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Very little information is available for Mediterranean areas about the soil N dynamics and crop N use efficiency during the transition phase from conventional tillage (CT) to no-tillage (NT). Hence, a 2-yr experiment was conducted under semiarid Mediterranean conditions in three sites to study how soil N dynamics, crop N uptake, grain yield, and N use efficiency vary with N-fertilization rate and crop genotype in the switch year from CT to NT. Treatments consisted of two tillage systems (CT and NT), five N-fertilization rates (0, 40, 80, 120, and 160 kg N ha−1), and two durum wheat (Triticum durum Desf.) genotypes (one modern variety and one old landrace). Irrespective of the genotype, NT reduced compared to CT both wheat N uptake and grain yield under low soil N availability. The greater soil N supply under CT was the main reason for this outcome, so much so that the differences between CT and NT for these traits gradually decreased with the increase of N fertilization rate, practically disappearing at 80 kg N ha−1). The analysis of the N use efficiency components corroborated this hypothesis showing clearly that the yield advantage observed in CT depended mainly on the increase in N supply in soil under CT than NT condition. The two wheat genotypes responded similarly to varying soil tillage system. However, the adverse effects of NT practice were more evident in the modern variety than the old landrace. This study ultimately indicates that in the Mediterranean areas the switch year from CT to NT regime is rather delicate. Given that the lack of soil cultivation considerably reduces the soil N availability, hence, using NT technique alone as a substitute for CT is not agronomically feasible. Instead, an optimal application of NT is achievable by acting simultaneously on other factors of the cropping management, particularly the N-fertilization strategy, to maximize the crop N use efficiency and increase crop yield, which are essential requirements for a more sustainable agriculture.

Collateral arteries bridge opposing artery branches, forming a natural bypass that can deliver blood flow downstream of an occlusion. Inducing coronary collateral arteries could treat cardiac ischemia, but more knowledge on their developmental mechanisms and functional capabilities is required. Here we used whole-organ imaging and three-dimensional computational fluid dynamics modeling to define spatial architecture and predict blood flow through collaterals in neonate and adult mouse hearts. Neonate collaterals were more numerous, larger in diameter and more effective at restoring blood flow. Decreased blood flow restoration in adults arose because during postnatal growth coronary arteries expanded by adding branches rather than increasing diameters, altering pressure distributions. In humans, adult hearts with total coronary occlusions averaged 2 large collaterals, with predicted moderate function, while normal fetal hearts showed over 40 collaterals, likely too small to be functionally relevant. Thus, we quantify the functional impact of collateral arteries during heart regeneration and repair–a critical step toward realizing their therapeutic potential.

Cell-free RNA from liquid biopsies can be analyzed to determine disease tissue of origin. We extend this concept to identify cell types of origin using the Tabula Sapiens transcriptomic cell atlas as well as individual tissue transcriptomic cell atlases in combination with the Human Protein Atlas RNA consensus dataset. We define cell type signature scores, which allow the inference of cell types that contribute to cell-free RNA for a variety of diseases.

Microplastic contamination, like other global change factors, can induce effects on ecosystem functions and processes, affecting various soil biophysical properties. However, effects of such contaminants on nutrient cycles in agroecosystems are still poorly understood. We here performed two pot experiments to investigate the effect of polyester microplastic fibers (PMFs) on soil physical properties, nitrogen cycle, and plant performance in a maize-based agroecosystem. Moreover, we followed the N loss via leaching in soil contaminated or not with PMFs by simulating heavy rainfall events that mimic a future scenario of climate change. Our results show that soil contaminated with PMFs (at a concentration of 0.5% w/w) can jeopardize agroecosystem sustainability by affecting soil physical properties and in particular soil macro- and microporosity, the nitrogen cycle, and plant performance. In particular, we found that soil PMF contamination limited crop growth and N uptake by circa 30%, and consequently increased N loss via leaching. Overall, our findings show that soil contamination with PMFs may pose problems to future agricultural challenges like food security and environmental protection.

Many aspects concerning the role of arbuscular mycorrhizal (AM) fungi in plant nutrient uptake from organic sources remain unclear. Here, we investigated the contribution of AM symbiosis to N and P uptake by durum wheat after the addition of a high C:N biomass to a P-limited soil. Plants were grown in pots in the presence or absence of a multispecies AM inoculum, with (Org) or without (Ctr) the addition of 15N-labelled organic matter (OM). A further treatment, in which 15N was applied in mineral form (Ctr+N) in the same amount as that supplied in the Org treatment, was also included. Inoculation with AM had positive effects on plant growth in both control treatments (Ctr and Ctr+N), mainly linked to an increase in plant P uptake. The addition of OM, increasing the P available in the soil for the plants, resulted in a marked decrease in the contribution of AM symbiosis to plant growth and nutrient uptake, although the percentage of mycorrhization was higher in the Org treatment than in the controls. In addition, mycorrhization drastically reduced the recovery of 15N from the OM added to the soil whereas it slightly increased the N recovery from the mineral fertiliser. This suggests that plants and AM fungi probably exert a differential competition for different sources of N available in the soil. On the whole, our results provide a contribution to a better understanding of the conditions under which AM fungi can play an effective role in mitigating the negative effects of nutritional stresses in plants. Supplementary Information The online version contains supplementary material available at 10.1007/s00572-021-01031-8.

