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991.
A greenhouse experiment was carried out to evaluate chromium (Cr) toxicity in urograndis (Eucalyptus urophylla S. T. Blake x grandis W. Hill ex. Maiden). Chromium nitrate was amended to Clark's nutrient solution (0.00, 0.04, 0.08, 0.16, 0.32 and 0.64 mmol L?1 Cr), which was used to breed one urograndis cutting per pot (four replications). Regression analysis revealed that Cr rates of 0.08 mmol L?1 or higher significantly decreased (P < 0.01) dry matter yield of shoot and root. Chromium accumulation order in plant was: root > stem > leaves. Critical Cr toxicity level in leaves was 0.74 mg kg?1. Uptake and translocation of nutrients were affected differently by Cr. Mostly have their uptake reduced due to root damage. Magnesium, iron and manganese translocation increases, supposedly to maintain normal photosynthetic activity. Wilting is the main visual symptom of Cr toxicity. Urograndis may be suitable for contaminated sites phytostabilization and receive industrial waste fertilization.  相似文献   
992.
This research deals with the effects of exogenous growth regulators on mineral nutrition of the tomato plant (Lyeopersieon esaulentum Mill. cv. Miguel Pereira). To study the influence on mineral nutrition, (2‐chloroethyl) trimethylammonium chloride (CCC) , at concentration of 2,000 ppm, succinic acid‐2, 2‐dimethylhydrazide (SADH) (4,000 ppm), gibberellic acid (GA) (100 ppm), (2‐chloroethyl) phosphonic acid (CEPA) (200 ppm), indole‐3‐acetic acid (IAA) (100 ppm) and 6‐furfurylamino purine (FAP) (500 ppm) were applied. Higher levels of nitrogen, calcium and magnesium occurred in the stem of plants sprayed with CCC. Treatments with FAP, SADH and CEPA caused an increase in nitrogen level in the stem. CEPA also increased calcium content in stems. These growth regulators did not alter the levels of macronutrients in the leaves in relation to control.  相似文献   
993.
Potassium (K) is required in high doses by the banana (Musa sp.) plant and interacts with other nutrient elements in which banana tissues are maintained under in vitro condition as a consequence modifications in the plant metabolism take place mainly in nitrogen (N) compounds, such as proteins, amino acids, and secondary compounds. When K is present in concentrations lower than that required, diamines such as putrescine and poliamines are formed. This metabolic disorder can also be correlated with the presence of different inorganic N forms, such as nitrate (NO3) and ammonium (NH4), and the ratios between both ions as well. In order to follow the physiological performance of the interrelationships, K/putrescine and of the NO3/NH4 ratio in the tissue of banana vitroplantlets, shoot apex of two banana cvs. Nanica and Prata Ana were maintained in modified MS medium in the presence of six different doses of K: 5, 10, 15, 20, 25, and 30 mM. After the period of tissue proliferation the cultures were transferred to rooting media containing the same different K doses. Dry matter, K, putrescine, and spermidine contents and their accumulation were determined in the shoots and roots of the vitroplantlets and in the shoot apex of the expiant donor cultivar as well as the corresponding values for the whole vitroplantlets calculated. The data were statistically analyzed. The contents and accumulations of putrescine and spermidine in banana tissues were enhanced as K concentration decreased in the medium: four times (0.19% of the dry matter) for cv. Nanica and eight times (0.25% of the dry matter) for cv. Prata Ana. This behavior was not only related to the K depletion but to the NO3/NH4 ratio as well.  相似文献   
994.
A 20-d experiment was conducted to test the hypothesis that phytase increases nutrient digestibility, bone ash, and growth performance of pigs fed diets containing 0.23%, 0.29%, or 0.35% phytate-bound P. Within each level of phytate, five diets were formulated to contain 0, 500, 1,000, 2,000, or 4,000 phytase units (FTU)/kg of a novel phytase (PhyG). Three reference diets were formulated by adding a commercial Buttiauxella phytase (PhyB) at 1,000 FTU/kg to diets containing 0.23%, 0.29%, or 0.35% phytate-bound P. A randomized complete block design with 144 individually housed pigs (12.70 ± 4.01 kg), 18 diets, and 8 replicate pigs per diet was used. Pigs were adapted to diets for 15 d followed by 4 d of fecal collection. Femurs were collected on the last day of the experiment. Results indicated that diets containing 0.35% phytate-bound P had reduced (P < 0.01) digestibility of Ca, P, Mg, and K compared with diets containing less phytate-bound P. Due to increased concentration of total P in diets with high phytate, apparent total tract digestible P and bone ash were increased by PhyG to a greater extent in diets with 0.29% or 0.35% phytate-bound P than in diets with 0.23% phytate-bound P (interaction, P < 0.05). At 1,000 FTU/kg, PhyG increased P digestibility and bone P more (P < 0.05) than PhyB. The PhyG increased (P < 0.01) pig growth performance, and pigs fed diets containing 0.35% or 0.29% phytate-bound P performed better (P < 0.01) than pigs fed the 0.23% phytate-bound P diets. In conclusion, the novel phytase (i.e., PhyG) is effective in increasing bone ash, mineral digestibility, and growth performance of pigs regardless of dietary phytate level.  相似文献   
995.
