Denitrification from an irrigated soil fertilized with pig slurry under Mediterranean conditions   总被引：3，自引：0，他引：3  

Vallejo  Antonio  Díez  José A.  López-Valdivia  Luís M.  Cartagena  María C.  Tarquis  Ana  Hernáiz  Pedro 《Biology and Fertility of Soils》2004,40(2):93-100

Under a Mediterranean climate, denitrification losses were quantified for 2 years on a sandy loam soil with an irrigated maize crop. The effect of pig slurry application at two different rates (165 and 495 kg N ha^–1, respectively, for PS1 and PS3) was compared with that of urea (U) applied at 165 kg N ha^–1 and with a control treatment (P0) without fertilizer. After application, the denitrification rate (DR) increased in PS1 and PS3 respect to P0 and decreased to the levels of the control treatment after 5 days. In July and August (the irrigation period) the DR increased considerably in all treatments with maximum values for the PS3 treatment (0.134 g N m^–2 day^–1 in the first year and 0.147 g N m^–2 day^–1 in the second year). The differences in DRs between each treatment could be explained by the pattern of water filled pore space, NO₃^– concentration of the soil solution and the soil temperature during the maize growing season. In the first year denitrification losses in the 0–10 cm layer were 1.90, 2.49, 2.87 and 4.00 g N m^–2 for P0, U, PS1 and PS3, respectively, while in the second year the losses were 1.21, 2.28, 2.47 and 3.42 g N m^–2. Finally, a simple predictive model (SOILN) was evaluated and found to give acceptable results.  相似文献   

Tree species composition and similarity in semideciduous forest fragments of southeastern Brazil     

Karin dos Santos  Luiza Sumiko Kinoshita 《Biological conservation》2007,135(2):268-277

This study investigates the influence of fragment size on tree species composition, species richness and on individual groups of species within 11 semideciduous forest fragments in southeastern Brazil. We compared same-sized samples of 500 trees from 10 fragments <100 ha, allocated to three size categories, with three 500-tree samples collected in different areas within a large forest, used as a reference forest. The variation in species richness, in the proportion of species/individuals in dispersal modes, and in the proportion of rare species was not related to fragment size. Nonetheless, comparisons between the mean values of these variables of each fragment size categories, using 95% confidence intervals, showed a wider range of variation within the category of small-sized fragments than in the other size categories. NMS ordination plot also suggested the absence of a relationship between fragment area and tree species composition. However, multiple regressions using the scores from the NMS ordination as response variables, and area and disturbance intensities as predictor variables, suggested that the interaction of area and disturbance might be a good predictor of species composition. Pre-existing environmental heterogeneity and geographical proximity also appeared to play a role in the variations of forest composition among the fragments studied. Our results demonstrated the high conservation value of small forest fragments.  相似文献   

Sweet basil (Ocimum basilicum L.) and potassium fertilization     

Bihter Çolak Esetlili  Bintuğ Öztürk  Özgür Çobanoğlu  Dilek Anaç 《Journal of plant nutrition》2016,39(1):35-44

The objective of the present study was to examine the effect of potassium (K) fertilization and soil texture on total yield (1st and 2nd cuttings) and yield components of sweet basil (Ocimum basilicum L.) A greenhouse pot experiment was conducted in a completely randomized statistical design. Basil growth was examined in two different textured soils under three different doses of K fertilization. Generally, for the basil grown under clay soil conditions, moderate amounts of K fertilization is proposed to be sufficient if higher linalool contents are wanted. However, if the growing conditions are sandy loam in texture, it is suggested that higher doses of K be used. Results also highlighted the contribution of second cut as an important cultural practice in the cultivation of an annual basil.  相似文献   

Characteristics of maize flour tortilla supplemented with ground Tenebrio molitor larvae.     

Erick D Aguilar-Miranda  Mercedes G López  Clara Escamilla-Santana  Ana P Barba de la Rosa 《Journal of agricultural and food chemistry》2002,50(1):192-195

The larva of the Tenebrio molitor, known as the yellow meal worm, is a plague of wheat and flours. Consumption of the raw insects is not well accepted because of their appearance. The objective of the present work was to grow T. molitor larvae under standard conditions, to analyze the chemical composition of the larvae powder, and to prepare supplemented maize tortillas. Protein and fat contents were performed with standard methods. Tenebrio larvae powder had a 58.4% protein content; this protein was rich in essential amino acids such as phenylalanine, tyrosine, and tryptophan; the found values satisfied those recommended by the Food and Agriculture Organization. Fatty acid composition was determined by GC-MS showing high contents of oleic acid and linoleic acid (19.8 and 8.51%, respectively). A large proportion of unsaturated fatty acids of longer chains was detected. Long-chain fatty acids having two or three double bonds have been claimed as highly beneficial to health. Tortillas supplemented with larvae powder had excellent consumer acceptance, and tortilla protein content increased by 2% as well as the amount of essential amino acids. These results show new ways to consume insects and at the same time increase the nutritional value of the original food products.  相似文献   