Plant performance is strongly dependent on nitrogen (N), and thus increasing N nutrition is of great relevance for the productivity of agroecosystems. The effects of arbuscular mycorrhizal (AM) fungi on plant N acquisition are debated because contradictory results have been reported. Using 15N-labeled fertilizers as a tracer, we evaluated the effects of AM fungi on N uptake and recovery from mineral or organic sources in durum wheat. Under sufficient N availability, AM fungi had no effects on plant biomass but increased N concentrations in plant tissue, plant N uptake, and total N recovered from the fertilizer. In N-deficient soil, AM fungi led to decreased aboveground biomass, which suggests that plants and AM fungi may have competed for N. When the organic source had a low carbon-to-nitrogen ratio, AM fungi favored both plant N uptake and N recovery. In contrast, when the organic source had a high carbon-to-nitrogen ratio, a clear reduction in N recovery from the fertilizer was observed. Overall, the results indicate an active role of arbuscular mycorrhizae in favoring plant N-related traits when N is not a limiting factor and show that these fungi help in N recovery from the fertilizer. These results hold great potential for increasing the sustainability of durum wheat production.

During development, the formation of a mature, well-functioning heart requires transformation of the ventricular wall from a loose trabecular network into a dense compact myocardium at mid-gestation. Failure to compact is associated in humans with congenital diseases such as left ventricular non-compaction (LVNC). The mechanisms regulating myocardial compaction are however still poorly understood. Here, we show that deletion of the Ino80 chromatin remodeler in vascular endothelial cells prevents ventricular compaction in the developing mouse heart. This correlates with defective coronary vascularization, and specific deletion of Ino80 in the two major coronary progenitor tissues—sinus venosus and endocardium—causes intermediate phenotypes. In vitro, endothelial cells promote myocardial expansion independently of blood flow in an Ino80-dependent manner. Ino80 deletion increases the expression of E2F-activated genes and endothelial cell S-phase occupancy. Thus, Ino80 is essential for coronary angiogenesis and allows coronary vessels to support proper compaction of the heart wall., Heart development requires compaction of the ventricular wall into a dense myocardium at mid-gestation. Here, Rhee and colleagues show that the chromatin remodeller Ino80 is critical for the formation of the coronary vasculature, and show that coronary vessels are needed for successful cardiac compaction during embryonic development.

The endocardium is a specialized endothelium that lines the inner surface of the heart. Functional studies in mice and zebrafish have established that the endocardium is a source of instructive signals for the development of cardiac structures, including the heart valves and chambers. Here, we characterized the NOTCH-dependent endocardial secretome by manipulating NOTCH activity in mouse embryonic endocardial cells (MEEC) followed by mass spectrometry-based proteomics. We profiled different sets of soluble factors whose secretion not only responds to NOTCH activation but also shows differential ligand specificity, suggesting that ligand-specific inputs may regulate the expression of secreted proteins involved in different cardiac development processes. NOTCH signaling activation correlates with a transforming growth factor-β2 (TGFβ2)-rich secretome and the delivery of paracrine signals involved in focal adhesion and extracellular matrix (ECM) deposition and remodeling. In contrast, NOTCH inhibition is accompanied by the up-regulation of specific semaphorins that may modulate cell migration. The secretome protein expression data showed a good correlation with gene profiling of RNA expression in embryonic endocardial cells. Additional characterization by in situ hybridization in mouse embryos revealed expression of various NOTCH candidate effector genes (Tgfβ2, Loxl2, Ptx3, Timp3, Fbln2, and Dcn) in heart valve endocardium and/or mesenchyme. Validating these results, mice with conditional Dll4 or Jag1 loss-of-function mutations showed gene expression alterations similar to those observed at the protein level in vitro These results provide the first description of the NOTCH-dependent endocardial secretome and validate MEEC as a tool for assaying the endocardial secretome response to a variety of stimuli and the potential use of this system for drug screening. We thank C. Martí Gómez-Aldaraví for help with graphic representation and critical reading of the manuscript, and S. Bartlett for English editing. RTC is supported by a Foundation La Caixa PhD fellowship (Ref LCF/BQ/ES15/10360023). LLZ is supported by a Ramón y Cajal postdoctoral contract (Ref: RYC-2016-20917). JLdlP is funded by grants SAF2016-78370-R, CB16/11/00399 (CIBER CV), and RD16/0011/0021 (TERCEL) from the Ministerio de Ciencia, Innovación y Universidades, and grants from the Fundación BBVA (Ref.: BIO14_298) and Fundación La Marató TV3 (Ref.: 20153431). JV is supported by grants BIO2015-67580-P and CB16/11/00277 (CIBER CV) from the Ministerio de Ciencia, Innovación y Universidades, and Carlos III Institute of Health-Fondo de Investigación Sanitaria (Grant ProteoRed-PRB3-IPT17/0019-ISCIII-SGEFI/ERDF), the Fundación La Marató TV3 (Ref. 122/C/2015) and “La Caixa” Banking Foundation (project code HR17-00247). The cost of this publication was supported in part with funds from the ERDF. The CNIC is supported by the Ministerio de Ciencia, Innovación y Universidades and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505). Sí

