Path analysis under multicollinearity for papaya production of the solo and Formosa groups

Sarah Ola Moreira,Karin Tesch Kuhlcamp,Fabíola Lacerda De Souza Barros,Sabrina Batista De Oliveira,Roberto Dos Santos Trindade

doi:10.1590/0100-29452018110

Abstract

Abstract Correlations and path analysis allow the understanding of the interrelations between characteristics of interest to the plant breeding. However, in order for their results to be reliable, the undesirable effect of multicollinearity must be excluded. The objective of this study was to estimate the correlations and their partitioning in direct and indirect effects, by path analysis, on the fruit production per plant (FP) of papaya from the heterotic Solo and Formosa groups, using two different strategies to circumvent multicollinearity. Eleven agronomic variables were evaluated in twelve papaya genotypes from the Solo group and nine from the Formosa group. Path analysis was obtained with the FP as the basic variable and to eliminate multicollinearity were used the discard of variables and the ridge path analysis. For the Solo group, fruit length and pulp thickness had greater direct effects on FP. In the Formosa group, the number of commercial fruits had a direct and indirect effect on FP. The two methodologies used to circumvent multicollinearity had high coefficient of determination, with better values for the ridge path analysis. The results indicated that the interrelation between the study characters was different in the Solo and Formosa groups. Thus, indirect selection strategies should be specific for each heterotic group.

Highlights

Due to the low number of papaya cultivars (Carica papaya L.) available to the producer, this crop becomes more susceptible to damage caused by pests, diseases and climatic adversities
For the soluble solids content, the values obtained were higher than 12.0 °Brix, a value considered optimal for the papaya, independently of the heterotic group (LUZ et al, 2015)
In the Formosa group, the fruit production per plant (FP) was between 9.5 and 43.4 kg plant-1. These values indicate the wide genetic variability available for the character, justifying the need to identify the direct and indirect effects of different variables on FP and that can be used in the selection of more productive genotypes

Summary

Introduction

Due to the low number of papaya cultivars (Carica papaya L.) available to the producer, this crop becomes more susceptible to damage caused by pests, diseases and climatic adversities. The correlation does not evaluate the cause and effect relationships, that is, they do not indicate the direct and indirect effects of other variables on the pair of characters under study (TEIXEIRA et al, 2012). To circumvent this limitation, Wright (1923) proposed the path analysis, which consists in quantifying the direct and indirect effects of explanatory characteristics on a basic variable. Estimates of this analysis are obtained by regression equations, where the variables are previously standardized (WRIGHT, 1923). In a review on path analysis, Olivoto et al (2016) have shown that it is used in different areas of knowledge, such as plant and animal breeding, and environmental and social sciences

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Conclusion