Resistance to <Emphasis Type="Italic">Penicillium</Emphasis><Emphasis Type="Italic">hirsutum</Emphasis> Dierckx in garlic accessions

Among the factors affecting the quality and yield of garlic production, blue mold caused by -- Penicillium spp. -- is responsible for economical losses in many countries. Allicin, present in garlic bulbs, has been suggested as having antifungal activity against some Penicillium species. This study was conducted to evaluate the response of garlic accessions against Penicillium hirsutum infection and to compare this response with bulb allicin content. Twelve garlic accessions were inoculated with P. hirsutum, and assayed in greenhouse and growth chamber experiments. Plant growth parameters and the fungal production of conidia were evaluated. Significant differences were found among the accessions. Accessions Castaño and Morado were most resistant whereas AR-I-125 and Fuego were always severely affected by the disease. A low correlation was found (r = 0.17) between allicin content and tolerance, indicating that allicin is not the main factor involved in the resistance against P. hirsutum.     

Influence of pasture on fatty acid profile of goat milk

The effect of pasture on the fatty acid profile of milk was evaluated using 30 pluriparous goats, which were divided into two homogeneous groups (H and P) of 15 goats each after kidding. Group H (control) goats were housed in a stall and received alfalfa hay, while group P was led to pasture. The goats of both the groups received the same concentrate. Average milk yield did not differ statistically between the groups. The goats of the P group had significantly higher fat content in milk than those of group H (53.7 vs. 61.5 g/day, p < 0.01), while lactose content was significantly higher for group H (66.2 and 61.4 g/day, for groups H and P, respectively, p < 0.05). Among milk fatty acids, pasture significantly affected the percentages of C18:1 cis9, C18:1 trans11, octadecadienoic acid, mono-unsaturated fatty acid and polyunsaturated fatty acid. Pasture highly influenced the c9 t11 conjugated linoleic acid (CLA) (0.778 and 0.513 g/100 g of fat, for group P and H, respectively, p < 0.01), t10 c12 CLA (0.046 vs. 0.029 g/100 g of fat: p < 0.01, for group P and H, respectively, p < 0.01) and SigmaCLA (0.84 vs. 0.56 g/100 g of fat for group P and H, respectively, p < 0.01) concentrations of milk.     

Performance and intestinal microbiota of chickens receiving probiotic in the feed and submitted to antibiotic therapy

The purpose of this study was to verify the ability of a probiotic in the feed to maintain the stability of the gut microbiota in chickens after antibiotic therapy and its association with growth performance. One thousand six hundred twenty 1‐day‐old Cobb male were housed in floor pens (36 pens, 45 birds/pen) and were fed corn‐/soya bean meal‐based diets supplemented with or without probiotic (Bacillus subtilis) during the entire rearing phase. From 21 to 24 days of age (three consecutive days), the chickens were submitted to antibiotic therapy via drinking water (bacitracin and neomycin) in order to mimic a field treatment and induce dysbiosis. Growth performance was monitored until 42 days of age. At 2, 4 and 6 days after antibiotic therapy, three chickens from each pen were euthanized and the contents of the small intestine and caeca were collected and pooled. The trial was conducted with four treatments and nine replicates in a 2 × 2 factorial arrangement for performance characteristics (with and without probiotic × with and without antibiotic therapy); for the intestinal microbiota, it was in a 2 × 2 × 3 factorial arrangement (with and without probiotic × with and without antibiotic therapy × 2, 4 and 6 days after the antibiotic therapy) with three replicates per treatment. Terminal restriction length polymorphism (T‐RFLP) analysis showed that the structure of gut bacterial community was shaped by the intestinal segment and by the time after the antibiotic therapy. The number of 16S rDNAs copies in caecum contents decreased with time after the therapeutic treatment. The antibiotic therapy and dietary probiotic supplementation decreased richness and diversity indexes in the caecal contents. The improved performance observed in birds supplemented with probiotic may be related to changes promoted by the feed additive in the structure of the intestinal bacterial communities and phylogenetic groups. Antibiotic therapy modified the bacterial structure, but did not cause loss of broiler performance.     