In organic farming, the adoption of the conventional tillage (CT) technique is considered by many farmers to be necessary to control weeds. Such tillage system, in fact, permits to bury weed seeds deep in the soil by means of soil inversion with moldboard plowing and to eliminate the weed plants that gradually emerge by means of the secondary tillage operations. However, it is also true that intensive tillage progressively reduces the soil organic matter content and the stability of soil aggregates, thus increasing the risk of soil erosion (Six et al. 2000). This is in contrast with one of the basic principles of organic agriculture, which is the conservation of soil fertility. Alternatively to CT, the no tillage (NT) technique can maintain or even enhance soil fertility by increasing C storage, soil biological activity, and soil aggregate stability, but, as a matter of fact, its application relies on herbicide use as the primary weed control mechanism (Gattinger et al. 2011). In the light of these considerations, efforts must be made to revisit the NT technique to make it applicable in organic farming. Without prejudice to the fact that this challenge should be addressed through a systemic approach (Peigné et al. 2007), one possible option could be to take advantage of the possibility given by the NT technique to sow the crop in an earlier period than what usually the farmer does when adopts the CT technique. Anticipating the sowing time would allow operating when most of the weed plants are still poorly developed, so that the sowing operation itself can kill many of them. Moreover, sowing early, when temperatures are still relatively mild, could accelerate the initial growth, thus reducing the period during which the crop is particularly vulnerable to weed competition. Usually, early sowing in the CT systems is not possible since a proper seedbed preparation needs time so that clods formed as a result of plowing could be broken down by natural weathering processes and by one or more secondary tillage operations. Therefore, an experiment was performed under organic management to study the effects of NT compared to CT on durum wheat (Triticum durum Desf.) grain yield, and to verify whether early sowing under NT conditions, compared to sowing at the ordinary time for the study area, can provide an advantage to the crop by increasing its competitiveness against weeds. Furthermore, the above effects were investigated on two durum wheat genotypes highly different for pheno-morphological and agronomic characteristics, assuming for them different competitiveness against weeds.

Durum wheat is the keystone of the agro-ecosystems in the arable land of the Mediterranean environments and an important part of its area falls within organic farms. For this crop competition exerted by weeds for the use of resources (natural and auxiliary) can determine drastic yield and quality reductions (Ruisi et al., 2015). In organic farming such critical issue is often addressed through a remodelling of several techniques such as soil tillage management, sowing time, plant density and genotype choice. With regard to the latter, there is a growing interest by organic farmers towards the old varieties as they, compared to the modern varieties, have a definitely greater competitive weed abilities thanks to some morpho-physiological plant traits (establishment speed, tillering capacity, plant height) (Röös et al., 2018); moreover, the old varieties/landraces are often characterized by a greater protein and gluten content and for peculiar sensory properties (Newton et al., 2010; Vita et al., 2016). On the other hand, the new varieties have a much higher production potential and technological characteristics of the grain often more responsive to the needs of the processing industry (De Vita et al., 2007). This study, carried out in a organic farming system, aimed to answer the following questions: 1) can the mixture of old and modern durum wheat varieties offer advantages over the monovarietal crop, combining the qualities of the different genotypes? 2) Which mixing ratio should be used in order to maximize the potential advantages of the mixture?

Intercropping is an agricultural practice that can offer several benefits allowing a better native resources use efficiency and, consequently, a restraint of the auxiliary inputs and often a greater production compared to the monocultures (Brooker et al. 2015). Several authors observed that, in a legume/non-legume mixture, one of the benefits could be the N transfer (up to 80 % of the non-legume N demand; Thilakarathna et al. 2016). The transfer may occur via different pathways: legume rhizodeposition, plant tissue decomposition and direct transfer through arbuscular mycorrhizal fungi (AMF) (Bedoussac et al. 2015). The latter, can simultaneously establish symbiotic relationship with different plant species creating a common mycorrhizal network, which serve as a preferential pathway for exchange among plants (He et al. 2003). However, contrasting results have been reported about the contribution of the AMF on N transfer; for instance, Li et al. (2009) showed that N transfer from mung bean to rice increased from 5.4% to 15.7% due to hyphal linkage, whereas Ikram et al. (1994) showed no significant differences with or without AMF inoculum. This experiment aimed to investigate the role of AMF on N transfer from faba bean to durum wheat grown in mixture, using the stem 15N injecting method.

