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Na + efflux by combined-N sources in Azolla pinnata-Anabaena azollae symbiotic association (communicated). Stewart, W. D. P., Fitzgerald, G. P., Burris, R. H. (1968) Acetylene reduction by nitrogen-fixing blue

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Cereal Research Communications
Authors: S. Pampana, A. Masoni, L. Ercoli, M. Mariotti, and I. Arduini

Optimum nitrogen fertilizer management for wheat production is important for maximum economic yield and minimum pollution of the environment. A lysimetric trial was conducted in Central Italy during 2008–2009 and 2009–2010 on durum wheat varieties Latinur and Svevo to evaluate effects of ammonium sulphate and Entec 46 at sowing, of ammonium sulphate and urea at topdressing and of three split applications (0–90–90, 30–75–75 and 60–60–60 kg N ha−1) of the same amount of nitrogen on grain yield and yield components, N uptake and N leaching. Grain yield was higher in Latinur than in Svevo. The highest production was achieved in 2009 with the 60–60–60 splitting, and in 2010 with 0–90–90. In both years, the highest total N uptake was recorded with the 30–75–75 splitting, regardless of N source. Nitrogen leaching increased with the increasing amount of N rate at sowing. Amount of N-NO3 lost by leaching during wheat cycle was 25 kg ha−1, almost entirely accounted for N leaching in the period November–January.

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Nitrogen (N) is an important nutrient for plant growth and yield production, and rice grown in paddy soil mainly uses ammonium (NH4 +) as its N source. Previous studies have shown that N status is tightly connected to plant defense; however, the roles of NH4 + uptake and assimilation in rice sheath blight disease response have not been studied previously. Here, we analyzed the effects of different N sources on plant defense against Rhizoctonia solani. The results indicated that rice plants grown in N-free conditions had higher resistance to sheath blight than those grown under N conditions. In greater detail, rice plants cultured with glutamine as the sole N source were more susceptible to sheath blight disease compared to the groups using NH4 + and nitrate (NO3 ) as sole N sources. N deficiency severely inhibited plant growth; therefore, ammonium transporter 1;2 overexpressors (AMT1;2 OXs) were generated to test their growth and defense ability under low N conditions. AMT1;2 OXs increased N use efficiency and exhibited less susceptible symptoms to R. solani and highly induced the expression of PBZ1 compared to the wild-type controls upon infection of R. solani. Furthermore, the glutamine synthetase 1;1 (GS1;1) mutant (gs1;1) was more susceptible to R. solani infection than the wild-type control, and the genetic combination of AMT1;2 OX and gs1;1 revealed that AMT1;2 OX was less susceptible to R. solani and required GS1;1 activity. In addition, cellular NH4 + content was higher in AMT1;2 OX and gs1;1 plants, indicating that NH4 + was not directly controlling plant defense. In conclusion, the present study showed that the activation of NH4 + uptake and assimilation were required for rice resistance against sheath blight disease.

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Winery wastewater treatment plants generally face severe nutrient deficiency, and therefore conventional technologies and supplementary nutrient dosing strategies may fail. The purpose of the paper is to show how traditional way of dosing N-source for marginal availability to nutrient deficient influents results in poorly settling activated sludge regardless of the application of aerated or non-aerated selectors. External N-source calculated for marginal availability resulted in nutrient deficiency due to the relatively high yield experienced (0.7 g biomass COD/g substrate COD). In the fully aerated system with overall N-deficiency, rapidly increasing overproduction of extracellular polysaccharide was experienced, leading to SVI (Sludge Volume Index) values up to 600 cm3 g−1. In the system with the non-aerated selector, initial nutrient deficiency could only be detected in the second reactor. Since neither overgrowth of floc-forming GAOs (Glycogen Accumulating Organisms) nor denitrification could be experienced, the non-aerated reactor operated as low-DO (Dissolved Oxygen) basin, attributing to the drastic overgrowth of filamentous bacteria leading to SVI values >1000 cm3 g−1. Since dosing external N-source for marginal availability is likely to cause severe biomass separability problems in activated sludge winery wastewater treatment, either pronounced N-overdosing and pre-denitrification or severe nutrient deficiency and GAO cultivation can rather be recommended.