Chemical-nutritional characteristics of diets in aquaculture

After a brief discussion on the chemical-nutritional characteristics of the diets currently used in aquaculture, the authors focus attention on the problems associated with the replacement of fish meals with vegetable protein sources. The chemical composition of vegetable sources has a high variability and it is necessary to know the exact energy content and digestibility of amino-acids for each source. Another question is the occurrence of anti-nutritional factors in vegetable protein sources and their effect on diet palatability. The authors also underline that the use of high levels of vegetable sources increases the risk of contamination by mycotoxins of which the effects on the health of fish are not yet completely clear. Finally, brief considerations are reported on the relationship between the chemical-nutritional characteristics of diets and that of the resulting fish fillets.     

Leaf gas exchange, chloroplastic pigments and dry matter accumulation in castor bean (Ricinus communis L) seedlings subjected to salt stress conditions

Brazilian castor bean (Ricinus communis L) crops have expanded towards semiarid lands, in which soil salinity is an important factor limiting plant development. In order to evaluate the effects of salt stress on leaf gas exchange, pigments, and dry matter accumulation of seedlings, seeds of castor bean var. BRS Nordestina were planted in 15-L pots filled with 13 kg of soil (control) or with soil plus 2 g NaCl kg⁻¹ soil corresponding to 30 mM NaCl (salt treatment). Seedlings were grown under greenhouse conditions and the effects of salinity were assessed by measuring physiological parameters at 38 and 59 days after germination. Salt treatment induced decreases in leaf water potential at pre-dawn (ψ_pd, 42%), stomatal conductance to water vapor (g_s, 36%), and net carbon assimilation rate (A, 24%) only at 38 days after germination. At the same time, the values for transpiration rate were unchanged and the hydraulic conductance was increased (34%). After 59 days under hypersalinity, leaf ψ_pd increased to −0.44 MPa, although g_s, A, transpiration rate, and hydraulic conductance were not different between treatments. Salt stress effects on chlorophyll a, chlorophyll b and chlorophyll a + b contents were evident only on experimental day 59. The dry matter accumulation of leaves, roots and stems, as well as the total dry matter, and the root to above ground ratio increased with plant growth in both treatments, however, these parameters were lowered in salt-stressed seedlings. In short, all physiological variables were more drastically affected after 38 days under high salinity, and despite acclimatization of A after 59 days exposure to salt, no recovery of the dry matter accumulation was observed in the seedlings, suggesting that this species does not tolerate salt stress at its initial growth stages.     

南方典型水稻土长期试验下有机碳积累机制研究Ⅳ.颗粒有机质热裂解-气相-质谱法分子结构初步表征

采用热裂解-气相-质谱(Pyr-TMAH-GC/MS)技术对长期不同施肥处理下太湖地区黄泥土本体土壤及水稳性团聚体中颗粒有机碳(POC)的化学组分进行了研究。结果表明,POC的热裂解产物主要来源于脂肪族化合物和木质素类化合物。木质素类化合物主要以愈疮木基丙烷(G)和p-羟苯基(P)两种木质素单体为主,从而揭示黄泥土POC积累中草本植物(水稻、油菜的残茬和秸秆)的输入贡献。脂肪族化合物主要为C8-C30脂肪酸甲基酯(FAMEs),且大多为偶数碳结构。施肥改变了各裂解产物在本体土壤和水稳性团聚体中的分布,从而使得不同施肥处理下各类化合物对POC稳定性的贡献出现了差异。化肥配施猪粪下木质素类化合物以及微生物源的脂肪族化合物均贡献于本体土壤POC的积累与稳定,而化肥配施秸秆下本体土壤POC的化学稳定性主要归因于高等植物源化合物的贡献,其次为微生物源脂肪族化合物。化肥配施有机肥下水稳性团聚体中较高的POC主要归因于植物源有机物质的分解贡献。本研究揭示了合理施肥下水稻土中有机碳的化学抗性组分在土壤有机碳积累中的促进作用,各组分的相对分布差异可指示有机碳积累的不同来源。     

Water Quality of Aroeira River for Use in Irrigation of Vegetable Crops in the Northern Region of the State of Espirito Santo,Brazil