Arbuscular mycorrhizal fungi (AMF) can play a key role in natural and agricultural ecosystems affecting plant nutrition, soil biological activity and modifying the availability of nutrients by plants. This research aimed at expanding the knowledge of the role played by AMF in the uptake of macro- and micronutrients and N transfer (using a 15 N stem-labelling method) in a faba bean/wheat intercropping system. It also investigates the role of AMF in biological N fixation (using the natural isotopic abundance method) in faba bean grown in pure stand and in mixture. Finally, it examines the role of AMF in driving competition and facilitation between faba bean and wheat. Durum wheat and faba bean were grown in pots (five pots per treatment) as sole crops or in mixture in the presence or absence of AMF. Root colonisation by AMF was greater in faba bean than in wheat and increased when species were mixed compared to pure stand (particularly for faba bean). Mycorrhizal symbiosis positively influenced root biomass, specific root length, and root density and increased the uptake of P, Fe, and Zn in wheat (both in pure stand and in mixture) but not in faba bean. Furthermore, AMF symbiosis increased the percentage of N derived from the atmosphere in the total N biomass of faba bean grown in mixture (+20%) but not in pure stand. Nitrogen transfer from faba bean to wheat was low (2.5–3.0 mg pot -1 ); inoculation with AMF increased N transfer by 20%. Overall, in terms of above- and belowground growth and uptake of nutrients, mycorrhization favoured the stronger competitor in the mixture (wheat) without negatively affecting the companion species (faba bean). Results of this study confirm the role of AMF in driving biological interactions among neighbouring plants. and analysis, decision to publish, or preparation of the manuscript.

Sufficient blood flow to tissues relies on arterial blood vessels, but the mechanisms regulating their development are poorly understood. Many arteries, including coronary arteries of the heart, form through remodeling of an immature vascular plexus in a process triggered and shaped by blood flow. However, little is known about how cues from fluid shear stress are translated into responses that pattern artery development. Here, we show that mice lacking endothelial Dach1 had small coronary arteries, decreased endothelial cell polarization, and reduced expression of the chemokine Cxcl12. Under shear stress in culture, Dach1 overexpression stimulated endothelial cell polarization and migration against flow, which was reversed upon CXCL12/CXCR4 inhibition. In vivo, DACH1 was expressed during early arteriogenesis but was down in mature arteries. Mature artery-type shear stress (high, uniform laminar) specifically down-regulated DACH1, while the remodeling artery-type flow (low, variable) maintained DACH1 expression. Together, our data support a model in which DACH1 stimulates coronary artery growth by activating Cxcl12 expression and endothelial cell migration against blood flow into developing arteries. This activity is suppressed once arteries reach a mature morphology and acquire high, laminar flow that down-regulates DACH1. Thus, we identified a mechanism by which blood flow quality balances artery growth and maturation.

Autoimmune diseases are a family of more than 80 chronic, and often disabling, illnesses that develop when underlying defects in the immune system lead the body to attack its own organs, tissues, and cells. Diagnosis of autoimmune pathologies is based on research and identification of antinuclear antibodies (ANA) through indirect immunofluorescence (IIF) method and is performed by analyzing patterns and fluorescence intensity. We propose here a method to automatically classify the centromere pattern based on the grouping of centromeres on the cells through a clustering K-means algorithm. The described method was tested on a public database (MIVIA). The results of the test showed an Accuracy equal to (92.0 ± 1.0)%. Comparing our results with the results obtained on the MIVIA database it is possible to note that our method has a performance comparable with the three best values obtained. Indeed, the method here proposed allows an automatic segmentation and counting of the cells in the images, while the participants to the contest received the training set with the original images of the cells already segmented by specialists.

No tillage (NT) soil management has largely been promoted because of its potential to generate both economic and environmental benefits. However, it often leads to reductions in crop yield and quality, which in many cases have been attributed to the effects this technique has on the nitrogen (N) dynamics in the soil–plant system. This 2-year study, performed within a long-term experiment in which NT was continuously applied for over 15 years, aimed to verify whether and to what extent the use of NT affects soil N availability, recovery of 15 N-labeled fertilizer, and N use efficiency (NUE) and its components (N uptake efficiency, NUpE; N utilization efficiency, NUtE). Durum wheat was the focal crop. NT was evaluated and compared with conventional tillage (CT) within three crop sequences: continuous wheat (WW), wheat–faba bean (WF), and wheat–berseem clover (WB). At the same time, the timing of N fertilization was varied (either distributing 100 kg N ha −1 all at once at crop emergence or applying 50% at crop emergence and 50% at the end of tillering; no N-fertilizer treatment was included as a control). The data indicated that, compared to CT, NT had a detrimental effect on wheat productivity in WW but improved yields in WF and WB. NT was associated with less N uptake by wheat, mainly attributable to a decrease in soil N availability, and to a lesser extent, to a decrease in the 15 N-fertilizer recovery. This reduction in uptake was markedly more evident in WW than in WF or WB, and when all of the 15 N-fertilizer was applied at crop emergence. The effects of tillage system on NUE varied by crop sequence: NT increased NUE (+18% on average compared to CT) in WF, but had the opposite effect in WW (−17% on average). These results suggest that the adoption of the NT technique by farmers must be accompanied by a reorganization of the components of crop management, such as crop rotation and the rate and timing of N fertilization.

