Leonardo Sulas

Associative effects of poor-quality forages combined with food industry byproducts determined in vitro with an automated gas-production system

Thisexperiment aimedtoinvestigatetheassociativeeffectsamongtwolow-qualityforages(crowndaisy,milk thistle) and three agro-industrial byproducts (apple pomace, citrus pulp, tomato peel), by means of an automated gas production(GP) system.All feedswere incubated alone or as 50:50 mixtures of eachforagewitheach byproduct.Samples (0.500 � 0.0010g)ofsinglefeedsormixtureswereincubatedfor96h,inthreereplicatesinindividualbottles(310mL),with 75 mLof buffered rumen fluid. Bottles were ventedby anopen-close valve whenthe internal pressure reached 3.4kPa.The metabolisable energy content of single feeds and mixtures was computed from GP at 24 h and feed chemical composition. Feed substrates were ranked for GP in the following way: byproducts, mixtures, and forages. The two forages did not differ for GP and metabolisable energy content, although differences were observed among byproducts and among mixtures. Both forages interacted positively with apple pomace from 6 h (P < 0.001) to 24 h (P= 0.029) of incubation and with citrus pulp at 12 h (P = 0.005) and 24 h (P = 0.012), whereas no associative effects were detected when forages were incubated with tomato peels. Results suggest that in vitro fermentability of low-quality forages could be efficiently improved by combining these two forages with apple pomace or citrus pulp. These findings are relevant, because the use of low-quality forages and byproducts in ruminant feeding is considered important for improving the environmental and economic sustainability of forage systems in arid and semi-arid areas.

Condensed tannin accumulation and nitrogen fixation potential of Onobrychis viciifolia Scop. grown in a Mediterranean environment

BACKGROUND Sainfoin (Onobrychis viciifolia Scop.) is a forage legume found in temperate areas but is less widespread in Mediterranean environments. Compared with other perennial legumes, it has the advantage of containing condensed tannins (CT) that can be important for their implications on ruminant nutrition and health. Data on nitrogen (N) fixation by sainfoin in the literature originate from very different environments and only a few field data are available, so it is important to improve knowledge on the N fixation potential of this species, particularly under a Mediterranean climate. Here the accumulation pattern of polyphenolic compounds (total, non-tannic polyphenols and CT) and the N fixation potential of sainfoin were studied in order to contribute to its valorisation for sustainable farming management in Mediterranean environments. RESULTS CT concentrations were always in the range considered beneficial for animals, not exceeding 50 g delphinidin equivalent kg⁻¹ dry matter (DM). The regression of aerial fixed N on aerial DM showed a relationship of 22 kg fixed N t⁻¹ aerial DM in a Mediterranean environment. CONCLUSION A wider exploitation of sainfoin is suggested for production under rain-fed conditions, thus enlarging the limited set of available perennial legumes suitable for Mediterranean environments.

Antioxidant treatments counteract the non-culturability of bacterial endophytes isolated from legume nodules

In many wild legumes, attempts to cultivate nodule bacteria fail. We hypothesized that the limited culturability could be related to injury from oxidative stress caused by disruption of plant tissues during isolation. To test that, we isolated bacteria from nodules of Hedysarum spinosissimum and Tetragonolobus purpureus using buffers supplemented with scavenging systems to prevent damage from reactive oxygen species (ROS). Treatments included the following: antioxidants (glutathione, ascorbate, EDTA) or enzymes (catalase, peroxidase, superoxide dismutase), tested either as modified squashing buffers or added in plates. Some combinations yielded dramatic increases of culturability. Different endophytes were found, including additional Rhizobiaceae that were not the primary symbiont and were unable to nodulate. Their H2O2 tolerance in broth culture showed differences consistent with the unequal culturability observed. In wild legumes species, ROS generation during extraction appears to be a major factor limiting microbiota isolation, and protocols presented here significantly improve the recovery of culturable bacterial endophytes from plants.

Yield and nitrogen fixation potential from white lupine grown in rainfed Mediterranean environments

There is renewed interest in white lupine (Lupinus albus L.), which is appreciated for its high protein content, full range of essential amino acids and as N source to rainfed cropping systems. Unfortunately, information on its N2 fixation ability is limited. This study aimed to: (i) quantify the N2 fixation ability of white lupine crop at the plot field scale in three different environments of Sardinia (Italy) under Mediterranean climate; (ii) determine the allocation of the plant-fixed N into different organs; and (iii) establish the relationship between fixed N and DM within plant organs. In a 2-year experiment, N2 fixation was estimated using the 15N isotopic dilution method. The productive performances and ability of white lupine to fix N2 widely differed in the three environments; peak values exceeded 300 kg ha−1 of fixed N. There were significant differences in the quantity of fixed N found in each plant organ at physiological maturity with 5, 20, 19 and 57 % of fixed N partitioned to roots, shoots, pod valves and grain, respectively. After grain harvesting, the net N balance ranged from negative values to 160 kg N ha−1. The relationship between fixed N and DM yield indicated 60, 34, 8 and 6 kg of fixed N per t of grain, pod valves, shoots and root, respectively, showing that fixed N preferentially accumulated in seeds at physiological maturity. Due to its high potential for N2 fixation and N benefit, white lupine represents a valuable crop option under rainfed Mediterranean conditions.

