Correlation and path coefficient analyses of dry weight yield components in the common sainfoin (Onobrychis viciifolia Scop.)

Abstract

Sainfoin (Onobrychis viciifolia Scop.) is a perennial forage crop with desirable forage properties adapted to temperate climate conditions. The purpose of this research was to study the phenotypic correlation coefficients between dry forage yield and some morphological traits, and to identify the direct and indirect effects of the associated traits. Thus, 32 ecotypes (landraces) were assessed in the randomized complete block design layout with four replications. Positive and statistically significant correlations were determined between total dry weight (TDW) and all measured traits except for internode length (IL) [r=0.29, P>0.05]. Regarding the variance inflation factor (VIF) as a multicollinearity statistic, number of nodes per main stem (VIF=1407.4) and number of internodes per main stem (VIF=1371.6) were removed from the analysis. Path coefficient analyses indicated that number of leaflets per leaf (NLL) [0.59 direct effect], height of the longest stem (HLS) [0.42 direct effect], and dry weight/fresh weight ratio (DFR) [0.27 direct effect] were influenced by TDW as a first-order trait. Five traits considered secondary or tertiary traits affected TDW - number of stems per area (NPA), number of stems per plant (NSP), number of leaves per stem (LS), length of inflorescence (LI) and stem weight/leaf weight ratio (SLR). The importance of main stem properties such as length or height, number of leaves, and number of leaflets can be used for selection in breeding programs aimed at improving common sainfoin forage yield under semi-arid conditions.