Investigation of the Potential Health Benefits as Lipase Inhibitor and Antioxidant of <Emphasis Type="Italic">Leopoldia comosa</Emphasis> (L.) Parl.: Variability of Chemical Composition of Wild and Cultivated Bulbs

There is a great interest in the nutritional value of vegetables and fruits and how the habitat affects nutritive and biological properties. In vitro studies here reported were performed to evaluate the inhibitory activity of formulations from edible plant on pancreatic lipase. The aim of this study was also to evaluate the biovariability of L. comosa (L.) Parl. bulbs from Italy. The wild bulbs were compared with the same cultivated species that are commonly commercialized to identify samples with the best quality for a potential therapeutic application. Hydroalcoholic extract and polar fraction of wild bulbs showed a very important pancreatic lipase inhibitory activity, with IC₅₀ values of 0.166 ± 0.005 and 0.153 ± 0.005 mg/mL, respectively. In order to characterize the extracts, gas chromatography associated with mass spectrometry (GC/MS) analysis was performed, revealing the predominance of palmitic acid. Phenolic and flavonoid composition was also evaluated. L. comosa extract obtained from wild bulbs demonstrated both antioxidant and anti-obesity activities that might be attributed to a wide range of present phenolic compounds.     

Light-stimulated 14CO2 uptake and acetylene reduction by bacteriochlorophyll containing stem nodule isolate BTAi 1

Summary Bradyrhizobial strain BTAi 1 nodulates both stems and roots of Aeschynomene spp. Previous work has shown that it contains bacteriochlorophyll a and forms photosynthetic reaction centers, and has provided indirect evidence of photosynthesis by bacteroids within stem nodules. Here we report physiological and biochemical characteristics of BTAi 1 ex planta, which also suggest the presence of photosynthetic activity. Light-stimulated uptake of ¹⁴CO₂ by BTAi 1 was detected at all stages of growth. Inhibitors of photosynthesis, 1,10-orthophenanthroline and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and the uncoupler NH₄Cl, immediately suppressed light-driven ¹⁴CO₂ uptake and increased O₂ uptake. BTAi 1 is strictly aerobic and was unable to grow without organic C even in the light; also, it was unable to grow chemoautotrophically in an atmosphere enriched with H₂ and CO₂. In micro-aerobic conditions, strain BTAi 1 expressed acetylene reducing activity ex planta in an N-free medium. The highest rates of light-stimulated ¹⁴CO₂ uptake and acetylene-reducing activity occurred during the exponential and early stationary phases of growth. Acetylene-reducing rates at a low glucose concentration were increased following a light-dark cycle in comparison with continuous dark conditions.     

Seasonal and interannual ecophysiological responses of beech (Fagus sylvatica) at its south-eastern distribution limit in Europe

Due to its wide European distribution and its drought-susceptibility, beech (Fagus sylvatica L.) received intensive attention recently in the light of global warming. Contrary to central European beech ecosystems, little is known about the ecophysiology of beech at its south-eastern European distribution limit. Here we tested whether climatic fluctuations during a three-year period affected the ecophysiology of a beech site in Greece. Attention was paid at comparing our findings to the intense effects the 2003 extreme drought had on beech forests in central Europe.     

Differences in common bean rhizobial populations associated with soil tillage management in southern Brazil

Progressive adoption of no-tillage (NT) agriculture in the tropics is finally reversing physical, chemical, and biological erosion of soil and in Brazil, an estimated 19 Mha are now devoted to NT. Common bean (Phaseolus vulgaris L.) is a main component of Brazilian agriculture, and enhancement of yields has been achieved under NT as a result of mitigation of environmental stresses, resulting in higher N₂ fixation. However, the effects of NT on rhizobial diversity are poorly understood. This study evaluated rhizobial diversity in soils planted to common bean under NT or conventional tillage (CT) systems that were compared with natural grassland used for grazing, in the State of Santa Catarina, southern Brazil. Genetic diversity was assessed by the amplification of the DNA by PCR with specific primers (BOX-PCR) and by RFLP-PCR analyses of the 16S rDNA region. A high level of diversity was observed among strains from all three systems, such that the similarity in the clustering analysis of BOX-PCR products ranged from 36% under natural grassland to only 23% for CT strains. High polymorphism was confirmed in the RFLP-PCR analysis; forty-seven different profiles were obtained, none sharing high similarity with the profiles of reference species of common bean rhizobia. These results indicate that other tropical rhizobial species remain to be described. Genetic diversity was higher among the NT than the CT rhizobial strains, especially when the RFLP-PCR profiles were considered. Genetic diversity in the natural grassland was lower than in the cropped systems, possibly due to absence of the host plant and stubble burning in winter. Average yields in the area under NT (e.g. common bean, approximately 1500 kg ha⁻¹) have been about 30% higher than under CT, therefore high rhizobial diversity may be a parameter indicative of superior soil quality.     

