Nitrogen redistribution to sorghum grains as affected by plant competition

An experiment was conducted to study nitrogen absorption and translocation in grain sorghum plants during their reproductive growth. Sorghum was grown in four row spacings: 50 and 70 cm in single rows, 80 and 120 cm in double rows 20 cm apart. Plant populations were 71000, 142000 and 213000 plants/ha. After flowering, samples were taken at 12 day intervals, and the plants were divided into grains and stover, where N was analyzed. There was an increase in N concentration in lower plant populations and in wider row spacings. However, total nitrogen accumulation (in kg/ha) increased as the number of plants was increased. In the vegetative parts of the plants there were higher N concentrations in lower populations showing that there was a higher N absorption and a lower translocation to the grains. When grain sorghum was grown in 50 cm rows, there was a high N accumulation, a high N translocation to the grains and the highest yield. This row spacing led to the highest N use efficiency.

Nitrogen management in maize cover crop rotations

Winter cover crops can affect N nutrition of the following maize crop. Although legumes have been recommend for maize rotations, in tropical areas grasses may be more interesting because they provide a longer protection of soil surface. Legumes can add N to the system and grasses can compete with maize for the available nutrient. An experiment was conducted in Botucatu, São Paulo State, Brazil, to study N dynamics in the soil surface straw-maize system as affected by N fertilization management and species included in the no-till rotation. Treatments were fallow, black oat (Avena strigosa), pearl millet (Pennisetum glaucum), white lupins (Lupinus albus), black oat fertilized with N. and pearl millet fertilized with N. Maize was grown afterwards in the same plots, receiving 0.0, 60.0 and 120.0 kg ha(-1) of N sidedressed 30 days after plant emergence. Soil, straw and maize samples were taken periodically. The highest corn yields were observed when it was cropped after pearl millet fertilized with N. Nitrogen side dressed application up to 120 kg ha(-1) was not able to avoid corn yield decrease caused by black oat. Grasses can be recommended in maize rotations in tropical areas, provided they receive nitrogen fertilizer and show no allelopathy. Due to its higher ON ratio and dry matter yield they are better than legumes, protecting the soil surface for a longer period. Pearl millet is particularly interesting because it enhances N use efficiency by the following maize crop. For a better N availability/demand synchronism, the cover crops should be desiccated right before maize planting.

Physiological and genomic variations in rice cells recovered from direct immersion and storage in liquid nitrogen

The use of cryoprotectants and slow cooling rates are routine procedures for the cryopreservation of plant cell lines. However, our results with rice (Oryza sativa L,, ev. Taipei 309) show that calli can be cryopreserved by direct immersion and stored in liquid nitrogen without any cryoprotection, the efficiency of recovery using this method, as well as a conventional method was generally increased with a previous abscisic acid (ABA) treatment. Following cryopreservation, calli demonstrated some differences with respect to unfrozen calli of the same lines, Thus, resistance to freezing stress (- 20 degrees C for 2 h) increased significantly in all lines tested, irrespective of their pre-incubation with ABA, Calli that had been directly stored in liquid nitrogen also demonstrated a higher competence for genetic transformation than their unfrozen counterparts, as indicated by the transient gene expression levels obtained after particle bombardment, These differences might lead to further biotechnological applications, A genetic analysis of amplified DNA polymorphisms was performed with three independent lines that had been subjected to four combinations of ABA treatment and direct immersion in liquid nitrogen, At the loci screened with the randomly amplified polymorphic DNA (RAPD) markers tested, the genetic variations among lines and among calli of the same line appear to bd more related to tissue-culture-induced somaclonal variation than to cryoselection.

Food intake and digestive efficiency in temperate wool and tropic semi-arid hair lambs fed different concentrate: forage ratio diets

This work was conducted to evaluate food intake and digestive efficiency of temperate wool and tropic semi-arid hair lambs, according to different concentrate: forage ratios in diet. Twenty-four lambs, averaging 90 +/- 1.8 days old and a mean body weight of 20 +/- 0.69 kg, 12 of them wool lambs, F, from Ideal x Ile de France crossing, and 12 others pure Santa Ines hair lambs, were distributed into a four replication 3 x 2 factorial arrangement consisting of three diets and two genotypes. Experimental diets consisted of: D1 = 60% concentrate mix (C) and 40% Cynodon sp. cv. Tifton-85 hay (F), D2 = 40% C and 60% F, and D3 = 20% C and 80% F. D1 was formulated for a daily gain of 300g per animal. Increasing forage levels in diets resulted in linear reductions (P < 0.01) in DM, OM, CP, TCH and metabolizable energy (ME) intake, and a linear increase (P < 0.01) in NDF ingestion. Tropic semi-arid hair lambs had higher DM, OM, NDF, CP, and TCH intake than temperate wool lambs. Although there were no genotype effects in OM and GE coefficient of digestibility, hair lambs showed more efficient (P < 0.05) digestibility of DM, CP, NDF and TCH. Increases in forage levels of diets corresponded to a negative linear effect (P < 0.01) in the apparent digestibility of DM, OM, CP, TCH and GE, while apparent digestibility of NDF increased linearly (P < 0.01). Total endogenous nitrogen (fecal plus urinary N) for F(1) Ideal x Ilede France wool and Santa Ines hair lambs were, respectively, 182 and 312 mg/kg(0.75) per day. Thus, Santa Ines tropic semi-arid hair lambs showed to be more responsive than F(1) Ideal x Ile de France temperate wool lambs to low quality fibrous diets. (C) 2004 Elsevier B.V. All rights reserved.

