Dynamic oxygen mapping in the root zone by fluorescence dye imaging combined with neutron radiography

Purpose  

The rooted zone of a soil, more precisely the rhizosphere, is a very dynamic system. Some of the key processes are water uptake and root respiration. We have developed a novel method for measuring the real-time distribution of water and oxygen concentration in the rhizosphere as a biogeochemical interface in soil. This enables understanding where and when roots are active in respect to root respiration and water uptake and how the soil responds to it.     

基于SIRMOD模型的畦灌入渗参数估算及灌溉模拟

土壤入渗参数是地面灌溉中制定灌溉制度、评价灌水质量的重要指标。针对现有估算方法存在计算工作量较大、精度不高的现状,根据田间实测资料,利用SIRMOD模型,对小麦畦灌条件下田间土壤入渗参数进行了估算。与用Maheshwari法计算结果较为接近,差异均在2.0%以内。根据估算的土壤入渗参数,应用SIRMOD模型进行了多组合灌溉模拟,在保证灌水质量较高的条件下,得出了在不同亏缺水量时的适宜灌水量和灌水流量,通过田间实例验证表明模拟效果较好。     

Changes in sorghum production,soil P forms and P use efficiency following long-term application of manure,compost and straw in a Ferric Lixisol

Low phosphorus availability in cultivated soils limits sustainable crop production in sub‐Saharan Africa. This study aimed at evaluating the effect of long‐term application of different types of organic amendments on soil P forms, P use efficiency and sorghum yields. A long term experiment established in 1980 at Saria in Burkina Faso, comparing the effects of manure, compost and sorghum straw was used. Manure and compost significantly increased organic P and resin‐P by about 35% and 64%, respectively after 10 and 32 years of sorghum cultivation, and HCl‐P after 32 years of cultivation compared to the control. Manure significantly increased NaHCO₃-Pi and NaOH-Pi by 63% and 26%, respectively compared to the control. Sorghum straw had little effect on measured soil P forms. Manure and compost were the best in increasing sorghum grain yield, which effect were strongly correlated to soil pH, carbon and nitrogen. The partial factors productivities of P resulting from the application of studied organic amendments were similar and low, but significantly higher than that of the control treatment. Organic amendments with high P content, maintaining soil carbon and pH could be used to improve soil P availability, sorghum yield and reduce the demand for mineral phosphorus fertilizers.     

Weed abundance and soil seedbank responses to tillage systems in continuous maize crops

Weed abundance in crops undergoes frequent changes, often due to changes in tillage practices. Annual species, with quick germination, a short vegetative stage, profuse seed production and long-lived seeds become problematic under zero-tillage systems. Portulaca oleracea L. and Amaranthus blitoides L. are widespread weeds in the Mediterranean area, prominent in irrigated crops. We studied the total weed abundance in the field, and specifically these two species (Portulaca oleracea and Amaranthus blitoides) with high frequency of occurrence in monoculture maize, from 2012 to 2014, in the field and soil seedbank. Results showed significant differences between zero-tillage (ZT) and conventional tillage (CT) systems on total weed abundance and relative abundance of Portulaca oleracea. Total weed abundance decreased in ZT plots (from 136 plants m^?2 to 25 and 46 plants m^?2, in 2013 and 2014 respectively). The same trend was observed in Portulaca oleracea recorded in ZT plots, but the abundance of Amaranthus blitoides did not vary in this system. Weed seedling germination and weed seed numbers both of total weed seedbank and Portulaca oleracea, were greater in ZT plots compared to CT, regarding Amaranthus blitoides seedling germination and seed count, the values did not increase with ZT, in continuous maize crops.     