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In deserts, biological processes decrease at the end of the vegetation period by lack of soil moisture and increasing heat. Important processes for plant nutrient uptake are negatively affected like N fixation, litter decomposition and denitrification. Desert plants must therefore adapt their mineral household towards best use of available nutrients and storage of minerals in perennial organs. Here we studied this pattern by experiments of the effect of nitrogen nutrition on mineral concentration and plant growth of Retama raetam (Forssk.) Webb. Berth for two years in sand culture. In summary, the mineral household of R raetam seems to be well adapted to unfavourable desert habitat independent from the N source and N level.

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Two wheat genotypes were grown in hydroponic culture, containing 4 mM KNO3, NH4Cl and NH4NO3. Activities of N metabolizing enzymes, aminotransferases, carbohydrate and TCA cycle enzymes were analyzed along with protein, amino acid, N, sugar content and growth parameters in shoot and root. After 12 days, the size of shoot and root system decreased significantly when plants were supplied with NH4Cl as exclusive N source. Under NH4NO3 growth parameters, N and carbon metabolism were elevated as compared to NH4Cl but less than KNO3 source indicating inhibition of NH4 + toxicity by NO3 uptake. Our results suggested that GDH, aminotransferases and PEPC play an important role in ammonium detoxification by its incorporation into amino acids. Thus, the morphologic differences among plants growing in NH4 + or NO3 nutrition confirm the hypothesis that N source determines the growth habit of plant in wheat by modulating the endogenous levels of protein and sugar content.

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Halomonas marina HMA 103 (MTCC 8968), the moderately halophilic bacterium isolated and characterized from the solar saltern of Orissa, India, grows optimally at 10% (w/v) NaCl in culture medium and is able to synthesize poly(3-hydroxybutyrate) [P(3HB)] during growth. This study is an attempt to optimize the cultural conditions for efficient production of P(3HB) by H. marina in batch cultivation. Growth of the organism under shake-flask culture using 2% (w/v) glucose resulted in P(3HB) accumulation accounting for more than 59% of cell dry weight after 50 h of incubation. The optimum P(3HB) production was attained with a combined supply of NH 4 Cl and yeast extract as N-source, 0.01% (w/v) phosphate, 1.5% (w/v) sulphate and 10% (w/v) NaCl. Qualitative and quantitative 1 HNMR and FT-IR analysis of cells grown in alkanoic acids (C 3 –C 6 ) as sole source of carbon and co-substrates revealed synthesis of PHA co-polymers composed of 3-hydroxybutyric acid and 3-hydroxyvaleric acid [P(3HB-co-3HV)]. In two-step cultivation, accumulation of the co-polymer was significantly improved (80% CDW) in glucose medium supplemented with valerate (0.1%, w/v) as co-substrate and the polymer contained 88.1 and 12.8 mol% 3HB and 3HV monomers, respectively.