Although sulla (Hedysarum coronarium L.) has many interesting features that could support the production of biofuels (e.g., a high yield and soluble sugar content, N-fixation capacity, low input requirements for its cultivation), no study has assessed the possibility of its use for that purpose. Our objective was to evaluate the potential value for energy production of sulla cut at various stages of growth. Furthermore, the potential of sulla as a dual purpose crop (energy and feed) was investigated. The crop was grown in rainfed conditions in a typical Mediterranean environment (over two complete 2-year crop cycles) and was cut at four different phenological stages. The biomass was divided into two fractions (stems and leaves), weighed, and analyzed to estimate the theoretical production of bioethanol and biomethane and the feed value of the whole biomass and of the two fractions. The total dry matter yield in the 2-year crop cycle was about 18 Mg ha−1; this level of production is similar to or higher than that of most other crops grown in the same environment in rainfed conditions. The stems had a high content of total soluble sugars (even higher than 200 g kg−1) and cell wall polysaccharides, markedly higher than the leaves. The leaves contained most of the protein of the plant, representing an actual protein concentrate. Thus, the crop seems particularly suitable for dual purpose use if stems are allocated to the production of biofuels and leaves to the production of livestock feed. Moreover, the results showed that the early seed set stage is the most appropriate cutting time for maximizing yield both for energy and for livestock use.

Aims: To evaluate the productivity and N2 fixation of a range of Mediterranean forage legume species as well as their ability to be grown in mixture with a forage grass, and to verify whether N transfer occurs from the legume to the non-legume component of the mixtures and, if so, to what extent this process is affected by legume species. Methods: Seven legume species (Hedysarum coronarium L., Medicago scutellata L., Trifolium resupinatum L., Trifolium squarrosum L., Trigonella foenum-graecum L., Vicia sativa L., Vicia villosa Roth) were grown alone or in mixture with annual ryegrass (Lolium multiflorum L.). Biomass and N yields and biological N2 fixation (15N dilution technique) were measured. N transfer from legume to the non-legume component was also assessed. The efficiency of the intercrops was evaluated using the land equivalent ratio (LER), aggressivity index, and competitive ratio. Results: Differences were observed among the monocropped legumes for biomass yield, N2 fixation, and ability to utilize inorganic soil N. Moreover, the proportion of legume species to the total biomass yield of the intercrop varied from 30 % (T. resupinatum) to 69 % (T. foenum-graecum). All intercrops showed an advantage over monocrops in terms of biomass and N yields (LER and NLER values always >1). No N transfer occurred from legume to ryegrass in any of the mixtures. Conclusions: The large differences observed among the studied legumes must be taken into account when trying to develop cropping systems with more efficient N use. Moreover, as all legume–ryegrass intercrops used natural resources more efficiently than pure crops, intercropping is a relevant cropping strategy for sustainable agricultural systems in Mediterranean environments.

Arbuscular mycorrhizal fungi (AMF) have a major impact on plant nutrition, defence against pathogens, a plant's reaction to stressful environments, soil fertility, and a plant's relationship with other microorganisms. Such effects imply a broad reprogramming of the plant's metabolic activity. However, little information is available regarding the role of AMF and their relation to other soil plant growth-promoting microorganisms in the plant metabolome, especially under realistic field conditions. In the present experiment, we evaluated the effects of inoculation with AMF, either alone or in combination with plant growth-promoting rhizobacteria (PGPR), on the metabolome and changes in metabolic pathways in the roots of durum wheat (Triticum durum Desf.) grown under N-limited agronomic conditions in a P-rich environment. These two treatments were compared to infection by the natural AMF population (NAT). Soil inoculation with AMF almost doubled wheat root colonization by AMF and decreased the root concentrations of most compounds in all metabolic pathways, especially amino acids (AA) and saturated fatty acids, whereas inoculation with AMF+PGPR increased the concentrations of such compounds compared to inoculation with AMF alone. Enrichment metabolomics analyses showed that AA metabolic pathways were mostly changed by the treatments, with reduced amination activity in roots most likely due to a shift from the biosynthesis of common AA to γ-amino butyric acid. The root metabolome differed between AMF and NAT but not AMF+PGPR and AMF or NAT. Because the PGPR used were potent mineralisers, and AMF can retain most nitrogen (N) taken as organic compounds for their own growth, it is likely that this result was due to an increased concentration of mineral N in soil inoculated with AMF+PGPR compared to AMF alone.

