet season. In some other instances, the inflow exceeded the outflow meaning that, more nutrients were generated by the wetland itself. Among the three processes analyzed, nutrients uptaken by macrophytes were more efficient in reducing nutrients in wetland water. Biological nitrification and denitrification which are believed to be the major pathway for ammonia removal in both natural and constructed wetlands were less important in this study. Among the macrophyte species, Eichhornia crassipes demonstrated higher uptake rate than the other two species possibly due to its high turnover rate. This ability can be exploited in removing excess nutrients from runoff by frequent harvesting of the mature plants.

Yield and uptake of bahiagrass under flooded environment as affected by nitrogen fertilization  [PDF]
Gilbert C. Sigua, Mimi M. Williams, Chad C. Chase, Jr., Joseph Albano, Manoch Kongchum
Agricultural Sciences (AS) , 2012, DOI: 10.4236/as.2012.34058
Abstract: Bahiagrass (Paspalum notatum) is one of the most important forage grasses in subtropical region of USA and other tropical regions of the world. Although tolerant to short term flooding, bahiagrass is classified as a facultative upland (FACU+) species that suggest yield and plant persistence might be reduced under periods of extended waterlogging. The objective of this greenhouse study (2008-2009) was to determine the effect of nitrogen fertilization (0, 100, and 200 kg·N·ha–1) on yield (DMY), crude protein content (CPC), and nitrogen uptake (NUP) of bahiagrass under varying flooded conditions (0, 14, 28, 56, and 84 days). Results disclosed an overwhelming effect of N application on yield and uptake component of bahiagrass. Averaged across flooding duration, results showed that DMY (R2 = 0.91**), CPC (R2= 0.96**), and NUP (R2 = 0.99**) were linearly related to increasing levels of N fertilization. Plants without N fertilization that were submerged between 14 to 84 days had significantly lower amount of DMY when compared with plants that were fertilized with 100 or 200 kg·N·ha–1. Comparable DMY and NUP were obtained between plants fertilized with 200 kg·N·ha–1) at 0 day of flooding (11.7 ± 5.0 ton·ha–1) and plants fertilized with 200 kg·N·ha–1 at 84 days of flooding (9.8 ± 2.7 ton·ha–1). The practical implication of this study is that waterlogging may hamper yield and uptake while nitrogen fertilization could improve yield and uptake of bahiagrass under waterlogged condition.
Uptake Nitrogen as Affected by Various Combinations of Nitrogen and Phosphorus
Johar Ali,Jehan Bakht,Mohammad Shafi,Sherin Khan
Asian Journal of Plant Sciences , 2002,
Abstract: An experiment to study the uptake of nitrogen by maize as affected by various combinations of nitrogen and phosphorus was conducted at Malakandher Research Farms, NWFP. Agricultural University Peshawar, Pakistan during 1997. Nitrogen and phosphorus had a significant effect on grain yield, nitrogen uptake at tasseling, maturity and in grain while non-significant effect of N and P was recorded for harvest index. Plots treated with NP combination of 150:90 kg ha -1 produced maximum grain yield while fertilizer combination of 150:120 NP kg ha -1 resulted in maximum nitrogen uptake at tesseling, maturity and in grain.
