Impacts of arbuscular mycorrhizal fungi on nutrient uptake, N2 fixation, N transfer, and growth in a wheat/faba bean intercropping system

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

Effects of harvesting methods on seed yield and quality of Scorpiurs muricatus L..

Scorpiurus muricatus L. is an annual legume, widely distributed in Mediterranean pastures, that is appreciated by farmers for its productivity, forage quality, and palatability. It is characterised by long flowering and ripening periods and by pod shedding. These characteristics cause high seed losses, which could reduce its seed harvest efficiency in terms of seed yield and quality. In this study, we investigated the effects on seed yield and quality of different harvesting methods (windrowing at different times with subsequent combining was compared with direct combining). Our results show that direct combining when the pods were fully ripened reduced pod losses compared with swathing methods, producing the highest yield of seed actually harvested. However, in this study, the unique climatic conditions during the pod development stage (extremely high temperatures) accelerated the ripening process, presumably limiting pod shedding

Wheat yield and grain quality as affected by tillage, sowing time and nitrogen fertilization under rainfed Mediterranean conditions

The research was carried out in 9 sites (5 in 1999-00 and 4 in 2000-01) of inner area of Sicily different for soil type, slope, exposure and preceding crop. The following treatments were studied: (i) conventional tillage and sowing at conventional time (CT); (ii) no tillage and sowing at conventional time (NTc); and (iii) no tillage and early sowing (NTe). In 2000-01 the effect of three nitrogen fertilization treatment (single application at planting, P, and split dressing at two different rates, S and S+) were also evaluated. No tillage systems (NTc and NTe) significantly increased grain yield compared to CT treatment; no differences were observed between the two sowing dates. The productive benefits of no tillage were associated with a decrease of grain protein content that was heavier with early sowing. Regarding N fertilization treatments, S compared with P allowed a significant yield increase; no interaction with tillage technique was found. At the lowest fertilizer rates, split fertilization allowed a significant increase of grain protein content only in NTe

Scorpiurus muricatus L.: an interesting legume species for Mediterranean forage systems

Scorpiurus muricatus L. (prickly scorpion’s tail) is a legume species widely distributed as a spontaneous plant in Mediterranean pastures. In Sicily, farmers ascribe to this species a very high palatability and galactogogue effect, so that its abundance increases the value of the pasture. However, despite its worthy traits, the use of S. muricatus as a forage within cropping systems has not been well investigated. A field experiment was performed during two growing seasons in a semiarid Mediterranean environment to acquire information on the productivity of S. muricatus in comparison with other forage species grown in Mediterranean areas (e.g. berseem clover, burr medic, subterranean clover) and on its response to different cutting managements (cuts made in different phenological stages). Results showed that S. muricatus can provide biomass yield similar to, and in some cases higher than, that of the other forage legumes evaluated, differing from these species in its temporal distribution of the biomass accumulation. The findings contribute to define the role that S. muricatus could play in improving the productivity sustainability of the Mediterranean forage systems

Berseem-annual ryegrass intercropping: effect of plant arrangement and seeding ratio on N2 fixation and yield

Various agronomic factors can affect the productivity and the efficiency of legume-grass intercropping systems. This research was carried out in a Mediterranean semi-arid environment (37°30’N; 13°31’E; 178 m a.s.l.) with the aim to study on berseem clover- annual ryegrass mixture (Trifolium alexandrinum L. – Lolium multiflorum Lam subsp. wersterwoldicum) the effects of different plant arrangement (sowing of the two components in alternate rows or in the same row) and seeding ratios (100:0; 75:25; 50:50; 25:75; 0:100) on forage yield, nitrogen content and nitrogen fixation. The experimental design was a split-plot with four replications. The 15N isotope dilution technique was used to estimate nitrogen fixation by berseem clover. All plots were cut four times (first cut 85 DAS; rest period of four weeks). The DM yield of mixtures and pure stand clover were similar; annual ryegrass in pure stand produced the lowest yields. No significant differences for DM yield were observed due to the plant arrangement and seeding ratio in the mixture. Intercropping berseem had always a significant higher percentage of Ndfa than monocropped berseem. The %Ndfa of mixed berseem was not influenced by plant arrangement but gradually decreased when proportion of berseem in the mixture increased

Energy use efficiency of livestock farms in a mountain area of Sicily

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

Effects of feeding green forage of sulla (Hedysarum coronarium L.) on lamb growth and carcass and meat quality.