Choosing genotypes with a high capacity for taking up nitrogen (N) from the soil and the ability to efficiently compete with weeds for this nutrient is essential to increasing the sustainability of cropping systems that are less dependent on auxiliary inputs. This research aimed to verify whether differences exist in N uptake and N fertilizer recovery capacity among wheat genotypes and, if so, whether these differences are related to a different competitive ability against weeds of wheat genotypes. To this end, 12 genotypes, varying widely in morphological traits and year of release, were grown in the presence or absence of interspecific competition (using Avena sativa L. as a surrogate weed). Isotopic tracer 15N was used to measure the fertilizer N uptake efficiencies of the wheat genotypes and weed. A field experiment, a split-plot design with four replications, was conducted during two consecutive growing seasons in a typical Mediterranean environment. In the absence of interspecific competition, few differences in either total N uptake (range: 98–112 kg N ha–1) or the 15N fertilizer recovery fraction (range: 30.0–36.7%) were observed among the wheat genotypes. The presence of competition, compared to competitor-free conditions, resulted in reductions in grain yield (49%), total N uptake (29%), and an 15N fertilizer recovery fraction (32%) that were on average markedly higher in modern varieties than in old ones. Both biomass and grain reductions were strongly related to the biomass of the competitor (correlation coefficients > 0.95), which ranged from 135 g m–2 to 573 g m–2. Variations in both grain and biomass yield due to interspecific competition were significantly correlated with percentage of soil cover and leaf area at tillering, plant height at heading, and total N uptake, thus highlighting that the ability to take up N from the soil played a certain role in determining the different competitive abilities against weed of the genotypes.

The research aimed to evaluate the performance (in terms of energy) of livestock farms located in a Mediterranean mountain area and characterized by different stocking rates. Farm data were collected from in-person interviews of farmers of 58 farms representative of the livestock farms of the Madonie and Nebrodi mountains area (Sicily, Italy), including several parameters related to farm characteristics, animal, crop and pasture management. The farm parameters were used to calculate input and output energy values from which agroecosystem performance indicators were derived. Increasing stocking rate corresponded to a more than proportional increase in total inputs per unit area because of a greater farm dependence on external energy sources derived from agriculture (mainly for concentrate feed) and to a lower energy use efficiency. The indicator of dependence on non-renewable energy sources was, on average, very low irrespective of stocking rate. As stocking rate increased the farm autonomy indicator fell and the immediate removal indicator increased. Overall, the best agroecosystem performance in terms of energy was found on farms with lower stocking rates, higher proportions of permanent pastures to total farm area, and longer periods of exclusive grazing.

Several studies, performed mainly in pots, have shown that arbuscular mycorrhizal symbiosis can mitigate the negative effects of water stress on plant growth. No information is available about the effects of arbuscular mycorrhizal symbiosis on berseem clover growth and nitrogen (N) fixation under conditions of water shortage. A field experiment was conducted in a hilly area of inner Sicily, Italy, to determine whether symbiosis with AM fungi can mitigate the detrimental effects of drought stress (which in the Mediterranean often occurs during the late period of the growing season) on forage yield and symbiotic N2 fixation of berseem clover. Soil was either left under water stress (i.e., rain-fed conditions) or the crop was well-watered. Mycorrhization treatments consisted of inoculation of berseem clover seeds with arbuscular mycorrhizal spores or suppression of arbuscular mycorrhizal symbiosis by means of fungicide treatments. Nitrogen biological fixation was assessed using the 15N-isotope dilution technique. Arbuscular mycorrhizal symbiosis was able to mitigate the negative effect of water stress on berseem clover grown in a typical semiarid Mediterranean environment. In fact, under water stress conditions, arbuscular mycorrhizal symbiosis resulted in increases in total biomass, N content, and N fixation, whereas no effect of crop mycorrhization was observed in the well-watered treatment.

Conservation tillage techniques are becoming increasingly popular worldwide as they have the potential to generate environmental, agronomic, and economic benefits. In Mediterranean areas, studies performed on the effects of conservation tillage [in comparison with the conventional tillage technique (CT)] on grain yield of cereal crops have reported contradictory results as well as considerable year-to-year variation, demonstrating how the impact of different soil tillage techniques on crop productivity is strongly site-specific. The present paper summarises the main results from a set of experiments carried out in Sicily during the last 20 years in which we compared no tillage (NT) to CT in terms of their respective effects on the productivity and quality of durum wheat, while at the same time varying some other crop management practices ( e.g. crop sequence, N fertilisation, wheat genotype, sowing time). On average, no differences were observed between the two tillage techniques; yields were 3.84 and 3.87 Mg ha –1 for CT and NT, respectively. However, NT guaranteed superior yield when water stress during the crop cycle was high, whereas CT led to higher yields when water availability was adequate. Moreover, the results suggest that the use of NT needs to be accompanied by a rational crop sequence. In fact, a cumulative detrimental effect of NT over time was found for continuous wheat. Finally, grain quality in terms of protein content was slightly higher for CT (15.1%) than NT (14.4%). Thus, when using NT, the rate of nitrogen fertiliser application should be increased to offset this difference.