Nitrate reductase and glutamine synthetase activities in S1 endogamic families of the maize populations Sol da Manh? NF and Catet?o
MACHADO, ALTAIR TOLEDO;SODEK, LADASLAV;PATERNIANI, ERNESTO;FERNANDES, M?NLIO SILVESTRE;
Revista Brasileira de Fisiologia Vegetal , 2001, DOI: 10.1590/S0103-31312001000100010
Abstract: the possibility of improving nitrogen use efficiency in maize was investigated using s1 endogamic families of the populations sol da manh? nf and catet?o. a simple 10 x 10 lattice design was adopted and the trials carried out at the experimental field of mitla agrícola ltda, in uberlandia, state of minas gerais, during the 1994/95 planting season. based on grain production figures, the three best and three worst performing s1 endogamic families were selected for this study. these were pooled to form four sub-populations denominated nfb, nfr (the best and worst families, respectively, of the sol da manh? nf variety), catb and catr (the best and worst families, respectively, of the catet?o variety). each of these sub-populations was evaluated under greenhouse conditions. the experimental design was factorial with treatments arranged in randomized blocks. sample replicates consisted of pots with four plants. feeding with modified hoagland?s nutrient solution began on the seventh day after sowing. the study involved four nitrogen regimes, where varying proportions of no3- and nh4+ were formulated, such that the nutrient solution contained the following mixtures: 75% no3- : 25% nh4+; 25% no3- : 75% nh4+; 50% no3- : 50% nh4+ (all high n mixtures) and 5% no3- : 5% nh4+ (low n mixture). twenty-five days after planting, the activities of the enzymes nitrate reductase and glutamine synthetase (transferase and synthetase assays) were determined for the leaves using the third topmost expanded leaf of the four plants in each pot. the data show that glutamine synthetase (transferase assay) and nitrate reductase activities were efficient in discriminating the s1 endogamic families and could therefore be useful biochemical parameters in breeding programs seeking nitrogen use efficiency.
Nitrate reductase and glutamine synthetase activities in S1 endogamic families of the maize populations Sol da Manh NF and Catet o
MACHADO ALTAIR TOLEDO,SODEK LADASLAV,PATERNIANI ERNESTO,FERNANDES M?NLIO SILVESTRE
Revista Brasileira de Fisiologia Vegetal , 2001,
Abstract: The possibility of improving nitrogen use efficiency in maize was investigated using S1 endogamic families of the populations Sol da Manh NF and Catet o. A simple 10 X 10 lattice design was adopted and the trials carried out at the experimental field of MITLA AGRíCOLA LTDA, in Uberlandia, State of Minas Gerais, during the 1994/95 planting season. Based on grain production figures, the three best and three worst performing S1 endogamic families were selected for this study. These were pooled to form four sub-populations denominated NFB, NFR (the best and worst families, respectively, of the Sol da Manh NF variety), CATB and CATR (the best and worst families, respectively, of the Catet o variety). Each of these sub-populations was evaluated under greenhouse conditions. The experimental design was factorial with treatments arranged in randomized blocks. Sample replicates consisted of pots with four plants. Feeding with modified Hoagland's nutrient solution began on the seventh day after sowing. The study involved four nitrogen regimes, where varying proportions of NO3- and NH4+ were formulated, such that the nutrient solution contained the following mixtures: 75% NO3- : 25% NH4+; 25% NO3- : 75% NH4+; 50% NO3- : 50% NH4+ (all high N mixtures) and 5% NO3- : 5% NH4+ (low N mixture). Twenty-five days after planting, the activities of the enzymes nitrate reductase and glutamine synthetase (transferase and synthetase assays) were determined for the leaves using the third topmost expanded leaf of the four plants in each pot. The data show that glutamine synthetase (transferase assay) and nitrate reductase activities were efficient in discriminating the S1 endogamic families and could therefore be useful biochemical parameters in breeding programs seeking nitrogen use efficiency.