Effects of binder type and binder addition on the growth of juvenile Palaemonetes varians and Palaemon elegans (Crustacea: Palaemonidae)

This investigation compared the effects of using two binders of no nutritional value, lignosol and agar, and the binding method, microbinding and microcoating, on the growth of juvenile Atlantic ditch shrimp, Palaemonetes varians, and rockpool prawn, Palaemon elegans. Shrimp were fed one basal diet which varied solely in binder type and method of inclusion (Diet A, with lignosol added by microbinding, Diet B, with agar added by microbinding, and Diet C with lignosol added by microcoating) for a period of 45 days. At the end of the experiment significant differences in the final wet weight were found between shrimps fed Diet A and Diet C and between shrimps fed Diet B and Diet C (P < 0.001), but no significant differences were found between Diet A and Diet B (P > 0.05). These results were verified for both species. Significant differences were found between the linear regression slopes of the three tested diets for P. varians (F _3,411 = 3.41; P < 0.04), and for P. elegans (F _3,431 = 10.51; P < 0.0003). Palaemon elegans grew faster than P. varians and at the end of the experiment significant differences were found between the final wet weight of the two species (F _3,842 = 48.17, P < 0.0001). The growth parameters analysed, weight gain (WG), thermal-unit growth coefficient (TGC), and food conversion rate (FCR) were always higher for P. elegans. Results indicate that use of either lignosol or agar, added to the diet by microbinding, is advisable.     

Soil organic carbon fractions and humic substances are affected by land uses of Caatinga forest in Brazil

Caatinga is a Brazilian dry ecosystem that occupies around 1 million km² and is one of the largest tropical dry forests of the world. About 46% of the area that was originally covered has been deforested. Land use can cause pronounced reduction in soil carbon stocks that play a major role in the global carbon cycle. The objective of this study was to improve our understanding of the effect of land use on oxidizable carbon fractions, total carbon stocks and humic substances in different layers of soil in a Brazilian semi-arid region. We analyzed soils from tropical dry forest (TDF), forest succession with Anadenanthera falcata (ANA), with Tabebuia alba (TAB), secondary scrubby regeneration (SCR), and non-irrigated maize (MS). Forests showed larger fractions of more labile carbon, except for TDF. The most recalcitrant fraction of carbon stock, humin fraction stock, with the different land use decreased by 38–53% compared to TDF. Oxidizable carbon fractions, carbon stocks, and humic fraction stocks were able to differentiate the successional land uses and agricultural cover from TDF, mainly in the 0–5?cm layer. Our results show that changes in land use, especially with ANA forest succession, showed a larger labile carbon fraction, indicating easy decomposition and loss. Our results provide an alternative tool for the management of deforested areas in tropical dry caatinga ecosystems. This would contribute to the conservation of dry forest systems and could serve as guideline for sustainable management of agriculturally impacted caatinga areas.     

Properties of deamidated gluten films enzymatically cross-linked

Films were prepared at neutral pH from deamidated gluten by casting with or without enzymatic treatment by transglutaminase in the presence of various concentrations of diamines added to the film-forming solution. Variation in the glycerol/deamidated gluten ratio from 0.2 to 0.5 had a major effect on the film mechanical properties, which is characteristic of a plasticizing effect. A ratio of 0.35, producing a tensile strength of 1.14 +/- 0.12 MPa and an elongation at break of 376 +/- 62%, was chosen for most of the enzymatic modifications. The action of transglutaminase with or without the addition of external diamines induced a simultaneous increase in tensile strength and elongation at break of the films but tended to decrease the contact angle between the film surface and a water droplet. The presence of diamines in the film solution affected the elongation at break more than the tensile strength of the films. These diamines, able to react at their two extremities, probably acted as spacers between gluten proteins. The decrease in solubility was related to the formation of high molecular weight polymers in the film. The film properties were unaffected by the type of diamine added as secondary substrate in the transglutaminase reaction.     

Evidence of the glycation and denaturation of LTP1 during the malting and brewing process

The influence of malting and brewing processes on the chemical and structural modifications occurring on LTP1 was investigated by mass spectrometry and circular dichroism. Proteins were first purified from malt, and samples were collected at various steps of beer processing performed on two barley cultivars. The levels of LTP1 found in malt were not significantly different from the amounts in barley seed. However, in malt, both LTP1b, a post-translational form of LTP1, and a third isoform named LTP1c were isolated. Moreover, both of these proteins were found to be heterogeneously glycated but still exhibited an alpha-helix structure. Both glycated LTP1 and LTP1b were recovered during mashing. It was also shown that glycated LTP1 was unfolded during heat treatment of wort boiling, which is in agreement with the denatured form previously isolated from beer.     