Relative efficiency,ureide transport and harvest index in soybeans inoculated with isogenic HUP mutants of Bradyrhizobium japonicum

Summary Differences between isogenic uptake hydrogenase (HUP) mutants of Bradyrhizobium japonicum in terms of nodule efficiency, N₂ fixation and N incorporation into various plant parts were studied in a monoxenic greenhouse experiment in order to confirm previous results with soybeans and beans inoculated with various HUP⁺ and HUP^– strains. The HUP+ revertant PJ17-1 of a HUP^– mutant (PJ17) of strain USDA DES 122 showed a completely restored relative efficiency (100% versus 78±2% for the HUP^– mutant), higher nodule efficiency (N₂ fixed per g nodules), higher ureide-N transport rates, higher N contents in pods and higher N harvest indices. All these observations confirm previous experiments with HUP⁺ and HUP^– strains.     

Site‐specific effects of variable water supply and nitrogen fertilisation on winter wheat

The plant‐available soil water, amount and distribution of rainfall or irrigation are primary factors that may affect yield and quality of winter wheat in heterogeneous fields. The objective of this 2‐y study was to vary N application and water supply in order to achieve a more mechanistic insight into the effects of underlying differences in the site‐specific productivity on heterogeneous fields. Two N fertilizer rates (120 and 180 kg N ha^–1) and three different water supply treatments (rain sheltering, irrigation, rain‐fed) were compared on field sites with lower or higher plant available soil water capacities. On the whole, the site, rather than rainfall or N fertilisation, was the primary factor that accounted for variability in grain yield. Rainfall distribution during the growing season affected the overall yield level in a given year. The sites characterised by lower plant available water capacity did not show higher grain yield and improved quality with the increased N rate. This suggests that the reduced N rate should be recommended on these sites to take into account the environmental sustainability of N fertilisation. With respect to the higher N application at sites of high plant available soil water capacity, although the already high yield levels were not increased further, the protein quality was significantly improved in the first season within all treatments and in the second season in the irrigated treatments. Therefore, a higher N‐rate proved to be advantageous, especially considering that the residual nitrate levels after harvest were low. The study demonstrated that the response of winter wheat to water shortage or abundance and N fertilisation is site‐specific and dependent on the availability of soil water.     

Co-inoculation of soybeans and common beans with rhizobia and azospirilla: strategies to improve sustainability

Plant–microorganism associations have long been studied, but their exploitation in agriculture partially or fully replacing chemical fertilizers is still modest. In this study, we evaluated the combined action of rhizobial and plant growth-promoting rhizobacteria inoculants on the yields of soybean and common bean. Seed inoculation with rhizobia (1.2?×?10⁶ cells seed^?1) was compared to co-inoculation with Azospirillum brasilense in-furrow (different doses) or on seeds (1.2?×?10⁵ cells seed^?1) in nine field experiments. The best in-furrow inoculant dose was 2.5?×?10⁵ cells of A. brasilense seed^?1 for both crops. Inoculation with Bradyrhizobium japonicum increased soybean yield by an average 222 kg?ha^?1 (8.4 %), and co-inoculation with A. brasilense in-furrow by an average 427 kg?ha^?1 (16.1 %); inoculation always improved nodulation. Seed co-inoculation with both microorganisms resulted in a mean yield increase of 420 kg?ha^?1 (14.1 %) in soybean relative to the non-inoculated control. For common bean, seed inoculation with Rhizobium tropici increased yield by 98 kg?ha^?1 (8.3 %), while co-inoculation with A. brasilense in-furrow resulted in the impressive increase of 285 kg?ha^?1 (19.6 %). The cheaper, more sustainable inoculated treatment produced yields equivalent to the more expensive non-inoculated + N-fertilizer treatment. The results confirm the feasibility of using rhizobia and azospirilla as inoculants in a broad range of agricultural systems, replacing expensive and environmentally unfriendly N-fertilizers.     

