Assessment of relationships among traits and evaluation of forage yield potential in the narrow-leaf genetic resources of forage grasses of the National Plant Gene Bank of Iran

forage grasses included a large group of annuals and perennials belonged to Poaceae in Iran and all over the world. In the many countries, these crops are used as grazing, haylage, silage and cultivated in mixed cultures with forage legumes. However, there are little utilization of these forages in Iran, although use of these crops has been initiated in recent decade. A preliminary characterization on of 280 accessions of forage grasses has been done. The object of this study is the estimation of forage yield and survey the relationships among agro-morphological traits and forage yield. Finally, it tries to identify and proposed the superior germplasms for utilization based on multivariate analysis procedures.

The research was conducted in two experiments, one for annuals (15 accessions), and the other for perennials (11 accessions) in a complete randomized block in two replicates in October in Mashhad. Annuals were planted in the second year too. Agro-morphological traits were evaluated according to standard descriptors. Data were analyzed with ANOVA, comparison of mean, correlations, factor analysis and cluster analysis.

Annuals: ANOVA showed significant differences for dry forage yield within accessions. Accessions 10TN00039, 14TN00072, and 14TN00091 as well as Broms diandrus showed the highest dray forage yield based on Duncan analysis. Whereas, all genus located in the same rank for this trait. Correlation analysis showed a positive significant relationship between dry forage yield with plant height and growth. Factor analysis indicated that 82.2% of community variance was explained by four first factors. Accessions with high forage production and low susceptibility to lodging were identified by produced bi-plot of factors 1 and 2. Cluster analysis grouped the materials in to 4 groups.Perennials: ANOVA showed significant differences for dry forage yield. Accession 12TN00012, species Phalaris tuberosa، Lolium persicum, and Festuca pratensis, and genus Phalaris showed the highest dray forage yield based on Duncan analysis. Correlation analysis showed a positive significant relationship between dry forage yield with NDVI and leaf area. Factor analysis indicated that 82.4% of community variance was explained by four first factors. Accessions with high forage production re-growth rate were identified by produced bi-plot of factors 1 and 2. Cluster analysis grouped the materials in to 3 groups.

The superior germplasms (high yielding) were proposed in both groups of annuals and perennials. In the annuals, the plant height can be used as estimator trait for forage yield; it can be proposed in the first cut for the perennials. However, NDVI can be used for this purpose in the both. Resulting bi-plot confirmed the comparison of means, however it showed other aspects of the germplasms that could not be identify by comparison of means. This finding is proposed to select superior accessions for utilization. Ultimately, the superior germplasms were proposed as following: in the annuals: 10TN00039(Bromus diandrus), 14TN00072 (Lolium rigidum), and 14TN0009 (L. rigidum); in the perennials: 12TN00012 (Phalaristuberosa) and 13TN00016 (Festuca pratensis).