Genetic evaluation for herbage yield and quality in two forage legume species ( Medicago sativa and Onobrychis sativa ) under dry land farming and Irrigated conditions.

In order to study of variation for forage yield and quality traits and relationships among them, 49 accessions of Alfalfa ( Medicago sativa) and 36 accessions of sainfoin (Onobrychis sativa) were examined in two separate experiment using simple lattice designs under normal and dry land farming system during 2006-2007 in Tabriz, Iran. Forage dry matter yield, plant stand, plant height, 30% flowering date, leaf to stem ratio and 7 quality traits as: dry matter digestibility (DMD), crude protein (CP), water soluble carbohydrates (WSC), crude fiber (CF), acid detergent fiber (ADF), neutral detergent fiber (NDF) and total ash were evaluated. The drought resistant genotypes were recognized using two drought tolerance indices (TOL and STI). Correlations among traits were estimated and genotypes were classified based on PCA and cluster analysis. The results of analysis of variances showed significant differences among genotypes for all of traits. In alfalfa, the genotypes 14, 43, 37, 10, 12 and 25 with average values of 10.5 to 16 ton/h and the genotypes 14, 32, 25, 41, 5 and 39 with average values of 6.5 to 8.5 ton/h had higher forage production and quality under irrigation and dryland farming system, respectively. Based on TOL and STI indices, the genotypes 14 (Khoramabad) and 32 (Faridan) were recognized as drought tolerant. Genotype 32 (Faridan) was early flowering couple with much leaf production, whereas, the genotypes 14 (Khoramabad) and 25 (Gorgan) had the best forage quality. In sainfoin, the genotypes 5, 3, 28, 31, 26, 19 and 22 with average values of 10 to 12.3 ton/h and the genotypes 5, 21, 25, 30, 13 and 28 with average values of 5 to 5.5 ton/h had higher forage production and quality under irrigation and dryland farming system respectively. Based on TOL and STI indices, the genotypes 5 (Zenoz) and 28 (Sardasht) were recognized as drought tolerant couple with good quality. Genotype 31 (Heris) was late flowering with higher leaf to stem ratio, whereas, 25 (Zenoz) and 30 (Bejnord) were early flowering genotypes. Mean annual forage yield were obtained for alfalfa as 4.9 and 9.1 ton/h and for sainfoin as 3.8 and 7.9 ton/h under irrigation and dryland farming system, respectively that suggested higher production for alfalfa than sainfoin in both condition. The results of correlation among traits were similar for both species. Forage yield had strong positive and significant correlation with plant height, plant stand, CF and NDF, whereas its relationships were negative with leaf to stem ratio, DMD, CP and WSC. The relationships between forage yield and 30% flowering date were strong negative and weak for alfalfa and sainfoin, respectively. Using cluster analysis Ward method the 49 genotypes of alfalfa and 36 genotypes of sainfoin were classified into 4 and 3 groups, respectively. Cluster analysis correctly distributed the genotypes in the relevant groups for yield, quality and drought tolerances. Key words: Alfalfa ( Medicago sativa) , sainfoin (Onobrychis sativa) , forage yield, Quality, drought indices , dry land farming system .