Colored plastic mulches affect soil temperature and tuber production of potato

Abstract

The main crops on which plastic mulch is widely used in Mexico include tomato, bell pepper, eggplant, melons, watermelons, and strawberry; however, very little research has been performed on potato. One of the main benefits associated with plastic mulching is the modification of the microclimate around the plant. To obtain a positive microclimate modification studies are required to understand how plastic mulch affects growth and yield of a given species. Previous field research assessing the response to colored plastic mulching in potato shows no consistent results on yield, maybe because it has been performed under different geographical latitudes. Potato in Mexico is conventionally cultivated on bare soil combined with various irrigation systems. The objective of the present study was to examine the effect of colored plastic mulches on soil temperature, growth, yield and photosynthetic response of potato plants. The experiment was conducted in Northeast Mexico and the treatments included were: black plastic mulch (BPM); white-on-black plastic mulch (W/B), silver-on-black (SPM), aluminum-on-black plastic mulch (APM) and a control that consisted of bare soil cultivated plants. Treatments were arranged in a randomized complete block design with four replications. Results suggest that average daily mean soil temperature was linearly and negatively correlated with total yield and yield of first-quality tubers. Total yield and yield of first-quality tubers of plants mulched with W/B, SPM and APM was significantly higher (p≤0.05) than those of control plants. Leaf area and shoot dry weight were increased when soil temperatures were higher due to the effect of radiation transmission to the soil, however, this decrease was associated with a decrease in tuber production. The results of our study indicate that plants grown under BPM, which induced the highest soil temperature, showed marginal difference in yield compared with control plants, suggesting that colored plastic mulches have a positive effect on yield through decreased rise in soil temperature.     

Detection, accumulation, distribution, and depletion of furaltadone and nifursol residues in poultry muscle, liver, and gizzard

Nitrofurans were broadly used as an extremely effective veterinary antibiotic especially in pig and poultry production farms. Because of fears of the carcinogenic effects on humans, the nitrofurans were banned from use in livestock production in many countries, including the European Union. The present study examines the accumulation, distribution, and depletion of furaltadone and nifursol and of their tissue-bound metabolites [3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ) and 3,5-dinitro-salicylic acid hydrazine (DNSAH), respectively, in poultry edible tissues (muscle, liver, and gizzards) following administration to chickens of therapeutic and subtherapeutic concentrations of both compounds. Nitrofurans determination was performed by high-performance liquid chromatography-diode array detection and liquid chromatography-tandem mass spectrometry, respectively, for feeds and for poultry tissues. Furaltadone and nifursol, in very low concentrations, were found in samples of muscle, liver, and chicken's gizzard collected from slaughtered animals after 5 weeks of treatment and no withdrawal time period. When a withdrawal time period of 3 weeks was respected, no detectable nitrofuran parent compounds was observed in all of the studied matrices. For AMOZ, concentrations of 270 μg/kg in meat, 80 μg/kg in liver, and 331 μg/kg in gizzard were determined after administration of a medicated feed with furaltadone (132 mg/kg), 3 weeks after withdrawal of treatment. For DNSAH, the concentration values obtained are much lower than those observed for AMOZ. For meat, liver, and gizzard, DNSAH concentrations of 2.5, 6.4, and 10.3 μg/kg, respectively, were determined, after administration of a medicated feed with nifursol (98 mg/kg), 3 weeks after withdrawal of treatment. The gizzard could be considered a selected matrix for nitrofuran residues evaluation in poultry, due to its capacity of retaining either nitrofuran parent compounds or metabolites in higher concentrations, regardless of the administered dose or of the respected withdrawal time period.     

Bioavailability of β-cryptoxanthin in the presence of phytosterols: in vitro and in vivo studies

Bioactive compounds are used in the design and development of new food products with potential health benefits, although little is known regarding their bioavailability and interactions. This study assessed the stability, in vitro bioaccessibility, and human bioavailability of β-cryptoxanthin from β-cryptoxanthin-rich drinks with and without added phytosterols developed for this purpose. The developed drinks showed no difference in the content of β-cryptoxanthin, and they were stable over 6 months. In vitro, hydrolysis of β-cryptoxanthin esters and the amount of free β-cryptoxanthin at duodenal and micellar phases were similar regardless of the presence of phytosterols. In the human study, the daily intake provoked significant increments of β-cryptoxanthin in serum regardless of the type of the drink. In conclusion, in vitro and in vivo human studies have shown that the bioavailability of β-cryptoxanthin is not significantly affected by the presence of phytosterols when they are simultaneously supplied in a drink.     