Optimization of solid-state enzymatic hydrolysis of chestnut using mixtures of alpha-amylase and glucoamylase     

López C  Torrado A  Guerra NP  Pastrana L 《Journal of agricultural and food chemistry》2005,53(4):989-995

Solid-state hydrolysis of starch present in chestnut was assayed in a single step with a mixture of a thermostable alpha-amylase and glucoamylase at three temperatures: 17 and 30 degrees C, for simultaneous hydrolysis and ethanol fermentation, and 70 degrees C, the optimal temperature for these enzymes. Total hydrolysis was only reached at the highest temperature, leading to a more concentrated hydrolysate than in submerged hydrolysis. Mass transfer limitations and starch retrogradation appear as the main causes for the incomplete hydrolysis of chestnut starch in solid-state operation at 17 and 30 degrees C. Even accepting that this limitation causes a 15% reduction of the yield of the hydrolysis with respect to the submerged process or the solid process at high temperature, solid-state hydrolysis at low temperatures seems to be adequate for simultaneous solid-state hydrolysis and fermentation processes.  相似文献   

A Potato Collecting Expedition in the Province of Jujuy,Argentina and Disease Indexing of Virus and Fungus Pathogens in Andean Cultivars     

Andrea?M.?ClausenEmail author  Mónica?Colavita  Iván?Butzonitch  Ana Valeria?Carranza 《Genetic Resources and Crop Evolution》2005,52(8):1099-1109

A potato collecting expedition was carried out in the province of Jujuy, Argentina in March 24 to April 15, 2001. The objective was to collect local cultivars of potatoes and wild potato species, covering high mountain valleys not previously collected or areas where germplasm was not available. A total of 247 accessions was collected, 188 cultivated accessions of S. tuberosum subsp. andigenum, four of Solanum tuberosum subsp. tuberosum, two of S. curtilobum and 53 accessions of wild species. The wild species collected were S. acaule subsp. acaule, S. chacoense, S. infundibuliforme, S. megistacrolobum subsp. megistacrolobum, S. microdontum, S. gourlayi, S. × viirsooi and S. oplocense. Herbarium voucher specimens were obtained when possible. For the collection of cultivated potatoes, tubers were gathered from farmer's fields and in a few cases from stores or markets. Seed samples were generally obtained for the wild species. Detailed collection site data were recorded at every site. After breaking dormancy, the accessions of the cultivated species were screened for the presence of Potato virus Y (PVY), Potato virus X (PVX), Potato leafroll virus (PLRV), Potato virus S (PVS), Potato virus M (PVM), Potato virus V (PVV), Andean potato latent virus (APLV), Andean potato mottle virus (APMoV), Potato rough dwarf virus (PRDV), Potato spindle tuber viroid (PSTVd) and Spongospora subterranea f. sp. subterranea. PSTVd, APLV and PRDV were not detected, but different levels of infection are reported for the other pathogens assayed.  相似文献   

Downed logs improve soil properties in old-growth temperate forests of northern Iran     

Negar MOGHIMIAN  Seyed Gholamali JALALI  Yahya KOOCH  Ana REY 《土壤圈》2020,30(3):378-389

Dead trees, particularly downed logs, play an important role in the dynamics of forest ecosystem. Contribution of decaying wood to C and nutrient pools of forest soils depends on the tree species and degree of wood decay. However, the extent to which the downed logs affect the soil properties of temperate forests has rarely been evaluated. In this study, a mixed beech forest was selected in Liresar region of Mazandaran Province, northern Iran, to investigate if and how the presence of downed logs affected soil quality and function by comparing soils underneath degraded logs and nearby soils of the two dominant tree species(beech and hornbeam). We then explored how these effects occurred as downed logs decomposed by comparing the woods of both tree species at four degrees of decomposition. Degree of decay of downed logs was classified into four classes(DC1–DC4). Eight dead trees of each tree species were selected at the center of each sample plot. Three composite soil samples underneath each decaying log and 100 cm away from a decaying log were collected at two soil depths(0–15 and 15–30 cm) to analyze soil main physicochemical properties and microbial activity. The results revealed that downed logs affected soil physical(5% wetter than control soils), chemical(2% lower pH, 100% increase in organic C and total N in the case of hornbeam, and 2% increase in P), and biological characteristics(soil microbial respiration enhanced by 10%, and microbial biomass C 620 and 351.5 mg kg~(-1) and microbial biomass N 66.47 and 32.18 mg kg~(-1), respectively, in the cases of beech and hornbeam), thus resulting in significantly different soil microsites from those without downed logs. Presence of downed logs increased soil microbial activity and soil fertility as wood decayed. Thus, the presence of downed logs is an important factor influencing forest soils and should be taken into consideration in forest management practices.  相似文献   

