Studying Varieties and Relationships of Yield and Quality Traits in Tall Wheatgrass (Agropyron elongatum) under Two Cutting Management Procedures

The objectives of this research were to study the varieties and relationships of yield and quality traits under two harvesting management procedures concerning forage dry matter (DM yield) and 5 quality traits such as Dry Matter Digestibility (DMD%), Water Soluble Carbohydrates (WSC%), Crude Protein (CP%), Acid Detergent Fibre (ADF%) and total ash in tall wheatgrass (Agropyron elongatum). In this study, 17 genotypes were examined in two separate experiments for conservation (1 cut per year) and frequent cutting management procedures (2 cuts per year) in a dry land farming system over three years (2006-2009) in Damavand rangelands, Iran. Results suggested that two cut management procedures resulted in lower yield with high quality. The means of annual DM yield were 1482 and 3053 kg ha-1 for two and one cutting management procedures. Considering the conservation management, the CP and DMD were decreased in the opposite direction to DM yield, WSC and ADF. The local population of 774M (Takestan) with the means of 1740 and 3837 Kg ha-1 for DM yield had a higher production for 2 and 1 cut management procedures, respectively. DM yield was positively correlated with total ash in frequent cutting. DMD was negatively correlated with ADF in both management procedures and positively correlated with CP in frequent cutting. Results of Principle Component Analysis (PCA) showed that the first three components were accounted for 78 and 82% of the total variety for the conservation and frequent cutting, respectively. In both management procedures, DMD and ADF in the PC1 were identified as the important traits. Using Ward cluster method, 17 genotypes were grouped into 3 clusters. For the conservation management, the genotypes in cluster 3 and for frequent cutting, genotypes in cluster 2 coupled with the quality traits had higher productivity.