• Identification of bacteriocin sources• Classification of bacteriocins• Antiviral pathways of bacteriocinsThe COVID-19 infections caused by SARS-CoV-2 have resulted in millions of people being infected and thousands of deaths globally since November 2019. To date, no unique therapeutic agent has been developed to slow the progression of this pandemic. Despite possessing antiviral traits the potential of bacteriocins to combat SARS-CoV-2 infection has not been fully investigated. This review summarizes the mechanisms by which bacteriocins can be manipulated and implemented as effective virus entry blockers with infection suppression potential properties to highly transmissible viruses through comprehensive immune modulations that are potentially effective against COVID-19. These antimicrobial peptides have been suggested as effective antiviral therapeutics and therapeutic supplements to prevent rapid virus transmission. This review also provides a new insight into the cellular and molecular alterations which have made SARS-CoV-2 self-modified with diversified infection patterns. In addition, the possible applications of antimicrobial peptides through both natural and induced mechanisms in infection prevention perspectives on changeable virulence cases are comprehensively analyzed. Specific attention is given to the antiviral mechanisms of the molecules along with their integrative use with synthetic biology and nanosensor technology for rapid detection. Novel bacteriocin based therapeutics with cutting-edge technologies might be potential substitutes for existing time-consuming and expensive approaches to fight this newly emerged global threat.  相似文献   
996.
The objective of this work was to describe the nutrition deficiencies symptoms in calla lily (Zantedeschia aethiopica). Seedlings were maintained in complete nutrition solution and with omission of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), boron (B), and manganese (Mn), totalizing 10 treatments. The first deficiencies symptoms appeared in plants cultivated in N omission, followed by treatments with omission of S, B, K, Fe, P, and Ca. Individual omissions of N and B prevented blooming, while S and K deficiencies resulted in production of small and greenish inflorescences with deformities. Reddish spots in leaves were observed in plants growing in solution with omission of P. Root development was affected either by omission of B or S. Death of the apical bud and formation of a “black center” in calla lily rhizome was caused by B deficiency. Nitrogen, B, and S are the most required nutrients for calla lily plants. The mineral composition of calla lily leaves is affected by nutritional deficiencies  相似文献   
997.
Iron(V)-oxo species have been proposed as key reactive intermediates in the catalysis of oxygen-activating enzymes and synthetic catalysts. Here, we report the synthesis of [Fe(TAML)(O)]- in nearly quantitative yield, where TAML is a macrocyclic tetraamide ligand. Mass spectrometry, M?ssbauer, electron paramagnetic resonance, and x-ray absorption spectroscopies, as well as reactivity studies and density functional theory calculations show that this long-lived (hours at -60 degrees C) intermediate is a spin S = 1/2 iron(V)-oxo complex. Iron-TAML systems have proven to be efficient catalysts in the decomposition of numerous pollutants by hydrogen peroxide, and the species we characterized is a likely reactive intermediate in these reactions.  相似文献   
998.

Alkaline residues of recycled paper production (ARRP) can be an alternative for correcting soil acidity and adding bases to Pinus taeda L. systems. Our aim was to investigate the effect of increasing doses of ARRP on tree, forest floor (litter and root), and soil composition in a 3-year-old Brazilian pine forest plantation. In 2007, ARRP treatments of 0, 10, 20, 30 and 40 T ha?1 were imposed. Tree growth and needle elemental composition were evaluated in 2008 and 2018; elemental composition of the trunk was evaluated in 2018. In 2017, accumulation and composition of litter layers were assessed: new litter, old litter, first and second sublayers of fragmented litter (Fr and Fm), and the humified layer (H); roots present in F and H layers were quantified (amount and elemental composition). In addition, soil chemical properties at different depths were evaluated in 2008, 2012, and 2017. The application of ARRP improved growth by ~?16% up to 20 T ha?1 after 10 years. Also, ARRP increased Ca concentration in needles, trunks, roots, and all litter fractions since Ca was a major component of ARRP. There was no change in total litter accumulation with ARRP application, but an increase in the humidified fraction was observed. Root growth was enhanced by ARRP, leading to great changes in root composition in Fr and H fractions. Changes in soil pH, Ca2+, and Al3+ were observed in the 0–10 cm soil layer. Findings suggest that application of ARRP to established pine forests has the potential for improving productivity.

  相似文献   
999.
New Forests - The quality of forest seeds may be maintained in the course of storage for their use in the restoration of degraded areas and the conservation of genetic resources. In this sense,...  相似文献   
1000.
New Forests - Mixed plantations composed of Eucalyptus intercropped with a high diversity of native tree species are a promising option for combining biodiversity recovery with wood production...  相似文献   
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