Bioassays and application of olive pomace compost on emmer: effects on yield and soil properties in organic farming

Abstract

Composting olive oil pomace could solve the problem of disposal, by recycling this organic waste for agricultural purposes. Furthermore, application of composted organic waste could be a way to sustain both soil fertility and production, especially in organic farming. Therefore, the aim of this research was to evaluate the phytotoxicity and the effects of application of olive pomace composts on emmer performance and soil properties. Two types of olive pomace composts, with a different initial C/N ratio, were stopped at the active phase and processed until maturation. The obtained four olive pomace composts were compared with a commercial fertilizer in a two-year field experiment. Before the field trial, a bioassay was performed to assess phytotoxicity both for the raw pomace and the not-stabilized composts. Growing and yielding data for emmer were determined during the two-year period and soil characteristics were measured at the start and at the end of the experiment.

The composts were not phytotoxic (germination index was higher than 90%) and their total organic carbon content was always higher than the minimum values established by the Italian fertilizers legislation. The emmer protein content was significantly higher in the matured compost treatment with low C/N, than in the other compost treatments. Its value was comparable with that of the commercial fertilizer, suggesting a good performance on crop yield quality. Although not significant, this compost showed an increase of 9.8% in grain yield compared with commercial fertilizer treatment. On the whole, it can be suggested that repeated compost application might preserve the soil organic carbon content and supply macronutrients to a crop.     

Soil microbial activity and crop sustainability in a long-term experiment with three soil-tillage and two crop-rotation systems

Reduction in soil disturbance can stimulate soil microbial biomass and improve its metabolic efficiency, resulting in better soil quality, which in turn, can increase crop productivity. In this study we evaluated microbial biomass of C (MB-C) by the fumigation-extraction (FE) or fumigation-incubation (FI) method; microbial biomass of N (MB-N); basal respiration (BR) induced or not with sucrose; metabolic quotient (obtained by the ratio BR/MB-C) induced (qCO₂(S)), or not with sucrose (qCO₂); and crop productivity in a 14-year experiment in the state of Paraná, southern Brazil. The experiment consisted of three soil-tillage systems [no-tillage (NT), conventional tillage (CT) and no-tillage using a field cultivator every 3 years (FC)] and two cropping systems [a soybean–wheat-crop sequence (CS), and a soybean–wheat–white lupin–maize–black oat–radish crop rotation (CR)]. There were six samplings in the 14th year, starting at the end of the winter crop (wheat in the CS and lupin in the CR plots) and finishing at full flowering of the summer crop (soybean in the CS and maize in the CR). Differences in microbiological parameters were greater than those detected in the total C (TCS) and total N (TNS) contents of the soil organic matter (SOM). Major differences were attributed to tillage, and on average NT was higher than the CT in the following parameters: TCS (19%), TNS (21%), MB-C evaluated by FE (74%) and FI (107%), and MB-N (142%). The sensibility of the microbial community and processes to soil disturbance in the tropics was highlighted, as even a moderate soil disturbance every 3 years (FC) affected microbial parameters but not SOM. The BR was the parameter that most promptly responded to soil disturbance, and strong differences were perceived by the ratio of qCO₂ evaluated with samples induced and non-induced with sucrose. At plowing, the qCO₂(S):qCO₂ was five times higher under CT, indicating a C-starving low-effective microbial population in the C-usage. In general, crop rotation had no effect on microbial parameters or SOM. Grain yield was affected by tillage and N was identified as a limiting nutrient. Linear regressions between grain yields and microbial parameters showed that soybean was benefited from improvements in the microbial biomass and metabolic efficiency, but with no significant effects observed for the maize crop. The results also indicate that the turnover of C and N in microbial communities in tropical soils is rapid, reinforcing the need to minimize soil disturbance and to balance inputs of N and C.