Much research around the world has compared the performance of cereals grown under conventional and conservation tillage systems; however, relatively few long-term experiments have been conducted in Mediterranean areas, and little attention has been given to interactions among tillage techniques and other system components across space and time. In this study, we investigated the effects of the long-term (18-yr) use of three tillage techniques (conventional tillage, CT; reduced tillage, RT; and no-till, NT) on wheat (Triticum durum Desf.) grain yield and quality within three crop sequences: continuous wheat, faba bean (Vicia faba L.)–wheat, and berseem clover (Trifolium alexandrinum L.)–wheat. In addition, we investigated the effects of climatic variability on the treatments and evaluated whether cumulative effects occurred from continuous treatment. On average, NT resulted in a grain yield advantage over CT when water stress was high and, conversely, a disadvantage when water stress was low. The effect of the tillage system on grain yield varied by crop sequence. Grain yield differences between NT and CT when wheat was grown after faba bean or berseem clover were explained primarily by climatic variability without a cumulative effect over time. In contrast, in continuous wheat, NT resulted in a progressive decrease in grain yield compared with CT. On average, wheat grain protein content varied significantly by tillage system (CT > RT > NT). This suggests that fertilizer N requirements increase with NT compared with CT because of changes in N cycling that lead to a reduction in plant-available soil N.

The seed yield of berseem clover (Trifolium alexandrinum L.) is usually obtained from regrowth after forage utilization. In stockless, cereal-growing, or specialized seed farms the forage is not needed and the mowed herbage is seldom marketable. Three different experiments were conducted in a Mediterranean environment to evaluate the effect of returning the cut biomass to the soil/crop on the regrowth, seed yield, and seed quality of berseem clover. Different forms of cut and post-cut management were examined, in which the time of cutting, the amount of biomass returned to the crop/soil, and the size of the returned material (unchopped or chopped) all varied. In addition, the effect of the berseem management on the grain yield and N content of a subsequent durum wheat (Triticum durum Desf.) crop was evaluated. The study showed that when cutting takes place during the early spring, removing and returning the herbage both result in similar seed yields but when cutting takes place later it is necessary to chop the herbage to eliminate or strongly attenuate the negative effects of mulching on seed yield. In farms in which it is not convenient or possible to use the cut herbage, returning the herbage to the crop/soil (without detrimental effects on seed yield) would increase N availability for subsequent non-legume crops. This option appears to be particularly relevant to organic farming.

Published in Agron. J. 104:1459–1466 (2012) Posted online [DATE] doi:10.2134/agronj2012.0070 Copyright © 2012 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. I agricultural practices that involve the use of agrochemicals such as fertilizers, pesticides, and herbicides have greatly increased the global food supply but often with detrimental effects on the environment, such as contamination of ground and surface water, air pollution, and loss of biodiversity. Thus, there is a need to give more attention to the sustainable agricultural systems that rely, as much as possible, on the use and effective management of internal resources (Bohlool et al., 1992). Cultivating N-fixing plants is a valuable approach to curbing the increasing reliance on chemical inputs. Introducing legumes into cereal-dominated cropping systems can provide many advantages, such as fixing great amounts of atmospheric N which will then be partly available to the subsequent crop; reducing the occurrence of pests and weeds; and improving the quality of the soil (Peoples et al., 1995; Stevenson and van Kessel, 1996; Unkovich et al., 1997; van Kessel and Hartley, 2000). Unfortunately, legumes are often considered crops of secondary importance, particularly in the Mediterranean regions (Lopez-Bellido et al., 2003), and as a consequence, they are usually grown without adequate crop management. To take advantage of all the benefits legumes can provide, it is necessary to develop more sustainable and environmentally friendly crop management methods, such as conservation tillage and NT. Reducing the intensity of tillage helps mitigate soil erosion (Jordan et al., 2000), increase soil organic matter (West and Post, 2002), improve soil biodiversity (Kladivko, 2001), enhance aggregation and aggregate stability (Madari et al., 2005), and increase water storage in the soil (Radford et al., 1995). Although these improvements often have positive effects on crop growth and yield (De Vita et al., 2007; He et al., 2011; Cullum, 2012; Giambalvo et al., 2012), contradictory results (as well as considerable year-to-year variation) have been reported for comparisons of conservation tillage and CT. For instance, in environments with a cold spring and poorly draining soil, plowing can result in quick soil warming and rapid drainage, leading to an increase in crop yield (Lal, 2007). Much research around the world has compared the performance of cereal crops grown under CT and conservative tillage, but few studies have examined legume crops, particularly in Mediterranean regions, and even fewer have done so by investigating more than one species. Thus, we studied the effects of the use of NT on the productivity of four grain legumes (chickpea, faba bean, field pea, and lentil) typically grown in semiarid Mediterranean regions. As the value of legume crops lies in great part in their ability to fix N2, an ability that can be affected by agronomic management practices such as soil management systems (Horn et al., 1996; Matus et al., 1997; van Kessel and Hartley, 2000), we also studied the effects of the tillage system (NT vs. CT) on N2 fixation and N accumulation by the four species and constructed a simple N balance to assess the incremental changes in soil N associated with each species and tillage technique. AbSTrACT