Antioxidant properties of prepared blueberry (Vaccinium myrtillus) extracts   总被引：3，自引：0，他引：3  

Faria A  Oliveira J  Neves P  Gameiro P  Santos-Buelga C  de Freitas V  Mateus N 《Journal of agricultural and food chemistry》2005,53(17):6896-6902

A blueberry extract (A) and two anthocyanin-derived extracts (B and C) were prepared. The contents of polyphenols, flavonoids, anthocyanins, and anthocyanin-derived pigments of the extracts were determined for the first time. The pigment profile of blueberry extract A corresponded to 15 anthocyanins, whereas extract B was mainly composed of anthocyanin-pyruvic acid adducts of the blueberry original anthocyanins and extract C was mainly composed of the respective vinylpyranoanthocyanin-catechins (portisins). The extracts' abilities to inhibit lipid peroxidation, induced by 2,2'-azobis(2-methyl-propanimidamide) dihydrochloride in a liposomal membrane system were examined. The antioxidant capacities of the extracts were evaluated through monitoring oxygen consumption and by measuring the formation of conjugated dienes. All of the extracts provided protection of membranes against peroxyl radicals by increasing the induction time of oxidation. This effect increased with the polyphenol content and with the structural complexity of the anthocyanin-derived pigments of the extracts. The pigments present in extract C seemed to induce a higher protection of the liposome membranes toward oxidation. In addition, the antiradical properties and the reducing power of the extracts were determined by using DPPH and FRAP methods, respectively. The results from these assays were in agreement with those obtained with the liposome membranes.  相似文献   

The use of artificial breeding chambers as a conservation measure for cavity-nesting procellariiform seabirds: a case study of the Madeiran storm petrel (Oceanodroma castro)     

Mark Bolton  Renata Medeiros  Becky Hothersall  Ana Campos 《Biological conservation》2004,116(1):73-80

Procellariiform seabirds are amongst the most severely threatened taxa worldwide. Whilst the specific threats vary among species, problems such as introduced predators, loss of suitable nesting habitat and inter- and intra-specific competition for nest sites are common to many situations. This paper reports on an experiment to increase the availability of secure nest sites at a colony of Madeiran storm petrels breeding on an islet (free from introduced predators) in the Azores islands where there is evidence of inter-specific competition. The provision of nest boxes that were designed to exclude larger species led to around a 12% increase in the size of the breeding population in the first year and a 28% increase over the original colony size in the second year. Over three seasons, the breeding success of storm petrels nesting in boxes averaged 2.9 times greater than that of birds at natural sites, despite their likely reproductive inexperience. The techniques presented here should serve as a model for conservation management of other burrowing procellariiform species in situations where colony size or breeding performance is believed to be constrained by nest site quality.  相似文献   

Effect of household processing and unit-to-unit variability of pyrifenox, pyridaben, and tralomethrin residues in tomatoes   总被引：3，自引：0，他引：3  

Boulaid M  Aguilera A  Camacho F  Soussi M  Valverde A 《Journal of agricultural and food chemistry》2005,53(10):4054-4058

Residue levels of pyrifenox, pyridaben, and tralomethrin were determined in unprocessed and processed tomatoes, grown in a experimental greenhouse, to evaluate the effect of three different household processes (washing, peeling, and cooking) and the "unit to unit" variability of these pesticides in tomatoes. The study was carried out on 11 greenhouse tomato samples collected during a 5 week period in which two successive treatments with the studied pesticides were applied. Residue levels in unprocessed and processed tomato samples were determined by means of ethyl acetate extraction and gas chromatography-electron capture detection determination. The washing processing factor results were 0.9 +/- 0.3 for pyridaben, 1.1 +/- 0.3 for pyrifenox, and 1.2 +/- 0.5 for tralomethrin, whereas the peeling processing factors were 0.3 +/- 0.2 for pyridaben and 0.0 +/- 0.0 for both pyrifenox and tralomethrin. The average loss of water in the tomato pure samples during the cooking process was approximately 50%; the cooking processing factors were 2.1 +/- 0.8 for pyridaben, 3.0 +/- 1.1 for pyrifenox, and 1.9 +/- 0.8 for tralomethrin. The unit-to-unit variability factors were determined on three different greenhouse samples analyzing 10 different units of unprocessed tomatoes from each sample. In all cases, the unit-to-unit variability factor results were within the range of 1.3-2.2.  相似文献