Genotypic Differences in Nitrogen Uptake and Utilization of Wet and Dry Season Rice as Influenced by Nitrogen Rate and Application Schedule
B.C. Roy,D.E. Leihner,T.H. Hilger,N. Steinmueller
Pakistan Journal of Biological Sciences , 2004,
Abstract: Nitrogen accumulation, uptake and use efficiency of wet and dry season varieties were determined from field experiments conducted in 1996 to 1998 at the Bangladesh Rice Research Institute (BRRI) in Gazipur, Bangladesh. Four rice varieties were tested, Nsail and BR31 were planted in the wet season (WS) and HB6 and BR29 were planted in the dry season (DS). Nsail and HB6 are local, whereas BR31 and BR29 are modern varieties. The experiments were laid out in a two-factorial randomized complete block design with four replications. The two factors were nitrogen rate and its application schedule. Four N rates-0, 50, 100 and 150 kg N ha 1 were given. The rates of 50, 100 and 150 kg N ha 1 were given in three application schedules-two, three and four splits. Transplanting was done on the first week of August and first week of January for the WS and DS, respectively. Nitrogen uptake differed greatly among the varieties and nitrogen rates. The increase of total N uptake with N rate was almost linear for the modern varieties, whereas the traditional varieties showed a quadratic relationship between total N uptake and N level. Effect of N split application on N uptake was small, but the difference among the split applications were more pronounced when higher amont of N was applied. Genotypic difference in grain and straw N concentration of all the varieties was observed and increased with each increment of N fertilizer. Averaged across treatments and years, the highest grain N concentration was observed in BR31 and the lowest in BR29. The straw N concentration at different N rates were more pronounced in the wet season varieties, especially Nsail, which had the lowest straw N concentration when no N was applied but showed highest straw N concentration when 150 kg N ha 1 was applied. The agronomic fertilizer efficiency and the apparent N recovery percentage varied greatly among the varieties and decreased with higher N rates. The agronomic efficiency of the DS varieties was higher compared to the WS varieties. Across the years, the N recovery percentage of the tested varieties at different N rates and application schedules ranged from 20 to 40% for Nsail, 24 to 43% for BR31, 29 to 40% for HB6 and 35 to 51% for BR29.
The Effects of Stabilized Urea and Split-Applied Nitrogen on Sunflower Yield and Oil Content  [PDF]
Christopher J. Graham, Jac J. Varco
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.88125
Abstract: Sunflower is an efficient nitrogen (N) accumulator due to its aggressive taproot and extensive root system. While N rate studies in sunflower have shown a yield response, the response is often highly variable and difficult to predict in many instances. Additionally, since most sunflower production is intended for the oil market, surplus nitrogen tends to decrease oil content. Therefore, it is critical to hone nitrogen rates to maximize both yield and oil production and to incorporate alternative approaches to fertilizer application, which includes timing and method of application. The objective of the present study was to assess the efficacy of a split-application of N at either the V4 or R1 growth stage to increase yield and/or oil content in sunflower. A second objective was to examine whether a urease inhibitor could be used to retain soil N longer and achieve a similar effect as a split-application. Studies were conducted at two locations over two growing seasons in South Dakota, USA. A target rate of 90 kg·ha-1 was applied as urea-ammonium nitrate (UAN) either as an at-planting application or split-applied. Overall, N additions did significantly increase yield over a control. On average, the urease inhibitor tended to increase grain yields over split-applying N at either growth stage, however, there was no statistical effect on either grain yield or oil content. Based on 15N analysis, approximately 27% of the N in the grain was derived from the UAN fertilizer, which indicates a relatively large reliance upon soil N for grain N content. The addition of a urease inhibitor significantly increased average fertilizer uptake by nearly 6% to 32.7%.
Combined Inoculation of Pseudomonas fluorescens and Trichoderma harzianum for Enhancing Plant Growth of Vanilla (Vanilla planifolia)
A.R. Sandheep,A.K. Asok,M.S. Jisha
Pakistan Journal of Biological Sciences , 2013,
Abstract: This study was conducted to evaluate the plant growth promoting efficiency of combined inoculation of rhizobacteria on Vanilla plants. Based on the in vitro performance of indigenous Trichoderma spp. and Pseudomonas spp., four effective antagonists were selected and screened under greenhouse experiment for their growth enhancement potential. The maximum percentage of growth enhancement were observed in the combination of Trichoderma harzianum with Pseudomonas fluorescens treatment followed by Pseudomonas fluorescens, Trichoderma harzianum, Pseudomonas putida and Trichoderma virens, respectively in decreasing order. Combined inoculation of Trichoderma harzianum and Pseudomonas fluorescens registered the maximum length of vine (82.88 cm), highest number of leaves (26.67/plant), recorded the highest fresh weight of shoots (61.54 g plant-1), fresh weight of roots (4.46 g plant-1) and dry weight of shoot (4.56 g plant-1) where as the highest dry weight of roots (2.0806 g plant-1) were achieved with treatments of Pseudomonas fluorescens. Among the inoculated strains, combined inoculation of Trichoderma harzianum and Pseudomonas fluorescens recorded the maximum nitrogen uptake (61.28 mg plant-1) followed by the combined inoculation of Trichoderma harzianum (std) and Pseudomonas fluorescens (std) (55.03 mg plant-1) and the highest phosphorus uptake (38.80 mg plant-1) was recorded in dual inoculation of Trichoderma harzianum and Pseudomonas fluorescens.
