Research Title
"Uso di foraggi con azione di controllo dei parassiti gastrointestinali per lo
 sviluppo di una zootecnia biologica."

Research Unit PALERMO - Dipartimento di Agronomia, Coltivazioni erbacee e Pedologia
Viale delle Scienze 90128 Palermo
Tel. 091 6650204 - Fax 091 6650229
Responsabile del progetto  Prof. Luigi Stringi - lstringi@unipa.it

               
 

Italian version
 

Objectives

The aim of this research was to improve our knowledge on the presence of condensed tannins and its content in different Mediterranean forage crops.

This parameter was evaluated in 18 different species, and then in 8 different genotypes of Hedysarum coronarium, in each botanical fraction of the plant (stem, leaves, petioles and flowers) and in relation to phenological stages.

Materials and Methods

 This research was carried out during 2001-2003 at Pietranera farm in a typical hilly semi-arid area of Sicily. In both years, the experimental design was a randomized complete block with 4 replications for evaluating interspecific variability on condensed tannins content (CT) in 18 different forage species. Then, in order to determine the variability of CT content in 8 different genotypes of Hedysarum coronarium we applied a randomized complete block design with 4 replications during 2002-2003.

 During both years, the differences in CT among the botanical fractions of the plants were only studied for the genotypes in which CT had been assessed. In the second year measurements were only carried out on genotypes of Hedysarum coronarium in order to assess the variability in TC content in relation to phenological stages: early vegetative, mid-vegetative and blooming (respectively stage number 0, 1 and 6 according to Borreani’s et al. (1999) stage classification system of Hedysarum coronarium)

 Biomass production was determined in all genotypes at the blooming stage. Two biomass sub-samples for each genotype (500g each) were collected; one of these was taken for dry matter analysis (65°C), the other was disaggregated in its botanical fractions (stem, leaves, petioles and flowers), and immediately stored at -18°C and then freeze-dried.

  Freeze-dried samples were analyzed in duplicate for total polyphenols (tannin and no-tannin) content using the Folin-Ciocalteu method, in accordance with the other national research groups, and for TC using the butanol-HCl-Fe+3 method. CT values were expressed in unit of leucocyanidin tannins equivalents (LT equivalents).

Rainfall and temperature

During the two trial periods, total rainfall and mean temperatures were different, with 350 mm in 2001/02 and 500 mm approximately in 2002/03 when the rain was well distributed during the growing season.

Results

The different climatic conditions during the experimental period affected the performance yield of the species studied. In fact, in the first year biomass productions were 3 t ha-1 on average, whereas in the second year yield values were three times more.

In both of years, the highest production was recorded for Trigonella foenum graecum, so showing high suitability in variable climatic conditions.

 

  Satisfactory productions were also obtained in both years by Hedysarum coronarium, Trifolium subterraneum and T. squarrosum; Medicago scutellata, M. truncatula and M. polymorpha only produced well under higher rainfall. Onobrychis vicifolia, Lotus corniculatus and Trifolium incarnatum showed less suitability to environmental conditions.

 
1. Campo di valutazione delle specie foraggere in prova
2. In primo piano - Trifolium subterraneum (Clare)

 
3.In primo piano - Lolium multiflorum (Elunaria)
4.In primo piano – Onobrychis viciifolia


5.In primo piano - Vicia villosa (Capello)
6.In primo piano – Medicago scutellata (Kelson)


7.Particolare di Medicago scutellata (Kelson)
8.In primo piano – Hedysarum coronarium


9.In primo piano – Trigonella foenum-graecum (ecotipo locale)
10.Particolare di Trigonella foenum-graecum (ecotipo locale)


11.Pianta spontanea di sulla a fiore bianco
12.Una delle aree di raccolta del germoplasma siciliano di sulla (Cavagrande - AG)


13. Una delle aree di raccolta del germoplasma siciliano di sulla (Realmente - AG)

 
14 - Una delle aree di raccolta del germoplasma siciliano di sulla (Spiaggia di Realmente - AG)