Effects of simulated herbivory on photosynthesis and N resorption efficiency in Quercus pyrenaica Willd. saplings

We examined the effects of simulated folivory by caterpillars on photosynthetic parameters and nitrogen (N) resorption efficiency in Quercus pyrenaica saplings. We analyzed the differences between intact leaves in control plants, punched leaves in damaged plants, and intact leaves in damaged plants. We then established two levels of simulated folivory: low (approximate to 13% of the leaf area of one main branch removed per plant) and high (approximate to 26% of the leaf area of one main branch removed per plant) treatments. No differences were found in net assimilation rate and conductance between either leaf type or treatment during the most favourable period for photosynthesis. However, the N content was lower in punched than in intact leaves, and as a result PNUE was higher in damaged leaves from treated trees. In leaf-litter samples, N mass was significantly higher in punched than in intact leaves in treated plants, and LMA was significantly higher in damaged than in intact leaves of both the treated and control plants. Consequently, N resorption efficiency was around 15% lower in damaged leaves as compared with intact leaves from treated and control plants. Mechanical injury to leaves not only triggered no compensatory photosynthetic response to compensate a lower carbon uptake due to leaf area loss, but also affected the resorption process that characterizes leaf senescence.

Effects of soil water deficit and nitrogen nutrition on water relations and photosynthesis of pot-grown Coffea canephora Pierre

Coffea canephora plants (clone INCAPER-99) were submitted to low N (LN) or high N (HN) applications and two watering regimes (daily irrigation and irrigation every 5 days for a month). Although water potential was not altered significantly by N, HN plants showed higher relative water content than did LN plants under water deficit. Only HN plants exhibited some ability for osmotic adjustment. Plants from both N treatments increased their cell wall rigidity under drought, with a more pronounced augmentation in HN plants. In well-watered plants, carbon assimilation rate increased with increasing N while stomatal conductance did not respond to N supply. Under drought conditions, carbon assimilation decreased by 68-80% compared to well-watered plants, whereas stomatal conductance and transpiration rate declined by 35% irrespective of the N applications. Stable carbon isotope analysis, combined with leaf gas exchange measurements, indicated that regardless of the watering treatments, N increased the long-term water use efficiency through changes in carbon assimilation with little or no effect on stomatal behaviour.

Evaluation of Rice Bran Extract as a Nitrogen Source for Improved Hemicellulosic Ethanol Production from Sugarcane Bagasse by New Xylose-Fermenting Yeast Strains Isolated from Brazilian Forests

Xylose is the main sugar in hemicellulosic hydrolysates and its fermentation into ethanol by microorganisms is influenced by nutritional factors, such as nitrogen source, vitamins and other elements. Rice bran extract (RBE) is an inexpensive nitrogen source primarily consisting of high amount of protein. This study evaluates the potential of RBE as a nitrogen source for the hemicellulosic ethanol production from sugarcane bagasse dilute acid hydrolysate by novel yeast strains Scheffersomyces shehatae (syn. Candida shehatae) CG8-8BY and Spathaspora arborariae UFMG-HM19.1A, isolated from Brazilian forests. Two different media formulations were used for inoculum preparation and production medium, using yeast extract and RBE as nitrogen sources. S. shehatae CG8-8BY showed ethanol production of 17.0 g/l with the ethanol yield (0.33 g/g) and fermentation efficiency (64 %) from medium supplemented with RBE. On the other hand, S. arborariae presented 5.4 g/l of ethanol production with ethanol yield (0.14 g/g) and fermentation efficiency (21 %) in a fermentation medium supplemented with RBE. Appropriate media formulation is an important parameter to increase the productivity of bioconversion process and RBE proved to be an efficient and inexpensive nitrogen source to supplement sugarcane bagasse hemicellulosic hydrolysate for second generation ethanol production. © 2013 Society for Sugar Research & Promotion.