Novel crop, novel pests: Assessment of insect damage to achenes of cardoon grown in a Mediterranean environment

Cardoon (Cynara cardunculus var. altilis) has gained interest as a novel crop for bioenergy, multipurpose uses, and industrial bio‐based productions, also based on the achene yield. However, achenes can be affected by various insects, which are considered as minor pests in traditional Cynara crops. Nonetheless, very little information is available on these pests. The aim of this research was to identify the frequency of different insect species with particular regard to weevils, and to quantify the achene yields and losses caused by these spermophagous insects on cardoon. Field measurements were performed across three consecutive years in Sardinia (Italy). Mature cardoon heads of different insertion orders (primary, secondary, tertiary and quaternary heads, respectively) were manually harvested. For each head, the achenes were counted and weighed, and bare receptacles were scored in terms of damaged areas by weevil larvae (i.e., the percentage of total area). The results highlighted a higher frequency of Larinus scolymi (90%) compared to Larinus cynarae. The total number of achenes per head and the 1000‐achene weight were markedly affected by head order. Actual achene yield ranged from 86.8 to 107.9 g per plant. The estimates of achene yield losses per plant due to Larinus weevils ranged from 36.3 in 2014 to 113.0 g per plant in 2015, corresponding to about 0.4 to 1.1 t per hectare, respectively. Our results showed that achene losses were caused mainly by L. scolymi, indicating that cardoon crop profitability could be jeopardised in the absence of insect controls. Based on the experimental data, appropriate strategies aimed at controlling weevil infestations are needed to preserve cardoon achene yields.

Bioactive compounds and antioxidants from a Mediterranean garland harvested at two stages of maturity

Abstract Chrysanthemum coronarium L. (garland) is an herbaceous plant rich in bioactive compounds. The chemical composition, bioactive compounds and antioxidant properties of a Mediterranean garland population were investigated in different organs at two phenological stages. Antioxidant capacity varied from 7.9 (vegetative) to 14.4 (flowering) mmol Trolox equivalent antioxidant capacity 100 g−1 dry weight (DW). A significant correlation between antioxidant capacity and total phenolics and total flavonoids was found at flowering stage. LC-MS/MS analysis revealed that chlorogenic acid reached a maximum of 4.7 μg g−1 DW in leaves; flowers were high in luteolin (2.37 μg g−1 DW), whereas leaves showed a remarkable content of rutin (1.78 μg g−1 DW). Results highlight differences in bioactive compound levels and antioxidant capacity related to plant stages and organs. This research provides new insights into antioxidant activities and chemistry of garland, in view of its exploitation in areas of fodder resources, functional foods and natural antioxidants.

Cropping systems sustainability: Inoculation and fertilisation effect on sulla performances in a new cultivation area

To assess the feasibility of the sulla [Sulla coronaria (L.) Medik] forage legume in a new agroecosystem, its host-specific symbiotic interaction needs to be taken into account. This study aimed to investigate the effects of inoculation and nitrogen (N) fertiliser on productive performances and N-fixation ability of sulla established in a new habitat within a Mediterranean agropastoral area. Sulla plants, previously inoculated (with peat-based, liquid inoculants, and using soil from an existing sulla field) and unfertilised or N fertilised were evaluated in Sardinia (Italy). During 2013-2014, sulla plants were sampled at four growing stages, from vegetative stage to seed set, and shoot length, shoot dry matter (DM) yield and N content were monitored. Moreover, atom% 15N isotopic excess, proportion of N derived from the atmosphere and fixed N of sulla shoots were quantified. Inoculation and N fertilisation both affected growth, DM and N yields, and N-fixation of sulla. Compared to the best inoculated treatment, the DM yield and fixed N of the control only represented 10 to 22% and 2 to 11%, respectively. Nitrogen fertilisation caused temporary decreases in the N fixing ability of sulla. Results pointed out that rhizobial inoculation is essential for the exploitation of sulla outside its traditional cropping area.