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Kisparcellás szabadföldi kísérletet állítottunk be 2000 tavaszán Mosonmagyaró-várról származó városi szennyvíziszappal (Moson-iszap) és vágóhídi hulladék komposzttal (ATEV-komposzt) csernozjom barna erdőtalajon, Sopronhorpácson. A talaj szántott rétegében a CaCO 3 1% alatti, a pH(H 2 O) 7,8, a pH(KCl) 7,0, az Arany-féle kötöttség (K A ) 40–42, a humusz- 2,5%, az NH 4 -N-, NO 3 -N-, AL-P 2 O 5 - és AL-K 2 O-tartalom 10, 6–9, 120–160 és 247–276 mg/kg értéket mutatott. A humuszos vályog talaj foszforral közepesen/kielégítően, káliummal jól ellátott volt. A szerves trágyákat 0, 25, 50, 100 és 200 t/ha friss tömegben alkalmaztuk. Az első évben cukorrépát, a 2. évben tavaszi árpát termesztettünk. Az 5 terhelési szint×4 ismétlés = 20 (egyenként 40 m² méretű) parcellát jelentett kísérletenként véletlen blokk elrendezésben. A kísérletben a szokásos üzemi agrotechnikát alkalmaztuk. A főbb eredmények: – A szerves trágyák által okozott maximális N-terhelés számításaink szerint elérte az 1500 kg/ha körüli N-mennyiséget. A cukorrépa termését és minőségét döntően a N-kínálat befolyásolhatta, amennyiben a PK-ellátottság kielégíthette a növény igényét. – A legnagyobb adagú (200 t/ha) friss szervestrágyázás nyomán 20 t/ha körüli gyökértermés-többlet képződött, termésdepresszió nem jelentkezett. A N-túlkíná-latra utalt viszont a tisztasági hányados, a digestio és a tiszta cukor %-ának visszaesése. Ezzel együtt nőtt a nemkívánatos K, Na és α-aminó N mennyisége a gyökérben, különösen a városi szennyvíziszap hatására. – A városi szennyvíziszap kisebb szervesanyag-tömege nagyobb minőségrom-lást okozott a répagyökérben, a maximális nyers- és tisztacukor-hozamot a 25 t/ha adag biztosította. A vágóhídi komposzttal több mint háromszor annyi nehezebben bomló, nagy CaCO 3 -tartalmú, de nitrogénben szegényebb szerves anyag került a talajba. A nyers és a tiszta cukor maximális hozama a legnagyobb (200 t/ha) adaghoz kötődött. Úgy tűnik, a vágóhídi komposzt lassú hatású N-forrásnak minősülhet. – A második évben termett tavaszi árpa termését a szervestrágyázás utóhatása nem módosította, feltehetően a kedvezőtlen csapadékviszonyok miatt. A vegetatív időszakban szárazság, érés idején esős periódus uralkodott. A kísérlet sajnos tovább nem folytatódott. – A növekvő városi szennyvíziszap-terheléssel emelkedett a talaj szántott rétegének cc. HNO 3 +cc. H 2 O 2 oldható „összes” P-, S- és Cu-készlete. A vágóhídi komposzttrágya pedig – összetételéből eredően – igazolhatóan többleteket eredményezett Ca-, P-, S-, Na- és Sr-tartalmában. – Az NH 4 -acetát+EDTA-oldható elemek koncentrációi látványosabban módosultak a feltalajban. Mindkét szerves trágya növelte a K, P, Fe, S és Zn elemek mennyiségét a szántott rétegben. A talaj Mo-tartalma az iszaptrágyázással megkétszereződött, míg a komposzttrágyázással mintegy a felére csökkent a trágyázatlan kontrollhoz képest. A komposzttrágyával bevitt nagymennyiségű szerves anyag (52 t/ha) hatására visszaesett a Mn, Al, Pb, Ni, Co és Cd elemek oldható tartalma is. – Az iszaptrágyák növelték a talaj „összes” só, szerves-C, illetve humusz %-át, valamint az NH 4 -N és NO 3 -N mennyiségét az 1. évben, a cukorrépa betakarítását követően. Az összes-N %-át a nagyobb komposztadagok igazolhatóan emelték. Kimutatható volt a kezelt talajok humuszminőségének változása, a humifikáltsági jelzőszám mérséklődése.

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Waddington, D.V., Moberg, E. L. & Duich, J. M. , 1972. Effect of N source, K source, and K rate on soil nutrient levels and the growth and elemental composition of Penncross creeping bentgrass, Agrostis palustris Huds. Agron. J. 64 . 562

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Otero, A., Vincenzini, M. (2003) Extracellular polysaccharide synthesis by Nostoc strains as affected by N source and light intensity. J. Biotech. 102 , 143–152. Vincenzini M

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