Levels of 131I and Six Natural Radionuclides in Sludge from the Sewage Treatment Plant of Valladolid, Spain

The levels of ¹³¹I and six natural radionuclides (²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Ra, ²²⁴Ra, and ⁴⁰K) were determined in sewage sludge samples obtained from an urban wastewater treatment plant that services a medium-sized town in Spain. Secondary treatment of wastewater consisting of anaerobic, anoxic, and oxic stages is collectively called A2O processing. Radio analytical determinations were performed by gamma spectrometry using a high-purity germanium detector. This technique has proven useful in identifying local radioactive pollution. This type of pollution was consistently detected throughout the year, with several increases associated with authorized discharges from hospitals. Finally, we examined the radiation dose that workers are exposed to due to the presence of ¹³¹I in the sludge. We found inhalation risk to be negligible, with external radiation as the main source of exposure to ¹³¹I.     

Status and distribution of the Mediterranean monk seal Monachus monachus on the Cabo Blanco peninsula (Western Sahara-Mauritania) in 1993–1994

The current geographical distribution of the Mediterranean monk seal Monachus monachus colony inhabiting the Cabo Blanco peninsula (Western Sahara-Mauritania) is described. Its distribution range has apparently not changed since surveys conducted in 1984–1988. Sightings of adults on the Tarf el Guerguerat coast, 20 km north of the known breeding caves, suggests the existence of other possible breeding groups further north. Two caves used by the seals are described for the first time. A review of historical trends in cave occupation by seals made it possible (1) to locate the so-called ‘maternity cave’, last reported in 1949; and (2) to establish that the colony, since its discovery, has occupied at least eight caves, five of which have collapsed. An index of population size based on counts of individuals of identified morphological types indicates that, during 1993–1994, the colony was composed of c.113–165 individuals (excluding pups), a larger number than previously assumed. Counting of seals at times of maximum haul-out is proposed as a tool to monitor population trends, although it is considered unreliable for estimating absolute numbers.     

Macromolecular Features of Amaranth Starch

High-performance size-exclusion chromatography (HPSEC), static light scattering (SLS) and dynamic light scattering (DLS) techniques were used for the structural characterization of amaranth starch, solubilized in water by microwave heating in a high-pressure vessel. Apparent average molar mass (M _w) gyration radius (R _G), and hydrodynamic radius (R _H) values were obtained from Berry and Zimm treatment of light-scattering data. When heating time increased from 35 to 90 sec, the M _w, R _G, and R _H decreased, demonstrating a possible polymer degradation due to temperature. Apparent M _r values from HPSEC at 35 sec (27 ± 2 × 10⁷ g/mol) and 50 sec (20 ± 2 × 10⁷ g/mol) were lower than those determined by SLS (35 sec = 69 × 10⁷ g/mol, 50 sec = 56 × 10⁷ g/mol). However, at 70 and 90 sec, the inverse pattern was obtained. The fractal dimensions (d′_f) from HPSEC study for samples dissolved for 35 (3.26), 50 (3.24), and 70 sec (3.14) are characteristic of a particle that has the internal structure of hard sphere, and for samples dissolved for 90 sec (2.19), are characteristic of a fully swollen, randomly branched macromolecule. From SLS, d′_f decreased with increasing treatment time (d′_f = 2.44, 2.18, 1.50, and 1.03 for 35, 50, 70, and 90 sec, respectively). The particle-scattering factors and Kratky plots, well-suited for studying the internal structure of a macromolecule, showed a sample degradation when treatment time increased. Results from DLS showed bimodal distributions with differences in the peak locations when treatment time increased. The ratio of R _G to R _H (ρ) for samples analyzed were between 0.88 and 1.3; these values are characteristic of a sphere or globular structure.     