The aim of this study was to evaluate the physical, chemical and microbiological quality of the water of the Aroeira River in the city of Silo Mateus, northern region of Espirito Santo State, Brazil, from April 2012 to March 2013, for use in irrigation of vegetable crops. Five points were selected along the river for analysis of pH, chloride （mg/L C1-）, total hardness （mg/L CaCO3）, dissolved oxygen （mg/L O2）, ammoniacal nitrogen （mg/L N-NH3）, total iron （mg/L Fe）, phosphate/orthophosphate （mg/L PO43-）, turbidity （NTU）, acidity （mg/L CO2）, temperature （℃）, electrical conductivity （dS/m）, as well as microbiological and parasitological analyses. Only point l, located upstream of the points of domestic sewage discharges, is the closest to be considered suitable for use in irrigation of vegetable crop, demonstrating the possible risks to the health of populations who use water with sewage discharges in urban communities for irrigation of vegetable crops.     

Molecular characterization of compost at increasing stages of maturity. 1. Chemical fractionation and infrared spectroscopy

Composted organic biomasses at 60, 90, and 150 days of maturity were studied for changes in molecular composition. Compost samples were subjected to a mild sequential fractionation based on (1) organic solvent extraction, (2) transesterification with boron trifluoride in methanol (BF3-CH3OH), and (3) methanolic alkaline hydrolysis (KOH-CH3OH). The general chemical variations in compost residues following fractionation were monitored by DRIFT spectroscopy, whereas the molecular components separated along the fractionation steps were identified by GC-MS. DRIFT spectra suggested a progressive decrease of biolabile compounds such as alkyls, carbohydrates, and proteinaceous materials with compost maturity. Extraction of unbound components in an organic solvent indicated a considerable reduction of linear and branched alkanoic acids, both saturated and unsaturated, n-alkanes, and n-alkanols with enhancing compost maturity. Extracts of weakly bound molecules by transesterification revealed a decrease, with compost maturity, of components from more recalcitrant plant polyesters, such as omega-, di-, and trihydroxy acids, dioic acids, and n-alkanols. Extracts of strongly bound molecules by alkaline hydrolysis indicated a lower decrease of the same components, suggesting their reduced availability when in stable hydrophobic domains of progressively mature compost. The largest decrease in molecular components occurred when compost was stabilized from 60 to 90 days, whereas its composition did not significantly vary after stabilization at 150 days. The molecular structures of a number of steroids and terpenes appeared to be less susceptible to transformation with composting maturity, thereby resulting as useful biomarkers to trace the fate of composted organic matter in the environment. This work showed that a detailed molecular characterization of compost by a stepwise chemical fractionation enables the evaluation of compost maturity and origin of composted biomasses, as well as the identification of environmental tracers.     

Influence of land use on the characteristics of humic substances in some tropical soils of Nigeria

In highly weathered tropical conditions, soil organic matter is important for soil quality and productivity. We evaluated the effects of deforestation and subsequent arable cropping on the qualitative and quantitative transformation of the humic pool of the soil at three locations in Nigeria. Cultivation reduced the humic pool in the order: acetone‐soluble hydrophobic fraction (HE) > humic acid (HA) > humin (HU) > fulvic acid (FA), but not to the same degree at all three sites. The C and N contents, as well as the C/N ratios of humic extracts, were large and not substantially influenced by land use. The δ¹³C values of the humic extracts were invariably more negative in forested soils thereby showing a dilution of δ¹³C signature with cultivation from C3 to C4 plants. The δ¹³C values of apolar HE fractions were generally more negative, indicating a reduced sensitivity compared with other humic fractions to turnover of crop residues. The contents of hydrophobic constituents (alkyl and aromatic C), as revealed by cross‐polarization magic angle spinning (CPMAS) ¹³C‐NMR spectroscopy, in HA, FA and HU were generally < 50%, with the exception of larger hydrophobicity in HU in the forested soil at Nsukka and HA in that at Umudike. The HE fraction contained significantly more apolar constituents, and consequently had a larger intrinsic hydrophobicity than the other humic fractions. The larger reduction of apolar humic constituents than of the less hydrophobic humic fractions, when these soils were deforested for cultivation, indicates that at those sites the stability of accumulated organic matter is to be ascribed mainly to the selective preservation of hydrophobic compounds.