In the first experimental year by carrying out chemical analysis on leaf samples a great variability in total polyphenols content was assessed, ranging from 0.83% to 4.29% respectively for Vicia villosa and Onobrychis viciifolia. Similar variability in tannin polyphenols content was obtained. Values over 1% were recorded for Hedysarum coronarium and Onobrychis viciifolia, values varied from 0.54% to 0.64% for Trifolium alexandrinum and T. squarrosum and Medicago polymorpha, however values were very low (< 0,10%) for Vicia sativa and V. villosa, Trigonella foenum graecum, Medicago rugosa and M. truncatula. (D.11).

In figure  (DIA 12)   the values of tannin and no-tannin polyphenols in Hedysarum coronarium are reported separately for each botanical fraction of the plant. The results showed a wider variability in tannin polyphenols content than no-tannin polyphenols. Higher amounts were found in leaves and flowers. In all species examined the CT existence was assessed by chemical analysis only in Hedysarum coronarium, Lotus corniculatus and Onobrychis viciifolia . In particular, in the first year CT concentrations were found to be 5% and 6% in Hedysarum coronarium and Onobrychis viciifolia respectively, but it was not possible to determine CT concentrations in Lotus corniculatus due to the very low biomass production obtained under water stress.

 In the second year CT concentrations were lower than in the first, values of 3.1% in Onobrychis vicifolia, 1.8% in Hedysarum coronarium and 0.7% in Lotus corniculatus were recorded. The highest CT concentration was observed during the first year under drought conditions - results which agree with data from other authors regarding abiotic stress affecting CT concentrations.

 As already mentioned, during the second year, research was carried out to assess the variability on CT content in genotypes of Hedysarum coronarium. In table…..the mean values of biomass production and of CT contents are reported. Data analysis showed that 5 genotypes produced 8 t   ha-1 of biomass and significantly lower biomass yields, on average 5 t ha-1, were obtained by the others. Significant differences in CT content were observed among genotypes. No relationship between biomass production and CT content was found. In fact, the highest values in CT concentrations (> 1,5%) were recorded in Resuttano and Sparacia genotypes and the lowest values in Irpinia genotype, all of these were characterized by low performance yields. Intermediate values and close to 1% were registered in the other genotypes.

Similar results of polyphenols data were found in CT content. In fact, the highest values of CT were assessed in leaves (on average 3.2%), whilst low values were found for petioles and stems.

 Analysing data on genotypes, the highest values for CT concentration in leaves was observed in Resuttano (4,9%) and the lowest in Irpinia (1,5%). In flowers the CT content recorded showed slight variations among genotypes, except in Irpinia which showed the lowest values. It is interesting to notice the total absence of tannins in petioles of S.Omero and the highest concentrations in petioles of Irpinia where the mean TC content values were limited. In all Irpinia showed lower variability in CT content among botanic fractions.

Chemical analysis on biomass samples harvested in different phenological stages showed that the CT content doubles from the early vegetative stage to the mid-vegetative stage and then decreases at the flowering stage.

Conclusions

  • In the species examined, condensed tannins were present only in Hedysarum coronarium, Onobrychis viciifolia and Lotus corniculatus.

  • CT content was strongly affected by temperature and rainfall. In fact, higher values in TC content were observed under pronounced water stress.

  • A wide variability in relation to the genotype, botanical fractions and phenological stages was assessed in Hedysarum coronarium. This further information may be used to improve herbage utilization in grazing.

Bearing in mind that Hedysarum coronarium is widely spread in natural pasture in Sicily and that it makes an important quanti-qualitative contribution to biomass production, we have decided to carried out research in 2003 in order to improve our knowledge of variability in CT content among different genotypes. Towards this aim over 100 populations of Hedysarum coronarium from varying environments were analysed. (see map of Sicily). Moreover, a detailed study was carried out aiming to improve our knowledge of intra-populations variability by analysing, the 100 genotypes with different morpho-structural characteristics taken from each population.

The analysis of these studies are still in progress due to the great number of biomass samples.