Alternative Model for Path Analysis of Small‐Grain Yield

Abstract

The model most widely used for path analysis of grain yield in small grains assumes bidirectional causal pathways between yield components; however, because yield components develop sequentially, it is questionable from a biological standpoint whether a yield component could influence others that develop earlier. The purpose of this research is to describe the theory and application of an alternative model for path analysis of grain yield that takes into account the sequential development of yield components. Path analysis was performed assuming bidirectional and unidirectional causal relationships among yield components of eight spring barley (Hordeum vulgare L.) cultivars grown at Palmer and Fairbanks, AK, in each of two years. Yield and the yield components spikes per square meter, kernels per spike, and kernel weight were estimated. The unidirectional model seems to reflect operative causal pathways more realisitically, and results in simpler estimates that present a clearer picture of the relationships among grain yield and yield components. Of the three yield components, spikes per square meter resulted in the greatest positive contribution to yield, while the effect of kernels per spike on kernel weight was the most negative compensatory response among yield components.

Developing selection criteria based on an ontogenetic path analysis approach to improve grain yield in barley

“…Positive and significant associations between grain yield/m 2 and spike/m 2 were also reported by Dofing and Knight (1992) and Deniz et al (2009). The positive association between grain-filling period and grain yield can be explained by the observation that a long period of sink formation results in a large seed size and consequently increased grain yield.…”

“…For each variable, the multiple regression was performed by taking only the variables that have a direct effect on the dependent variable. Throughout the path model, the yield components that directly influence the dependent variable were included as regressors as described by Dofing and Knight (1992) and Kozak and Azevedo (2011). The beta weight from the multiple regressions is used as path coefficient P ij , where i indicates the effect and j indicates the cause.…”

“…Therefore, the path analysis model considering the sequential ontogenetic plant development of yield components meets this objective and shows the cause and effect relationship among yield components (Zadoks et al, 1974). Based on this assumption, Dofing and Knight (1992) compared the bidirectional association of yield components (Dewey and Lu, 1959) and the sequential ontogenetic plant development (Zadoks et al, 1974) approach to select the best model that explains the relationship; they concluded that the sequential ontogenetic approach better explained the path analysis model. In this study, they found that spike/m 2 , kernel weight, and kernel number/spike had positive direct effects on grain yield and can be used as selection criteria in the breeding of spring barley.…”

Genetic variation and interrelationships of agronomic characteristics in durum wheat under two constructing water regimes

“…The SAS (SAS Institute, Inc., 1997) procedures and programs were used for these calculations. After computing the correlation coefficients between all the characteristics, path-coefficient analyses were performed using a combination of the methods described by Garcia del Moral et al (1991) and Dofing and Knight (1992). Before computing the path coefficients, data were transformed to decimal logarithms in order to convert the relationships between the variables from multiplicative to additive, and subsequently standardize them (Garcia del Moral et al, 1991).…”

Applying statistics for nonsequential yield component analysis - Information

“…Dofing andKnight 1992, García del Moral et al 2003), but to what is called the non-sequantial development of yield components. Therein, yield components co-develop, making none of them a cause or an effect of another.…”