Enzymatic treatment to improve extraction of capsaicinoids and carotenoids from chili (Capsicum annuum) fruits

Enzymatic treatments using noncommercial enzymes as a means to the improve the extraction of carotenoids and capsaicinoids from chili fruits are explored in this study. The results show that it is possible to obtain chili fruit powder with a higher concentration of both capsaicinoids and carotenoids than previously reported for similar processes. Furthermore, extraction yields above 96% for carotenoids and 85% for capsaicinoids as separate fractions can be achieved using a sequential and selective two-stage extraction. Evidence is presented demonstrating that the content and extraction yield depend directly on the extent of the enzymatic hydrolysis of chili cell walls, and higher yields are obtained when the sample is completely hydrolyzed. The enzymatic treatment described here is a promising alternative to current industrial practices, and it improves the extraction of carotenoids and capsaicinoids from chili fruits.     

Hypolipidemic effect in cholesterol-fed rats of a soluble fiber-rich product obtained from cocoa husks

A new soluble cocoa fiber product (SCFP), obtained after enzymatic treatment of cocoa husks, was characterized and its potential health effects studied in an animal model of dietary-induced hypercholesterolemia. The SCFP was rich in soluble dietary fiber (DF) and antioxidant polyphenols. Consumption of a cholesterol-rich diet containing the SCFP as a source of DF resulted in lower food intake and body weight gain in comparison with control groups consuming cholesterol-free or cholesterol-rich diets with cellulose as DF. The cholesterol-rich diet caused remarkable hypercholesterolemia. However, the SCFP diminished the negative impact of the cholesterol-rich diet, buffering the decrease of high density lipoprotein-cholesterol, and the increase of total and low density lipoprotein-cholesterol levels, and lipid peroxidation (malondialdehyde levels) induced by the fatty diet. The SCFP also decreased triglyceride levels to values lower than those in the group fed the cholesterol-free diet. These results put forward the potential application of the SCFP as a dietary supplement or functional food ingredient.     

Characterization of exopolysaccharides produced by Bifidobacterium longum NB667 and its cholate-resistant derivative strain IPLA B667dCo

Bifidobacteria are natural members of the human intestinal microbiota and some strains are being used as probiotics. Adaptation to bile can allow them to increase survival in gastrointestinal conditions, thus improving their viability. Bifidobacterium longum NB667 and the cholate-resistant strain B. longum IPLA B667dCo produced exopolysaccharides (EPS) that were partially characterized. Analysis by size exclusion chromatography-multiangle laser light scattering indicated that the EPS crude fractions of both strains contained two polymer peaks of different molar mass. On the basis of chromatographic techniques both peaks appeared to be heteropolysaccharides. The smaller peak was mainly composed of glucose, galactose and rhamnose whose molar ratios and linkage types showed slight variations between the EPS fractions of both strains. The bigger peak consisted of glucose and galactose; the monosaccharide composition was identical in the EPS fractions of the two microorganisms, but their infrared spectra presented some differences regarding compounds other than carbohydrates that seem to be associated to the polymer. Differences in the composition of EPS fractions did not affect the capability of crude EPS from B. longum to be fermented by the human intestinal microbiota in fecal batch cultures.     

Simultaneous determination of eight water-soluble vitamins in supplemented foods by liquid chromatography

A fast, simple, and reliable method for the isolation and determination of the vitamins thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, folic acid, cyanocobalamin, and ascorbic acid in food samples is proposed. The most relevant advantages of the proposed method are the simultaneous determination of the eight more common vitamins in enriched food products and a reduction of the time required for quantitative extraction, because the method consists merely of the addition of a precipitation solution and centrifugation of the sample. Furthermore, this method saves a substantial amount of reagents as compared with official methods, and minimal sample manipulation is achieved due to the few steps required. The chromatographic separation is carried out on a reverse phase C18 column, and the vitamins are detected at different wavelengths by either fluorescence or UV-visible detection. The proposed method was applied to the determination of water-soluble vitamins in supplemented milk, infant nutrition products, and milk powder certified reference material (CRM 421, BCR) with recoveries ranging from 90 to 100%.