Nitrogen fertilization management in no-tillage maize with different winter crops

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nitrogen fertilization (15NH4NO3) of palisadegrass and residual effect on subsequent no-tillage corn

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modelling of the nitrogen deposition and dietary lysine requirements of Redbro broilers

The aim of this study was to determine the coefficients of the Goettingen model for Redbro birds and estimate the digestible lysine requirements. To determine the model parameters, three nitrogen balance trials were performed in Periods I (14-28 days), II (42-56 days) and III (70-84 days), using 42 birds per trial. The birds were individually housed and subjected to six diets with increasing levels of nitrogen, with lysine as the limiting amino acid (deficient by 20% in relation to other amino acids). Dietary nitrogen concentrations were 8, 16, 24, 32, 40 and 48 g/kg. A control diet was added to confirm lysine as the first limiting amino acid. Nitrogen balance trials were divided into 5 days of adaptation and two periods of excreta collection, each one of 5 days. The response of the birds to a control diet confirmed that lysine was the first limiting amino acid. The adjustment of the exponential functions between nitrogen retention or excretion and nitrogen intake allowed estimation of parameters of the Goettingen model. The maximum potential for nitrogen retention was 3276, 2585 and 2603 mg/BWkg0.67.day, nitrogen maintenance requirement was 225, 135 and 122 mg/BWkg0.67.day and efficiency of nitrogen utilisation was 313 x 10(-6), 406 x 10(-6) and 415 x 10(-6) in the phases of 14-28, 42-56 and 70-84 days. The digestible lysine intake for Periods I, II and III, based on 60% of the maximum potential for nitrogen retention, was 711, 989 and 1272 mg/day (1.225%, 1.137% and 1.09% of lysine in the diet for a daily feed intake of 58, 87 and 117 g/day), respectively.

Physiological performances of two populations of Compsopogon caeruleus (Rhodophyta) to inorganic nitrogen and phosphorus impoverishment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Treatment efficiency of effluent prawn culture by wetland with floating aquatic macrophytes arranged in series

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sistemas de cultivo antecessores e doses de nitrogênio em cobertura no feijoeiro em plantio direto = cover crop systems and nitrogen topdressing on common bean in no tillage

The objective of this work was to evaluate the grass cover crop production in crop systems involving maize and Urochloa ruziziensis, and the influence of topdressing nitrogen rates in the yield and agronomic efficiency on common-bean cultivated in succession in no-tillage. The experiments were conducted in Jaboticabal-SP, in a eutrophic red latosol, in the second year of no-tillage system implementation. The IPR 139 cultivar was used in split plot design with three replications, in randomized block. The plots had been composed for three crop systems in the summer season, with maize exclusive, maize intercropped with U. ruziziensis and U. ruziziensis exclusive. The subplots had been constituted for five nitrogen rates (0, 40, 80, 120 and 160 kg ha(-1)), applied as topdressing at V4-4 in irrigated common-bean cultivated in the winter-spring season. The use of U. ruziziensis in crops systems, exclusive or intercropped with maize favors the grass cover crop production sufficiently to total soli surface covered, possibility similar grain yield compared to maize exclusive. The topdressing nitrogen application doesn't affect the common-bean yield in succession to maize and U. ruziziensis intercropped. The increase of nitrogen rates in common-bean in succession to maize exclusive improves the yield, although decreases the agronomic efficiency.

Comparison of the digestive efficiency of extruded diets fed to ferrets (Mustela putorius furo), dogs (Canis familiaris) and cats (Felis catus)

The digestive tract of ferrets is anatomically simple, with no caecum, ileocolic valve or external differentiation between the transition of ileum and colon. The species has a short large intestine that provides minor contributions to the digestive process. Aiming to better understand the digestibility efficiency of ferrets, the present study compared the digestibility of extruded diets with different amounts of macronutrients fed to dogs, cats and ferrets. Three formulations for cat maintenance were used (values in % of DM basis): high carbohydrate (HC; nitrogen-free extract (NFE) = 54 %, protein = 31 % and fat = 8 %); moderate carbohydrate (MC; NFE = 37 %, protein = 41 % and fat = 10 %); and low carbohydrate (LC; NFE = 19 %, protein = 46 % and fat = 23 %). Apparent total tract macronutrient digestibility was determined by the method of total collection of faeces. Results were compared by ANOVA, considering the diet and species effects and their interactions. Means were compared by the Tukey's test (P < 0·05). Dogs and cats presented similar food intakes, but ferrets consumed almost two times more food (g/kg body weight). Species × diet interactions were verified for apparent total tract digestibility (ATTD; P < 0·05). Ferrets presented lower DM digestibility than dogs and cats for all three diets (P < 0·05), lower NFE digestibility than dogs for the three diets and lower NFE digestibility than cats for the HC and LC diets (P < 0·05). For crude protein (CP), ferrets presented lower ATTD than dogs and cats (P < 0·05), whereas for fat, dogs and ferrets presented similar ATTD, and higher values than those presented by cats (P < 0·05). Kibble diets had a lower DM, CP and NFE digestibility when fed to ferrets compared with dogs and cats. Fat digestibility was similar between dogs and ferrets and higher than that for cats.

Effect of nitrogen and application ways of a plant biostimulant on different wheat genotypes contrasting in stature

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)