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

Morpho-agronomic and genetic diversity among twelve Sicilian agro-ecotypes of lentil (Lens culinaris)

Although Sicily is relatively small (about 25000 km2), it accounts for several agro-ecotypes of lentil (Lens culinaris Medik.), for many of which no data on morphological, agronomic, and organoleptic characteristics are available to date. Thus, experiments were performed to characterize 12 lentil agro-ecotypes from different areas of Sicily, including some small islands surrounding the main island, and to assess the extent of genetic diversity (by means of six inter-simple sequence repeat [ISSR] primers). A famous agro-ecotype from central Italy (CastellucciodiNorcia) and two commercial varieties from Canada (Eston and Laird) were also included in the study. The results showed a large degree of genetic diversity (based on ISSR markers) and variability in pheno-morphological and agronomic traits. In contrast, the intra-accession variability was on average rather low. The agronomic (productivity, nitrogen fixation capacity) and qualitative (lipid content, hydration coefficient) attributes of several Sicilian agro-ecotypes were more pronounced than those of the controls. This fact certainly represents a prerequisite for their future economic valorization. Moreover, the observed variability may be of interest from the point of view of breeding

Molecular and agronomic responses to plant-growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal (AM) fungi in durum wheat

Plant-growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal (AM) fungi contribute to plant nutrient uptake by increasing the availability of nutrients and the root adsorbing surface (Garg et al., 2006; Asghar et al. 2002). The first objective of this study was to determine the effects of these associations on plant total biomass and grain yield in durum wheat (cv. Anco Marzio). Secondly, we aimed to analyze the root transcriptomic and metabolomic changes in response to mychorrizal infections and the expression pattern of key genes involved in nutrient uptake and stress responses. Field analysis were carried out in inner Sicily, a typical Mediterranean area. Four types of biotic association in presence/absence of easily mineralizable organic nitrogen were studied: 1) not inoculated soil (control); 2) inoculated with a commercial mix of 8 AM fungal species; 3) inoculated with a commercial mix of 13 PGPR (Bacillus spp.); 4) inoculated of both AMF and PGPR mixes. Nitrogen content in aboveground biomass was determined at stem elongation stage. Quantitative RT-PCR assays were designed for nitrogen and phosphate transporter genes basing on sequence homologies with Triticum aestivum. An increase of total biomass when both PGPR and AM fungi were inoculated. In addition, PGPR inoculum determined a biomass increase when the organic fertilizer was supplied. Data showed a general downregulation of the 13 analyzed genes when crop is fertilized. In absence of fertilization, the co-inoculation of PGPR and AM fungi upregulated phosphate transporter genes (PT1, PT2, PT2.1). Mycorrizal inoculation seemed to contribute a greater extent. When organic fertilizer was supplied, similar trend was obserbed only for PT2.1. Transcript abundance of ammonium transporters were higher when crop was co-inoculated with AM fungi and PGPR. In unfertilized conditions, the inoculation of AM fungi significantly induced the expression of the nitrate transporter genes (NRT1.1; NRT2 and NAR2.2) irrespective of the inoculation of PGPR. Mycorrhizal and PGPR inoculation seemed to be synergistically efficient to increase the total durum wheat biomass. Preliminary results of durum wheat transcriptome and metabolome in response to mycorrhizal infections will be additionally presented. Gene expression analysis could lead to the identification of biomarkers usable to early select genotypes for an increased nutrient uptake efficiency