Molecular characterization and PCR detection of a nitrogen-fixing Pseudomonas strain promoting rice growth

Nitrogen-fixing plant growth-promoting rhizobacteria (PGPR) from the genus Pseudomonas have received little attention so far. In the present study, a nitrogen-fixing phytohormone-producing bacterial isolate from kallar grass (strain K1) was identified as Pseudomonas sp. by rrs (16S ribosomal RNA gene) sequence analysis. rrs identity level was high with an uncharacterized marine bacterium (99%), Pseudomonas sp. PCP2 (98%), uncultured bacteria (98%), and Pseudomonas alcaligenes (97%). Partial nifH gene amplified from strain K1 showed 93% and 91% sequence similarities to those of Azotobacter chroococcum and Pseudomonas stutzeri, respectively. The effect of Pseudomonas strain K1 on rice varieties Super Basmati and Basmati 385 was compared with those of three non-Pseudomonas nitrogen-fixing PGPR (Azospirillum brasilense strain Wb3, Azospirillum lipoferum strain N4 and Zoogloea strain Ky1) used as single-strain inoculants. Pseudomonas sp. K1 was detected in the rhizosphere of inoculated plants by enrichment culture in nitrogen-free growth medium, which was followed by observation under the microscope as well as by PCR using a rrs-specific primer. For both rice varieties, an increase in shoot biomass and/or grain yield over that of noninoculated control plants was recorded in each inoculated treatment. The effect of Pseudomonas strain K1 on grain yield was comparable to those of A. brasilense Wb3 and Zoogloea sp. Ky1 for both rice varieties. These results show that nitrogen-fixing pseudomonads deserve attention as potential PGPR inoculants for rice.     

Food consumption patterns in an adult urban population in Beirut, Lebanon

OBJECTIVES: To investigate, measure and assess the food consumption pattern of the adult population living in Beirut, Lebanon, and to identify inadequate or excessive intake of food groups particularly linked to non-communicable diseases. DESIGN: A cross-sectional food consumption survey was conducted in 2001. Dietary habits were assessed by means of a quantitative food-frequency questionnaire. SETTING: Dietary survey of the urban population (Beirut). SUBJECTS: Random sample of 444 adult subjects (aged 25-54 years) in Beirut. RESULTS: The mean consumption of food by the study population was estimated to be 3,030 g day(-1), providing an energy intake of 2,523.57 kcal day(-1). Fat contributed 38.9% to the average daily energy intake, protein 13.4% and carbohydrates 47.2%. Mean consumption of fruits and vegetables was approximately 367 g day(-1) and 45.3% of subjects consumed less than the recommended 400 g daily. Cereals contributed 324.5 g day(-1), providing 35.0% of daily energy intake, with bread being the most highly consumed (146.2 g day(-1)) in this food group. The mean intake of meat and poultry products was 91.7 g day(-1) and provided 8.8% of daily energy intake, with consumption of butchery products especially beef being the highest (47.6 g day(-1)) followed by poultry (36.1 g day(-1)). A low consumption of fish was noted (19.7 g day(-1)), with 73.6% of subjects consuming less than the recommended 2 servings of fish per week. Dairy products contributed 243.1 g day(-1) or 10.9% of daily energy intake, and milk was the least consumed dairy product (56.8% of consumers). The intake of added fats and oils, excluding those in cooked recipes, was 20.4 g day(-1); olive oil was not used in cooking but was added solely at the table and its mean intake was 5 g day(-1). The consumption of butter was low (0.86 g day(-1)) and vegetable oil was the type of fat mostly used in cooking. The average intake of alcoholic beverages was low (33.6 g day(-1)), accounting for 0.7% of total energy intake. Women had significantly higher intakes of milk, dairy products, vegetables and coffee than men (P < 0.05). The percentage of women who reported the use of low-fat items was significantly higher than that of men. Younger people (25-34 years) ate significantly more meat, sugar, alcoholic beverages and soft drinks, and consumed significantly less cooked vegetables and legumes, than older ones (P < 0.05). CONCLUSIONS: The rather high contribution of fat to daily energy intake, the low intake of fish and the relatively high percentage of people consuming less than the recommended amount of fruits and vegetables observed in this study suggest that the adult Lebanese population is at increased risk of cardiovascular diseases, obesity and other non-communicable diseases, which provides the basis for recommending increased intakes of fish, particularly fatty fish, and fruits and vegetables.