Variation in Root Water and Nitrogen Uptake and their Interactive Effects on Growth and Yield of Spring Wheat and Barley Genotypes
Jamal Y. Ayad,Ayed M. Al-Abdallat,Hani M. Saoub
International Journal of Botany , 2010,
Abstract: The study was conducted to investigate the effects of water and nitrogen on growth and to identify root traits that improve crop water and nitrogen uptake of wheat and barley genotypes at the Faculty of Agriculture Research Station, University of Jordan, Amman, during 2007. Two barley genotypes (Hordeum vulgare L., Vars Rum and ACSAD 176) and two wheat genotypes (Triticum turgidum L. var. durum, vars. Hourani and Om Qaise were subjected to two water treatments (rain-fed and rain-fed plus supplementary irrigation) and three nitrogen levels of 0, 50 and 100 kg N ha-1. Barley produced higher above ground dry matter and Green Area Index (GAI) and leaf area ratio than wheat at anthesis stage. Root Length Density (RLD) was affected by genotype and nitrogen at depths from 0-80 cm. The effect of irrigation on root characteristics was only at depths below 20 cm where rainfed treatments produced higher RLD and root weight as compared to irrigation treatments. Results also showed an exponential decrease in RLD of various genotypes with soil depth. Barley vars had higher root weight and RLD than wheat vars especially at soil depths of 0-40 cm. Positive relationship between RLD and water and nitrogen used by wheat and barley plants was observed. Root water capture rate was higher for barley under irrigation by 4.5 folds as compared to rain-fed. On the other hand, stronger association between RLD and nitrogen uptake were observed for wheat genotypes under both rainfed and under irrigation as compared to barley.
Fertilización con n, p, k y s, y curvas de absorción de nutrimentos en arroz var. Cfx 18 en Guanacaste
Molina,Eloy; Rodríguez,José Hernán;
Agronomía Costarricense , 2012,
Abstract: an experiment of fertilization with n, p, k and s on rice (cv. cfx 18) was evaluated under flooded conditions in a eutric inceptisol in guanacaste; also, the absorption curve of macro and micronutrients during the growing season was determined. the treatments were 0, 80, 120 and 160 kg.ha-1 of n; 0, 40 and 80 kg.ha-1 of p2o5; 0 and 50 kg.ha-1 of k2o, and 0 and 20 kg.ha-1 of s, for a total of 8 treatments with 4 replicates, in a randomized complete block design. foliar analysis was performed at pre-flowering, and the yield of dry and clean grain was determined at harvest. in the treatment of 120 kg.ha-1 of n, 40 kg.ha-1 of p2o5, 50 kg.ha-1 of k2o, and 20 kg.ha-1 of s, 5 whole-plant samples were taken at 28, 43, 66, 79 and 93 days after germination, for dry weight determination and chemical analysis of nutrients and for development of the absorption curves as a function of plant age. there was a significant response in yield to n, p, k and s. the treatment of 120 kg.ha1 of n, 40 kg.ha-1 of p2o5, 50 kg.ha-1 of k2o, and 20 kg.ha-1 of s presented the highest grain yield, in a soil that had an adequate content of p and k, but low in s. these same treatments brought about the higher foliar contents of n and p and were significantly different from treatments with no n and no p. the nutrient absorption curve was directly related to biomass production. most of the absorption of nutrients occurred during the reproductive and ripening stages. the maximum absorption of n, p, k, ca, mg and s was 61, 25, 197, 17, 11 and 9 kg.ha-1 , respectively
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