In Mediterranean countries, forage grasses and legumes are commonly grown in mixture because of their ability to increase herbage yield and quality compared with monocrop systems. However, the benefits of intercropping over a monocrop system are not always realized because the efficiency of a grass–legume mixture is strongly affected by agronomic factors. The present study evaluated productivity, N2 fixation, N transfer, and N recovery of berseem clover (Trifolium alexandrinum) grown in pure stand and in mixture with annual ryegrass (Lolium multiflorum) under high or low defoliation frequencies and varying plant arrangements (sowing in the same row or in alternating rows). On average, the berseem–ryegrass mixtures resulted in a greater yield and N yield than the monocrops. When mixed together, ryegrass was more efficient than berseem at absorbing soil N, increasing the reliance of berseem on N2 fixation. Both defoliation management and plant arrangement affected forage yield and the quality of the mixture, modifying the proportion of the two components, the N content of the forage, and the symbiotic N2 fixation of the legume. Reducing the proximity between plants of the two species may benefit the weaker component of the mixture. No apparent transfer of fixed N from berseem to ryegrass was detected.

The nutritional effects of sulla (Hedysarum coronarium L.) forage containing condensed tannins (CT) on growth of lambs, and carcass and meat quality were investigated. Thirty-two male Comisana lambs aged 100 ± 8 days weighing 19.0 ± 2.8 kg were fed fresh forage of sulla or CT-free annual ryegrass (Lolium multiflorum Lam. subsp. Wersterwoldicum) for 49 days until slaughter; in addition, each lamb was supplied with 200 g/days of concentrate. Eight lambs per diet had been previously treated with anthelmintic drugs to remove nematode parasites. Measurements of BW and feed intake, and counts of faecal nematode eggs were made. Carcass parameters were recorded after slaughter, and tissue components of the hind leg were determined. Longissimus dorsi meat was evaluated for pH, colour, thawing and cooking losses, Warner-Bratzler shear force, chemical composition and sensory properties based on triangle tests. Relative to ryegrass-fed lambs, sulla-fed lambs had significantly greater dry matter (DM) and protein intake, a more favourable feed conversion ratio, and superior growth rate, final BW at 150 days of age, carcass weight, yield and fatness. These results were attributed to the high protein and non-structural carbohydrate content of sulla, and also to the moderate CT content of sulla (16.7 and 20.3 g/kg of DM in offered and consumed sulla forage, respectively). Anthelmintic treatment did not affect lamb growth, as the level of parasitic infection (initial and final) was low. The physical, chemical and sensory properties of the lamb meat were not influenced by diet.

Defoliation management of forage crops affects endogenous reserves (in the root and in the stubble), the residual leaf area, and, consequently, the regrowth and biomass yield. The aim of this study was to evaluate the effect of cutting frequency (28-d vs. 35-d intervals) and stubble height (3 vs. 6 cm) on forage yield, regrowth, and persistence of berseem clover (Trifolium alexandrinum L.). Neither cutting interval nor cutting height affected plant survival during the crop cycle. Frequent clipping reduced crop yield. Residual biomass and leaf area were less when plants were cut at a height of 3 cm compared with 6 cm, but stubble height did not affect the total amount of dry matter (DM) removed. However, with a cutting interval of 28 d, DM yield was greater with a stubble height of 6 cm compared with 3 cm, whereas stubble height generally had no effect with a cutting interval of 35 d. This study shows that severe defoliation, which substantially reduces residual photosynthetic area, forces berseem clover plants to mobilize reserves from the taproot. With frequent clipping, taproot reserves are depleted and regrowth is impaired, whereas less frequent clipping enables taproot reserves to be restored. In contrast, less severe defoliation, which results in a considerable residual leaf area, promotes rapid regrowth regardless of the frequency of defoliation.

SUMMARYPrickly scorpion's tail (Scorpiurus muricatus L.) is a self-reseeding annual legume widely distributed in natural pastures of the Mediterranean area and appreciated by farmers for its productivity, forage quality and palatability. Twenty-eight natural populations were collected throughout Sicily in 2005; two field experiments were carried out in 2005/06 in a hilly area of the Sicilian inland to assess the genetic variation based on pheno-morphological and agronomic characters. The pheno-morphological traits observed were analysed using a principal component analysis (PCA). The first four components of PCA (eigenvalues >1) explained 0·84 of the total variation. Similarities obtained by PCA were investigated by means of cluster analysis, which clearly identified five clusters.The pheno-morphological and agronomic traits were mainly affected by latitude of the collection site (0·69 of the correlations were significant), spring rainfall (0·63) and rain days per year (0·63). Altitude was not significantly correlated with any of the traits.A strong positive correlation was found between the days to the first flower and spring rainfall at the collection site. Populations originating from subhumid or dry-subhumid Mediterranean climate zones showed greater leaf dimensions when compared with those originating from semi-arid zones. Seed weight decreased with increasing number of rain days per year and spring rainfall. Populations from drier environments showed, on the whole, a more prostrate growth habit. Dry matter yield at spring cut exhibited a significant correlation with latitude (positive) and longitude (negative). Seed production was highly correlated with spring rainfall, number of rain days per year and latitude of collection site. The presence of a large diversity among populations appears to be valuable when searching for suitable S. muricatus material to exploit in pastures and crop–livestock farming systems of Mediterranean areas.